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Kientega M, Clarkson CS, Traoré N, Hui TYJ, O'Loughlin S, Millogo AA, Epopa PS, Yao FA, Belem AMG, Brenas J, Miles A, Burt A, Diabaté A. Whole-genome sequencing of major malaria vectors reveals the evolution of new insecticide resistance variants in a longitudinal study in Burkina Faso. Malar J 2024; 23:280. [PMID: 39285410 PMCID: PMC11406867 DOI: 10.1186/s12936-024-05106-7] [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: 05/08/2024] [Accepted: 09/08/2024] [Indexed: 09/19/2024] Open
Abstract
BACKGROUND Intensive deployment of insecticide based malaria vector control tools resulted in the rapid evolution of phenotypes resistant to these chemicals. Understanding this process at the genomic level is important for the deployment of successful vector control interventions. Therefore, longitudinal sampling followed by whole genome sequencing (WGS) is necessary to understand how these evolutionary processes evolve over time. This study investigated the change in genetic structure and the evolution of the insecticide resistance variants in natural populations of Anopheles gambiae over time and space from 2012 to 2017 in Burkina Faso. METHODS New genomic data have been generated from An. gambiae mosquitoes collected from three villages in the western part of Burkina Faso between 2012 and 2017. The samples were whole-genome sequenced and the data used in the An. gambiae 1000 genomes (Ag1000G) project as part of the Vector Observatory. Genomic data were analysed using the analysis pipeline previously designed by the Ag1000G project. RESULTS The results showed similar and consistent nucleotide diversity and negative Tajima's D between An. gambiae sensu stricto (s.s.) and Anopheles coluzzii. Principal component analysis (PCA) and the fixation index (FST) showed a clear genetic structure in the An. gambiae sensu lato (s.l.) species. Genome-wide FST and H12 scans identified genomic regions under divergent selection that may have implications in the adaptation to ecological changes. Novel voltage-gated sodium channel pyrethroid resistance target-site alleles (V402L, I1527T) were identified at increasing frequencies alongside the established alleles (Vgsc-L995F, Vgsc-L995S and N1570Y) within the An. gambiae s.l. POPULATIONS Organophosphate metabolic resistance markers were also identified, at increasing frequencies, within the An. gambiae s.s. populations from 2012 to 2017, including the SNP Ace1-G280S and its associated duplication. Variants simultaneously identified in the same vector populations raise concerns about the long-term efficacy of new generation bed nets and the recently organophosphate pirimiphos-methyl indoor residual spraying in Burkina Faso. CONCLUSION These findings highlighted the benefit of genomic surveillance of malaria vectors for the detection of new insecticide resistance variants, the monitoring of the existing resistance variants, and also to get insights into the evolutionary processes driving insecticide resistance.
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Affiliation(s)
- Mahamadi Kientega
- Institut de Recherche en Sciences de la Santé (IRSS), 01 BP 545, Bobo-Dioulasso 01, Burkina Faso.
- Université Nazi Boni, 01 BP 1091, Bobo-Dioulasso, Burkina Faso.
| | - Chris S Clarkson
- Vector Surveillance Programme, Genomic Surveillance Unit, Wellcome Sanger Institute, Hinxton, Cambridge, UK
| | - Nouhoun Traoré
- Institut de Recherche en Sciences de la Santé (IRSS), 01 BP 545, Bobo-Dioulasso 01, Burkina Faso
- Université Nazi Boni, 01 BP 1091, Bobo-Dioulasso, Burkina Faso
| | - Tin-Yu J Hui
- Department of Life Sciences, Imperial College London, Silwood Park, Ascot, SL5 7PY, UK
| | - Samantha O'Loughlin
- Department of Life Sciences, Imperial College London, Silwood Park, Ascot, SL5 7PY, UK
| | - Abdoul-Azize Millogo
- Institut de Recherche en Sciences de la Santé (IRSS), 01 BP 545, Bobo-Dioulasso 01, Burkina Faso
- Institut des Sciences des Sociétés, 03 BP 7047, Ouagadougou 03, Burkina Faso
| | - Patric Stephane Epopa
- Institut de Recherche en Sciences de la Santé (IRSS), 01 BP 545, Bobo-Dioulasso 01, Burkina Faso
| | - Franck A Yao
- Institut de Recherche en Sciences de la Santé (IRSS), 01 BP 545, Bobo-Dioulasso 01, Burkina Faso
| | | | - Jon Brenas
- Vector Surveillance Programme, Genomic Surveillance Unit, Wellcome Sanger Institute, Hinxton, Cambridge, UK
| | - Alistair Miles
- Vector Surveillance Programme, Genomic Surveillance Unit, Wellcome Sanger Institute, Hinxton, Cambridge, UK
| | - Austin Burt
- Department of Life Sciences, Imperial College London, Silwood Park, Ascot, SL5 7PY, UK
| | - Abdoulaye Diabaté
- Institut de Recherche en Sciences de la Santé (IRSS), 01 BP 545, Bobo-Dioulasso 01, Burkina Faso.
