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Wagman J, Chanda B, Chanda J, Saili K, Orange E, Mambo P, Muyabe R, Kaniki T, Mwenya M, Ng'andu M, Sakala J, Ngulube W, Miller J, Arnzen A, Silumbe K, Mwaanga G, Simubali L, Mungo A, Mburu MM, Simulundu E, Mambwe B, Kasaro R, Mulube C, Mwenda M, Hamainza B, Ashton RA, Eisele TP, Harris AF, Entwistle J, Yukich J, Slutsker L, Burkot TR, Littrell M. Entomological effects of attractive targeted sugar bait station deployment in Western Zambia: vector surveillance findings from a two-arm cluster randomized phase III trial. Malar J 2024; 23:214. [PMID: 39026236 PMCID: PMC11264679 DOI: 10.1186/s12936-024-05045-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2024] [Accepted: 07/16/2024] [Indexed: 07/20/2024] Open
Abstract
BACKGROUND Attractive targeted sugar bait (ATSB) stations are a novel tool with potential to complement current approaches to malaria vector control. To assess the public health value of ATSB station deployment in areas of high coverage with standard vector control, a two-arm cluster-randomized controlled trial (cRCT) of Sarabi ATSB® stations (Westham Ltd., Hod-Hasharon, Israel) was conducted in Western Province, Zambia, a high-burden location were Anopheles funestus is the dominant vector. The trial included 70 clusters and was designed to measure the effect of ATSBs on case incidence and infection prevalence over two 7-month deployments. Reported here are results of the vector surveillance component of the study, conducted in a subset of 20 clusters and designed to provide entomological context to guide overall interpretation of trial findings. METHODS Each month, 200 paired indoor-outdoor human landing catch (HLC) and 200 paired light trap (LT) collections were conducted to monitor An. funestus parity, abundance, biting rates, sporozoite prevalence, and entomological inoculation rates (EIR). RESULTS During the study 20,337 female An. funestus were collected, 11,229 from control and 9,108 from intervention clusters. A subset of 3,131 HLC specimens were assessed for parity: The mean non-parous proportion was 23.0% (95% CI 18.2-28.7%, total n = 1477) in the control and 21.2% (95% CI 18.8-23.9%, total n = 1654) in the intervention arm, an OR = 1.05 (95% CI 0.82-1.34; p = 0.688). A non-significant reduction in LT abundance (RR = 0.65 [95% CI 0.30-1.40, p = 0.267]) was associated with ATSB deployment. HLC rates were highly variable, but model results indicate a similar non-significant trend with a RR = 0.68 (95%CI 0.22-2.00; p = 0.479). There were no effects on sporozoite prevalence or EIR. CONCLUSIONS Anopheles funestus parity did not differ across study arms, but ATSB deployment was associated with a non-significant 35% reduction in vector LT density, results that are consistent with the epidemiological impact reported elsewhere. Additional research is needed to better understand how to maximize the potential impact of ATSB approaches in Zambia and other contexts. TRIAL REGISTRATION NUMBER This trial was registered with Clinicaltrials.gov (NCT04800055, 16 March 2021).
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Ruth A Ashton
- Centre for Applied Malaria Research and Evaluation, Tulane School of Public Health and Tropical Medicine, New Orleans, LA, USA
| | - Thomas P Eisele
- Centre for Applied Malaria Research and Evaluation, Tulane School of Public Health and Tropical Medicine, New Orleans, LA, USA
| | | | | | - Joshua Yukich
- Centre for Applied Malaria Research and Evaluation, Tulane School of Public Health and Tropical Medicine, New Orleans, LA, USA
| | | | - Thomas R Burkot
- Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, Australia
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Mwanga EP, Kweyamba PA, Siria DJ, Mshani IH, Mchola IS, Makala FE, Seleman G, Abbasi S, Mwinyi SH, González-Jiménez M, Waynne K, Baldini F, Babayan SA, Okumu FO. Reagent-free detection of Plasmodium falciparum malaria infections in field-collected mosquitoes using mid-infrared spectroscopy and machine learning. Sci Rep 2024; 14:12100. [PMID: 38802488 PMCID: PMC11130311 DOI: 10.1038/s41598-024-63082-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Accepted: 05/24/2024] [Indexed: 05/29/2024] Open
Abstract
Field-derived metrics are critical for effective control of malaria, particularly in sub-Saharan Africa where the disease kills over half a million people yearly. One key metric is entomological inoculation rate, a direct measure of transmission intensities, computed as a product of human biting rates and prevalence of Plasmodium sporozoites in mosquitoes. Unfortunately, current methods for identifying infectious mosquitoes are laborious, time-consuming, and may require expensive reagents that are not always readily available. Here, we demonstrate the first field-application of mid-infrared spectroscopy and machine learning (MIRS-ML) to swiftly and accurately detect Plasmodium falciparum sporozoites in wild-caught Anopheles funestus, a major Afro-tropical malaria vector, without requiring any laboratory reagents. We collected 7178 female An. funestus from rural Tanzanian households using CDC-light traps, then desiccated and scanned their heads and thoraces using an FT-IR spectrometer. The sporozoite infections were confirmed using enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR), to establish references for training supervised algorithms. The XGBoost model was used to detect sporozoite-infectious specimen, accurately predicting ELISA and PCR outcomes with 92% and 93% accuracies respectively. These findings suggest that MIRS-ML can rapidly detect P. falciparum in field-collected mosquitoes, with potential for enhancing surveillance in malaria-endemic regions. The technique is both fast, scanning 60-100 mosquitoes per hour, and cost-efficient, requiring no biochemical reactions and therefore no reagents. Given its previously proven capability in monitoring key entomological indicators like mosquito age, human blood index, and identities of vector species, we conclude that MIRS-ML could constitute a low-cost multi-functional toolkit for monitoring malaria risk and evaluating interventions.
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Affiliation(s)
- Emmanuel P Mwanga
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania.
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK.
| | - Prisca A Kweyamba
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland
- University of Basel, Petersplatz 1, 4001, Basel, Switzerland
| | - Doreen J Siria
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Issa H Mshani
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Idrisa S Mchola
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
| | - Faraja E Makala
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
| | - Godian Seleman
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
| | - Said Abbasi
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
| | - Sophia H Mwinyi
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
| | | | - Klaas Waynne
- School of Chemistry, The University of Glasgow, Glasgow, G12 8QQ, UK
| | - Francesco Baldini
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Simon A Babayan
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Fredros O Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania.
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK.
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
- School of Life Science and Bioengineering, The Nelson Mandela African Institution of Science and Technology, P. O. Box 447, Arusha, Tanzania.
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3
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Wong W, Schaffner SF, Thwing J, Seck MC, Gomis J, Diedhiou Y, Sy N, Ndiop M, Ba F, Diallo I, Sene D, Diallo MA, Ndiaye YD, Sy M, Sene A, Sow D, Dieye B, Tine A, Ribado J, Suresh J, Lee A, Battle KE, Proctor JL, Bever CA, MacInnis B, Ndiaye D, Hartl DL, Wirth DF, Volkman SK. Evaluating the performance of Plasmodium falciparum genetic metrics for inferring National Malaria Control Programme reported incidence in Senegal. Malar J 2024; 23:68. [PMID: 38443939 PMCID: PMC10916253 DOI: 10.1186/s12936-024-04897-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 02/29/2024] [Indexed: 03/07/2024] Open
Abstract
BACKGROUND Genetic surveillance of the Plasmodium falciparum parasite shows great promise for helping National Malaria Control Programmes (NMCPs) assess parasite transmission. Genetic metrics such as the frequency of polygenomic (multiple strain) infections, genetic clones, and the complexity of infection (COI, number of strains per infection) are correlated with transmission intensity. However, despite these correlations, it is unclear whether genetic metrics alone are sufficient to estimate clinical incidence. METHODS This study examined parasites from 3147 clinical infections sampled between the years 2012-2020 through passive case detection (PCD) across 16 clinic sites spread throughout Senegal. Samples were genotyped with a 24 single nucleotide polymorphism (SNP) molecular barcode that detects parasite strains, distinguishes polygenomic (multiple strain) from monogenomic (single strain) infections, and identifies clonal infections. To determine whether genetic signals can predict incidence, a series of Poisson generalized linear mixed-effects models were constructed to predict the incidence level at each clinical site from a set of genetic metrics designed to measure parasite clonality, superinfection, and co-transmission rates. RESULTS Model-predicted incidence was compared with the reported standard incidence data determined by the NMCP for each clinic and found that parasite genetic metrics generally correlated with reported incidence, with departures from expected values at very low annual incidence (< 10/1000/annual [‰]). CONCLUSIONS When transmission is greater than 10 cases per 1000 annual parasite incidence (annual incidence > 10‰), parasite genetics can be used to accurately infer incidence and is consistent with superinfection-based hypotheses of malaria transmission. When transmission was < 10‰, many of the correlations between parasite genetics and incidence were reversed, which may reflect the disproportionate impact of importation and focal transmission on parasite genetics when local transmission levels are low.
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Affiliation(s)
- Wesley Wong
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA, USA
| | - Stephen F Schaffner
- Infectious Disease and Microbiome Program, The Broad Institute, Cambridge, MA, USA
| | - Julie Thwing
- Malaria Branch, Division of Parasitic Diseases and Malaria, Global Health Center, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Mame Cheikh Seck
- Centre International de recherche, de formation en Genomique Appliquee et de Surveillance Sanitaire (CIGASS), Dakar, Senegal
| | - Jules Gomis
- Centre International de recherche, de formation en Genomique Appliquee et de Surveillance Sanitaire (CIGASS), Dakar, Senegal
| | - Younouss Diedhiou
- Centre International de recherche, de formation en Genomique Appliquee et de Surveillance Sanitaire (CIGASS), Dakar, Senegal
| | - Ngayo Sy
- Section de Lutte Anti-Parasitaire (SLAP) Clinic, Thies, Senegal
| | - Medoune Ndiop
- Programme National de Lutte contre le Paludisme (PNLP), Dakar, Senegal
| | - Fatou Ba
- Programme National de Lutte contre le Paludisme (PNLP), Dakar, Senegal
| | - Ibrahima Diallo
- Programme National de Lutte contre le Paludisme (PNLP), Dakar, Senegal
| | - Doudou Sene
- Programme National de Lutte contre le Paludisme (PNLP), Dakar, Senegal
| | - Mamadou Alpha Diallo
- Centre International de recherche, de formation en Genomique Appliquee et de Surveillance Sanitaire (CIGASS), Dakar, Senegal
| | - Yaye Die Ndiaye
- Centre International de recherche, de formation en Genomique Appliquee et de Surveillance Sanitaire (CIGASS), Dakar, Senegal
| | - Mouhamad Sy
- Centre International de recherche, de formation en Genomique Appliquee et de Surveillance Sanitaire (CIGASS), Dakar, Senegal
| | - Aita Sene
- Centre International de recherche, de formation en Genomique Appliquee et de Surveillance Sanitaire (CIGASS), Dakar, Senegal
| | - Djiby Sow
- Centre International de recherche, de formation en Genomique Appliquee et de Surveillance Sanitaire (CIGASS), Dakar, Senegal
| | - Baba Dieye
- Centre International de recherche, de formation en Genomique Appliquee et de Surveillance Sanitaire (CIGASS), Dakar, Senegal
| | - Abdoulaye Tine
- Centre International de recherche, de formation en Genomique Appliquee et de Surveillance Sanitaire (CIGASS), Dakar, Senegal
| | - Jessica Ribado
- Institute for Disease Modeling at the Bill and Melinda Gates Foundation, Seattle, WA, USA
| | - Joshua Suresh
- Institute for Disease Modeling at the Bill and Melinda Gates Foundation, Seattle, WA, USA
| | - Albert Lee
- Institute for Disease Modeling at the Bill and Melinda Gates Foundation, Seattle, WA, USA
| | - Katherine E Battle
- Institute for Disease Modeling at the Bill and Melinda Gates Foundation, Seattle, WA, USA
| | - Joshua L Proctor
- Institute for Disease Modeling at the Bill and Melinda Gates Foundation, Seattle, WA, USA
| | - Caitlin A Bever
- Institute for Disease Modeling at the Bill and Melinda Gates Foundation, Seattle, WA, USA
| | - Bronwyn MacInnis
- Infectious Disease and Microbiome Program, The Broad Institute, Cambridge, MA, USA
| | - Daouda Ndiaye
- Centre International de recherche, de formation en Genomique Appliquee et de Surveillance Sanitaire (CIGASS), Dakar, Senegal
| | - Daniel L Hartl
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA
| | - Dyann F Wirth
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA, USA
- Infectious Disease and Microbiome Program, The Broad Institute, Cambridge, MA, USA
| | - Sarah K Volkman
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA, USA.
- Infectious Disease and Microbiome Program, The Broad Institute, Cambridge, MA, USA.
- College of Natural, Behavioral, and Health Sciences, Simmons University, Boston, MA, USA.
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4
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Akoton R, Sovegnon PM, Djihinto OY, Medjigbodo AA, Agonhossou R, Saizonou HM, Tchigossou GM, Atoyebi SM, Tossou E, Zeukeng F, Lagnika HO, Mousse W, Adegnika AA, Djouaka R, Djogbénou LS. Vectorial competence, insecticide resistance in Anopheles funestus and operational implications for malaria vector control strategies in Benin Republic. Malar J 2023; 22:385. [PMID: 38129880 PMCID: PMC10740250 DOI: 10.1186/s12936-023-04815-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 12/06/2023] [Indexed: 12/23/2023] Open
Abstract
The primary reason for the failure of malaria vector control across endemic regions is the widespread insecticide resistance observed in Anopheles vectors. The most dominant African vectors of malaria parasites are Anopheles gambiae and Anopheles funestus mosquitoes. These species often exhibit divergent behaviours and adaptive changes underscoring the importance of deploying active and effective measures in their control. Unlike An. gambiae, An. funestus mosquitoes are poorly studied in Benin Republic. However, recent reports indicated that An. funestus can adapt and colonize various ecological niches owing to its resistance against insecticides and adaptation to changing breeding habitats. Unfortunately, scientific investigations on the contribution of An. funestus to malaria transmission, their susceptibility to insecticide and resistance mechanism developed are currently insufficient for the design of better control strategies. In an attempt to gather valuable information on An. funestus, the present review examines the progress made on this malaria vector species in Benin Republic and highlights future research perspectives on insecticide resistance profiles and related mechanisms, as well as new potential control strategies against An. funestus. Literature analysis revealed that An. funestus is distributed all over the country, although present in low density compared to other dominant malaria vectors. Interestingly, An. funestus is being found in abundance during the dry seasons, suggesting an adaptation to desiccation. Among the An. funestus group, only An. funestus sensu stricto (s.s.) and Anopheles leesoni were found in the country with An. funestus s.s. being the most abundant species. Furthermore, An. funestus s.s. is the only one species in the group contributing to malaria transmission and have adapted biting times that allow them to bite at dawn. In addition, across the country, An. funestus were found resistant to pyrethroid insecticides used for bed nets impregnation and also resistant to bendiocarb which is currently being introduced in indoor residual spraying formulation in malaria endemic regions. All these findings highlight the challenges faced in controlling this malaria vector. Therefore, advancing the knowledge of vectorial competence of An. funestus, understanding the dynamics of insecticide resistance in this malaria vector, and exploring alternative vector control measures, are critical for sustainable malaria control efforts in Benin Republic.
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Affiliation(s)
- Romaric Akoton
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Abomey-Calavi, Benin.
- Fondation Pour la Recherche Scientifique (FORS), Cotonou, Benin.
| | - Pierre Marie Sovegnon
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Abomey-Calavi, Benin
| | - Oswald Y Djihinto
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Abomey-Calavi, Benin
| | - Adandé A Medjigbodo
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Abomey-Calavi, Benin
| | - Romuald Agonhossou
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Abomey-Calavi, Benin
- Fondation Pour la Recherche Scientifique (FORS), Cotonou, Benin
| | - Helga M Saizonou
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Abomey-Calavi, Benin
| | | | - Seun M Atoyebi
- Cell Biology and Genetics Unit, Department of Zoology, University of Ibadan, Ibadan, Oyo, Nigeria
| | - Eric Tossou
- International Institute of Tropical Agriculture, Cotonou, Benin
| | - Francis Zeukeng
- Department of Biochemistry and Molecular Biology, Faculty of Science, University of Buea, Buea, Cameroon
| | - Hamirath O Lagnika
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Abomey-Calavi, Benin
| | - Wassiyath Mousse
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Abomey-Calavi, Benin
| | - Ayola Akim Adegnika
- Centre de Recherches Médicales de Lambaréné (CERMEL), Lambaréné, Gabon
- Institute for Tropical Medicine (ITM), University of Tübingen, Tübingen, Germany
| | | | - Luc S Djogbénou
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Abomey-Calavi, Benin
- Regional Institute of Public Health, University of Abomey-Calavi, Ouidah, Benin
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5
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Wong W, Schaffner SF, Thwing J, Seck MC, Gomis J, Diedhiou Y, Sy N, Ndiop M, Ba F, Diallo I, Sene D, Diallo MA, Ndiaye YD, Sy M, Sene A, Sow D, Dieye B, Tine A, Ribado J, Suresh J, Lee A, Battle KE, Proctor JL, Bever CA, MacInnis B, Ndiaye D, Hartl DL, Wirth DF, Volkman SK. Evaluating the performance of Plasmodium falciparum genetics for inferring National Malaria Control Program reported incidence in Senegal. RESEARCH SQUARE 2023:rs.3.rs-3516287. [PMID: 37961451 PMCID: PMC10635402 DOI: 10.21203/rs.3.rs-3516287/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Genetic surveillance of the Plasmodium falciparum parasite shows great promise for helping National Malaria Control Programs (NMCPs) assess parasite transmission. Genetic metrics such as the frequency of polygenomic (multiple strain) infections, genetic clones, and the complexity of infection (COI, number of strains per infection) are correlated with transmission intensity. However, despite these correlations, it is unclear whether genetic metrics alone are sufficient to estimate clinical incidence. Here, we examined parasites from 3,147 clinical infections sampled between the years 2012-2020 through passive case detection (PCD) across 16 clinic sites spread throughout Senegal. Samples were genotyped with a 24 single nucleotide polymorphism (SNP) molecular barcode that detects parasite strains, distinguishes polygenomic (multiple strain) from monogenomic (single strain) infections, and identifies clonal infections. To determine whether genetic signals can predict incidence, we constructed a series of Poisson generalized linear mixed-effects models to predict the incidence level at each clinical site from a set of genetic metrics designed to measure parasite clonality, superinfection, and co-transmission rates. We compared the model-predicted incidence with the reported standard incidence data determined by the NMCP for each clinic and found that parasite genetic metrics generally correlated with reported incidence, with departures from expected values at very low annual incidence (<10/1000/annual [‰]). When transmission is greater than 10 cases per 1000 annual parasite incidence (annual incidence >10 ‰), parasite genetics can be used to accurately infer incidence and is consistent with superinfection-based hypotheses of malaria transmission. When transmission was <10 ‰, we found that many of the correlations between parasite genetics and incidence were reversed, which we hypothesize reflects the disproportionate impact of importation and focal transmission on parasite genetics when local transmission levels are low.