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Mahenge HH, Muyaga LL, Nkya JD, Kafwenji AD, Mwalugelo YA, Kahamba NF, Ngowo HS, Kaindoa EW. Semi-field evaluation of aquatic predators for the control of Anopheles funestus in rural south-eastern Tanzania. Malar J 2024; 23:228. [PMID: 39090658 PMCID: PMC11295350 DOI: 10.1186/s12936-024-05055-1] [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: 08/30/2023] [Accepted: 07/24/2024] [Indexed: 08/04/2024] Open
Abstract
BACKGROUND Biological control is a promising alternative or complementary approach for controlling vector populations in response to the spread of insecticide resistance in malaria vectors. This study evaluated the efficacy of three selected potential predators on the density and fitness parameters of Anopheles funestus larvae in rural Tanzania. METHODS Common predator families Aeshnidae (dragonflies), Coenagrionidae (damselflies), and Notonectidae (backswimmers) and An. funestus group larvae were collected from natural aquatic habitats in rural south-eastern Tanzania. Predators were starved for 12-h while An. funestus larvae were given fish food before starting the experiment. Anopheles funestus larvae were placed into artificial habitats containing predators, exposing them to potential predation. The number of surviving An. funestus larvae were counted every 24-h. An emergence traps were placed at the top of artificial habitats to capture emerging mosquitoes. Emerged mosquitoes were monitored until they died. Female wings were measured and used as a proxy for body size. Generalized linear mixed models (GLMM) with binomial variates at 95% CI and Cox proportional hazard models were used to assess the proportion of dead mosquitoes and the daily survival determined. RESULTS There were significant differences in the number of emerged mosquitoes between the treatment and control groups (P < 0.001). Thus, all predator species played a significant role in reducing the density of An. funestus mosquitoes (P < 0.001). Furthermore, these predators had notable effects on the fitness parameters and survival of emerged mosquitoes (P < 0.001). Among the three predators studied, Coenagrionidae (damselflies) were most efficient followed by Notonectidae (backswimmers), with Aeshnidae (dragonflies) being the least efficient. CONCLUSION Selected aquatic predators have the potential to reduce the survival and density of An. funestus larvae. They might eventually be included within an integrated malaria vector control strategy, ultimately leading to a reduction in malaria transmission.
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Affiliation(s)
- Herieth H Mahenge
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania.
- School of Life Sciences and Bio Engineering, The Nelson Mandela, African Institution of Science and Technology, Tengeru, Arusha, United Republic of Tanzania.
| | - Letus L Muyaga
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow, UK
| | - Joel D Nkya
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
| | - Andrew D Kafwenji
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
| | - Yohana A Mwalugelo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
- Department of Biomedical Sciences, Jaramogi Oginga Odinga University of Science and Technology, P. O Box 210-40601, Bondo, Kenya
| | - Najat F Kahamba
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow, UK
| | - Halfan S Ngowo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow, UK
| | - Emmanuel W Kaindoa
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
- School of Life Sciences and Bio Engineering, The Nelson Mandela, African Institution of Science and Technology, Tengeru, Arusha, United Republic of Tanzania
- Faculty of Health Sciences, School of Pathology, The Centre for Emerging Zoonotic and Parasitic Diseases, Wits Research Institute for Malaria, National Institute for Communicable Diseases, University of the Witwatersrand, Johannesburg, South Africa
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Gari T, Lindtjørn B. Insecticide-treated bed nets and residual indoor spraying reduce malaria in areas with low transmission: a reanalysis of the Maltrials study. Malar J 2024; 23:67. [PMID: 38439099 PMCID: PMC10913548 DOI: 10.1186/s12936-024-04894-2] [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: 08/25/2023] [Accepted: 02/28/2024] [Indexed: 03/06/2024] Open
Abstract
BACKGROUND The malaria incidence data from a malaria prevention study from the Rift Valley, Central Ethiopia, were reanalysed. The objective was to investigate whether including an administrative structure within the society, which may have required consideration in the protocol or previous analysis, would provide divergent outcomes on the effect measures of the interventions. METHODS A cluster-randomized controlled trial lasting 121 weeks with 176 clusters in four groups with 6071 households with 34,548 persons was done: interventions combining indoor residual spraying (IRS) and insecticide-treated nets (ITNs), IRS alone, ITNs alone and routine use. The primary outcome was malaria incidence. A multilevel negative binomial regression model was employed to examine the impact of the kebele (smallest administrative unit) and the proximity of homes to the primary mosquito breeding sites as potential residual confounders (levels). The study also assessed whether these factors influenced the effect measures of the interventions. RESULTS The study's initial findings revealed 1183 malaria episodes among 1059 persons, with comparable effects observed across the four intervention groups. In the reanalysis, the results showed that both ITN + IRS (incidence rate ratio [IRR] 0.63, P < 0.001) and ITN alone (IRR 0.78, P = 0.011) were associated with a greater reduction in malaria cases compared to IRS (IRR 0.90; P = 0.28) or the control (reference) group. The combined usage of IRS with ITN yields better outcomes compared to the standalone use of ITN and surpasses the effectiveness of IRS in isolation. CONCLUSION The findings indicate that implementing a combination of IRS and ITN and also ITN alone decrease malaria incidence. Furthermore, there was an observed synergistic impact when ITN and IRS were used in combination. Considering relevant social structures as potential residual confounders is of paramount importance. TRIAL REGISTRATION PACTR201411000882128 (08 September 2014).
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Affiliation(s)
- Taye Gari
- School of Public Health, Hawassa University, Hawassa, Ethiopia
| | - Bernt Lindtjørn
- School of Public Health, Hawassa University, Hawassa, Ethiopia.
- Centre for International Health, University of Bergen, Bergen, Norway.
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Damien BG, Kesteman T, Dossou-Yovo GA, Dahounto A, Henry MC, Rogier C, Remoué F. Long-Lasting Insecticide-Treated Nets Combined or Not with Indoor Residual Spraying May Not Be Sufficient to Eliminate Malaria: A Case-Control Study, Benin, West Africa. Trop Med Infect Dis 2023; 8:475. [PMID: 37888603 PMCID: PMC10611126 DOI: 10.3390/tropicalmed8100475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 10/09/2023] [Accepted: 10/09/2023] [Indexed: 10/28/2023] Open
Abstract
In sub-Saharan Africa, despite the implementation of multiple control interventions, the prevalence of malaria infection and clinical cases remains high. The primary tool for vector control against malaria in this region is the use of long-lasting insecticide-treated nets (LLINs) combined or not with indoor residual spraying (IRS) to achieve a synergistic effect in protection. The objective of this study was to assess the effectiveness of LLINs, with or without IRS, protected against Plasmodium falciparum infection and uncomplicated clinical cases (UCC) of malaria in Benin. A case-control study was conducted, encompassing all age groups, in the urban area of Djougou and the rural area of Cobly. A cross-sectional survey was conducted that included 2080 individuals in the urban area and 2770 individuals in the rural area. In the urban area, sleeping under LLINs did not confer significant protection against malaria infection and UCC when compared to no intervention. However, certain neighbourhoods benefited from a notable reduction in infection rates ranging from 65% to 85%. In the rural area, the use of LLINs alone, IRS alone, or their combination did not provide additional protection compared to no intervention. IRS alone and LLINs combined with IRS provided 61% and 65% protection against malaria infection, respectively, compared to LLINs alone. The effectiveness of IRS alone and LLINs combined with IRS against UCC was 52% and 54%, respectively, when compared to LLINs alone. In both urban and rural areas, the use of LLINs alone, IRS alone, and their combination did not demonstrate significant individual protection against malaria infection and clinical cases when compared to no intervention. In the conditions of this study, LLINs combined or not with IRS are not effective enough to eliminate malaria. In addition to the interventions, this study identified factors associated with malaria in Benin as housing design, neglected social groups like gender-marginalised individuals and adolescents, and socio-economic conditions acting as barriers to effective malaria prevention. Addressing these factors is crucial in order to facilitate malaria elimination efforts in sub-Saharan Africa.
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Affiliation(s)
- Barikissou G. Damien
- MIVEGEC (Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle), Université de Montpellier, CNRS, IRD, 911 Avenue Agropolis BP 64501, 34394 Montpellier, France; (G.A.D.-Y.); (A.D.); (M.-C.H.); (F.R.)
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou 06 BP 2604, Benin
| | - Thomas Kesteman
- Malaria Research Unit, Institute Pasteur de Madagascar, BP 1274 Avaradoha, Antananarivo 101, Madagascar; (T.K.); (C.R.)
| | - Gatien A. Dossou-Yovo
- MIVEGEC (Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle), Université de Montpellier, CNRS, IRD, 911 Avenue Agropolis BP 64501, 34394 Montpellier, France; (G.A.D.-Y.); (A.D.); (M.-C.H.); (F.R.)
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou 06 BP 2604, Benin
| | - Amal Dahounto
- MIVEGEC (Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle), Université de Montpellier, CNRS, IRD, 911 Avenue Agropolis BP 64501, 34394 Montpellier, France; (G.A.D.-Y.); (A.D.); (M.-C.H.); (F.R.)
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou 06 BP 2604, Benin
| | - Marie-Claire Henry
- MIVEGEC (Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle), Université de Montpellier, CNRS, IRD, 911 Avenue Agropolis BP 64501, 34394 Montpellier, France; (G.A.D.-Y.); (A.D.); (M.-C.H.); (F.R.)
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou 06 BP 2604, Benin
| | - Christophe Rogier
- Malaria Research Unit, Institute Pasteur de Madagascar, BP 1274 Avaradoha, Antananarivo 101, Madagascar; (T.K.); (C.R.)
- Primum Vitare, 118 Avenue Félix Faure, 75015 Paris, France
| | - Franck Remoué
- MIVEGEC (Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle), Université de Montpellier, CNRS, IRD, 911 Avenue Agropolis BP 64501, 34394 Montpellier, France; (G.A.D.-Y.); (A.D.); (M.-C.H.); (F.R.)