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Affiliation(s)
| | | | | | - Mame Cheikh Seck
- Centre International de recherche, de formation en Genomique Appliquee et de Surveillance Sanitaire (CIGASS)
| | - Jules Gomis
- Centre International de recherche, de formation en Genomique Appliquee et de Surveillance Sanitaire (CIGASS)
| | - Younouss Diedhiou
- Centre International de recherche, de formation en Genomique Appliquee et de Surveillance Sanitaire (CIGASS)
| | - Ngayo Sy
- Section de Lutte Anti-Parasitaire (SLAP) Clinic
| | | | - Fatou Ba
- Programme National de Lutte Contre le Paludisme
| | - Ibrahima Diallo
- Centre International de recherche, de formation en Genomique Appliquee et de Surveillance Sanitaire (CIGASS)
| | - Doudou Sene
- Programme National de Lutte Contre le Paludisme
| | - Mamadou Alpha Diallo
- Centre International de recherche, de formation en Genomique Appliquee et de Surveillance Sanitaire (CIGASS)
| | - Yaye Die Ndiaye
- Centre International de recherche, de formation en Genomique Appliquee et de Surveillance Sanitaire (CIGASS)
| | - Mouhamad Sy
- Centre International de recherche, de formation en Genomique Appliquee et de Surveillance Sanitaire (CIGASS)
| | - Aita Sene
- Centre International de recherche, de formation en Genomique Appliquee et de Surveillance Sanitaire (CIGASS)
| | - Djiby Sow
- Centre International de recherche, de formation en Genomique Appliquee et de Surveillance Sanitaire (CIGASS)
| | - Baba Dieye
- Centre International de recherche, de formation en Genomique Appliquee et de Surveillance Sanitaire (CIGASS)
| | - Abdoulaye Tine
- Centre International de recherche, de formation en Genomique Appliquee et de Surveillance Sanitaire (CIGASS)
| | - Jessica Ribado
- Institute for Disease Modeling, Bill and Melinda Gates Foundation
| | - Joshua Suresh
- Institute for Disease Modeling, Bill and Melinda Gates Foundation
| | - Albert Lee
- Institute for Disease Modeling, Bill and Melinda Gates Foundation
| | | | - Joshua L Proctor
- Institute for Disease Modeling, Bill and Melinda Gates Foundation
| | - Caitlin A Bever
- Institute for Disease Modeling, Bill and Melinda Gates Foundation
| | | | - Daouda Ndiaye
- Centre International de recherche, de formation en Genomique Appliquee et de Surveillance Sanitaire (CIGASS)
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Fall P, Diouf I, Deme A, Diouf S, Sene D, Sultan B, Famien AM, Janicot S. Bias-Corrected CMIP5 Projections for Climate Change and Assessments of Impact on Malaria in Senegal under the VECTRI Model. Trop Med Infect Dis 2023; 8:310. [PMID: 37368728 DOI: 10.3390/tropicalmed8060310] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 05/19/2023] [Accepted: 05/29/2023] [Indexed: 06/29/2023] Open
Abstract
On the climate-health issue, studies have already attempted to understand the influence of climate change on the transmission of malaria. Extreme weather events such as floods, droughts, or heat waves can alter the course and distribution of malaria. This study aims to understand the impact of future climate change on malaria transmission using, for the first time in Senegal, the ICTP's community-based vector-borne disease model, TRIeste (VECTRI). This biological model is a dynamic mathematical model for the study of malaria transmission that considers the impact of climate and population variability. A new approach for VECTRI input parameters was also used. A bias correction technique, the cumulative distribution function transform (CDF-t) method, was applied to climate simulations to remove systematic biases in the Coupled Model Intercomparison Project Phase 5 (CMIP5) global climate models (GCMs) that could alter impact predictions. Beforehand, we use reference data for validation such as CPC global unified gauge-based analysis of daily precipitation (CPC for Climate Prediction Center), ERA5-land reanalysis, Climate Hazards InfraRed Precipitation with Station data (CHIRPS), and African Rainfall Climatology 2.0 (ARC2). The results were analyzed for two CMIP5 scenarios for the different time periods: assessment: 1983-2005; near future: 2006-2028; medium term: 2030-2052; and far future: 2077-2099). The validation results show that the models reproduce the annual cycle well. Except for the IPSL-CM5B model, which gives a peak in August, all the other models (ACCESS1-3, CanESM2, CSIRO, CMCC-CM, CMCC-CMS, CNRM-CM5, GFDL-CM3, GFDL-ESM2G, GFDL-ESM2M, inmcm4, and IPSL-CM5B) agree with the validation data on a maximum peak in September with a period of strong transmission in August-October. With spatial variation, the CMIP5 model simulations show more of a difference in the number of malaria cases between the south and the north. Malaria transmission is much higher in the south than in the north. However, the results predicted by the models on the occurrence of malaria by 2100 show differences between the RCP8.5 scenario, considered a high emission scenario, and the RCP4.5 scenario, considered an intermediate mitigation scenario. The CanESM2, CMCC-CM, CMCC-CMS, inmcm4, and IPSL-CM5B models predict decreases with the RCP4.5 scenario. However, ACCESS1-3, CSIRO, NRCM-CM5, GFDL-CM3, GFDL-ESM2G, and GFDL-ESM2M predict increases in malaria under all scenarios (RCP4.5 and RCP8.5). The projected decrease in malaria in the future with these models is much more visible in the RCP8.5 scenario. The results of this study are of paramount importance in the climate-health field. These results will assist in decision-making and will allow for the establishment of preventive surveillance systems for local climate-sensitive diseases, including malaria, in the targeted regions of Senegal.
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Affiliation(s)
- Papa Fall
- Laboratoire Environnement-Ingénierie-Télécommunication-Energies Renouvelables (LEITER), Unité de Formation et de Recherche de Sciences Appliquées et de Technologie, Université Gaston Berger de Saint-Louis, BP 234, Saint-Louis 32000, Senegal
| | - Ibrahima Diouf
- Laboratoire de Physique de l'Atmosphère et de l'Océan-Siméon Fongang, Ecole Supérieure Polytechnique de l'Université Cheikh Anta Diop (UCAD), BP 5085, Dakar-Fann, Dakar 10700, Senegal
| | - Abdoulaye Deme
- Laboratoire Environnement-Ingénierie-Télécommunication-Energies Renouvelables (LEITER), Unité de Formation et de Recherche de Sciences Appliquées et de Technologie, Université Gaston Berger de Saint-Louis, BP 234, Saint-Louis 32000, Senegal
| | - Semou Diouf
- Laboratoire Environnement-Ingénierie-Télécommunication-Energies Renouvelables (LEITER), Unité de Formation et de Recherche de Sciences Appliquées et de Technologie, Université Gaston Berger de Saint-Louis, BP 234, Saint-Louis 32000, Senegal
| | - Doudou Sene
- Programme National de Lutte Contre le Paludisme (PNLP), BP 5085, Dakar-Fann, Dakar 10700, Senegal
| | - Benjamin Sultan
- ESPACE-DEV, Université Montpellier, IRD, Université Guyane, Université Réunion, Université Antilles, Université Avignon, 34093 Montpellier, France
| | - Adjoua Moïse Famien
- Laboratoire d'Océanographie et du Climat: Expérimentations et Approches Numériques (LOCEAN), Sorbonne Université, IRD, CNRS, MNHN, 75005 Paris, France
- Département de Sciences et Techniques, Université Alassane Ouattara de Bouaké, Bouaké 01 BPV 18, Côte d'Ivoire
| | - Serge Janicot
- Laboratoire d'Océanographie et du Climat: Expérimentations et Approches Numériques (LOCEAN), Sorbonne Université, IRD, CNRS, MNHN, 75005 Paris, France
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Dahoui MMC, Adou KA, Coulibaly B, Niamien KL, Koné A, Cornelie S, Zoh DD, Assouho KF, Moiroux N, Adja AM, Fournet F. Entomological drivers of uneven malaria transmission in urban lowland areas in Bouaké, Côte d'Ivoire. Malar J 2023; 22:34. [PMID: 36717848 PMCID: PMC9887790 DOI: 10.1186/s12936-023-04457-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 01/16/2023] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND The use of urban lowlands for agriculture contributes to the food security of city- dwellers, but promotes malaria transmission. The objective of the study was to characterize the entomological drivers of malaria transmission in two lowlands (N'Gattakro and Odiennekourani) in the city of Bouaké, Côte d'Ivoire. METHODS The human landing catch technique was used to capture mosquitoes in houses located at the edge of two lowlands in Bouaké from February to December 2019. Cultivated surfaces were calculated monthly in both lowlands for each crop type (rice and market gardening) using images acquired by a drone. The different mosquito species were identified morphologically and by PCR analysis for the Anopheles gambiae complex. Anopheles infection by Plasmodium parasites was assessed by quantitative PCR. Mosquito diversity, biting behaviour and rhythmicity, and malaria transmission were determined in each lowland and compared. RESULTS Anopheles gambiae sensu lato (s.l.) was predominant in N'Gattakro and Culex quinquefasciatus in Odiennekourani. Four Anopheles species were identified: An. gambiae s.l. and Anopheles funestus s.l. in both lowlands, Anopheles pharoensis in N'Gattakro, and Anopheles ziemanni in Odiennekourani. Within the An. gambiae complex, three species were caught: An. gambiae sensu stricto (s.s.), Anopheles coluzzii, and Anopheles arabiensis for the first time in Côte d'Ivoire (30.1%, 69.9% and 0% in N'Gattakro, and 45.1%, 52.6% and 2.4% in Odiennekourani, respectively). Anopheles gambiae s.l. species exhibited a significant exophagic behaviour in N'Gattakro (77.1% of outdoor bites versus 52.2% in Odiennekourani). In N'Gattakro, 12.6% of captures occurred before bedtime (09.00 pm) and after waking up (05.00 am), 15.1% in Odiennekourani. The mean human biting rate was higher in N'Gattakro than in Odiennekourani (61.6 versus 15.5 bites per person per night). Overall, Anopheles infection rate was 0.68%, with 0.539 and 0.029 infected bites per person per night in N'Gattakro and Odiennekourani, respectively. CONCLUSION The risk of malaria in urban agricultural lowland areas is uneven. The role of agricultural developments and irrigation patterns in the production of larval habitat should be explored. The exophagic behaviour of Anopheles vectors raises the question of the residual transmission that needs to be assessed to implement appropriate control strategies.
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Affiliation(s)
- Milossé M. C. Dahoui
- MIVEGEC (Université de Montpellier, CNRS, IRD), 911 Avenue Agropolis, BP 64501, 34394 Montpellier, France ,grid.452477.70000 0005 0181 5559Institut Pierre Richet, Institut National de Santé Publique, 01 BP 1500, Bouaké, Côte d’Ivoire
| | - Kouassi A. Adou
- MIVEGEC (Université de Montpellier, CNRS, IRD), 911 Avenue Agropolis, BP 64501, 34394 Montpellier, France ,grid.452477.70000 0005 0181 5559Institut Pierre Richet, Institut National de Santé Publique, 01 BP 1500, Bouaké, Côte d’Ivoire
| | - Baba Coulibaly
- grid.452477.70000 0005 0181 5559Institut Pierre Richet, Institut National de Santé Publique, 01 BP 1500, Bouaké, Côte d’Ivoire
| | - Koffi L. Niamien
- grid.452477.70000 0005 0181 5559Institut Pierre Richet, Institut National de Santé Publique, 01 BP 1500, Bouaké, Côte d’Ivoire
| | - Aboubacar Koné
- grid.452477.70000 0005 0181 5559Institut Pierre Richet, Institut National de Santé Publique, 01 BP 1500, Bouaké, Côte d’Ivoire
| | - Sylvie Cornelie
- MIVEGEC (Université de Montpellier, CNRS, IRD), 911 Avenue Agropolis, BP 64501, 34394 Montpellier, France
| | - Dounin D. Zoh
- grid.452477.70000 0005 0181 5559Institut Pierre Richet, Institut National de Santé Publique, 01 BP 1500, Bouaké, Côte d’Ivoire ,grid.410694.e0000 0001 2176 6353Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, 08 BP 3800, Abidjan, Côte d’Ivoire
| | - Konan F. Assouho
- grid.452477.70000 0005 0181 5559Institut Pierre Richet, Institut National de Santé Publique, 01 BP 1500, Bouaké, Côte d’Ivoire ,grid.410694.e0000 0001 2176 6353Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, 08 BP 3800, Abidjan, Côte d’Ivoire
| | - Nicolas Moiroux
- MIVEGEC (Université de Montpellier, CNRS, IRD), 911 Avenue Agropolis, BP 64501, 34394 Montpellier, France
| | - Akré M. Adja
- grid.452477.70000 0005 0181 5559Institut Pierre Richet, Institut National de Santé Publique, 01 BP 1500, Bouaké, Côte d’Ivoire ,grid.410694.e0000 0001 2176 6353Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, 08 BP 3800, Abidjan, Côte d’Ivoire
| | - Florence Fournet
- MIVEGEC (Université de Montpellier, CNRS, IRD), 911 Avenue Agropolis, BP 64501, 34394 Montpellier, France ,grid.452477.70000 0005 0181 5559Institut Pierre Richet, Institut National de Santé Publique, 01 BP 1500, Bouaké, Côte d’Ivoire ,Centre d’Entomologie Médicale et Vétérinaire, BP V 18 01, Bouaké, Côte d’Ivoire
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Tokponnon TF, Ossè R, Padonou GG, Affoukou CD, Sidick A, Sewade W, Fassinou A, Koukpo CZ, Akinro B, Messenger LA, Okê M, Tchévoédé A, Ogouyemi-Hounto A, Gazard DK, Akogbeto M. Entomological Characteristics of Malaria Transmission across Benin: An Essential Element for Improved Deployment of Vector Control Interventions. INSECTS 2023; 14:52. [PMID: 36661980 PMCID: PMC9864170 DOI: 10.3390/insects14010052] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 12/19/2022] [Accepted: 12/28/2022] [Indexed: 06/17/2023]
Abstract
Entomological surveillance in Benin has historically been limited to zones where indoor residual spraying was performed or where long-standing sentinel surveillance sites existed. However, there are significant country-wide gaps in entomological knowledge. The National Malaria Control Program (NMCP) assessed population dynamics of Anopheles vectors and malaria transmission in each of Benin’s 12 departments to create an entomological risk profile. Two communes per department (24/77 communes) were chosen to reflect diverse geographies, ecologies and malaria prevalence. Two villages per commune were selected from which four households (HH) per village were used for human landing catches (HLCs). In each HH, an indoor and outdoor HLC occurred between 7 p.m. and 7 a.m. on two consecutive nights between July−September 2017. Captured Anopheles were identified, and ovaries were dissected to determine parous rate. Heads and thoraces were tested for Plasmodium falciparum sporozoites by ELISA. The Entomological Inoculation Rate (EIR) was calculated as the product of mosquito bite rate and sporozoite index. Bite rates from An. gambiae s.l., the primary vector species complex, differed considerably between communes; average sporozoite infection index was 3.5%. The EIR ranged from 0.02 infectious bites (ib) per human per night in the departments of Ouémé and Plateau to 1.66 ib/human/night in Collines. Based on transmission risk scales, Avrankou, Sakété and Nikki are areas of low transmission (0 < EIR < 3 ib/human/year), Adjarra, Adja Ouèrè, Zè, Toffo, Bopa, Pehunco, Pèrèrè and Kandi are of medium transmission (3 < EIR < 30 ib/human/year), and the other remaining districts are high transmission (EIR > 30 ib/human/year). The heterogeneous and diverse nature of malaria transmission in Benin was not readily apparent when only assessing entomological surveillance from sentinel sites. Prospectively, the NMCP will use study results to stratify and deploy targeted vector control interventions in districts with high EIRs to better protect populations most at-risk.
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Affiliation(s)
- Tatchémè Filémon Tokponnon
- Ministère de la Santé, Cotonou 08 BP 882, Benin
- Cotonou Entomological Research Center, Cotonou 06 BP 2604, Benin
- Centre Béninois de la Recherche Scientifique et de l’Innovation (CBRSI), Agbondjèdo, Étoile Rouge, Cotonou 03 BP 1665, Benin
- Ecole Polytechnique d’Abomey-Calavi, Université d’Abomey-Calavi, Cotonou 01 BP 2009, Benin
| | - Razaki Ossè
- Cotonou Entomological Research Center, Cotonou 06 BP 2604, Benin
| | | | | | - Aboubakar Sidick
- Cotonou Entomological Research Center, Cotonou 06 BP 2604, Benin
| | - Wilfried Sewade
- Cotonou Entomological Research Center, Cotonou 06 BP 2604, Benin
| | - Arsène Fassinou
- Cotonou Entomological Research Center, Cotonou 06 BP 2604, Benin
| | - Côme Z. Koukpo
- Cotonou Entomological Research Center, Cotonou 06 BP 2604, Benin
| | - Bruno Akinro
- Cotonou Entomological Research Center, Cotonou 06 BP 2604, Benin
| | - Louisa A. Messenger
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
- Department of Environmental and Occupational Health, School of Public Health, University of Nevada, Las Vegas, NV 89154, USA
| | - Mariam Okê
- Ministère de la Santé, Cotonou 08 BP 882, Benin
| | | | - Aurore Ogouyemi-Hounto
- National Malaria Control Program, Cotonou 01 BP 882, Benin
- Parasitology-Mycologie Research Unit, Faculté des Sciences de la Santé, University of Abomey-Calavi, Cotonou 01 BP 188, Benin
| | - Dorothée Kinde Gazard
- Parasitology-Mycologie Research Unit, Faculté des Sciences de la Santé, University of Abomey-Calavi, Cotonou 01 BP 188, Benin
| | - Martin Akogbeto
- Cotonou Entomological Research Center, Cotonou 06 BP 2604, Benin
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Tomas T, Eligo N, Tamiru G, Massebo F. Outdoor and early hour human biting activities of malaria mosquitoes and the suitability of clay pot for outdoor resting mosquito collection in malaria endemic villages of southern Rift Valley, Ethiopia. Parasite Epidemiol Control 2022; 19:e00278. [PMID: 36345433 PMCID: PMC9636569 DOI: 10.1016/j.parepi.2022.e00278] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 08/21/2022] [Accepted: 10/26/2022] [Indexed: 11/07/2022] Open
Abstract
Background Sampling adult Anopheles mosquitoes is important for assessing vector density, estimating the sporozoite infection rate, and quantifying the impact of vector control interventions. The objective of this study was to assess the Anopheles mosquito species composition, and their outdoor and indoor biting activities, and to evaluate the suitability of clay pots for indoor and outdoor resting mosquito collections. Methods Two malaria-endemic villages in the Gamo zone were purposely selected. Forty clay pots were deployed for outdoor resting mosquitoes sampling and another forty for indoor resting sampling. Twenty pit shelters were constructed for outdoor resting mosquito collection. The human landing catch (HLC) technique was employed to collect indoor and outdoor host-seeking mosquitoes in two households in each village. Morphological identification of the Anopheles mosquito was done using an identification key. Enzyme-linked immunosorbent assay technique was used for blood meal origin and circumsporozoite proteins (CSP) test. Speciation of An. gambiae complex was done using polymerase chain reaction. A Chi-square test was used to compare the effectiveness of clay pot and pit shelters for outdoor resting sampling. Results A total of 904 female Anopheles mosquitoes comprising An. gambiae complex, An. pharoensis, An. tenebrosus, An. dencalicus and An. demelloni were sampled. The majority (64%) of them were sampled by the HLC technique. There was a slight difference between the outdoor clay pot (19%) and pit shelter (17%) collection. No Anopheles mosquitoes were collected indoor using clay pots. All mosquitoes were tested for CSPs, but none of them were found to be positive. Anopheles mosquitoes were tending to bite humans outdoor than indoors, and their peak biting hours was 10–11 pm. The human blood meal index of Anopheles mosquitoes was 0.07 from pit shelters and it was 0.04 from clay pots. The bovine blood meal index was 0.45 for mosquitoes from both pit shelters and clay pot collections. Conclusion Anopheles arabiensis was the predominant species and it was tending to bite cattle more than humans. Clay pot could be suitable for outdoor resting mosquito collection, but not for indoor resting species.
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Bihoun B, Zango SH, Traoré-Coulibaly M, Valea I, Ravinetto R, Van Geertruyden JP, D'Alessandro U, Tinto H, Robert A. Age-modified factors associated with placental malaria in rural Burkina Faso. BMC Pregnancy Childbirth 2022; 22:248. [PMID: 35331181 PMCID: PMC8951713 DOI: 10.1186/s12884-022-04568-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 01/31/2022] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Malaria in pregnancy can result in placental infection with fetal implications. This study aimed at assessing placental malaria (PM) prevalence and its associated factors in a cohort of pregnant women with peripheral malaria and their offspring. METHOD The data were collected in the framework of a clinical trial on treatments for malaria in pregnant women . Placental malaria (PM) was diagnosed by histopathological detection of parasites and/or malaria pigment on placenta biopsies taken at delivery. Factors associated with PM were assessed using logistic regression. RESULTS Out of 745 biopsies examined, PM was diagnosed in 86.8 % of women. Acute, chronic and past PM were retrieved in 11 (1.5 %), 170 (22.8 %), and 466 (62.6 %) women, respectively. A modifying effect was observed in the association of gravidity or anemia at the study start with pooled PM (presence of parasites and/or malaria pigment). In women under 30, gravidity ≤ 2 was associated with an increased prevalence of pooled PM but in women aged 30 years or more, gravidity was no more associated with pooled PM (OR 6.81, 95 % CI 3.18 - 14.60; and OR 0.52, 95 % CI 0.10 - 2.76, respectively). Anemia was associated with pooled PM in women under 30 (OR 1.96, 95 % CI 1.03 - 3.72) but not in women aged 30 years or more (OR 0.68, 95 % CI 0.31 - 1.49). Similarly, the association of gravidity with past-chronic PM depended also on age. A higher prevalence of active PM was observed in women under 30 presenting with symptomatic malaria (OR 3.79, 95 % CI 1.55 - 9.27), while there was no significant increase in the prevalence of active PM (presence of parasites only) in women with symptomatic malaria when aged 30 years or more (OR 0.42, 95 % CI 0.10 - 1.75). In women with chronic PM, the prevalence of low birth weight or prematurity was the highest (31.2 %) as compared with past PM or no PM. CONCLUSION Despite the rapid diagnosis and efficacious treatment of peripheral infection, the prevalence of placental malaria remained high in women with P. falciparum peripheral infection in Nanoro, especially in younger women This underlines the importance of preventive measures in this specific group.