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou 06 BP 2604, Benin
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Sagna AB, Zéla L, Ouedraogo COW, Pooda SH, Porciani A, Furnival-Adams J, Lado P, Somé AF, Pennetier C, Chaccour CJ, Dabiré RK, Mouline K. Ivermectin as a novel malaria control tool: Getting ahead of the resistance curse. Acta Trop 2023; 245:106973. [PMID: 37352998 DOI: 10.1016/j.actatropica.2023.106973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 06/14/2023] [Accepted: 06/16/2023] [Indexed: 06/25/2023]
Abstract
Reduction in malaria clinical cases is strongly dependent on the ability to prevent Anopheles infectious bites. Vector control strategies using long-lasting insecticidal nets and indoor residual spraying with insecticides have contributed to significantly reduce the incidence of malaria in many endemic countries, especially in the Sub-Saharan region. However, global progress in reducing malaria cases has plateaued since 2015 mostly due to the increased insecticide resistance and behavioral changes in Anopheles vectors. Additional control strategies are thus required to further reduce the burden of malaria and contain the spread of resistant and invasive Anopheles vectors. The use of endectocides such as ivermectin as an additional malaria control tool is now receiving increased attention, driven by its different mode of action compared to insecticides used so far and its excellent safety record for humans. In this opinion article, we discuss the advantages and disadvantages of using ivermectin for malaria control with a focus on the risk of selecting ivermectin resistance in malaria vectors. We also highlight the importance of understanding how ivermectin resistance could develop in mosquitoes and what its underlying mechanisms and associated molecular markers are, and propose a research agenda to manage this phenomenon.
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Affiliation(s)
- André B Sagna
- MIVEGEC, University of Montpellier, IRD, CNRS, Montpellier, France.
| | - Lamidi Zéla
- Centre International de Recherche-Développement sur l'Elevage en zone Subhumide, Bobo-Dioulasso, Burkina Faso
| | - Cheick Oumar W Ouedraogo
- Institut de Recherche en Sciences de la Santé, Direction Régionale de l'Ouest, Centre National de Recherche Scientifique et Technologique, Bobo-Dioulasso, Burkina Faso
| | - Sié H Pooda
- Centre International de Recherche-Développement sur l'Elevage en zone Subhumide, Bobo-Dioulasso, Burkina Faso; Université de Dédougou, Dédougou, Burkina Faso
| | | | | | - Paula Lado
- Center for Vector-borne Infectious Diseases, Colorado State University, Fort Collins, CO, USA
| | - Anyirékun F Somé
- Institut de Recherche en Sciences de la Santé, Direction Régionale de l'Ouest, Centre National de Recherche Scientifique et Technologique, Bobo-Dioulasso, Burkina Faso
| | - Cédric Pennetier
- MIVEGEC, University of Montpellier, IRD, CNRS, Montpellier, France
| | - Carlos J Chaccour
- ISGlobal, Barcelona Institute for Global Health, Barcelona, Spain; Centro de Investigación Biomédica en Red de Enfermedades Infecciosas, Madrid, Spain; Universidad de Navarra, Pamplona, Spain
| | - Roch K Dabiré
- Institut de Recherche en Sciences de la Santé, Direction Régionale de l'Ouest, Centre National de Recherche Scientifique et Technologique, Bobo-Dioulasso, Burkina Faso
| | - Karine Mouline
- MIVEGEC, University of Montpellier, IRD, CNRS, Montpellier, France
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Ayele T, Wondale B, Tamiru G, Eligo N, Lindtjørn B, Massebo F. Infectivity of symptomatic Plasmodium vivax cases to different generations of wild-caught and laboratory-adapted Anopheles arabiensis using a membrane feeding assay, Ethiopia. CURRENT RESEARCH IN PARASITOLOGY & VECTOR-BORNE DISEASES 2023; 4:100137. [PMID: 37637351 PMCID: PMC10457422 DOI: 10.1016/j.crpvbd.2023.100137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Revised: 07/18/2023] [Accepted: 07/22/2023] [Indexed: 08/29/2023]
Abstract
When measuring human to mosquito transmission of Plasmodium spp., laboratory-adapted (colony) mosquitoes can be utilized. To connect transmission studies to the local epidemiology, it can be important to comprehend the relationship between infectivity in laboratory-adapted (colony) and wild-caught (wild) mosquitoes of the same species. Microscopically confirmed Plasmodium vivax cases were recruited from health facilities in Arba Minch town, and a nested polymerase chain reaction (nPCR) was used for subsequent confirmation. We performed paired membrane-feeding assays using colony An. arabiensis and three generations of wild origin An. arabiensis. Anopheles arabiensis aged 3-6 days were fed after being starved for 8-14 h. Microscopically, the oocyst development was evaluated at day 7 after feeding. Circumsporozoite proteins (CSPs) assay was carried out by enzyme-linked immunosorbent assay (ELISA). In 19 paired feeding experiments, the feeding efficiency was more than doubled in colony (median: 62.5%; interquartile range, IQR: 35-78%) than in wild mosquitoes (median: 28.5%; IQR: 17.5-40%; P < 0.001). Among the 19 P. vivax gametocyte-positive blood samples, 63.2% (n = 12) were infective to wild An. arabiensis and 73.7% (n = 14) were infective to colony An. arabiensis. The median infection rate was twice as high (26%) in the colony than in the wild (13%) An. arabiensis, although the difference was marginally insignificant (P = 0.06). Although the observed difference was not statistically significant (P = 0.19), the median number of oocysts per midgut was more than twice as high (17.8/midgut) in colony than in wild (7.2/midgut) An. arabiensis. The median feeding efficiency was 26.5% (IQR: 18-37%) in F1, 29.3% (IQR: 28-40%) in F2 and 31.2% (IQR: 30-37%) in F3 generations of wild An. arabiensis. Also, no significant difference was observed in oocyst infection rate and load between generations of wild An. arabiensis. CSP rate of P. vivax was 3.1% (3/97; 95% CI: 0.6-8.8%) in wild and 3.6% (3/84; 95% CI: 0.7-10.1%) in colony An. arabiensis. The results of the present study revealed that oocyst infection and load/midgut, and CSP rate were roughly comparable, indicating that colony mosquitoes can be employed for infectivity studies, while larger sample sizes may be necessary in future studies.
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Affiliation(s)
- Tenaye Ayele
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
- Department of Biology, Wolaita Sodo University, Sodo, Ethiopia
| | - Biniam Wondale
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
| | - Girum Tamiru
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
| | - Nigatu Eligo
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
| | - Bernt Lindtjørn
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
- Centre for International Health, University of Bergen, Norway
| | - Fekadu Massebo
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
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Loha E. Association between Livestock Ownership and Malaria Incidence in South-Central Ethiopia: A Cohort Study. Am J Trop Med Hyg 2023; 108:1145-1150. [PMID: 37094783 PMCID: PMC10540100 DOI: 10.4269/ajtmh.22-0719] [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: 11/21/2022] [Accepted: 03/02/2023] [Indexed: 04/26/2023] Open
Abstract
Zooprophylaxis is one of the possible environmental vector control strategies for malaria prevention. However, its effect on reducing malaria transmission has been questionable, requiring a detailed understanding of contextual factors. This study aims to evaluate the effect of keeping livestock on malaria incidence in south-central Ethiopia. A cohort of 34,548 people in a total of 6,071 households was followed for 121 weeks from October 2014 to January 2017. Baseline data were collected, including livestock ownership. Weekly home visits were done to actively search for malaria cases, and passive case detection was also carried out. Malaria was diagnosed with rapid diagnostic tests. Log binomial and parametric regression survival-time models were used to estimate effect measures. A total of 27,471 residents had complete follow-ups, and the majority (87.5%) lived in households owning livestock, including cattle, sheep, goats, and chickens. The overall incidence risk of malaria was 3.7%, and there was a 24% reduction in the risk of malaria among livestock owners. The total cohort contributed to 71,861.62 person-years of observation. The incidence rate of malaria was 14.7 cases per 1,000 person-years. There was a 17% reduction in the rate of malaria among livestock owners. Meanwhile, the protective effect of livestock ownership increased as the number of livestock or the livestock-to-human ratio increased. In conclusion, livestock owners had less malaria. In a setup where domestication of livestock is a common practice and the predominant malaria vector tends to feed more on livestock than humans, zooprophylaxis remains a promising strategy for malaria prevention.
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Affiliation(s)
- Eskindir Loha
- Centre for International Health, University of Bergen, Bergen, Norway
- Chr. Michelsen Institute, Bergen, Norway
- School of Public Health, Hawassa University, Hawassa, Ethiopia
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Saili K, de Jager C, Sangoro OP, Nkya TE, Masaninga F, Mwenya M, Sinyolo A, Hamainza B, Chanda E, Fillinger U, Mutero CM. Anopheles rufipes implicated in malaria transmission both indoors and outdoors alongside Anopheles funestus and Anopheles arabiensis in rural south-east Zambia. Malar J 2023; 22:95. [PMID: 36927373 PMCID: PMC10018844 DOI: 10.1186/s12936-023-04489-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 02/12/2023] [Indexed: 03/18/2023] Open
Abstract
BACKGROUND The primary malaria vector-control interventions, indoor residual spraying and long-lasting insecticidal nets, are effective against indoor biting and resting mosquito species. Consequently, outdoor biting and resting malaria vectors might elude the primary interventions and sustain malaria transmission. Varied vector biting and resting behaviour calls for robust entomological surveillance. This study investigated the bionomics of malaria vectors in rural south-east Zambia, focusing on species composition, their resting and host-seeking behaviour and sporozoite infection rates. METHODS The study was conducted in Nyimba District, Zambia. Randomly selected households served as sentinel houses for monthly collection of mosquitoes indoors using CDC-light traps (CDC-LTs) and pyrethrum spray catches (PSC), and outdoors using only CDC-LTs for 12 months. Mosquitoes were identified using morphological taxonomic keys. Specimens belonging to the Anopheles gambiae complex and Anopheles funestus group were further identified using molecular techniques. Plasmodium falciparum sporozoite infection was determined using sandwich enzyme-linked immunosorbent assays. RESULTS From 304 indoor and 257 outdoor light trap-nights and 420 resting collection, 1409 female Anopheles species mosquitoes were collected and identified morphologically; An. funestus (n = 613; 43.5%), An. gambiae sensu lato (s.l.)