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Affiliation(s)
- Biébo Bihoun
- Unité de recherche clinique de Nanoro, Institut de recherche en science de la santé, Nanoro, Burkina Faso.
| | - Serge Henri Zango
- Unité de recherche clinique de Nanoro, Institut de recherche en science de la santé, Nanoro, Burkina Faso.,Pôle Epidémiologie et Biostatistiques, Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain, Brussels, Belgium
| | - Maminata Traoré-Coulibaly
- Unité de recherche clinique de Nanoro, Institut de recherche en science de la santé, Nanoro, Burkina Faso
| | - Innocent Valea
- Unité de recherche clinique de Nanoro, Institut de recherche en science de la santé, Nanoro, Burkina Faso
| | | | | | - Umberto D'Alessandro
- MRC Unit The Gambia at the London School of Hygiene and Tropical Medicine, Fajara, Gambia
| | - Halidou Tinto
- Unité de recherche clinique de Nanoro, Institut de recherche en science de la santé, Nanoro, Burkina Faso
| | - Annie Robert
- Pôle Epidémiologie et Biostatistiques, Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain, Brussels, Belgium
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Adugna T, Getu E, Yewhelew D. Parous rate and longevity of anophelines mosquitoes in bure district, northwestern Ethiopia. PLoS One 2022; 17:e0263295. [PMID: 35120146 PMCID: PMC8815865 DOI: 10.1371/journal.pone.0263295] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 12/14/2021] [Indexed: 11/18/2022] Open
Abstract
The intensity of malaria transmission is measured by parous rate, daily survival rate, human blood meal frequency, sporozoite rate, and entomological inoculation rates. Female parous status is a key index of vector competence, adult vector longevity, recruitment rate of adult, and the length of a gonotrophic cycle. Hence, the present study was aimed to investigate the parous rate and the longevity of Anopheles mosquitoes in Bure District, Northwestern Ethiopia. Parous rate was estimated as the number of mosquitoes with parous ovaries divided by the number of females dissected multiplied by 100. Mosquito life expectancy (longevity as d) was estimated by. One way- ANOVA was applied to confirm the presence of parous rate difference in the villages (p < 0.05). A total of 952 unfed hosts-seeking Anopheles mosquitoes was dissected for parous rate determination. The overall parous rate of An. arabiensis in the district was 52.0%, and the highest parous rate was recorded in Shnebekuma than other villages (F 2, 33 = 6.974; p = 0.003). Similarly, the parous rate of An. cinereus showed significant variation among villages (F 2, 33 = 5.044, p = 0.012) and the highest rate (63.0%) was recorded in Bukta. The mean longevity of An. funestus, An. arabiensis, An. coustani, An. squamosus, An. pharoensis, and An. cinereus was 6.5 days, 4.6 days, 3.5 days, 3.7 days, 2.7 days, and 2.2 days, respectively. The longevity of each species was not sufficient to complete the life cycle of malaria parasite for malaria transmission throughout the year because P. falciparum requires from 12–14 day.
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Affiliation(s)
- Tilahun Adugna
- Department of Biology, Faculty of Natural and Computational Sciences, Debre Tabor, Amhara, Ethiopia
- * E-mail: ,
| | - Emana Getu
- Department of Zoological Science, Addis Ababa University, Addis Ababa, Addis Ababa, Ethiopia
| | - Delenasaw Yewhelew
- Department of Medical Laboratory Sciences and Pathology, College of Health Sciences, Jimma, Oromia, Ethiopia
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Assessment of Climate-Driven Variations in Malaria Transmission in Senegal Using the VECTRI Model. ATMOSPHERE 2022. [DOI: 10.3390/atmos13030418] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Several vector-borne diseases, such as malaria, are sensitive to climate and weather conditions. When unusual conditions prevail, for example, during periods of heavy rainfall, mosquito populations can multiply and trigger epidemics. This study, which consists of better understanding the link between malaria transmission and climate factors at a national level, aims to validate the VECTRI model (VECtor borne disease community model of ICTP, TRIeste) in Senegal. The VECTRI model is a grid-distributed dynamical model that couples a biological model for the vector and parasite life cycles to a simple compartmental Susceptible-Exposed-Infectious-Recovered (SEIR) representation of the disease progression in the human host. In this study, a VECTRI model driven by reanalysis data (ERA-5) was used to simulate malaria parameters, such as the entomological inoculation rate (EIR) in Senegal. Observed malaria data from the National Malaria Control Program in Senegal (PNLP/Programme National de Lutte contre le Paludisme au Senegal) and outputs from the climate data used in this study were compared. The findings highlight the unimodal shape of temporal malaria occurrence, and the seasonal malaria transmission contrast is closely linked to the latitudinal variation of the rainfall, showing a south–north gradient over Senegal. This study showed that the peak of malaria takes place from September to October, with a lag of about one month from the peak of rainfall in Senegal. There is an agreement between observations and simulations about decreasing malaria cases on time. These results indicate that the southern area of Senegal is at the highest risk of malaria spread outbreaks. The findings in the paper are expected to guide community-based early-warning systems and adaptation strategies in Senegal, which will feed into the national malaria prevention, response, and care strategies adapted to the needs of local communities.
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Kearney EA, Agius PA, Chaumeau V, Cutts JC, Simpson JA, Fowkes FJI. Anopheles salivary antigens as serological biomarkers of vector exposure and malaria transmission: A systematic review with multilevel modelling. eLife 2021; 10:e73080. [PMID: 34939933 PMCID: PMC8860437 DOI: 10.7554/elife.73080] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 12/21/2021] [Indexed: 12/25/2022] Open
Abstract
Background Entomological surveillance for malaria is inherently resource-intensive and produces crude population-level measures of vector exposure which are insensitive in low-transmission settings. Antibodies against Anopheles salivary proteins measured at the individual level may serve as proxy biomarkers for vector exposure and malaria transmission, but their relationship is yet to be quantified. Methods A systematic review of studies measuring antibodies against Anopheles salivary antigens (PROSPERO: CRD42020185449). Multilevel modelling (to account for multiple study-specific observations [level 1], nested within study [level 2], and study nested within country [level 3]) estimated associations between seroprevalence with Anopheles human biting rate (HBR) and malaria transmission measures. Results From 3981 studies identified in literature searches, 42 studies across 16 countries were included contributing 393 study-specific observations of anti-Anopheles salivary antibodies determined in 42,764 samples. A positive association between HBR (log transformed) and seroprevalence was found; overall a twofold (100% relative) increase in HBR was associated with a 23% increase in odds of seropositivity (OR: 1.23, 95% CI: 1.10-1.37; p<0.001). The association between HBR and Anopheles salivary antibodies was strongest with concordant, rather than discordant, Anopheles species. Seroprevalence was also significantly positively associated with established epidemiological measures of malaria transmission: entomological inoculation rate, Plasmodium spp. prevalence, and malarial endemicity class. Conclusions Anopheles salivary antibody biomarkers can serve as a proxy measure for HBR and malaria transmission, and could monitor malaria receptivity of a population to sustain malaria transmission. Validation of Anopheles species-specific biomarkers is important given the global heterogeneity in the distribution of Anopheles species. Salivary biomarkers have the potential to transform surveillance by replacing impractical, inaccurate entomological investigations, especially in areas progressing towards malaria elimination. Funding Australian National Health and Medical Research Council, Wellcome Trust.
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Affiliation(s)
- Ellen A Kearney
- The McFarlane Burnet Institute of Medical Research and Public HealthMelbourneAustralia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of MelbourneMelbourneAustralia
| | - Paul A Agius
- The McFarlane Burnet Institute of Medical Research and Public HealthMelbourneAustralia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of MelbourneMelbourneAustralia
- Department of Epidemiology and Preventive Medicine, Monash UniversityMelbourneAustralia
| | - Victor Chaumeau
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol UniversityMae SotThailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of OxfordOxfordUnited Kingdom
| | - Julia C Cutts
- The McFarlane Burnet Institute of Medical Research and Public HealthMelbourneAustralia
- Department of Medicine at the Doherty Institute, The University of MelbourneMelbourneAustralia
| | - Julie A Simpson
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of MelbourneMelbourneAustralia
| | - Freya JI Fowkes
- The McFarlane Burnet Institute of Medical Research and Public HealthMelbourneAustralia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of MelbourneMelbourneAustralia
- Department of Epidemiology and Preventive Medicine, Monash UniversityMelbourneAustralia
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Larson PS, Eisenberg JNS, Berrocal VJ, Mathanga DP, Wilson ML. An urban-to-rural continuum of malaria risk: new analytic approaches characterize patterns in Malawi. Malar J 2021; 20:418. [PMID: 34689786 PMCID: PMC8543962 DOI: 10.1186/s12936-021-03950-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 10/12/2021] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND The urban-rural designation has been an important risk factor in infectious disease epidemiology. Many studies rely on a politically determined dichotomization of rural versus urban spaces, which fails to capture the complex mosaic of infrastructural, social and environmental factors driving risk. Such evaluation is especially important for Plasmodium transmission and malaria disease. To improve targeting of anti-malarial interventions, a continuous composite measure of urbanicity using spatially-referenced data was developed to evaluate household-level malaria risk from a house-to-house survey of children in Malawi. METHODS Children from 7564 households from eight districts throughout Malawi were tested for presence of Plasmodium parasites through finger-prick blood sampling and slide microscopy. A survey questionnaire was administered and latitude and longitude coordinates were recorded for each household. Distances from households to features associated with high and low levels of development (health facilities, roads, rivers, lakes) and population density were used to produce a principal component analysis (PCA)-based composite measure for all centroid locations of a fine geo-spatial grid covering Malawi. Regression methods were used to test associations of the urbanicity measure against Plasmodium infection status and to predict parasitaemia risk for all locations in Malawi. RESULTS Infection probability declined with increasing urbanicity. The new urbanicity metric was more predictive than either a governmentally defined rural/urban dichotomous variable or a population density variable. One reason for this was that 23% of cells within politically defined rural areas exhibited lower risk, more like those normally associated with "urban" locations. CONCLUSIONS In addition to increasing predictive power, the new continuous urbanicity metric provided a clearer mechanistic understanding than the dichotomous urban/rural designations. Such designations often ignore urban-like, low-risk pockets within traditionally rural areas, as were found in Malawi, along with rural-like, potentially high-risk environments within urban areas. This method of characterizing urbanicity can be applied to other infectious disease processes in rapidly urbanizing contexts.
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Affiliation(s)
- Peter S Larson
- Department of Epidemiology, School of Public Health, University of Michigan, 1415 Washington Heights, Ann Arbor, MI, 48109, USA
| | - Joseph N S Eisenberg
- Department of Epidemiology, School of Public Health, University of Michigan, 1415 Washington Heights, Ann Arbor, MI, 48109, USA
| | - Veronica J Berrocal
- Department of Statistics, School of Information and Computer Sciences, University of California, Irvine, CA, 92697, USA
| | - Don P Mathanga
- Malaria Alert Centre, College of Medicine, University of Malawi, Blantyre, Malawi
- Department of Community Health, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Mark L Wilson
- Department of Epidemiology, School of Public Health, University of Michigan, 1415 Washington Heights, Ann Arbor, MI, 48109, USA.
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15
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A generalized differential equation compartmental model of infectious disease transmission. Infect Dis Model 2021; 6:1073-1091. [PMID: 34585030 PMCID: PMC8449186 DOI: 10.1016/j.idm.2021.08.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 08/11/2021] [Accepted: 08/30/2021] [Indexed: 11/17/2022] Open
Abstract
For decades, mathematical models of disease transmission have provided researchers and public health officials with critical insights into the progression, control, and prevention of disease spread. Of these models, one of the most fundamental is the SIR differential equation model. However, this ubiquitous model has one significant and rarely acknowledged shortcoming: it is unable to account for a disease's true infectious period distribution. As the misspecification of such a biological characteristic is known to significantly affect model behavior, there is a need to develop new modeling approaches that capture such information. Therefore, we illustrate an innovative take on compartmental models, derived from their general formulation as systems of nonlinear Volterra integral equations, to capture a broader range of infectious period distributions, yet maintain the desirable formulation as systems of differential equations. Our work illustrates a compartmental model that captures any Erlang distributed duration of infection with only 3 differential equations, instead of the typical inflated model sizes required by traditional differential equation compartmental models, and a compartmental model that captures any mean, standard deviation, skewness, and kurtosis of an infectious period distribution with 4 differential equations. The significance of our work is that it opens up a new class of easy-to-use compartmental models to predict disease outbreaks that do not require a complete overhaul of existing theory, and thus provides a starting point for multiple research avenues of investigation under the contexts of mathematics, public health, and evolutionary biology.
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16
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Bamou R, Rono M, Degefa T, Midega J, Mbogo C, Ingosi P, Kamau A, Ambelu A, Birhanu Z, Tushune K, Kopya E, Awono-Ambene P, Tchuinkam T, Njiokou F, Yewhalaw D, Antonio Nkondjio C, Mwangangi J. Entomological and Anthropological Factors Contributing to Persistent Malaria Transmission in Kenya, Ethiopia, and Cameroon. J Infect Dis 2021; 223:S155-S170. [PMID: 33906217 PMCID: PMC8079137 DOI: 10.1093/infdis/jiaa774] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Introduction In order to improve our understanding of the fundamental limits of core interventions and guide efforts based on prioritization and identification of effective/novel interventions with great potentials to interrupt persistent malaria transmission in the context of high vector control coverage, the drivers of persistent disease transmission were investigated in three eco-epidemiological settings; forested areas in Cameroon, coastal area in Kenya and highland areas in Ethiopia. Methods Mosquitoes were sampled in three eco-epidemiological settings using different entomological sampling techniques and analysed for Plasmodium infection status and blood meal origin in blood-fed specimens. Human behavioural surveys were conducted to assess the knowledge and attitude of the population on malaria and preventive measures, their night activities, and sleeping pattern. The parasitological analysis was conducted to determine the prevalence of Plasmodium infection in the population using rapid diagnostic tests. Results Despite the diversity in the mosquito fauna, their biting behaviour was found to be closely associated to human behaviour in the three settings. People in Kenya and Ethiopia were found to be more exposed to mosquito bites during the early hours of the evening (18-21h) while it was in the early morning (4-6 am) in Cameroon. Malaria transmission was high in Cameroon compared to Kenya and Ethiopia with over 50% of the infected bites recorded outdoors. The non-users of LLINs were 2.5 to 3 times more likely to be exposed to the risk of acquiring malaria compared to LLINs users. Malaria prevalence was high (42%) in Cameroon, and more than half of the households visited had at least one individual infected with Plasmodium parasites. Conclusions The study suggests high outdoor malaria transmission occurring in the three sites with however different determinants driving residual malaria transmission in these areas.
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Affiliation(s)
- Roland Bamou
- Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale, Yaounde, Cameroon.,Vector-Borne Diseases Laboratory, Applied Biology and Ecology Research Unit, Department of Animal Biology, Faculty of Science, University of Dschang, Yaounde, Cameroon
| | - Martin Rono
- Kenya Medical Research Institute-Wellcome Trust Research Program, Kilifi,Kenya.,Center for Geographic Medicine Research Coast, Kenya Medical Research Institute, Kilifi, Kenya.,Pwani University Bioscience Research Centre, Kilifi, Kenya
| | - Teshome Degefa
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia.,Tropical and Infectious Diseases Research Center, Jimma University, Jimma, Ethiopia
| | - Janet Midega
- Kenya Medical Research Institute-Wellcome Trust Research Program, Kilifi,Kenya.,Center for Geographic Medicine Research Coast, Kenya Medical Research Institute, Kilifi, Kenya
| | - Charles Mbogo
- Kenya Medical Research Institute-Wellcome Trust Research Program, Kilifi,Kenya.,Center for Geographic Medicine Research Coast, Kenya Medical Research Institute, Kilifi, Kenya
| | - Prophet Ingosi
- Pwani University Bioscience Research Centre, Kilifi, Kenya
| | - Alice Kamau
- Kenya Medical Research Institute-Wellcome Trust Research Program, Kilifi,Kenya
| | - Argaw Ambelu
- Department of Environmental Health Sciences and Technology, Public Health Faculty, Jimma University, Jimma, Ethiopia
| | - Zewdie Birhanu
- Department of Health, Behavior and Society, Faculty of Public Health, Jimma University, Jimma, Ethiopia
| | - Kora Tushune
- Department of Health Management, Institute of Health, Jimma University, Jimma, Ethiopia
| | - Edmond Kopya
- Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale, Yaounde, Cameroon.,Laboratory of Parasitology and Ecology, Faculty of Sciences, University of Yaoundé, Yaoundé, Cameroon
| | - Parfait Awono-Ambene
- Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale, Yaounde, Cameroon
| | - Timoléon Tchuinkam
- Vector-Borne Diseases Laboratory, Applied Biology and Ecology Research Unit, Department of Animal Biology, Faculty of Science, University of Dschang, Yaounde, Cameroon
| | - Flobert Njiokou
- Laboratory of Parasitology and Ecology, Faculty of Sciences, University of Yaoundé, Yaoundé, Cameroon
| | - Delenasaw Yewhalaw
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia.,Tropical and Infectious Diseases Research Center, Jimma University, Jimma, Ethiopia
| | - Christophe Antonio Nkondjio
- Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale, Yaounde, Cameroon.,Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Joseph Mwangangi
- Center for Geographic Medicine Research Coast, Kenya Medical Research Institute, Kilifi, Kenya.,Pwani University Bioscience Research Centre, Kilifi, Kenya.,Centre for Vector Disease Control, Kenya Medical Research Institute, Kwale,Kenya
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17
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Amadi M, Shcherbacheva A, Haario H. Agent-based modelling of complex factors impacting malaria prevalence. Malar J 2021; 20:185. [PMID: 33858432 PMCID: PMC8048062 DOI: 10.1186/s12936-021-03721-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 04/03/2021] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Increasingly complex models have been developed to characterize the transmission dynamics of malaria. The multiplicity of malaria transmission factors calls for a realistic modelling approach that incorporates various complex factors such as the effect of control measures, behavioural impacts of the parasites to the vector, or socio-economic variables. Indeed, the crucial impact of household size in eliminating malaria has been emphasized in previous studies. However, increasing complexity also increases the difficulty of calibrating model parameters. Moreover, despite the availability of much field data, a common pitfall in malaria transmission modelling is to obtain data that could be directly used for model calibration. METHODS In this work, an approach that provides a way to combine in situ field data with the parameters of malaria transmission models is presented. This is achieved by agent-based stochastic simulations, initially calibrated with hut-level experimental data. The simulation results provide synthetic data for regression analysis that enable the calibration of key parameters of classical models, such as biting rates and vector mortality. In lieu of developing complex dynamical models, the approach is demonstrated using most classical malaria models, but with the model parameters calibrated to account for such complex factors. The performance of the approach is tested against a wide range of field data for Entomological Inoculation Rate (EIR) values. RESULTS The overall transmission characteristics can be estimated by including various features that impact EIR and malaria incidence, for instance by reducing the mosquito-human contact rates and increasing the mortality through control measures or socio-economic factors. CONCLUSION Complex phenomena such as the impact of the coverage of the population with long-lasting insecticidal nets (LLINs), changes in behaviour of the infected vector and the impact of socio-economic factors can be included in continuous level modelling. Though the present work should be interpreted as a proof of concept, based on one set of field data only, certain interesting conclusions can already be drawn. While the present work focuses on malaria, the computational approach is generic, and can be applied to other cases where suitable in situ data is available.
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Affiliation(s)
- Miracle Amadi
- LUT School of Engineering Science, Lappeenranta University of Technology, Yliopistonkatu 34, Lappeenranta, Finland
| | - Anna Shcherbacheva
- LUT School of Engineering Science, Lappeenranta University of Technology, Yliopistonkatu 34, Lappeenranta, Finland
- Finnish Geospatial Research Institute, Geodeetinrinne 2, 02431 Masala, Finland
| | - Heikki Haario
- LUT School of Engineering Science, Lappeenranta University of Technology, Yliopistonkatu 34, Lappeenranta, Finland
- Finnish Meteorological Institute, Erik Palménin aukio 1, 00560 Helsinki, Finland
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18
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Soma DD, Zogo B, Taconet P, Somé A, Coulibaly S, Baba-Moussa L, Ouédraogo GA, Koffi A, Pennetier C, Dabiré KR, Moiroux N. Quantifying and characterizing hourly human exposure to malaria vectors bites to address residual malaria transmission during dry and rainy seasons in rural Southwest Burkina Faso. BMC Public Health 2021; 21:251. [PMID: 33516197 PMCID: PMC7847557 DOI: 10.1186/s12889-021-10304-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 01/21/2021] [Indexed: 11/17/2022] Open
Abstract
Background To sustain the efficacy of malaria vector control, the World Health Organization (WHO) recommends the combination of effective tools. Before designing and implementing additional strategies in any setting, it is critical to monitor or predict when and where transmission occurs. However, to date, very few studies have quantified the behavioural interactions between humans and Anopheles vectors in Africa. Here, we characterized residual transmission in a rural area of Burkina Faso where long lasting insecticidal nets (LLIN) are widely used. Methods We analysed data on both human and malaria vectors behaviours from 27 villages to measure hourly human exposure to vector bites in dry and rainy seasons using a mathematical model. We estimated the protective efficacy of LLINs and characterised where (indoors vs. outdoors) and when both LLIN users and non-users were exposed to vector bites. Results The percentage of the population who declared sleeping under a LLIN the previous night was very high regardless of the season, with an average LLIN use ranging from 92.43 to 99.89%. The use of LLIN provided > 80% protection against exposure to vector bites. The proportion of exposure for LLIN users was 29–57% after 05:00 and 0.05–12% before 20:00. More than 80% of exposure occurred indoors for LLIN users and the estimate reached 90% for children under 5 years old in the dry cold season. Conclusions LLINs are predicted to provide considerable protection against exposure to malaria vector bites in the rural area of Diébougou. Nevertheless, LLIN users are still exposed to vector bites which occurred mostly indoors in late morning. Therefore, complementary strategies targeting indoor biting vectors in combination with LLIN are expected to be the most efficient to control residual malaria transmission in this area. Supplementary Information The online version contains supplementary material available at 10.1186/s12889-021-10304-y.