(n = 293; 20.8%), Anopheles pretoriensis (n = 282; 20.0%), Anopheles maculipalpis (n = 130; 9.2%), Anopheles rufipes (n = 55; 3.9%), Anopheles coustani s.l. (n = 33; 2.3%), and Anopheles squamosus (n = 3, 0.2%). Anopheles funestus sensu stricto (s.s.) (n = 144; 91.1%) and Anopheles arabiensis (n = 77; 77.0%) were the dominant species within the An. funestus group and An. gambiae complex, respectively. Overall, outdoor CDC-LTs captured more Anopheles mosquitoes (mean = 2.25, 95% CI 1.22-3,28) than indoor CDC-LTs (mean = 2.13, 95% CI 1.54-2.73). Fewer resting mosquitoes were collected with PSC (mean = 0.44, 95% CI 0.24-0.63). Sporozoite infectivity rates for An. funestus, An. arabiensis and An. rufipes were 2.5%, 0.57% and 9.1%, respectively. Indoor entomological inoculation rates (EIRs) for An. funestus s.s, An. arabiensis and An. rufipes were estimated at 4.44, 1.15 and 1.20 infectious bites/person/year respectively. Outdoor EIRs for An. funestus s.s. and An. rufipes at 7.19 and 4.31 infectious bites/person/year, respectively. CONCLUSION The findings of this study suggest that An. rufipes may play an important role in malaria transmission alongside An. funestus s.s. and An. arabiensis in the study location.
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Affiliation(s)
- Kochelani Saili
- International Centre of Insect Physiology and Ecology (Icipe), P.O. Box 30772-00100, Nairobi, Kenya. .,University of Pretoria Institute for Sustainable Malaria Control, School of Health Systems and Public Health, University of Pretoria, Pretoria, South Africa.
| | - Christiaan de Jager
- University of Pretoria Institute for Sustainable Malaria Control, School of Health Systems and Public Health, University of Pretoria, Pretoria, South Africa
| | - Onyango P Sangoro
- International Centre of Insect Physiology and Ecology (Icipe), P.O. Box 30772-00100, Nairobi, Kenya
| | - Theresia E Nkya
- International Centre of Insect Physiology and Ecology (Icipe), P.O. Box 30772-00100, Nairobi, Kenya.,Mbeya College of Health and Allied Sciences, University of Dar es Salaam, Mbeya, Tanzania
| | | | | | - Andy Sinyolo
- National Malaria Elimination Centre, Lusaka, Zambia
| | | | - Emmanuel Chanda
- World Health Organization, Regional Office for Africa, Brazzaville, Congo
| | - Ulrike Fillinger
- International Centre of Insect Physiology and Ecology (Icipe), P.O. Box 30772-00100, Nairobi, Kenya
| | - Clifford M Mutero
- International Centre of Insect Physiology and Ecology (Icipe), P.O. Box 30772-00100, Nairobi, Kenya.,University of Pretoria Institute for Sustainable Malaria Control, School of Health Systems and Public Health, University of Pretoria, Pretoria, South Africa
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9
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Musoke D, Atusingwize E, Namata C, Ndejjo R, Wanyenze RK, Kamya MR. Integrated malaria prevention in low- and middle-income countries: a systematic review. Malar J 2023; 22:79. [PMID: 36879237 PMCID: PMC9987134 DOI: 10.1186/s12936-023-04500-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Accepted: 02/16/2023] [Indexed: 03/08/2023] Open
Abstract
BACKGROUND As many countries aim to eliminate malaria, use of comprehensive approaches targeting the mosquito vector and environment are needed. Integrated malaria prevention advocates the use of several malaria prevention measures holistically at households and in the community. The aim of this systematic review was to collate and summarize the impact of integrated malaria prevention in low- and middle-income countries on malaria burden. METHODS Literature on integrated malaria prevention, defined as the use of two or more malaria prevention methods holistically, was searched from 1st January 2001 to 31st July 2021. The primary outcome variables were malaria incidence and prevalence, while the secondary outcome measures were human biting and entomological inoculation rates, and mosquito mortality. RESULTS A total of 10,931 studies were identified by the search strategy. After screening, 57 articles were included in the review. Studies included cluster randomized controlled trials, longitudinal studies, programme evaluations, experimental hut/houses, and field trials. Various interventions were used, mainly combinations of two or three malaria prevention methods including insecticide-treated nets (ITNs), indoor residual spraying (IRS), topical repellents, insecticide sprays, microbial larvicides, and house improvements including screening, insecticide-treated wall hangings, and screening of eaves. The most common methods used in integrated malaria prevention were ITNs and IRS, followed by ITNs and topical repellents. There was reduced incidence and prevalence of malaria when multiple malaria prevention methods were used compared to single methods. Mosquito human biting and entomological inoculation rates were significantly reduced, and mosquito mortality increased in use of multiple methods compared to single interventions. However, a few studies showed mixed results or no benefits of using multiple methods to prevent malaria. CONCLUSION Use of multiple malaria prevention methods was effective in reducing malaria infection and mosquito density in comparison with single methods. Results from this systematic review can be used to inform future research, practice, policy and programming for malaria control in endemic countries.
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Affiliation(s)
- David Musoke
- Department of Disease Control and Environmental Health, School of Public Health, Makerere University College of Health Sciences, Kampala, Uganda.
| | - Edwinah Atusingwize
- Department of Disease Control and Environmental Health, School of Public Health, Makerere University College of Health Sciences, Kampala, Uganda
| | - Carol Namata
- Department of Disease Control and Environmental Health, School of Public Health, Makerere University College of Health Sciences, Kampala, Uganda
| | - Rawlance Ndejjo
- Department of Disease Control and Environmental Health, School of Public Health, Makerere University College of Health Sciences, Kampala, Uganda
| | - Rhoda K Wanyenze
- Department of Disease Control and Environmental Health, School of Public Health, Makerere University College of Health Sciences, Kampala, Uganda
| | - Moses R Kamya
- Department of Medicine, School of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
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10
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Zhou Y, Zhang WX, Tembo E, Xie MZ, Zhang SS, Wang XR, Wei TT, Feng X, Zhang YL, Du J, Liu YQ, Zhang X, Cui F, Lu QB. Effectiveness of indoor residual spraying on malaria control: a systematic review and meta-analysis. Infect Dis Poverty 2022; 11:83. [PMID: 35870946 PMCID: PMC9308352 DOI: 10.1186/s40249-022-01005-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 06/30/2022] [Indexed: 11/18/2022] Open
Abstract
Background Indoor residual spraying (IRS) is one of the key interventions recommended by World Health Organization in preventing malaria infection. We aimed to conduct a systematic review and meta-analysis of global studies about the impact of IRS on malaria control. Method We searched PubMed, Web of Science, Embase, and Scopus for relevant studies published from database establishment to 31 December 2021. Random-effects models were used to perform meta-analysis and subgroup analysis to pool the odds ratio (OR) and 95% confidence interval (CI). Meta-regression was used to investigate potential factors of heterogeneity across studies. Results Thirty-eight articles including 81 reports and 1,174,970 individuals were included in the meta-analysis. IRS was associated with lower rates of malaria infection (OR = 0.35, 95% CI: 0.27–0.44). The significantly higher effectiveness was observed in IRS coverage ≥ 80% than in IRS coverage < 80%. Pyrethroids was identified to show the greatest performance in malaria control. In addition, higher effectiveness was associated with a lower gross domestic product
as well as a higher coverage of IRS and bed net utilization. Conclusions IRS could induce a positive effect on malaria infection globally. The high IRS coverage and the use of pyrethroids are key measures to reduce malaria infection. More efforts should focus on increasing IRS coverage, developing more effective new insecticides against malaria, and using multiple interventions comprehensively to achieve malaria control goals. Supplementary Information The online version contains supplementary material available at 10.1186/s40249-022-01005-8.
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11
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Yewhalaw D, Balkew M, Zemene E, Chibsa S, Mumba P, Flatley C, Seyoum A, Yoshimizu M, Zohdy S, Dengela D, Irish S. An experimental hut study evaluating the impact of pyrethroid-only and PBO nets alone and in combination with pirimiphos-methyl-based IRS in Ethiopia. Malar J 2022; 21:238. [PMID: 35987650 PMCID: PMC9392245 DOI: 10.1186/s12936-022-04263-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 08/10/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Pyrethroid resistance observed in populations of malaria vectors is widespread in Ethiopia and could potentially compromise the effectiveness of insecticide-based malaria vector control interventions. In this study, the impact of combining indoor residual spraying (IRS) and insecticide-treated nets (ITNs) on mosquito behaviour and mortality was evaluated using experimental huts. METHODS A Latin Square Design was employed using six experimental huts to collect entomological data. Human volunteers slept in huts with different types of nets (pyrethroid-only net, PBO net, and untreated net) either with or without IRS (Actellic 300CS). The hut with no IRS and an untreated net served as a negative control. The study was conducted for a total of 54 nights. Both alive and dead mosquitoes were collected from inside nets, in the central rooms and verandah the following morning. Data were analysed using Stata/SE 14.0 software package (College Station, TX, USA). RESULTS The personal protection rate of huts with PermaNet® 2.0 alone and PermaNet® 3.0 alone was 33.3% and 50%, respectively. The mean killing effect of huts with PermaNet® 2.0 alone and PermaNet® 3.0 alone was 2% and 49%, respectively. Huts with PermaNet® 2.0 alone and PermaNet® 3.0 alone demonstrated significantly higher excito-repellency than the control hut. However, mosquito mortality in the hut with IRS + untreated net, hut with IRS + PermaNet® 2.0 and hut with IRS + PermaNet® 3.0 were not significantly different from each other (p > 0.05). Additionally, pre-exposure of both the susceptible Anopheles arabiensis laboratory strain and wild Anopheles gambiae sensu lato to PBO in the cone bioassay tests of Actellic 300CS sprayed surfaces did not reduce mosquito mortality when compared to mortality without pre-exposure to PBO. CONCLUSION Mosquito mortality rates from the huts with IRS alone were similar to mosquito mortality rates from the huts with the combination of vector control intervention tools (IRS + ITNs) and mosquito mortality rates from huts with PBO nets alone were significantly higher than huts with pyrethroid-only nets. The findings of this study help inform studies to be conducted under field condition for decision-making for future selection of cost-effective vector control intervention tools.