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Affiliation(s)
- D D Soma
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso. .,Université Nazi Boni (UNB), Bobo-Dioulasso, Burkina Faso. .,MIVEGEC, Univ. Montpellier, CNRS, IRD, Montpellier, France.
| | - B Zogo
- MIVEGEC, Univ. Montpellier, CNRS, IRD, Montpellier, France.,Institut Pierre Richet (IPR), Bouaké, Côte d'Ivoire.,Université d'Abomey Calavi, Abomey-Calavi, Benin
| | - P Taconet
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso.,MIVEGEC, Univ. Montpellier, CNRS, IRD, Montpellier, France
| | - A Somé
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso
| | - S Coulibaly
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso
| | | | - G A Ouédraogo
- Université Nazi Boni (UNB), Bobo-Dioulasso, Burkina Faso
| | - A Koffi
- Institut Pierre Richet (IPR), Bouaké, Côte d'Ivoire
| | - C Pennetier
- MIVEGEC, Univ. Montpellier, CNRS, IRD, Montpellier, France.,Institut Pierre Richet (IPR), Bouaké, Côte d'Ivoire
| | - K R Dabiré
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso
| | - N Moiroux
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso.,MIVEGEC, Univ. Montpellier, CNRS, IRD, Montpellier, France
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19
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Guerra CA, Fuseini G, Donfack OT, Smith JM, Ondo Mifumu TA, Akadiri G, Eyang DEM, Eburi CO, Motobe Vaz L, Micha VM, Okenve LA, Janes CR, Andeme RM, Rivas MR, Phiri WP, Slotman MA, Smith DL, García GA. Malaria outbreak in Riaba district, Bioko Island: lessons learned. Malar J 2020; 19:277. [PMID: 32746919 PMCID: PMC7398070 DOI: 10.1186/s12936-020-03347-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 07/25/2020] [Indexed: 11/18/2022] Open
Abstract
At the beginning of 2019, a sudden surge of malaria cases was observed in the district of Riaba, Bioko Island. Between January and April, confirmed malaria cases increased 3.8-fold compared to the same period in 2018. Concurrently, anopheline human biting rate (HBR) increased 2.1-fold. During the outbreak, 82.2% of the district population was tested for malaria with a rapid diagnostic test; 37.2% of those tested had a detectable infection and were treated according to national guidelines. Vector control interventions, including indoor residual spraying and larval source management were scaled-up. After the interventions, the number of confirmed cases decreased by 70% and the overall parasite prevalence in the communities by 43.8%. Observed prevalence in a follow up malaria indicator survey, however, was significantly higher than elsewhere on the island, and higher than in previous years. There was no significant reduction in HBR, which remained high for the rest of the year. The surge was attributed to various factors, chiefly increased rainfall and a large number of anthropogenic anopheline breeding sites created by construction works. This case study highlights the need for sustained vector control interventions and multi-sector participation, particularly in malaria control and elimination settings with persistently high local malaria receptivity.
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Affiliation(s)
- Carlos A Guerra
- Medical Care Development International, 8401 Colesville Road, Suite 425, Silver Spring, MD, 20910, USA
| | - Godwin Fuseini
- MedicalCare Development International, Av. Parques de Africa, Malabo, Equatorial Guinea
| | | | - Jordan M Smith
- MedicalCare Development International, Av. Parques de Africa, Malabo, Equatorial Guinea
| | - Teresa Ayingono Ondo Mifumu
- MedicalCare Development International, Av. Parques de Africa, Malabo, Equatorial Guinea.,National Malaria Control Programme, Ministry of Health and Social Welfare, Malabo, Equatorial Guinea
| | - Gninoussa Akadiri
- MedicalCare Development International, Av. Parques de Africa, Malabo, Equatorial Guinea
| | - Delicias Esono Mba Eyang
- MedicalCare Development International, Av. Parques de Africa, Malabo, Equatorial Guinea.,National Malaria Control Programme, Ministry of Health and Social Welfare, Malabo, Equatorial Guinea
| | - Consuelo Oki Eburi
- MedicalCare Development International, Av. Parques de Africa, Malabo, Equatorial Guinea.,National Malaria Control Programme, Ministry of Health and Social Welfare, Malabo, Equatorial Guinea
| | - Liberato Motobe Vaz
- MedicalCare Development International, Av. Parques de Africa, Malabo, Equatorial Guinea
| | - Victor Mba Micha
- MedicalCare Development International, Av. Parques de Africa, Malabo, Equatorial Guinea
| | - Leonor Ada Okenve
- MedicalCare Development International, Av. Parques de Africa, Malabo, Equatorial Guinea.,National Malaria Control Programme, Ministry of Health and Social Welfare, Malabo, Equatorial Guinea
| | - Christopher R Janes
- Department of Entomology, Texas A&M University, TAMU 2475, College Station, TX, 77843, USA
| | - Ramona Mba Andeme
- National Malaria Control Programme, Ministry of Health and Social Welfare, Malabo, Equatorial Guinea
| | - Matilde Riloha Rivas
- National Malaria Control Programme, Ministry of Health and Social Welfare, Malabo, Equatorial Guinea
| | - Wonder P Phiri
- MedicalCare Development International, Av. Parques de Africa, Malabo, Equatorial Guinea
| | - Michel A Slotman
- Department of Entomology, Texas A&M University, TAMU 2475, College Station, TX, 77843, USA
| | - David L Smith
- Institute for Health Metrics and Evaluation, University of Washington, 2301 Fifth Avenue, Seattle, WA, 98121, USA
| | - Guillermo A García
- Medical Care Development International, 8401 Colesville Road, Suite 425, Silver Spring, MD, 20910, USA.
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Chaturvedi S, Dwivedi S. Estimating the malaria transmission over the Indian subcontinent in a warming environment using a dynamical malaria model. JOURNAL OF WATER AND HEALTH 2020; 18:358-374. [PMID: 32589621 DOI: 10.2166/wh.2020.148] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Malaria is a major public health problem in India. The malaria transmission is sensitive to climatic parameters. The regional population-related factors also influence malaria transmission. To take into account temperature and rainfall variability and associated population-related effects (in a changing climate) on the malaria transmission over India, a regional dynamical malaria model, namely VECTRI (vector-borne disease community model) is used. The daily temperature and rainfall data derived from the historical (years 1961-2005) and representative concentration pathway (years 2006-2050) runs of the Coupled Model Intercomparison Project Phase 5 models have been used for the analysis. The model results of the historical run are compared with the observational data. The spatio-temporal changes (region-specific as well as seasonal changes) in the malaria transmission as a result of climate change are quantified over the India. The parameters related to the breeding cycle of malaria as well as those which estimate the malaria cases are analyzed in the global warming scenario.
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Affiliation(s)
- Shweta Chaturvedi
- K Banerjee Centre of Atmospheric and Ocean Studies and M N Saha Centre of Space Studies, University of Allahabad, Allahabad, Uttar Pradesh 211002, India E-mail:
| | - Suneet Dwivedi
- K Banerjee Centre of Atmospheric and Ocean Studies and M N Saha Centre of Space Studies, University of Allahabad, Allahabad, Uttar Pradesh 211002, India E-mail:
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21
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Degefa T, Yewhalaw D, Zhou G, Atieli H, Githeko AK, Yan G. Evaluation of human-baited double net trap and human-odour-baited CDC light trap for outdoor host-seeking malaria vector surveillance in Kenya and Ethiopia. Malar J 2020; 19:174. [PMID: 32381009 PMCID: PMC7206766 DOI: 10.1186/s12936-020-03244-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 04/23/2020] [Indexed: 11/19/2022] Open
Abstract
Background Surveillance of outdoor host-seeking malaria vectors is crucial to monitor changes in vector biting behaviour and evaluate the impact of vector control interventions. Human landing catch (HLC) has been considered the most reliable and gold standard surveillance method to estimate human-biting rates. However, it is labour-intensive, and its use is facing an increasing ethical concern due to potential risk of exposure to infectious mosquito bites. Thus, alternative methods are required. This study was conducted to evaluate the performance of human-odour-baited CDC light trap (HBLT) and human-baited double net trap (HDNT) for outdoor host-seeking malaria vector surveillance in Kenya and Ethiopia. Methods The sampling efficiency of HBLT and HDNT was compared with CDC light trap and HLC using Latin Square Design in Ahero and Iguhu sites, western Kenya and Bulbul site, southwestern Ethiopia between November 2015 and December 2018. The differences in Anopheles mosquito density among the trapping methods were compared using generalized linear model. Results Overall, 16,963 female Anopheles mosquitoes comprising Anopheles gambiae sensu lato (s.l.), Anopheles funestus s.l., Anopheles pharoensis, Anopheles coustani and Anopheles squamosus were collected. PCR results (n = 552) showed that Anopheles arabiensis was the only member of An. gambiae s.l. in Ahero and Bulbul, while 15.7% An. arabiensis and 84.3% An. gambiae sensu stricto (s.s.) constituted An. gambiae s.l. in Iguhu. In Ahero, HBLT captured 2.23 times as many An. arabiensis and 2.11 times as many An. funestus as CDC light trap. In the same site, HDNT yielded 3.43 times more An. arabiensis and 3.24 times more An. funestus than HBLT. In Iguhu, the density of Anopheles mosquitoes did not vary between the traps (p > 0.05). In Bulbul, HBLT caught 2.19 times as many An. arabiensis as CDC light trap, while HDNT caught 6.53 times as many An. arabiensis as CDC light trap. The mean density of An. arabiensis did not vary between HDNT and HLC (p = 0.098), whereas the HLC yielded significantly higher density of An. arabiensis compared to HBLT and CDC light trap. There was a significant density-independent positive correlation between HDNT and HLC (r = 0.69). Conclusion This study revealed that both HBLT and HDNT caught higher density of malaria vectors than conventional CDC light trap. Moreover, HDNT yielded a similar vector density as HLC, suggesting that it could be an alternative tool to HLC for outdoor host-seeking malaria vector surveillance.
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Affiliation(s)
- Teshome Degefa
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia. .,Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya.
| | - Delenasaw Yewhalaw
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia.,Tropical and Infectious Diseases Research Center (TIDRC), Jimma University, Jimma, Ethiopia
| | - Guofa Zhou
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, 92697, USA
| | - Harrysone Atieli
- School of Public Health and Community Development, Maseno University, Kisumu, Kenya
| | - Andrew K Githeko
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Guiyun Yan
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, 92697, USA
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Monthly Entomological Inoculation Rate Data for Studying the Seasonality of Malaria Transmission in Africa. DATA 2020. [DOI: 10.3390/data5020031] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
A comprehensive literature review was conducted to create a new database of 197 field surveys of monthly malaria Entomological Inoculation Rates (EIR), a metric of malaria transmission intensity. All field studies provide data at a monthly temporal resolution and have a duration of at least one year in order to study the seasonality of the disease. For inclusion, data collection methodologies adhered to a specific standard and the location and timing of the measurements were documented. Auxiliary information on the population and hydrological setting were also included. The database includes measurements that cover West and Central Africa and the period from 1945 to 2011, and hence facilitates analysis of interannual transmission variability over broad regions.
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Species Composition, Phenotypic and Genotypic Resistance Levels in Major Malaria Vectors in Teso North and Teso South Subcounties in Busia County, Western Kenya. J Parasitol Res 2020; 2020:3560310. [PMID: 32411419 PMCID: PMC7204121 DOI: 10.1155/2020/3560310] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 11/12/2019] [Accepted: 12/11/2019] [Indexed: 12/13/2022] Open
Abstract
Introduction Knockdown resistance (kdr) is strongly linked to pyrethroid insecticide resistance in Anopheles gambiae in Africa, which may have vital significance to the current increased use of pyrethroid-treated bed net programmes. The study is aimed at determining species composition, levels of insecticide resistance, and knockdown patterns in Anopheles gambiae sensu lato in areas with and areas without insecticide resistance in Teso North and Teso South subcounties, Western Kenya. Materials and Methods For WHO vulnerability tests, mosquito larvae were sampled using a dipper, reared into 3-5-day-old female mosquitoes (4944 at 100 mosquitoes per insecticide) which were exposed to 0.75% permethrin, 0.05% deltamethrin, and 0.1% bendiocarb using the WHO tube assay method. Species identification and kdr East gene PCRs were also performed on randomly selected mosquitoes from the collections; including adult mosquitoes (3448) sampled using standard collection methods. Results Anopheles gambiae sensu stricto were the majority in terms of species composition at 78.9%. Bendiocarb caused 100% mortality while deltamethrin had higher insecticidal effects (77%) on female mosquitoes than permethrin (71%). Susceptible Kengatunyi cluster had higher proportion of An. arabiensis (20.9%) than resistant Rwatama (10.7%). Kengatunyi mosquitoes exposed to deltamethrin had the highest KDT50 R of 8.2. Both Anopheles gambiae sensu stricto and Anopheles arabiensis had equal S allelic frequency of 0.84. Indoor resting mosquitoes had 100% mortality rate after 24 h since exposure. Overall SS genotypic frequency in Teso North and Teso South subcounties was 79.4% against 13.7% homozygous LL genotype and 6.9% heterozygous LS genotype. There was a significant difference (ρ < 0.05) in S allele frequencies between Kengatunyi (0.61) and Rwatama (0.95). Mosquito samples collected in 2013 had the highest S allelic frequency of 0.87. Discussion. Most likely, the higher the selection pressure exerted indoors by insecticidal nets, the higher were the resistance alleles. Use of pyrethroid impregnated nets and agrochemicals may have caused female mosquitoes to select for pyrethroid resistance. Different modes of action and chemical properties in different types of pyrethroids aggravated by a variety of edaphic and climatic factors may have caused different levels of susceptibility in both indoor and outdoor vectors to pyrethroids and carbamate. Species composition and populations in each collection method may have been influenced by insecticide resistance capacity in different species. Conclusions and Recommendations. Both phenotypic and genotypic insecticide resistance levels have been confirmed in Teso North and Teso South subcounties in Western Kenya. Insecticide resistance management practices in Kenya should be fast tracked and harmonized with agricultural sector agrochemical-based activities and legislation, and possibly switch to carbamate use in order to ease selection pressure on pyrethroids which are useable in insecticidal nets and indoor residual spray due to their low human toxicity. The implication of such high resistance levels in mosquitoes collected in Teso subcounties is that resistance is likely to persist and or even increase if monomolecules of permethrin and deltamethrin or both continue to be used in all net- and nonnet-based mosquito control purposes. Usage of mutually reinforcing piperonyl butoxide (PBO) that prohibits particular enzymes vital in metabolic activities inside mosquito systems and has been integrated into pyrethroid-LLINs to create pyrethroid-PBO nets is an extremely viable option.
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Ortega-López LD, Pondeville E, Kohl A, León R, Betancourth MP, Almire F, Torres-Valencia S, Saldarriaga S, Mirzai N, Ferguson HM. The mosquito electrocuting trap as an exposure-free method for measuring human-biting rates by Aedes mosquito vectors. Parasit Vectors 2020; 13:31. [PMID: 31941536 PMCID: PMC6961254 DOI: 10.1186/s13071-020-3887-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 01/04/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Entomological monitoring of Aedes vectors has largely relied on surveillance of larvae, pupae and non-host-seeking adults, which have been poorly correlated with human disease incidence. Exposure to mosquito-borne diseases can be more directly estimated using human landing catches (HLC), although this method is not recommended for Aedes-borne arboviruses. We evaluated a new method previously tested with malaria vectors, the mosquito electrocuting trap (MET) as an exposure-free alternative for measuring landing rates of Aedes mosquitoes on people. Aims were to (i) compare the MET to the BG-sentinel (BGS) trap gold standard approach for sampling host-seeking Aedes vectors; and (ii) characterize the diel activity of Aedes vectors and their association with microclimatic conditions. METHODS The study was conducted over 12 days in Quinindé (Ecuador) in May 2017. Mosquito sampling stations were set up in the peridomestic area of four houses. On each day of sampling, each house was allocated either a MET or a BGS trap, which were rotated amongst the four houses daily in a Latin square design. Mosquito abundance and microclimatic conditions were recorded hourly at each sampling station between 7:00-19:00 h to assess variation between vector abundance, trapping methods, and environmental conditions. All Aedes aegypti females were tested for the presence of Zika (ZIKV), dengue (DENV) and chikungunya (CHIKV) viruses. RESULTS A higher number of Ae. aegypti females were found in MET than in BGS collections, although no statistically significant differences in mean Ae. aegypti abundance between trapping methods were found. Both trapping methods indicated female Ae. aegypti had bimodal patterns of host-seeking, being highest during early morning and late afternoon hours. Mean Ae. aegypti daily abundance was negatively associated with daily temperature. No infection by ZIKV, DENV or CHIKV was detected in any Aedes mosquitoes caught by either trapping method. CONCLUSION We conclude the MET performs at least as well as the BGS standard and offers the additional advantage of direct measurement of per capita human-biting rates. If detection of arboviruses can be confirmed in MET-collected Aedes in future studies, this surveillance method could provide a valuable tool for surveillance and prediction on human arboviral exposure risk.
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Affiliation(s)
- Leonardo D. Ortega-López
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ UK
- MRC-University of Glasgow Centre for Virus Research, Glasgow, G61 1QH UK
| | - Emilie Pondeville
- MRC-University of Glasgow Centre for Virus Research, Glasgow, G61 1QH UK
| | - Alain Kohl
- MRC-University of Glasgow Centre for Virus Research, Glasgow, G61 1QH UK
| | - Renato León
- Laboratorio de Entomología Médica & Medicina Tropical (LEMMT), Universidad San Francisco de Quito, Quito, 170901 Ecuador
| | | | - Floriane Almire
- MRC-University of Glasgow Centre for Virus Research, Glasgow, G61 1QH UK
| | - Sergio Torres-Valencia
- Laboratorio de Entomología Médica & Medicina Tropical (LEMMT), Universidad San Francisco de Quito, Quito, 170901 Ecuador
| | - Segundo Saldarriaga
- Laboratorio de Entomología Médica & Medicina Tropical (LEMMT), Universidad San Francisco de Quito, Quito, 170901 Ecuador
| | - Nosrat Mirzai
- Bioelectronics Unit, University of Glasgow, Glasgow, G12 8QQ UK
| | - Heather M. Ferguson
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ UK
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Mbouna AD, Tompkins AM, Lenouo A, Asare EO, Yamba EI, Tchawoua C. Modelled and observed mean and seasonal relationships between climate, population density and malaria indicators in Cameroon. Malar J 2019; 18:359. [PMID: 31707994 PMCID: PMC6842545 DOI: 10.1186/s12936-019-2991-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 10/31/2019] [Indexed: 11/17/2022] Open
Abstract
Background A major health burden in Cameroon is malaria, a disease that is sensitive to climate, environment and socio-economic conditions, but whose precise relationship with these drivers is still uncertain. An improved understanding of the relationship between the disease and its drivers, and the ability to represent these relationships in dynamic disease models, would allow such models to contribute to health mitigation and adaptation planning. This work collects surveys of malaria parasite ratio and entomological inoculation rate and examines their relationship with temperature, rainfall, population density in Cameroon and uses this analysis to evaluate a climate sensitive mathematical model of malaria transmission. Methods Co-located, climate and population data is compared to the results of 103 surveys of parasite ratio (PR) covering 18,011 people in Cameroon. A limited set of campaigns which collected year-long field-surveys of the entomological inoculation rate (EIR) are examined to determine the seasonality of disease transmission, three of the study locations are close to the Sanaga and Mefou rivers while others are not close to any permanent water feature. Climate-driven simulations of the VECTRI malaria model are evaluated with this analysis. Results The analysis of the model results shows the PR peaking at temperatures of approximately 22 °C to 26 °C, in line with recent work that has suggested a cooler peak temperature relative to the established literature, and at precipitation rates at 7 mm day−1, somewhat higher than earlier estimates. The malaria model is able to reproduce this broad behaviour, although the peak occurs at slightly higher temperatures than observed, while the PR peaks at a much lower rainfall rate of 2 mm day−1. Transmission tends to be high in rural and peri-urban relative to urban centres in both model and observations, although the model is oversensitive to population which could be due to the neglect of population movements, and differences in hydrological conditions, housing quality and access to healthcare. The EIR follows the seasonal rainfall with a lag of 1 to 2 months, and is well reproduced by the model, while in three locations near permanent rivers the annual cycle of malaria transmission is out of phase with rainfall and the model fails. Conclusion Malaria prevalence is maximum at temperatures of 24 to 26 °C in Cameroon and rainfall rates of approximately 4 to 6 mm day−1. The broad relationships are reproduced in a malaria model although prevalence is highest at a lower rainfall maximum of 2 mm day−1. In locations far from water bodies malaria transmission seasonality closely follows that of rainfall with a lag of 1 to 2 months, also reproduced by the model, but in locations close to a seasonal river the seasonality of malaria transmission is reversed due to pooling in the transmission to the dry season, which the model fails to capture.
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Affiliation(s)
- Amelie D Mbouna
- Laboratory for Environmental Modelling and Atmospheric Physics (LEMAP), Department of Physics, Faculty of Science, University of Yaoundé́ I, Yaoundé, Cameroon. .,Earth System Physics, Abdus Salam International Centre for Theoretical Physics (ICTP), Strada Costiera 11, Trieste, Italy.
| | - Adrian M Tompkins
- Earth System Physics, Abdus Salam International Centre for Theoretical Physics (ICTP), Strada Costiera 11, Trieste, Italy
| | - Andre Lenouo
- Department of Physics, Faculty of Science, University of Douala, Douala, Cameroon
| | - Ernest O Asare
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, Yale University, New Haven, USA
| | - Edmund I Yamba
- Department of Physics, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Clement Tchawoua
- Laboratory for Environmental Modelling and Atmospheric Physics (LEMAP), Department of Physics, Faculty of Science, University of Yaoundé́ I, Yaoundé, Cameroon
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Brief Report: Antimalarial Benefit of HIV Antiretroviral Therapy in Areas of Low to Moderate Malaria Transmission Intensity. J Acquir Immune Defic Syndr 2019; 79:249-254. [PMID: 30212437 DOI: 10.1097/qai.0000000000001783] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND We previously used mathematical modeling to predict reduced malaria incidence in children with protease inhibitor (PI)-, compared with nonnucleoside reverse transcriptase inhibitor-, based highly active antiretroviral therapy (HAART), in moderate to high malaria transmission areas. These effects were accounted for, in part, by pharmacokinetic (PK) interactions between PIs and artemether-lumefantrine (AL). OBJECTIVE Because of potentially reduced malaria transmission reservoirs in HIV-infected children due to PI/AL PK interactions impacting non-HIV-infected children, we estimate the antimalarial benefit of PI-based HAART in all children, and in HIV-infected children only residing in low to moderate malaria transmission areas. DESIGN A dynamic model of malaria transmission was developed to evaluate the PK interaction of PI-based HAART with the antimalarial, AL for preventing malaria. METHODS To evaluate the benefit of HIV PI-based HAART on malaria incidence, a malaria transmission model with varying degrees of HIV newborn prevalence was developed using recent pediatric clinical trial data in Lilongwe, Malawi. RESULTS Comparing situations of low to high HIV newborn prevalence, and low to moderate malaria transmission intensities, our model predicts the combination of PI-based HAART with AL-treated malaria prevents 0.04-24.8 and 0.05-34.5 annual incidences of malaria overall per 1000 children, and saves 0.003-1.66 and 0.003-2.30 disability-adjusted life years per 1000 children, respectively. When incorporating seasonality, 0.01-7.3 and 0.01-5.9 annual incidences of malaria overall per 1000 children, and 0.0-0.5 and 0.001-0.41 disability-adjusted life years per 100 children, are prevented, respectively. CONCLUSIONS In low to moderate malaria transmission intensity areas, PI-based HAART may reduce malaria events in children when AL is used.
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Rund SSC, Braak K, Cator L, Copas K, Emrich SJ, Giraldo-Calderón GI, Johansson MA, Heydari N, Hobern D, Kelly SA, Lawson D, Lord C, MacCallum RM, Roche DG, Ryan SJ, Schigel D, Vandegrift K, Watts M, Zaspel JM, Pawar S. MIReAD, a minimum information standard for reporting arthropod abundance data. Sci Data 2019; 6:40. [PMID: 31024009 PMCID: PMC6484025 DOI: 10.1038/s41597-019-0042-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 03/20/2019] [Indexed: 11/29/2022] Open
Abstract
Arthropods play a dominant role in natural and human-modified terrestrial ecosystem dynamics. Spatially-explicit arthropod population time-series data are crucial for statistical or mathematical models of these dynamics and assessment of their veterinary, medical, agricultural, and ecological impacts. Such data have been collected world-wide for over a century, but remain scattered and largely inaccessible. In particular, with the ever-present and growing threat of arthropod pests and vectors of infectious diseases, there are numerous historical and ongoing surveillance efforts, but the data are not reported in consistent formats and typically lack sufficient metadata to make reuse and re-analysis possible. Here, we present the first-ever minimum information standard for arthropod abundance, Minimum Information for Reusable Arthropod Abundance Data (MIReAD). Developed with broad stakeholder collaboration, it balances sufficiency for reuse with the practicality of preparing the data for submission. It is designed to optimize data (re)usability from the "FAIR," (Findable, Accessible, Interoperable, and Reusable) principles of public data archiving (PDA). This standard will facilitate data unification across research initiatives and communities dedicated to surveillance for detection and control of vector-borne diseases and pests.
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Affiliation(s)
- Samuel S C Rund
- VectorBase, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA.
| | - Kyle Braak
- Global Biodiversity Information Facility (GBIF) Secretariat, Copenhagen, Denmark
| | - Lauren Cator
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot, Berkshire, United Kingdom
| | - Kyle Copas
- Global Biodiversity Information Facility (GBIF) Secretariat, Copenhagen, Denmark
| | - Scott J Emrich
- Department of Electrical Engineering and Computer Science, University of Tennessee, Knoxville, TN, USA
| | - Gloria I Giraldo-Calderón
- VectorBase, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
- Universidad Icesi, Facultad de Ciencias Naturales, Calle 18 No. 122-135, Cali, Colombia
| | - Michael A Johansson
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, 1324 Calle Cañada, San Juan, PR, USA
- Department of Epidemiology, Harvard School of Public Health, 677 Huntington Ave, Boston, MA, USA
| | - Naveed Heydari
- Center for Global Health and Translational Science, State University of New York Upstate Medical University, Syracuse, NY, USA
| | - Donald Hobern
- Global Biodiversity Information Facility (GBIF) Secretariat, Copenhagen, Denmark
| | - Sarah A Kelly
- VectorBase and Vector Immunogenomics and Infection Laboratory, Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Daniel Lawson
- VectorBase and Vector Immunogenomics and Infection Laboratory, Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Cynthia Lord
- Florida Medical Entomology Lab, University of Florida-IFAS, Vero Beach, FL, USA
| | - Robert M MacCallum
- VectorBase and Vector Immunogenomics and Infection Laboratory, Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Dominique G Roche
- Institute of Biology, University of Neuchâtel, 2000, Neuchâtel, Switzerland
| | - Sadie J Ryan
- Quantitative Disease Ecology and Conservation Lab, Department of Geography, University of Florida, Gainesville, FL, USA
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA
- College of Life Sciences, University of Kwa-Zulu Natal, Durban, South Africa
| | - Dmitry Schigel
- Global Biodiversity Information Facility (GBIF) Secretariat, Copenhagen, Denmark
| | - Kurt Vandegrift
- Center for Infectious Disease Dynamics, Department of Biology, The Pennsylvania State University, University Park, PA, USA
| | - Matthew Watts
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot, Berkshire, United Kingdom
| | | | - Samraat Pawar
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot, Berkshire, United Kingdom
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Meza FC, Kreppel KS, Maliti DF, Mlwale AT, Mirzai N, Killeen GF, Ferguson HM, Govella NJ. Mosquito electrocuting traps for directly measuring biting rates and host-preferences of Anopheles arabiensis and Anopheles funestus outdoors. Malar J 2019; 18:83. [PMID: 30885205 PMCID: PMC6423841 DOI: 10.1186/s12936-019-2726-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 03/13/2019] [Indexed: 11/26/2022] Open
Abstract
Background Mosquito biting rates and host preferences are crucial determinants of human exposure to vector-borne diseases and the impact of vector control measures. The human landing catch (HLC) is a gold standard method for measuring human exposure to bites, but presents risks to participants by requiring some exposure to mosquito vectors. Mosquito electrocuting traps (METs) represent an exposure-free alternative to HLCs for measuring human exposure to malaria vectors. However, original MET prototypes were too small for measuring whole-body biting rates on humans or large animals like cattle. Here a much larger MET capable of encompassing humans or cattle was designed, and its performance was evaluated relative to both the original small MET and HLC and for quantifying malaria vector host preferences. Methods Human landing catch, small human-baited METs (MET-SH), and large METs baited with either a human (MET-LH) or calves (MET-LC) were simultaneously used to capture wild malaria vectors outdoors in rural southern Tanzania. The four capture methods were compared in a Latin-square design over 20 nights. Malaria vector host preferences were estimated through comparison of the number of mosquitoes caught by large METs baited with either humans or cattle. Results The MET-LH caught more than twice as many Anopheles arabiensis than either the MET-SH or HLC. It also caught higher number of Anopheles funestus sensu lato (s.l.) compared to the MET-SH or HLC. Similar numbers of An. funestus sensu stricto (s.s.) were caught in MET-LH and MET-SH collections. Catches of An. arabiensis with human or cattle-baited large METs were similar, indicating no clear preference for either host. In contrast, An. funestus s.s. exhibited a strong, but incomplete preference for humans. Conclusions METs are a sensitive, practical tool for assessing mosquito biting rates and host preferences, and represent a safer alternative to the HLC. Additionally these findings suggest the HLC underestimate whole-body human exposure. MET collections indicated the An. funestus s.s. population in this setting had a higher than expected attack rate on cattle, potentially making eliminating of this species more difficult with human-targetted control measures. Supplementary vector control tools targetted at livestock may be required to effectively tackle this species.
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Affiliation(s)
- Felician C Meza
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Off Mlabani Passage, P.O. Box 53, Ifakara, Tanzania.
| | - Katharina S Kreppel
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Off Mlabani Passage, P.O. Box 53, Ifakara, Tanzania.,Animal Health and Comparative Medicine, Institute of Biodiversity, University of Glasgow, Graham Kerr Building, Glasgow, G12 8QQ, UK
| | - Deodatus F Maliti
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Off Mlabani Passage, P.O. Box 53, Ifakara, Tanzania.,Animal Health and Comparative Medicine, Institute of Biodiversity, University of Glasgow, Graham Kerr Building, Glasgow, G12 8QQ, UK
| | - Amos T Mlwale
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Off Mlabani Passage, P.O. Box 53, Ifakara, Tanzania
| | - Nosrat Mirzai
- Bioelectronics Unit, University of Glasgow, Graham Kerr Building, Glasgow, G12 8QQ, UK
| | - Gerry F Killeen
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Off Mlabani Passage, P.O. Box 53, Ifakara, Tanzania.,Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Heather M Ferguson
- Animal Health and Comparative Medicine, Institute of Biodiversity, University of Glasgow, Graham Kerr Building, Glasgow, G12 8QQ, UK
| | - Nicodem J Govella
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Off Mlabani Passage, P.O. Box 53, Ifakara, Tanzania.,Animal Health and Comparative Medicine, Institute of Biodiversity, University of Glasgow, Graham Kerr Building, Glasgow, G12 8QQ, UK
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Abstract
Malaria infection is one of the major causes of deaths in the African continent. The high burden of malaria in Africa is due to P. falciparum, which adapts and cospecializes with Anopheles gambiae, the most effective and widespread malaria vector. Since 2000, the incidence of malaria has been reduced by 17% and malaria mortality rates by 26%. However, the rate of decline has stalled and even reversed in some regions since 2014. In 2017 as described by the latest World malaria report, 219 million malaria cases were reported, up from 2017 million cases reported in 2016 in 91 countries, and the global tally of malaria deaths reached 435,000 deaths, compared with 451,000 estimated deaths in 2016. Despite these achievements, the African region continues to account for about 92% of malaria cases and deaths worldwide. Therefore, it is important to master the current situation of malaria in Africa to see how to better plan its elimination. In this chapter, we present the current situation and prospective means to improve it, including a salutogenesis approach.
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Burkot TR, Bugoro H, Apairamo A, Cooper RD, Echeverry DF, Odabasi D, Beebe NW, Makuru V, Xiao H, Davidson JR, Deason NA, Reuben H, Kazura JW, Collins FH, Lobo NF, Russell TL. Spatial-temporal heterogeneity in malaria receptivity is best estimated by vector biting rates in areas nearing elimination. Parasit Vectors 2018; 11:606. [PMID: 30482239 PMCID: PMC6260740 DOI: 10.1186/s13071-018-3201-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 11/14/2018] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Decisions on when vector control can be withdrawn after malaria is eliminated depend on the receptivity or potential of an area to support vector populations. To guide malaria control and elimination programmes, the potential of biting rates, sporozoite rates, entomological inoculation rates and parity rates to estimate malaria receptivity and transmission were compared within and among geographically localised villages of active transmission in the Western Province of the Solomon Islands. RESULTS Malaria transmission and transmission potential was heterogeneous in both time and space both among and within villages as defined by anopheline species composition and biting densities. Biting rates during the peak biting period (from 18:00 to 00:00 h) of the primary vector, Anopheles farauti, ranged from less than 0.3 bites per person per half night in low receptivity villages to 26 bites per person in highly receptive villages. Within villages, sites with high anopheline biting rates were significantly clustered. Sporozoite rates provided evidence for continued transmission of Plasmodium falciparum, P. vivax and P. ovale by An. farauti and for incriminating An. hinesorum, as a minor vector, but were unreliable as indicators of transmission intensity. CONCLUSIONS In the low transmission area studied, sporozoite, entomological inoculation and parity rates could not be measured with the precision required to provide guidance to malaria programmes. Receptivity and potential transmission risk may be most reliably estimated by the vector biting rate. These results support the meaningful design of operational research programmes to ensure that resources are focused on providing information that can be utilised by malaria control programmes to best understand both transmission, transmission risk and receptivity across different areas.
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Affiliation(s)
- Thomas R. Burkot
- James Cook University, Australian Institute of Tropical Health and Medicine, Cairns, QLD 4870 Australia
| | - Hugo Bugoro
- National Vector Borne Disease Control Programme, Ministry of Health and Medical Services, Honiara, Solomon Islands
- Research Department, Solomon Islands National University, Honiara, Solomon Islands
| | - Allan Apairamo
- National Vector Borne Disease Control Programme, Ministry of Health and Medical Services, Honiara, Solomon Islands
| | - Robert D. Cooper
- Australian Army Malaria Institute, Gallipoli Barracks, Enoggera, 4052 Australia
| | - Diego F. Echeverry
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN 46556 USA
| | - Danyal Odabasi
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Nigel W. Beebe
- University of Queensland, School of Biological Sciences, QLD, St. Lucia, 4068 Australia
- CSIRO, Dutton Park, Brisbane, QLD 4102 Australia
| | - Victoria Makuru
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN 46556 USA
| | - Honglin Xiao
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN 46556 USA
| | - Jenna R. Davidson
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN 46556 USA
| | - Nicholas A. Deason
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN 46556 USA
| | - Hedrick Reuben
- Western Province Malaria Control, Gizo, Western Province Solomon Islands
| | - James W. Kazura
- Center for Global Health & Diseases, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106–4983 USA
| | - Frank H. Collins
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN 46556 USA
| | - Neil F. Lobo
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN 46556 USA
| | - Tanya L. Russell
- James Cook University, Australian Institute of Tropical Health and Medicine, Cairns, QLD 4870 Australia
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Salako AS, Ahogni I, Kpanou C, Sovi A, Azondekon R, Sominahouin AA, Tokponnon F, Gnanguenon V, Dagnon F, Iyikirenga L, Akogbeto MC. Baseline entomologic data on malaria transmission in prelude to an indoor residual spraying intervention in the regions of Alibori and Donga, Northern Benin, West Africa. Malar J 2018; 17:392. [PMID: 30373576 PMCID: PMC6206707 DOI: 10.1186/s12936-018-2507-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2018] [Accepted: 10/06/2018] [Indexed: 11/16/2022] Open
Abstract
Background Despite the success of indoor residual insecticide spraying (IRS) in Africa, particularly in Benin, some gaps of information need to be filled to optimize the effectiveness of this intervention in the perspective of the country’s effort to eliminate malaria. In anticipation to the 2018 IRS campaign in two targeted regions of northern Benin, this study aimed, to collect baseline information on vector composition, spatio-temporal variation and peak malaria transmission in the Alibori and Donga, two targeted regions of northern Benin. Information collected will help to better plan the implementation and later on the impact assessment of this IRS campaign. Methods The study was carried out in four districts of the two IRS targeted regions of northern Benin. Human landing catches and pyrethrum spray catches protocols were used to assess the biting rate (HBR) and, biting/resting behaviour of malaria vector populations. After morphological identification of collected Anopheles, the heads and thoraxes of Anopheles gambiae sensu lato (s.l.) were analysed by the ELISA CSP tests to estimate the sporozoite index (SI). The entomological inoculation rate was calculated as the product of mosquito biting rate (HBR) and the SI. Results The biting rates of An. gambiae s.l., the major vector in this study sites, varied significantly from region to region. It was higher: in rural than in urban areas, in rainy season than in dry season, indoors than outdoors. Overall, SI was comparable between sites. The highest EIRs were observed in the Donga region (16.84 infectious bites/man/month in Djougou district and 17.64 infectious bites/man/month in Copargo district) and the lowest in the Alibori region (10.74 infectious bites/man/month at Kandi district and 11.04 infectious bites/man/month at Gogounou district). Conclusion This study showed the heterogeneous and various nature of malaria epidemiology in Northern Benin. Indeed, the epidemiological profile of malaria transmission in the Alibori and Donga regions is made of a single season of transmission interrupted by a dry season. This period of transmission is relatively longer in Donga region than in Alibori. This information can be used to guide the extension of IRS in the Alibori and in the Donga, by primarily targeting areas with short periods of transmission, and easy to cover.
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Affiliation(s)
- Albert S Salako
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Benin. .,Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin.
| | - Idelphonse Ahogni
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Benin.,Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
| | - Casimir Kpanou
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Benin.,Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
| | - Arthur Sovi
- PMI VectorLink Project, Abt Associates, Bamako, Mali
| | - Roseric Azondekon
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Benin.,University of Wisconsin Milwaukee, Milwaukee, WI, USA
| | - André A Sominahouin
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Benin.,Faculté des Sciences Humaines et Sociales de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
| | | | | | - Fortuné Dagnon
- US President's Malaria Initiative, US Agency for International Development, Cotonou, Benin
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Finda MF, Limwagu AJ, Ngowo HS, Matowo NS, Swai JK, Kaindoa E, Okumu FO. Dramatic decreases of malaria transmission intensities in Ifakara, south-eastern Tanzania since early 2000s. Malar J 2018; 17:362. [PMID: 30326881 PMCID: PMC6192315 DOI: 10.1186/s12936-018-2511-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 10/08/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Ongoing epidemiological transitions across Africa are particularly evident in fast-growing towns, such as Ifakara in the Kilombero valley, south-eastern Tanzania. This town and its environs (population ~ 70,000) historically experienced moderate to high malaria transmission, mediated mostly by Anopheles gambiae and Anopheles funestus. In early 2000s, malaria transmission [Plasmodium falciparum entomological inoculation rate (PfEIR)] was estimated at ~ 30 infectious bites/person/year (ib/p/yr). This study assessed the PfEIR after 15 years, during which there had been rapid urbanization and expanded use of insecticide-treated nets (ITNs). METHODS Randomly-selected 110 households were sampled across Ifakara town and four adjacent wards. Mosquitoes were trapped nightly or monthly (June.2015-May.2016) using CDC-light-traps indoors, Suna® traps outdoors and human landing catches (HLC) indoors and outdoors. All Anopheles mosquitoes were morphologically identified and analysed by ELISA for Plasmodium circumsporozoite proteins. Mosquito blood meals were identified using ELISA, and sub-samples of An. gambiae and An. funestus examined by PCR to distinguish morphologically-similar siblings. Insecticide resistance was assessed using WHO-susceptibility assays, and some Anopheles were dissected to examine ovariole tracheoles for parity. RESULTS After 3572 trap-nights, one Plasmodium-infected Anopheles was found (an An. funestus caught outdoors in Katindiuka-ward by HLC), resulting in overall PfEIR of 0.102 ib/p/yr. Nearly 80% of malaria vectors were from Katindiuka and Mlabani wards. Anopheles gambiae densities were higher outdoors (64%) than indoors (36%), but no such difference was observed for An. funestus. All An. funestus and 75% of An. gambiae dissected were parous. Anopheles gambiae complex consisted entirely of Anopheles arabiensis, while An. funestus included 84.2% An. funestus s.s., 4.5% Anopheles rivulorum, 1.4% Anopheles leesoni and 9.9% with unamplified-DNA. Anopheles gambiae were susceptible to bendiocarb and malathion, but resistant to pyrethroids, DDT and pirimiphos-methyl. Most houses had brick walls and/or iron roofs (> 90%), and 52% had screened windows. CONCLUSION Malaria transmission in Ifakara has decreased by > 99% since early-2000s, reaching levels nearly undetectable with current entomological methods. These declines are likely associated with ITNs use, urbanization and improved housing. Remaining risk is now mostly in peri-urban wards, but concerted efforts could further decrease local transmission. Parasitological surveys are required to assess actual prevalence, incidence and importation rates.
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Affiliation(s)
- Marceline F Finda
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania. .,School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
| | - Alex J Limwagu
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
| | - Halfan S Ngowo
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
| | - Nancy S Matowo
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania.,University of Basel, Basel, Switzerland.,Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Johnson K Swai
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
| | - Emmanuel Kaindoa
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania.,School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Fredros O Okumu
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania.,School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.,Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
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Dynamics of Plasmodium falciparum gametocyte carriage in pregnant women under intermittent preventive treatment with sulfadoxine-pyrimethamine in Benin. Malar J 2018; 17:356. [PMID: 30305101 PMCID: PMC6180446 DOI: 10.1186/s12936-018-2498-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 09/29/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In sub-Saharan Africa, malaria is a major cause of morbidity and mortality, in particular in children and pregnant women. During pregnancy, Plasmodium falciparum infected red blood cells expressing VAR2CSA are selected from circulation by selective cytoadherence to chondroitin sulfate proteoglycan receptors expressed in the placenta, leading to an increased susceptibility to malaria, long-lasting infections and poor pregnancy outcome. Partly because of these long-lasting infections, women were reported to have a higher density of gametocytes in their peripheral blood, and are considered as a potential reservoir for malaria transmission. To improve pregnancy outcome in areas of high malaria transmission, The WHO recommends intermittent preventive treatment with sulfadoxine/pyrimethamine (IPTp-SP) during antenatal care visits. The effect of IPTp-SP on gametocyte carriage in infected pregnant women was studied. METHODS The levels of transcription of three gametocytes stage-specific genes Pfs16 (expressed by sexually-committed ring stage parasites and fully matured gametocytes), Pfs25 (expressed by female mature gametocytes) and Pfs230 (expressed by male mature gametocytes) were assessed by real-time PCR in 50 P. falciparum infected women at early pregnancy (before implementation of IPTp-SP), and in 50 infected women at delivery. Sex ratios of male and female gametocytes were determined in these women to assess the effect of IPTp-SP on the gametocyte populations. RESULTS The data show that the three transcript types specific to Pfs16, Pfs25 and Pfs230 were detected in all samples, both at inclusion and delivery. Levels of Pfs25 and Pfs230 transcripts were higher at delivery than at inclusion (p = 0.042 and p = 0.003), while the opposite was observed for Pfs16 (p = 0.048). The ratio of male/female gametocyte transcript levels was higher at delivery than at inclusion (p = 0.018). Since a mixed gender late stage gametocyte culture was used as a positive control, male and female gametocytes could not be quantified in an absolute way in the samples. However, the amplification reliability of the Pfs25 and Pfs230 markers in the samples could be checked. A relative quantity of each type of Pfs transcript was, therefore, used to calculate the sex ratio proxy. CONCLUSION This study demonstrates that IPTp-SP treatment contributes to modify the parasite populations' structure during pregnancy. In line with previous studies, we suggest that the continued use of SP in pregnant women as IPTp, despite having a beneficial effect on the pregnancy outcome, could be a risk factor for increased transmission. This reinforces the need for an alternative to the SP drug for malaria prevention during pregnancy.
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Batista EPA, Ngowo H, Opiyo M, Shubis GK, Meza FC, Siria DJ, Eiras AE, Okumu FO. Field evaluation of the BG-Malaria trap for monitoring malaria vectors in rural Tanzanian villages. PLoS One 2018; 13:e0205358. [PMID: 30296287 PMCID: PMC6175526 DOI: 10.1371/journal.pone.0205358] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Accepted: 09/24/2018] [Indexed: 11/19/2022] Open
Abstract
BG-Malaria (BGM) trap is a simple adaptation of the widely-used BG-Sentinel trap (BGS). It is proven to be highly effective for trapping the Brazilian malaria vector, Anopheles darlingi, in field conditions, and the African vector, Anopheles arabiensis, under controlled semi-field environments, but has not been field-tested in Africa. Here, we validated the BGM for field sampling of malaria vectors in south-eastern Tanzania. Using a series of Latin-Square experiments conducted nightly (6pm-7am) in rural villages, we compared mosquito catches between BGM, BGS and human landing catches (HLC). We also compared BGMs baited with different attractants (Ifakara-blend, Mbita-blend, BG-Lure and CO2). Lastly, we tested BGMs baited with Ifakara-blend from three odour-dispensing methods (BG-Cartridge, BG-Sachet and Nylon strips). One-tenth of the field-collected female Anopheles gambiae s.l. and Anopheles funestus were dissected to assess parity. BGM captured more An. gambiae s.l. than BGS (p < 0.001), but HLC caught more than either trap (p < 0.001). However, BGM captured more An. funestus than HLC. Proportions of parous An. gambiae s.l. and An. funestus consistently exceeded 50%, with no significant difference between methods. While the dominant species caught by HLC was An. gambiae s.l. (56.0%), followed by Culex spp. (33.1%) and Mansonia spp. (6.0%), the BGM caught mostly Culex (81.6%), followed by An. gambiae s.l. (10.6%) and Mansonia (5.8%). The attractant-baited BGMs were all significantly superior to un-baited controls (p < 0.001), although no difference was found between the specific attractants. The BG-Sachet was the most efficient dispenser for capturing An. gambiae s.l. (14.5(2.75–42.50) mosquitoes/trap/night), followed by BG-Cartridge (7.5(1.75–26.25)). The BGM caught more mosquitoes than BGS in field-settings, but sampled similar species diversity and physiological states as BGS. The physiological states of malaria vectors caught in BGM and BGS were similar to those naturally attempting to bite humans (HLC). The BGM was most efficient when baited with Ifakara blend, dispensed from BG-Sachet. We conclude that though BGM traps have potential for field-sampling of host-seeking African malaria vectors with representative physiological states, both BGM and BGS predominantly caught more culicines than Anopheles, compared to HLC, which caught mostly An. gambiae s.l.
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Affiliation(s)
- Elis P. A. Batista
- Laboratório de Ecologia Química de Insetos Vetores, Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
- * E-mail:
| | - Halfan Ngowo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Mercy Opiyo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Gasper K. Shubis
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Felician C. Meza
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Doreen J. Siria
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Alvaro E. Eiras
- Laboratório de Ecologia Química de Insetos Vetores, Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Fredros O. Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Parktown, Republic of South Africa
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
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Calzetta M, Perugini E, Seixas G, Sousa CA, Guelbeogo WM, Sagnon N, Della Torre A, Pinto J, Pombi M, Mancini E. A novel nested polymerase chain reaction assay targeting Plasmodium mitochondrial DNA in field-collected Anopheles mosquitoes. MEDICAL AND VETERINARY ENTOMOLOGY 2018; 32:372-377. [PMID: 29344968 DOI: 10.1111/mve.12293] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 11/01/2017] [Accepted: 11/25/2017] [Indexed: 06/07/2023]
Abstract
Sensitive techniques for the detection of Plasmodium (Aconoidasida: Plasmodiidae) sporozoites in field-collected malaria vectors are essential for the correct assessment of risk for malaria transmission. A real-time polymerase chain reaction (RT-PCR) protocol targeting Plasmodium mtDNA proved to be much more sensitive in detecting sporozoites in mosquitoes than the widely used enzyme-linked immunosorbent assay targeting Plasmodium circumsporozoite protein (CSP-ELISA). However, because of the relatively high costs associated with equipment and reagents, RT-PCRs are mostly used to assess the outcomes of experimental infections in the frame of research experiments, rather than in routine monitoring of mosquito infection in the field. The present authors developed a novel mtDNA-based nested PCR protocol, modified from a loop-mediated isothermal amplification (LAMP) assay for Plasmodium recognition in human blood samples, and compared its performance with that of routinely used CSP-ELISAs in field-collected Anopheles coluzzii (Diptera: Culicidae) samples. The nested PCR showed 1.4-fold higher sensitivity than the CSP-ELISA. However, nested PCR results obtained in two laboratories and in different replicates within the same laboratory were not 100% consistent, probably because the copy number of amplifiable Plasmodium mtDNA was close in some specimens to the threshold of nested PCR sensitivity. This implies that Plasmodium-positive specimens should be confirmed by a second nested PCR to avoid false positives. Overall, the results emphasize the need to use molecular approaches to obtain accurate estimates of the actual level of Plasmodium circulation within malaria vector populations.
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Affiliation(s)
- M Calzetta
- Dipartimento di Sanità Pubblica e Malattie Infettive, Istituto Pasteur Italia Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome, Italy
| | - E Perugini
- Dipartimento di Sanità Pubblica e Malattie Infettive, Istituto Pasteur Italia Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome, Italy
- Dipartimento di Scienze, Roma Tre University, Rome, Italy
| | - G Seixas
- Global Health and Tropical Medicine (GHTM), Instituto de Higiene e Medicina Tropical (IHMT), Universidade Nova de Lisboa, Lisbon, Portugal
| | - C A Sousa
- Global Health and Tropical Medicine (GHTM), Instituto de Higiene e Medicina Tropical (IHMT), Universidade Nova de Lisboa, Lisbon, Portugal
| | - W M Guelbeogo
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou, Burkina Faso
| | - N Sagnon
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou, Burkina Faso
| | - A Della Torre
- Dipartimento di Sanità Pubblica e Malattie Infettive, Istituto Pasteur Italia Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome, Italy
| | - J Pinto
- Global Health and Tropical Medicine (GHTM), Instituto de Higiene e Medicina Tropical (IHMT), Universidade Nova de Lisboa, Lisbon, Portugal
| | - M Pombi
- Dipartimento di Sanità Pubblica e Malattie Infettive, Istituto Pasteur Italia Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome, Italy
| | - E Mancini
- Dipartimento di Scienze, Roma Tre University, Rome, Italy
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Lee EH, Olsen CH, Koehlmoos T, Masuoka P, Stewart A, Bennett JW, Mancuso J. A cross-sectional study of malaria endemicity and health system readiness to deliver services in Kenya, Namibia and Senegal. Health Policy Plan 2018; 32:iii75-iii87. [PMID: 29149315 DOI: 10.1093/heapol/czx114] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/15/2017] [Indexed: 11/13/2022] Open
Abstract
Despite good progress towards elimination, malaria continues to contribute substantially to the sub-Saharan African disease burden. Sustaining previous gains requires continued readiness to deliver malaria services in response to actual disease burden, which in turn contributes to health systems strengthening. This study investigates a health system innovation. We examined whether malaria prevalence, or endemicity, is a driver of health facility readiness to deliver malaria services. To estimate this association, we geo-linked cross-sectional facility survey data to endemicity data for Kenya, Namibia and Senegal. We tested the validity and reliability of the primary study outcome, the malaria service readiness index and mapped service readiness components in a geographic information system. We conducted a weighted multivariable linear regression analysis of the relationship between endemicity and malaria service readiness, stratified for urban or rural facility location. As endemicity increased in rural areas, there was a concurrent, modest increase in service readiness at the facility level [β: 0.028; (95% CI 0.008, 0.047)], whereas no relationship existed in urban settings. Private-for-profit facilities were generally less prepared than public [β: -0.102; (95% CI - 0.154, -0.050)]. Most facilities had the necessary supplies to diagnose malaria, yet availability of malaria guidelines and adequately trained staff as well as medicines and commodities varied. Findings require cautious interpretation outside the study sample, which was a more limited subset of the original surveys' sampling schemes. Our approach and findings may be used by national malaria programs to identify low performing facilities in malarious areas for targeted service delivery interventions. This study demonstrates use of existing data sources to evaluate health system performance and to identify within- and cross-country variations for targeted interventions.
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Affiliation(s)
- Elizabeth H Lee
- The Henry M. Jackson Foundation for the Advancement of Military Medicine, 6720-A Rockledge Drive, Suite 100, Bethesda, MD 20817, USA.,Division of Tropical Public Health, The Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA
| | - Cara H Olsen
- Division of Tropical Public Health, The Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA
| | - Tracey Koehlmoos
- Division of Tropical Public Health, The Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA
| | - Penny Masuoka
- The Henry M. Jackson Foundation for the Advancement of Military Medicine, 6720-A Rockledge Drive, Suite 100, Bethesda, MD 20817, USA.,Division of Tropical Public Health, The Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA
| | - Ann Stewart
- Division of Tropical Public Health, The Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA
| | - Jason W Bennett
- Division of Tropical Public Health, The Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.,Multidrug Resistant Organism Repository and Surveillance Network, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD 20910, USA
| | - James Mancuso
- United States Army Medical Directorate - Kenya, Nyanza, Kenya
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Hakizimana E, Karema C, Munyakanage D, Githure J, Mazarati JB, Tongren JE, Takken W, Binagwaho A, Koenraadt CJ. Spatio-temporal distribution of mosquitoes and risk of malaria infection in Rwanda. Acta Trop 2018; 182:149-157. [PMID: 29476726 DOI: 10.1016/j.actatropica.2018.02.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 01/26/2018] [Accepted: 02/11/2018] [Indexed: 11/24/2022]
Abstract
To date, the Republic of Rwanda has not systematically reported on distribution, diversity and malaria infectivity rate of mosquito species throughout the country. Therefore, we assessed the spatial and temporal variation of mosquitoes in the domestic environment, as well as the nocturnal biting behavior and infection patterns of the main malaria vectors in Rwanda. For this purpose, mosquitoes were collected monthly from 2010 to 2013 by human landing catches (HLC) and pyrethrum spray collections (PSC) in seven sentinel sites. Mosquitoes were identified using morphological characteristics and PCR. Plasmodium falciparum sporozoite infection rates were determined using ELISA. A total of 340,684 mosquitoes was collected by HLC and 73.8% were morphologically identified as culicines and 26.2% as anophelines. Of the latter, 94.3% were Anopheles gambiae s.l., 0.4% Anopheles funestus and 5.3% other Anopheles species. Of An. gambiae s.l., An. arabiensis and An. gambiae s.s. represented 84.4% and 15.6%, respectively. Of all An. gambiae s.l. collected indoor and outdoor, the proportion collected indoors was 51.3% in 2010 and 44.9% in 2013. A total of 17,022 mosquitoes was collected by PSC of which 20.5% were An. gambiae s.l. and 79.5% were culicines. For the seven sentinel sites, the mean indoor density for An. gambiae s.l. varied from 0.0 to 1.0 mosquitoes/house/night. P. falciparum infection rates in mosquitoes varied from 0.87 to 4.06%. The entomological inoculation rate (EIR) ranged from 1.0 to 329.8 with an annual average of 99.5 infective bites/person/year. This longitudinal study shows, for the first time, the abundance, species composition, and entomological inoculation rate of malaria mosquitoes collected throughout Rwanda.
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Ya-Umphan P, Cerqueira D, Cottrell G, Parker DM, Fowkes FJI, Nosten F, Corbel V. Anopheles Salivary Biomarker as a Proxy for Estimating Plasmodium falciparum Malaria Exposure on the Thailand-Myanmar Border. Am J Trop Med Hyg 2018; 99:350-356. [PMID: 29869601 DOI: 10.4269/ajtmh.18-0081] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Timely identification and treatment of malaria transmission "hot spots" is essential to achieve malaria elimination. Here we investigate the relevance of using an Anopheles salivary biomarker to estimate Plasmodium falciparum malaria exposure risk along the Thailand-Myanmar border to guide malaria control. Between May 2013 and December 2014, > 9,000 blood samples collected in a cluster randomized control trial were screened with serological assays to measure the antibody responses to Anopheles salivary antigen (gSG6-P1) and P. falciparum malaria antigens (circumsporozoite protein, merozoite surface protein 119 [MSP-119]). Plasmodium falciparum infections were monitored through passive and active case detection. Seroprevalence to gSG6-P1, MSP-119, and CSP were 71.8% (95% Confidence interval [CI]: 70.9, 72.7), 68.6% (95% CI: 67.7, 69.5), and 8.6% (95% CI: 8.0, 9.2), respectively. Multivariate analysis showed that individuals with the highest Ab response to gSG6-P1 had six times the odds of being positive to CSP antigens (P < 0.001) and two times the odds of P. falciparum infection compared with low gSG6-P1 responders (P = 0.004). Spatial scan statistics revealed the presence of clusters of gSG6-P1 that partially overlapped P. falciparum infections. The gSG6-P1 salivary biomarker represents a good proxy for estimating P. falciparum malaria risk and could serve to implement hot spot-targeted vector control interventions to achieve malaria elimination.
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Affiliation(s)
- Phubeth Ya-Umphan
- Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle (IRD 224-CNRS 5290 UM1-UM2), Institut de Recherche pour le Développement (IRD), University of Montpellier, Montpellier, France
| | - Dominique Cerqueira
- Shoklo Malaria Research Unit, Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Tak, Thailand
| | - Gilles Cottrell
- Institut de Recherche pour le Développement (IRD), Université Paris Descartes, Sorbonne Paris Cité, UMR 216, Paris, France
| | - Daniel M Parker
- Department of Population Health and Disease Prevention, University of California, Irvine, California.,Shoklo Malaria Research Unit, Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Tak, Thailand
| | - Freya J I Fowkes
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Australia.,Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia.,Disease Elimination Program, Life Sciences, Burnet Institute, Melbourne, Australia
| | - Francois Nosten
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research Building, University of Oxford Old Road Campus, Oxford, United Kingdom.,Shoklo Malaria Research Unit, Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Tak, Thailand
| | - Vincent Corbel
- Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle (IRD 224-CNRS 5290 UM1-UM2), Institut de Recherche pour le Développement (IRD), University of Montpellier, Montpellier, France
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Brugman VA, Kristan M, Gibbins MP, Angrisano F, Sala KA, Dessens JT, Blagborough AM, Walker T. Detection of malaria sporozoites expelled during mosquito sugar feeding. Sci Rep 2018; 8:7545. [PMID: 29765136 PMCID: PMC5954146 DOI: 10.1038/s41598-018-26010-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 05/03/2018] [Indexed: 12/17/2022] Open
Abstract
Malaria is a severe disease of global importance transmitted by mosquitoes of the genus Anopheles. The ability to rapidly detect the presence of infectious mosquitoes able to transmit malaria is of vital importance for surveillance, control and elimination efforts. Current methods principally rely on large-scale mosquito collections followed by labour-intensive salivary gland dissections or enzyme-linked immunosorbent (ELISA) methods to detect sporozoites. Using forced salivation, we demonstrate here that Anopheles mosquitoes infected with Plasmodium expel sporozoites during sugar feeding. Expelled sporozoites can be detected on two sugar-soaked substrates, cotton wool and Whatman FTA cards, and sporozoite DNA is detectable using real-time PCR. These results demonstrate a simple and rapid methodology for detecting the presence of infectious mosquitoes with sporozoites and highlight potential laboratory applications for investigating mosquito-malaria interactions. Our results indicate that FTA cards could be used as a simple, effective and economical tool in enhancing field surveillance activities for malaria.
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Affiliation(s)
- V A Brugman
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.
- Evolution Biotechnologies, Colworth Science Park, Sharnbrook, Bedford, MK44 1LZ, UK.
| | - M Kristan
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - M P Gibbins
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - F Angrisano
- Department of Life Sciences, Sir Alexander Fleming Building, Imperial College London, Imperial College Road, South Kensington, London, SW7 2AZ, UK
| | - K A Sala
- Department of Life Sciences, Sir Alexander Fleming Building, Imperial College London, Imperial College Road, South Kensington, London, SW7 2AZ, UK
| | - J T Dessens
- Department of Pathogen Molecular Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - A M Blagborough
- Department of Life Sciences, Sir Alexander Fleming Building, Imperial College London, Imperial College Road, South Kensington, London, SW7 2AZ, UK
| | - T Walker
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
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Standley CJ, Graeden E, Kerr J, Sorrell EM, Katz R. Decision support for evidence-based integration of disease control: A proof of concept for malaria and schistosomiasis. PLoS Negl Trop Dis 2018; 12:e0006328. [PMID: 29649260 PMCID: PMC5896906 DOI: 10.1371/journal.pntd.0006328] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 02/19/2018] [Indexed: 11/19/2022] Open
Abstract
AUTHOR SUMMARY Designing and implementing effective programs for infectious disease control requires complex decision-making, informed by an understanding of the diseases, the types of disease interventions and control measures available, and the disease-relevant characteristics of the local community. Though disease modeling frameworks have been developed to address these questions and support decision-making, the complexity of current models presents a significant barrier to on-the-ground end users. The picture is further complicated when considering approaches for integration of different disease control programs, where co-infection dynamics, treatment interactions, and other variables must also be taken into account. Here, we describe the development of an application available on the internet with a simple user interface, to support on-the-ground decision-making for integrating disease control, given local conditions and practical constraints. The model upon which the tool is built provides predictive analysis for the effectiveness of integration of schistosomiasis and malaria control, two diseases with extensive geographical and epidemiological overlap. This proof-of-concept method and tool demonstrate significant progress in effectively translating the best available scientific models to support pragmatic decision-making on the ground, with the potential to significantly increase the impact and cost-effectiveness of disease control.
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Affiliation(s)
- Claire J. Standley
- Center for Global Health Science and Security, Georgetown University, Washington, DC, United States of America
- * E-mail:
| | - Ellie Graeden
- Talus Analytics, LLC, Lyons, CO, United States of America
| | - Justin Kerr
- Talus Analytics, LLC, Lyons, CO, United States of America
| | - Erin M. Sorrell
- Center for Global Health Science and Security, Georgetown University, Washington, DC, United States of America
| | - Rebecca Katz
- Center for Global Health Science and Security, Georgetown University, Washington, DC, United States of America
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Ryan SJ, Lippi CA, Boersch-Supan PH, Heydari N, Silva M, Adrian J, Noblecilla LF, Ayala EB, Encalada MD, Larsen DA, Krisher JT, Krisher L, Fregosi L, Stewart-Ibarra AM. Quantifying seasonal and diel variation in Anopheline and Culex human biting rates in Southern Ecuador. Malar J 2017; 16:479. [PMID: 29166907 PMCID: PMC5700746 DOI: 10.1186/s12936-017-2121-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 11/14/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Quantifying mosquito biting rates for specific locations enables estimation of mosquito-borne disease risk, and can inform intervention efforts. Measuring biting itself is fraught with ethical concerns, so the landing rate of mosquitoes on humans is often used as a proxy measure. Southern coastal Ecuador was historically endemic for malaria (Plasmodium falciparum and Plasmodium vivax), although successful control efforts in the 2000s eliminated autochthonous transmission (since 2011). This study presents an analysis of data collected during the elimination period. METHODS Human landing catch (HLC) data for three mosquito taxa: two malaria vectors, Anopheles albimanus and Anopheles punctimacula, and grouped Culex spp. were examined for this study. These data were collected by the National Vector Control Service of the Ministry of Health over a 5-year time span (2007-2012) in five cities in southern coastal Ecuador, at multiple households, in all months of the year, during dusk-dawn (18:00-6:00) hours, often at both indoor and outdoor locations. Hurdle models were used to determine if biting activity was fundamentally different for the three taxa, and to identify spatial and temporal factors influencing bite rate. Due to the many different approaches to studying and quantifying bite rates in the literature, a glossary of terms was created, to facilitate comparative studies in the future. RESULTS Biting trends varied significantly with species and time. All taxa exhibited exophagic feeding behavior, and outdoor locations increased both the odds and incidence of bites across taxa. Anopheles albimanus was most frequently observed biting, with an average of 4.7 bites/h. The highest and lowest respective months for significant biting activity were March and July for An. albimanus, July and August for An. punctimacula, and February and July for Culex spp. CONCLUSIONS Fine-scale differences in endophagy and exophagy, and temporal differences among months and hours exist in biting patterns among mosquito taxa in southern coastal Ecuador. This analysis provides detailed information for targeting vector control activities, and household level vector prevention strategies. These data were collected as part of routine vector surveillance conducted by the Ministry of Health, and such data have not been collected since. Reinstating such surveillance measures would provide important information to aid in preventing malaria re-emergence.
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Affiliation(s)
- Sadie J. Ryan
- Emerging Pathogens Institute, University of Florida, Gainesville, FL USA
- Department of Geography, University of Florida, Gainesville, FL USA
- Center for Global Health and Translational Science and Department of Medicine, State University of New York Upstate Medical University, Syracuse, NY USA
- College of Agriculture, Engineering, and Science, University of KwaZulu-Natal, Durban, South Africa
| | - Catherine A. Lippi
- Emerging Pathogens Institute, University of Florida, Gainesville, FL USA
- Department of Geography, University of Florida, Gainesville, FL USA
| | - Philipp H. Boersch-Supan
- Emerging Pathogens Institute, University of Florida, Gainesville, FL USA
- Department of Geography, University of Florida, Gainesville, FL USA
- Department of Integrative Biology, University of South Florida, Tampa, FL USA
| | - Naveed Heydari
- Center for Global Health and Translational Science and Department of Medicine, State University of New York Upstate Medical University, Syracuse, NY USA
| | - Mercy Silva
- Laboratorio Clínico Hospital Teófilo Dávila, Ministerio de Salud Pública, Machala, Ecuador
| | - Jefferson Adrian
- Center for Global Health and Translational Science and Department of Medicine, State University of New York Upstate Medical University, Syracuse, NY USA
| | | | - Efraín B. Ayala
- Facultad de Medicina, Universidad Técnica de Machala, Machala, Ecuador
| | - Mayling D. Encalada
- Dirección Nacional de Vigilancia Epidemiológica, Ministerio de Salud Pública, Av. República de El Salvador 36-64 y Suecia, 170515 Quito, Ecuador
| | - David A. Larsen
- Department of Public Health, Food Studies, and Nutrition, Syracuse University, Syracuse, NY USA
| | - Jesse T. Krisher
- Division of Nutritional Sciences, Cornell University, Ithaca, NY USA
| | - Lyndsay Krisher
- Center for Health, Work & Environment, Department of Environmental and Occupational Health, Colorado School of Public Health, University of Colorado Denver, Aurora, CO USA
- Colorado Consortium on Climate Change and Human Health, University of Colorado Denver, Aurora, CO USA
| | - Lauren Fregosi
- Emerging Pathogens Institute, University of Florida, Gainesville, FL USA
- Dirección Nacional de Vigilancia Epidemiológica, Ministerio de Salud Pública, Av. República de El Salvador 36-64 y Suecia, 170515 Quito, Ecuador
| | - Anna M. Stewart-Ibarra
- Center for Global Health and Translational Science and Department of Medicine, State University of New York Upstate Medical University, Syracuse, NY USA
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Drakeley C, Abdulla S, Agnandji ST, Fernandes JF, Kremsner P, Lell B, Mewono L, Bache BE, Mihayo MG, Juma O, Tanner M, Tahita MC, Tinto H, Diallo S, Lompo P, D'Alessandro U, Ogutu B, Otieno L, Otieno S, Otieno W, Oyieko J, Asante KP, Dery DBE, Adjei G, Adeniji E, Atibilla D, Owusu-Agyei S, Greenwood B, Gesase S, Lusingu J, Mahende C, Mongi R, Segeja M, Adjei S, Agbenyega T, Agyekum A, Ansong D, Bawa JT, Boateng HO, Dandalo L, Escamilla V, Hoffman I, Maenje P, Martinson F, Carter T, Leboulleux D, Kaslow DC, Usuf E, Pirçon JY, Bahmanyar ER. Longitudinal estimation of Plasmodium falciparum prevalence in relation to malaria prevention measures in six sub-Saharan African countries. Malar J 2017; 16:433. [PMID: 29078773 PMCID: PMC5658967 DOI: 10.1186/s12936-017-2078-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 10/19/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Plasmodium falciparum prevalence (PfPR) is a widely used metric for assessing malaria transmission intensity. This study was carried out concurrently with the RTS,S/AS01 candidate malaria vaccine Phase III trial and estimated PfPR over ≤ 4 standardized cross-sectional surveys. METHODS This epidemiology study (NCT01190202) was conducted in 8 sites from 6 countries (Burkina Faso, Gabon, Ghana, Kenya, Malawi, and Tanzania), between March 2011 and December 2013. Participants were enrolled in a 2:1:1 ratio according to age category: 6 months-4 years, 5-19 years, and ≥ 20 years, respectively, per year and per centre. All sites carried out surveys 1-3 while survey 4 was conducted only in 3 sites. Surveys were usually performed during the peak malaria parasite transmission season, in one home visit, when medical history and malaria risk factors/prevention measures were collected, and a blood sample taken for rapid diagnostic test, microscopy, and haemoglobin measurement. PfPR was estimated by site and age category. RESULTS Overall, 6401 (survey 1), 6411 (survey 2), 6400 (survey 3), and 2399 (survey 4) individuals were included in the analyses. In the 6 months-4 years age group, the lowest prevalence (assessed using microscopy) was observed in 2 Tanzanian centres (4.6% for Korogwe and 9.95% for Bagamoyo) and Lambaréné, Gabon (6.0%), while the highest PfPR was recorded for Nanoro, Burkina Faso (52.5%). PfPR significantly decreased over the 3 years in Agogo (Ghana), Kombewa (Kenya), Lilongwe (Malawi), and Bagamoyo (Tanzania), and a trend for increased PfPR was observed over the 4 surveys for Kintampo, Ghana. Over the 4 surveys, for all sites, PfPR was predominantly higher in the 5-19 years group than in the other age categories. Occurrence of fever and anaemia was associated with high P. falciparum parasitaemia. Univariate analyses showed a significant association of anti-malarial treatment in 4 surveys (odds ratios [ORs]: 0.52, 0.52, 0.68, 0.41) and bed net use in 2 surveys (ORs: 0.63, 0.68, 1.03, 1.78) with lower risk of malaria infection. CONCLUSION Local PfPR differed substantially between sites and age groups. In children 6 months-4 years old, a significant decrease in prevalence over the 3 years was observed in 4 out of the 8 study sites. Trial registration Clinical Trials.gov identifier: NCT01190202:NCT. GSK Study ID numbers: 114001.
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Affiliation(s)
- Chris Drakeley
- London School of Hygiene and Tropical Medicine, London, UK
| | - Salim Abdulla
- Ifakara Institute of Health, Bagamoyo Research and Training Centre, Bagamoyo District Hospital, P.O. Box 74, Bagamoyo, Tanzania.
| | - Selidji Todagbe Agnandji
- Albert Schweitzer Hospital, Lambaréné, Gabon and Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
| | - José Francisco Fernandes
- Albert Schweitzer Hospital, Lambaréné, Gabon and Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
| | - Peter Kremsner
- Albert Schweitzer Hospital, Lambaréné, Gabon and Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
| | - Bertrand Lell
- Albert Schweitzer Hospital, Lambaréné, Gabon and Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
| | - Ludovic Mewono
- Albert Schweitzer Hospital, Lambaréné, Gabon and Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
| | - Bache Emmanuel Bache
- Albert Schweitzer Hospital, Lambaréné, Gabon and Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
| | - Michael Gabriel Mihayo
- Ifakara Institute of Health, Bagamoyo Research and Training Centre, Bagamoyo District Hospital, P.O. Box 74, Bagamoyo, Tanzania
| | - Omar Juma
- Ifakara Institute of Health, Bagamoyo Research and Training Centre, Bagamoyo District Hospital, P.O. Box 74, Bagamoyo, Tanzania
| | - Marcel Tanner
- Ifakara Institute of Health, Bagamoyo Research and Training Centre, Bagamoyo District Hospital, P.O. Box 74, Bagamoyo, Tanzania.,Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | | | - Halidou Tinto
- Institut de Recherche en Sciences de la Santé, Nanoro, Burkina Faso
| | - Salou Diallo
- Institut de Recherche en Sciences de la Santé, Nanoro, Burkina Faso
| | | | - Umberto D'Alessandro
- London School of Hygiene and Tropical Medicine, London, UK.,Medical Research Council Unit, The Gambia, Banjul, Gambia
| | | | | | | | | | | | | | | | - George Adjei
- Kintampo Health Research Center, Kintampo, Ghana
| | | | | | - Seth Owusu-Agyei
- London School of Hygiene and Tropical Medicine, London, UK.,Kintampo Health Research Center, Kintampo, Ghana
| | - Brian Greenwood
- London School of Hygiene and Tropical Medicine, London, UK.,Kintampo Health Research Center, Kintampo, Ghana
| | - Samwel Gesase
- National Institute for Medical Research, Korogwe, Tanzania
| | - John Lusingu
- National Institute for Medical Research, Korogwe, Tanzania
| | - Coline Mahende
- National Institute for Medical Research, Korogwe, Tanzania
| | - Robert Mongi
- National Institute for Medical Research, Korogwe, Tanzania
| | - Method Segeja
- National Institute for Medical Research, Korogwe, Tanzania
| | - Samuel Adjei
- Kwame Nkrumah University of Science and Technology, Agogo, Ghana
| | - Tsiri Agbenyega
- Kwame Nkrumah University of Science and Technology, Agogo, Ghana
| | - Alex Agyekum
- Kwame Nkrumah University of Science and Technology, Agogo, Ghana
| | - Daniel Ansong
- Kwame Nkrumah University of Science and Technology, Agogo, Ghana
| | - John Tanko Bawa
- Kwame Nkrumah University of Science and Technology, Agogo, Ghana
| | | | | | | | | | - Peter Maenje
- University of North Carolina Project, Lilongwe, Malawi
| | | | - Terrell Carter
- The PATH Malaria Vaccine Initiative, Washington, D.C., USA
| | | | - David C Kaslow
- The PATH Malaria Vaccine Initiative, Washington, D.C., USA
| | - Effua Usuf
- Medical Research Council Unit, The Gambia, Banjul, Gambia.,GSK Vaccines, Wavre, Belgium
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Niass O, Saint-Pierre P, Niang M, Diop F, Diouf B, Faye MM, Sarr FD, Faye J, Diagne N, Sokhna C, Trape JF, Perraut R, Tall A, Diongue AK, Toure Balde A. Modelling dynamic change of malaria transmission in holoendemic setting (Dielmo, Senegal) using longitudinal measures of antibody prevalence to Plasmodium falciparum crude schizonts extract. Malar J 2017; 16:409. [PMID: 29020949 PMCID: PMC5637097 DOI: 10.1186/s12936-017-2052-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 10/04/2017] [Indexed: 11/25/2022] Open
Abstract
Background Evaluation of local Plasmodium falciparum malaria transmission has been investigated previously using the reversible catalytic model based on prevalence of antibody responses to single antigen to estimate seroconversion rates. High correlations were observed between seroconversion rates and entomological inoculation rates (EIR). However, in this model, the effects of malaria control interventions and clinical episodes on serological measurements were not assessed. This study monitors the use of antibody responses to P. falciparum crude extracts for assessing malaria transmission, compares seroconversion rates estimated from longitudinal data to those derived from cross-sectional surveys and investigates the effects of malaria control interventions on these measures in an area of declining malaria transmission. In addition, the validity of this model was evaluated by comparison with the alternative model. Methods Five cross-sectional surveys were carried out at the end of the wet season in Dielmo, a malaria-endemic Senegalese rural area in 2000, 2002, 2008, 2010 and 2012. Antibodies against schizonts crude extract of a local P. falciparum strain adapted to culture (Pf 07/03) were measured by ELISA. Age-specific seroprevalence model was used both for cross-sectional surveys and longitudinal data (combined data of all surveys). Results A total of 1504 plasma samples obtained through several years follow-up of 350 subjects was used in this study. Seroconversion rates based on P. falciparum schizonts crude extract were estimated for each cross-sectional survey and were found strongly correlated with EIR. High variability between SCRs from cross-sectional and longitudinal surveys was observed. In longitudinal studies, the alternative catalytic reversible model adjusted better with serological data than the catalytic model. Clinical malaria attacks and malaria control interventions were found to have significant effect on seroconversion. Discussion The results of the study suggested that crude extract was a good serological tool that could be used to assess the level of malaria exposure in areas where malaria transmission is declining. However, additional parameters such as clinical malaria and malaria control interventions must be taken into account for determining serological measurements for more accuracy in transmission assessment. Electronic supplementary material The online version of this article (doi:10.1186/s12936-017-2052-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Oumy Niass
- Immunology Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal.,Laboratoire d'étude et de Recherche en Statistique et Développement, Université Gaston Berger, BP 237, Saint-Louis, Senegal
| | | | - Makhtar Niang
- Immunology Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Fode Diop
- Immunology Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Babacar Diouf
- Immunology Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Michel Matar Faye
- Immunology Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Fatoumata Diène Sarr
- Epidemiology of Infectious Diseases Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Joseph Faye
- Epidemiology of Infectious Diseases Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Nafissatou Diagne
- Institut de Recherche pour le Développement, BP 1386, Dakar, Senegal
| | - Cheikh Sokhna
- Institut de Recherche pour le Développement, BP 1386, Dakar, Senegal
| | | | - Ronald Perraut
- Immunology Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Adama Tall
- Epidemiology of Infectious Diseases Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Abdou Kâ Diongue
- Laboratoire d'étude et de Recherche en Statistique et Développement, Université Gaston Berger, BP 237, Saint-Louis, Senegal
| | - Aïssatou Toure Balde
- Immunology Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal.
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Mburu MM, Mweresa CK, Omusula P, Hiscox A, Takken W, Mukabana WR. 2-Butanone as a carbon dioxide mimic in attractant blends for the Afrotropical malaria mosquitoes Anopheles gambiae and Anopheles funestus. Malar J 2017; 16:351. [PMID: 28836977 PMCID: PMC5571623 DOI: 10.1186/s12936-017-1998-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 08/20/2017] [Indexed: 11/21/2022] Open
Abstract
Background Most odour baits designed to attract host-seeking mosquitoes contain carbon dioxide (CO2), which enhances trap catches, given its role as a mosquito flight activator. However, the use of CO2 is expensive and logistically demanding for prolonged area-wide use. Methods This study explored the possibility of replacing organically-produced CO2 with 2-butanone in odour blends targeting host-seeking malaria mosquitoes. During semi-field and field experiments MM-X traps were baited with a human odour mimic (MB5 blend) plus CO2 or 2-butanone at varying concentrations. Unbaited traps formed a control. The attraction of Anopheles gambiae s.s., Anopheles arabiensis and Anopheles funestus to these differently baited traps was measured and mean catch sizes were compared to determine whether 2-butanone could form a viable replacement for CO2 for these target species. Results Under semi-field conditions significantly more female An. gambiae mosquitoes were attracted to a reference attractant blend (MB5 + CO2) compared to MB5 without CO2 (P < 0.001), CO2 alone (P < 0.001), or a trap without a bait (P < 0.001). Whereas MB5 + CO2 attracted significantly more mosquitoes than its variants containing MB5 plus different dilutions of 2-butanone (P = 0.001), the pure form (99.5%) and the 1.0% dilution of 2-butanone gave promising results. In the field mean indoor catches of wild female An. gambiae s.l. in traps containing MB5 + CO2 (5.07 ± 1.01) and MB5 + 99.5% 2-butanone (3.10 ± 0.65) did not differ significantly (P = 0.09). The mean indoor catches of wild female An. funestus attracted to traps containing MB5 + CO2 (3.87 ± 0.79) and MB5 + 99.5% 2-butanone (3.37 ± 0.70) were also similar (P = 0.635). Likewise, the mean outdoor catches of An. gambiae and An. funestus associated with MB5 + CO2 (1.63 ± 0.38 and 0.53 ± 0.17, respectively) and MB5 + 99.5% 2-butanone (1.33 ± 0.32 and 0.40 ± 0.14, respectively) were not significantly different (P = 0.544 and P = 0.533, respectively). Conclusion These results demonstrate that 2-butanone can serve as a good replacement for CO2 in synthetic blends of attractants designed to attract host-seeking An. gambiae s.l. and An. funestus mosquitoes. This development underscores the possibility of using odour-baited traps (OBTs) for monitoring and surveillance as well as control of malaria vectors and potentially other mosquito species.
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Affiliation(s)
- Monicah M Mburu
- International Centre of Insect Physiology and Ecology, P.O. Box 30772, Nairobi, 00100, Kenya.,School of Biological Sciences, University of Nairobi, P.O. Box 30197, Nairobi, 00100, Kenya.,Laboratory of Entomology, Wageningen University and Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
| | - Collins K Mweresa
- International Centre of Insect Physiology and Ecology, P.O. Box 30772, Nairobi, 00100, Kenya.,School of Biological and Physical Sciences, Jaramogi Oginga Odinga University of Science and Technology, P.O. Box 210, Bondo, 40601, Kenya.,Science for Health, P.O. Box 44970, Nairobi, 00100, Kenya
| | - Philemon Omusula
- International Centre of Insect Physiology and Ecology, P.O. Box 30772, Nairobi, 00100, Kenya.,International Centre for Aids Care and Treatment Program, Ministry of Health, Jaramogi Oginga Odinga Teaching and Referral Hospital, P.O. Box 849, Kisumu, 50100, Kenya
| | - Alexandra Hiscox
- Laboratory of Entomology, Wageningen University and Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
| | - Willem Takken
- Laboratory of Entomology, Wageningen University and Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
| | - Wolfgang R Mukabana
- International Centre of Insect Physiology and Ecology, P.O. Box 30772, Nairobi, 00100, Kenya. .,School of Biological Sciences, University of Nairobi, P.O. Box 30197, Nairobi, 00100, Kenya. .,Science for Health, P.O. Box 44970, Nairobi, 00100, Kenya.
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45
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Niare S, Almeras L, Tandina F, Yssouf A, Bacar A, Toilibou A, Doumbo O, Raoult D, Parola P. MALDI-TOF MS identification of Anopheles gambiae Giles blood meal crushed on Whatman filter papers. PLoS One 2017; 12:e0183238. [PMID: 28817629 PMCID: PMC5560667 DOI: 10.1371/journal.pone.0183238] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 08/01/2017] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Identification of the source of mosquito blood meals is an important component for disease control and surveillance. Recently, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) profiling has emerged as an effective tool for mosquito blood meal identification, using the abdomens of freshly engorged mosquitoes. In the field, mosquito abdomens are crushed on Whatman filter papers to determine the host feeding patterns by identifying the origin of their blood meals. The aim of this study was to test whether crushing engorged mosquito abdomens on Whatman filter papers was compatible with MALDI-TOF MS for mosquito blood meal identification. Both laboratory reared and field collected mosquitoes were tested. MATERIAL AND METHODS Sixty Anopheles gambiae Giles were experimentally engorged on the blood of six distinct vertebrate hosts (human, sheep, rabbit, dog, chicken and rat). The engorged mosquito abdomens were crushed on Whatman filter papers for MALDI-TOF MS analysis. 150 Whatman filter papers, with mosquitoes engorged on cow and goat blood, were preserved. A total of 77 engorged mosquito abdomens collected in the Comoros Islands and crushed on Whatman filter papers were tested with MALDI-TOF MS. RESULTS The MS profiles generated from mosquito engorged abdomens crushed on Whatman filter papers exhibited high reproducibility according to the original host blood. The blood meal host was correctly identified from mosquito abdomens crushed on Whatman filter papers by MALDI-TOF MS. The MS spectra obtained after storage were stable regardless of the room temperature and whether or not they were frozen. The MS profiles were reproducible for up to three months. For the Comoros samples, 70/77 quality MS spectra were obtained and matched with human blood spectra. This was confirmed by molecular tools. CONCLUSION The results demonstrated that MALDI-TOF MS could identify mosquito blood meals from Whatman filter papers collected in the field during entomological surveys. The application of MALDI-TOF MS has proved to be rapid and successful, making it a new and efficient tool for mosquito-borne disease surveillance.
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Affiliation(s)
- Sirama Niare
- Aix Marseille Université, Unité de Recherche en Maladies Infectieuses et Tropicales Emergentes (URMITE), UM63, CNRS 7278, IRD 198 (Dakar, Sénégal), Inserm 1095, AP-HM, IHU Méditerranée Infection, Marseille, France
- Malaria Research and Training Center, DEAP/FMOS, UMI 3189, University of Science, Techniques and Technology, Bamako, Mali
| | - Lionel Almeras
- Aix Marseille Université, Unité de Recherche en Maladies Infectieuses et Tropicales Emergentes (URMITE), UM63, CNRS 7278, IRD 198 (Dakar, Sénégal), Inserm 1095, AP-HM, IHU Méditerranée Infection, Marseille, France
- Unité de Parasitologie et d’Entomologie, Département des Maladies Infectieuses, Institut de Recherche Biomédicale des Armées, Marseille, France
| | - Fatalmoudou Tandina
- Aix Marseille Université, Unité de Recherche en Maladies Infectieuses et Tropicales Emergentes (URMITE), UM63, CNRS 7278, IRD 198 (Dakar, Sénégal), Inserm 1095, AP-HM, IHU Méditerranée Infection, Marseille, France
- Malaria Research and Training Center, DEAP/FMOS, UMI 3189, University of Science, Techniques and Technology, Bamako, Mali
| | - Amina Yssouf
- Malaria Control Program, Moroni, Union of the Comoros
| | - Affane Bacar
- Malaria Control Program, Moroni, Union of the Comoros
| | - Ali Toilibou
- Malaria Control Program, Moroni, Union of the Comoros
| | - Ogobara Doumbo
- Malaria Research and Training Center, DEAP/FMOS, UMI 3189, University of Science, Techniques and Technology, Bamako, Mali
| | - Didier Raoult
- Aix Marseille Université, Unité de Recherche en Maladies Infectieuses et Tropicales Emergentes (URMITE), UM63, CNRS 7278, IRD 198 (Dakar, Sénégal), Inserm 1095, AP-HM, IHU Méditerranée Infection, Marseille, France
| | - Philippe Parola
- Aix Marseille Université, Unité de Recherche en Maladies Infectieuses et Tropicales Emergentes (URMITE), UM63, CNRS 7278, IRD 198 (Dakar, Sénégal), Inserm 1095, AP-HM, IHU Méditerranée Infection, Marseille, France
- * E-mail:
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46
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Tétard M, Milet J, Dechavanne S, Fievet N, Dorin-Semblat D, Elion J, Fairhurst RM, Deloron P, Tuikue-Ndam N, Gamain B. Heterozygous HbAC but not HbAS is associated with higher newborn birthweight among women with pregnancy-associated malaria. Sci Rep 2017; 7:1414. [PMID: 28469130 PMCID: PMC5431107 DOI: 10.1038/s41598-017-01495-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 03/28/2017] [Indexed: 12/21/2022] Open
Abstract
Pregnancy-associated malaria (PAM) is associated with poor pregnancy outcomes. Hemoglobin S (HbS) and hemoglobin C (HbC) mutations are frequently encountered in malaria-endemic areas of Africa, where they protect children from severe and uncomplicated Plasmodium falciparum malaria. However, scant epidemiological data exist on the impact of these Hb variants on PAM. A prospective cohort of 635 Beninese pregnant women was recruited before 24 weeks of gestational age and followed until the end of pregnancy. HbAA, HbAC, and HbAS genotypes were determined and tested for association with pregnancy outcomes and PAM indicators using linear and logistic multivariate models. Newborns from HbAC mothers had higher birthweights than those from HbAA mothers among women infected at any time during pregnancy (mean difference 182.9 g, p = 0.08), or during the first half of pregnancy (654.3 g, p = 0.0006). No such birthweight differences were observed between newborns from HbAS and HbAA mothers. HbAC and HbAS were not associated with other pregnancy outcomes or PAM indicators. In conclusion, HbAC but not HbAS is associated with an improved birth outcome in pregnant women with documented PAM. Higher-birthweight newborns from HbAC mothers may have a survival advantage that contributes to the natural selection of HbC in malaria-endemic areas.
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Affiliation(s)
- Marilou Tétard
- Université Sorbonne Paris Cité, Université Paris Diderot, Inserm, INTS, Unité Biologie Intégrée du Globule Rouge, Laboratoire d'Excellence GR-Ex, Paris, France
| | - Jacqueline Milet
- Institut de Recherche pour le Développement, UMR 216, Mère et Enfant face aux Infections Tropicales, Paris, France.,COMUE Sorbonne Paris Cité, Faculté de Pharmacie, Paris, France
| | - Sébastien Dechavanne
- Université Sorbonne Paris Cité, Université Paris Diderot, Inserm, INTS, Unité Biologie Intégrée du Globule Rouge, Laboratoire d'Excellence GR-Ex, Paris, France
| | - Nadine Fievet
- Institut de Recherche pour le Développement, UMR 216, Mère et Enfant face aux Infections Tropicales, Paris, France.,COMUE Sorbonne Paris Cité, Faculté de Pharmacie, Paris, France
| | - Dominique Dorin-Semblat
- Université Sorbonne Paris Cité, Université Paris Diderot, Inserm, INTS, Unité Biologie Intégrée du Globule Rouge, Laboratoire d'Excellence GR-Ex, Paris, France
| | - Jacques Elion
- Université Sorbonne Paris Cité, Université Paris Diderot, Inserm, INTS, Unité Biologie Intégrée du Globule Rouge, Laboratoire d'Excellence GR-Ex, Paris, France
| | - Rick M Fairhurst
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Philippe Deloron
- Institut de Recherche pour le Développement, UMR 216, Mère et Enfant face aux Infections Tropicales, Paris, France.,COMUE Sorbonne Paris Cité, Faculté de Pharmacie, Paris, France
| | - Nicaise Tuikue-Ndam
- Institut de Recherche pour le Développement, UMR 216, Mère et Enfant face aux Infections Tropicales, Paris, France.,COMUE Sorbonne Paris Cité, Faculté de Pharmacie, Paris, France
| | - Benoît Gamain
- Université Sorbonne Paris Cité, Université Paris Diderot, Inserm, INTS, Unité Biologie Intégrée du Globule Rouge, Laboratoire d'Excellence GR-Ex, Paris, France.
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47
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Biggs J, Raman J, Cook J, Hlongwana K, Drakeley C, Morris N, Serocharan I, Agubuzo E, Kruger P, Mabuza A, Zitha A, Machaba E, Coetzee M, Kleinschmidt I. Serology reveals heterogeneity of Plasmodium falciparum transmission in northeastern South Africa: implications for malaria elimination. Malar J 2017; 16:48. [PMID: 28126001 PMCID: PMC5270351 DOI: 10.1186/s12936-017-1701-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 01/18/2017] [Indexed: 12/22/2022] Open
Abstract
Background It is widely acknowledged that modifications to existing control interventions are required if South Africa is to achieve malaria elimination. Targeting indoor residual spraying (IRS) to areas where cases have been detected is one strategy currently under investigation in northeastern South Africa. This seroprevalence baseline study, nested within a targeted IRS trial, was undertaken to provide insights into malaria transmission dynamics in South Africa and evaluate whether sero-epidemiological practices have the potential to be routinely incorporated into elimination programmes. Methods Filter-paper blood spots, demographic and household survey data were collected from 2710 randomly selected households in 56 study wards located in the municipalities of Ba-Phalaborwa and Bushbuckridge. Blood spots were assayed for Plasmodium falciparum apical membrane antigen-1 and merozoite surface protein-119 blood-stage antigens using an enzyme linked immunosorbent assay. Seroprevalence data were analysed using a reverse catalytic model to determine malaria seroconversion rates (SCR). Geospatial cluster analysis was used to investigate transmission heterogeneity while random effects logistic regression identified risk factors associated with malaria exposure. Results The overall SCR across the entire study site was 0.012 (95% CI 0.008–0.017) per year. Contrasting SCRs, corresponding to distinct geographical regions across the study site, ranging from <0.001 (95% CI <0.001–0.005) to 0.022 (95% CI 0.008–0.062) per annum revealed prominent transmission heterogeneity. Geospatial cluster analysis of household seroprevalence and age-adjusted antibody responses detected statistically significant (p < 0.05) spatial clusters of P. falciparum exposure. Formal secondary education was associated with lower malaria exposure in the sampled population (AOR 0.72, 95% CI 0.56–0.95, p = 0.018). Conclusions Although overall transmission intensity and exposure to malaria was low across both study sites, malaria transmission intensity was highly heterogeneous and associated with low socio-economic status in the region. Findings suggest focal targeting of interventions has the potential to be an appropriate strategy to deploy in South Africa. Furthermore, routinely incorporating sero-epidemiological practices into elimination programmes may prove useful in monitoring malaria transmission intensity in South Africa, and other countries striving for malaria elimination. Electronic supplementary material The online version of this article (doi:10.1186/s12936-017-1701-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Joseph Biggs
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Jaishree Raman
- Centre for Opportunistic Tropical and Hospital Infections, National Institute for Communicable Diseases, Johannesburg, South Africa. .,Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa. .,Institute for Sustainable Malaria Control, University of Pretoria, Pretoria, South Africa.
| | - Jackie Cook
- Tropical Epidemiology Group, Department of Infectious Diseases Epidemiology, London School of Hygiene and Tropical Medicine, London, UK
| | - Khumbulani Hlongwana
- School of Nursing and Public Health, University of KwaZulu-Natal, Durban, South Africa
| | - Chris Drakeley
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Natashia Morris
- Health GIS Centre, South Africa Medical Research Council, Durban, South Africa
| | - Ishen Serocharan
- Health GIS Centre, South Africa Medical Research Council, Durban, South Africa
| | - Eunice Agubuzo
- Centre for Opportunistic Tropical and Hospital Infections, National Institute for Communicable Diseases, Johannesburg, South Africa.,Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Philip Kruger
- Limpopo Provincial Malaria Control Programme, Polokwane, South Africa
| | - Aaron Mabuza
- Mpumalanga Provincial Malaria Control Programme, Nelspruit, South Africa
| | - Alpheus Zitha
- Mpumalanga Provincial Malaria Control Programme, Nelspruit, South Africa
| | - Elliot Machaba
- Limpopo Provincial Malaria Control Programme, Polokwane, South Africa
| | - Maureen Coetzee
- Centre for Opportunistic Tropical and Hospital Infections, National Institute for Communicable Diseases, Johannesburg, South Africa.,Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Immo Kleinschmidt
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.,Tropical Epidemiology Group, Department of Infectious Diseases Epidemiology, London School of Hygiene and Tropical Medicine, London, UK
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48
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Churcher TS, Sinden RE, Edwards NJ, Poulton ID, Rampling TW, Brock PM, Griffin JT, Upton LM, Zakutansky SE, Sala KA, Angrisano F, Hill AVS, Blagborough AM. Probability of Transmission of Malaria from Mosquito to Human Is Regulated by Mosquito Parasite Density in Naïve and Vaccinated Hosts. PLoS Pathog 2017; 13:e1006108. [PMID: 28081253 PMCID: PMC5230737 DOI: 10.1371/journal.ppat.1006108] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 12/02/2016] [Indexed: 11/19/2022] Open
Abstract
Over a century since Ronald Ross discovered that malaria is caused by the bite of an infectious mosquito it is still unclear how the number of parasites injected influences disease transmission. Currently it is assumed that all mosquitoes with salivary gland sporozoites are equally infectious irrespective of the number of parasites they harbour, though this has never been rigorously tested. Here we analyse >1000 experimental infections of humans and mice and demonstrate a dose-dependency for probability of infection and the length of the host pre-patent period. Mosquitoes with a higher numbers of sporozoites in their salivary glands following blood-feeding are more likely to have caused infection (and have done so quicker) than mosquitoes with fewer parasites. A similar dose response for the probability of infection was seen for humans given a pre-erythrocytic vaccine candidate targeting circumsporozoite protein (CSP), and in mice with and without transfusion of anti-CSP antibodies. These interventions prevented infection more efficiently from bites made by mosquitoes with fewer parasites. The importance of parasite number has widespread implications across malariology, ranging from our basic understanding of the parasite, how vaccines are evaluated and the way in which transmission should be measured in the field. It also provides direct evidence for why the only registered malaria vaccine RTS,S was partially effective in recent clinical trials. Malaria is transmitted to humans by the bite of an infectious mosquito though it is unclear whether a mosquito with a high number of parasites is more infectious than one with only a few. Here we show that the greater the number of parasites within the salivary gland of the mosquito following blood-feeding the more likely it is to have transmitted the disease. A clear dose-response is seen with highly infected mosquitoes being more likely to have caused infection (and to have done so quicker) than lightly infected mosquitoes. This suggesting that mosquito-based methods for measuring transmission in the field need to be refined as they currently only consider whether a mosquito is infected or not (and not how heavily infected the mosquito is). Novel transmission reducing drugs and vaccines are tested by experimentally infecting people using infectious mosquitoes. This work indicates that it is important to further standardise infectious dose in malaria experimental infections to enable the efficacy of new interventions to be accurately compared. The work also provides direct evidence to suggest that the world’s first licenced malaria vaccine may be partially effective because it fails to provide protection against highly infected mosquitoes.
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Affiliation(s)
- Thomas S. Churcher
- MRC Centre for Outbreak Analysis and Modelling, Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
- * E-mail:
| | - Robert E. Sinden
- Department of Life Sciences, Imperial College London, South Kensington, London, United Kingdom
- The Jenner Institute, University of Oxford, Roosevelt Drive, Oxford, United Kingdom
| | - Nick J. Edwards
- The Jenner Institute, University of Oxford, Roosevelt Drive, Oxford, United Kingdom
| | - Ian D. Poulton
- The Jenner Institute, University of Oxford, Roosevelt Drive, Oxford, United Kingdom
| | - Thomas W. Rampling
- The Jenner Institute, University of Oxford, Roosevelt Drive, Oxford, United Kingdom
| | - Patrick M. Brock
- MRC Centre for Outbreak Analysis and Modelling, Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Jamie T. Griffin
- MRC Centre for Outbreak Analysis and Modelling, Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Leanna M. Upton
- Department of Life Sciences, Imperial College London, South Kensington, London, United Kingdom
| | - Sara E. Zakutansky
- Department of Life Sciences, Imperial College London, South Kensington, London, United Kingdom
| | - Katarzyna A. Sala
- Department of Life Sciences, Imperial College London, South Kensington, London, United Kingdom
| | - Fiona Angrisano
- Department of Life Sciences, Imperial College London, South Kensington, London, United Kingdom
| | - Adrian V. S. Hill
- The Jenner Institute, University of Oxford, Roosevelt Drive, Oxford, United Kingdom
| | - Andrew M. Blagborough
- Department of Life Sciences, Imperial College London, South Kensington, London, United Kingdom
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49
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Kulkarni MA, Garrod G, Berrang-Ford L, Ssewanyana I, Harper SL, Baraheberwa N, Donnelly B, Patterson K, Namanya DB, Lwasa S, Drakeley C. Examination of Antibody Responses as a Measure of Exposure to Malaria in the Indigenous Batwa and Their Non-Indigenous Neighbors in Southwestern Uganda. Am J Trop Med Hyg 2016; 96:330-334. [PMID: 27895271 DOI: 10.4269/ajtmh.16-0559] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 10/20/2016] [Indexed: 01/27/2023] Open
Abstract
Understanding variations in malaria transmission and exposure is critical to identify populations at risk and enable better targeting of interventions. The indigenous Batwa of southwestern Uganda have a disproportionate burden of malaria infection compared with their non-indigenous neighbors. To better understand the individual- and community-level determinants of malaria exposure, a seroepidemiological study was conducted in 10 local council cells in Kanungu District, Uganda, in April 2014. The Batwa had twice the odds of being seropositive to two Plasmodium falciparum-specific antigens, apical membrane antigen-1 and merozoite surface protein-119, compared with the non-indigenous Bakiga (odds ratio = 2.08, 95% confidence interval = 1.51-2.88). This trend was found irrespective of altitude level and after controlling for cell location. Seroconversion rates in the Batwa were more than twice those observed in the Bakiga. For the Batwa, multiple factors may be associated with higher exposure to malaria and antibody levels relative to their non-indigenous neighbors.
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Affiliation(s)
- Manisha A Kulkarni
- School of Epidemiology, Public Health and Preventive Medicine, University of Ottawa, Ottawa, Canada.
| | - Gala Garrod
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Lea Berrang-Ford
- Department of Geography, McGill University, Montreal, Canada.,Indigenous Health Adaptation to Climate Change (IHACC) Research Team
| | - Isaac Ssewanyana
- London School of Hygiene and Tropical Medicine, London, United Kingdom.,Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Sherilee L Harper
- Indigenous Health Adaptation to Climate Change (IHACC) Research Team.,Department of Population Medicine, University of Guelph, Guelph, Canada
| | | | | | - Kaitlin Patterson
- Department of Geography, McGill University, Montreal, Canada.,Department of Population Medicine, University of Guelph, Guelph, Canada
| | - Didacus B Namanya
- Indigenous Health Adaptation to Climate Change (IHACC) Research Team.,Department of Population Medicine, University of Guelph, Guelph, Canada.,Infectious Diseases Research Collaboration, Kampala, Uganda.,Ministry of Health, Kampala, Uganda
| | - Shuaib Lwasa
- Indigenous Health Adaptation to Climate Change (IHACC) Research Team.,Infectious Diseases Research Collaboration, Kampala, Uganda.,Makerere University, Kampala, Uganda
| | - Chris Drakeley
- London School of Hygiene and Tropical Medicine, London, United Kingdom
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50
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Stevenson JC, Pinchoff J, Muleba M, Lupiya J, Chilusu H, Mwelwa I, Mbewe D, Simubali L, Jones CM, Chaponda M, Coetzee M, Mulenga M, Pringle JC, Shields T, Curriero FC, Norris DE. Spatio-temporal heterogeneity of malaria vectors in northern Zambia: implications for vector control. Parasit Vectors 2016; 9:510. [PMID: 27655231 PMCID: PMC5031275 DOI: 10.1186/s13071-016-1786-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 09/01/2016] [Indexed: 11/16/2022] Open
Abstract
Background Despite large reductions in malaria burden across Zambia, some regions continue to experience extremely high malaria transmission. In Nchelenge District, Luapula Province, northern Zambia, almost half the human population carries parasites. Intervention coverage has increased substantially over the past decade, but comprehensive district-wide entomological studies to guide delivery of vector control measures are lacking. This study describes the bionomics and spatio-temporal patterns of malaria vectors in Nchelenge over a two and a half year period, investigates what household factors are associated with high vector densities and determines why vector control may not have been effective in the past to better guide future control efforts. Methods Between April 2012 and September 2014, twenty-seven households from across Nchelenge District were randomly selected for monthly light trap collections of mosquitoes. Anopheline mosquitoes were identified morphologically and molecularly to species. Foraging rates were estimated and sporozoite rates were determined by circumsporozoite ELISAs to calculate annual entomological inoculation rates. Blood feeding rates and host preference were determined by PCR. Zero-inflated negative binomial models measured environmental and household factors associated with mosquito abundance at study households such as season, proximity to the lake, and use of vector control measures. Results The dominant species in Nchelenge was An. funestus (s.s.) with An. gambiae (s.s.) as a secondary vector. Both vectors were found together in large numbers across the district and the combined EIRs of the two vectors exceeded 80 infectious bites per person per annum. An. funestus household densities increased in the dry season whilst An. gambiae surged during the rains. Presence of insecticide treated nets (ITNs) and closed eaves in the houses were found to be associated with fewer numbers of An. gambiae but not An. funestus. There was no association with indoor residual spraying (IRS). Conclusion In Nchelenge, the co-existence of two highly anthropophagic vectors, present throughout the year, is likely to be driving the high malaria transmission evident in the district. The vectors here have been shown to be highly resistant to pyrethroids used for IRS during the study. Vector control interventions in this area would have to be multifaceted and district-wide for effective control of malaria. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1786-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jennifer C Stevenson
- The W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD, 21205, USA. .,Macha Research Trust, P.O. Box 630166, Choma, Zambia.
| | - Jessie Pinchoff
- The W. Harry Feinstone Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD, 21205, USA
| | - Mbanga Muleba
- Tropical Diseases Research Centre Room 727, Ndola Central Hospital, P.O. Box 71769, Ndola, Zambia
| | - James Lupiya
- Tropical Diseases Research Centre Room 727, Ndola Central Hospital, P.O. Box 71769, Ndola, Zambia
| | - Hunter Chilusu
- Tropical Diseases Research Centre Room 727, Ndola Central Hospital, P.O. Box 71769, Ndola, Zambia
| | - Ian Mwelwa
- Tropical Diseases Research Centre Room 727, Ndola Central Hospital, P.O. Box 71769, Ndola, Zambia
| | - David Mbewe
- Tropical Diseases Research Centre Room 727, Ndola Central Hospital, P.O. Box 71769, Ndola, Zambia
| | | | - Christine M Jones
- The W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD, 21205, USA
| | - Mike Chaponda
- Tropical Diseases Research Centre Room 727, Ndola Central Hospital, P.O. Box 71769, Ndola, Zambia
| | - Maureen Coetzee
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Modest Mulenga
- Tropical Diseases Research Centre Room 727, Ndola Central Hospital, P.O. Box 71769, Ndola, Zambia
| | - Julia C Pringle
- The W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD, 21205, USA
| | - Tim Shields
- The W. Harry Feinstone Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD, 21205, USA
| | - Frank C Curriero
- The W. Harry Feinstone Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD, 21205, USA
| | - Douglas E Norris
- The W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD, 21205, USA
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