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Affiliation(s)
- 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
| | - Meshesha Balkew
- Abt Associates, PMI VectorLink Project Ethiopia, Addis Ababa, Ethiopia
| | - Endalew Zemene
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia
- Tropical and Infectious Diseases Research Center, Jimma University, Jimma, Ethiopia
| | - Sheleme Chibsa
- US President’s Malaria Initiative (PMI), Addis Ababa, Ethiopia
| | - Peter Mumba
- US President’s Malaria Initiative (PMI), Addis Ababa, Ethiopia
| | | | - Aklilu Seyoum
- Abt Associates, PMI VectorLink Project, Rockville, MD USA
| | | | - Sarah Zohdy
- US President’s Malaria Initiative, Center for Disease Control and Prevention, Atlanta, GA USA
| | - Dereje Dengela
- Abt Associates, PMI VectorLink Project Ethiopia, Addis Ababa, Ethiopia
| | - Seth Irish
- US President’s Malaria Initiative, Center for Disease Control and Prevention, Atlanta, GA USA
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12
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Krezanoski PJ, Rek J, Musiime A, Otto G, Kyagamba P, Rwatooro JA, Walters K, Romanel A, Arinaitwe E, Nankabirwa JI, Drakeley CJ, Kamya M, Dorsey G. Remote bednet use monitoring to describe patterns of use and exposure to female Anopheles mosquitoes in an Ugandan cohort. FRONTIERS IN EPIDEMIOLOGY 2022; 2:934557. [PMID: 37854770 PMCID: PMC10583855 DOI: 10.3389/fepid.2022.934557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 07/13/2022] [Indexed: 10/20/2023]
Abstract
Background Long lasting insecticide-treated bednets (LLINs) are the most widely used tool for preventing malaria. There has been a plateau in progress in the highest burden African countries since 2015, leading to questions about the effectiveness of LLINs. In this study, remote LLIN use monitors were deployed in a cohort in Eastern Uganda to explore how LLIN use interacts with mosquito exposure. Methods The SmartNet study included 20 households from May to October 2019. SmartNet devices recorded, every 15 min, whether an LLIN was unfurled or folded up. Unannounced visits were used to assess SmartNet accuracy. Risk factors associated with poor LLIN use were assessed using generalized linear equations. Female Anopheles exposure was estimated by combining hourly probabilities of exposure from human landing catches and measures of density from biweekly CDC light traps in participants rooms. Mosquito exposure averted by LLINs was quantified using SmartNet measurements and age-related differences were estimated using generalized linear equations, adjusting for relevant covariates and household clustering. Results 96 individuals contributed 5,640 SmartNet observation nights. In 126 unannounced visits, SmartNet had an area under the curve of 0.869 in classifying whether the LLIN was up or down. The rate of non-use was 13.5% of nights (95% CI: 12.6-14.3%). Compared to children under 5, non-use was 1.8 times higher (95% CI: 1.6-2.1; p < 0.001) in children 5-15 years and 2.6 times higher (95% CI: 2.2-3.1; p < 0.001) in participants aged 15-<30years. There was no difference between children under 5 years and adults > 30 years. LLIN use averted 50.3% of female Anopheles mosquito exposure (95% CI: 40.0-60.0%), with decreasing point estimates of efficacy across age groups: from 61.7% (95% CI: 42.6-80.7%) in children under 5 years to 48.0% (95% CI: 29.1-66.8%) in adults over 30. Conclusions Objective monitors are accurate and can feasibly be deployed to obtain data about LLIN use. LLINs provided protection from only 50% of female Anopheles mosquito exposure in this cohort and protection was dependent upon age. In assessing the role of LLINs in malaria prevention it is crucial to consider the dynamics between mosquito exposure and LLIN use behaviors.
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Affiliation(s)
- Paul J. Krezanoski
- University of California, San Francisco, San Francisco, CA, United States
- Opportunity Solutions International, San Francisco, CA, United States
| | - John Rek
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Alex Musiime
- US President's Malaria Initiative, Kampala, Uganda
| | - Geoffrey Otto
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | | | | | - Kelly Walters
- University of California, San Francisco, San Francisco, CA, United States
| | - Alina Romanel
- University of California, San Francisco, San Francisco, CA, United States
| | | | - Joaniter I. Nankabirwa
- Infectious Diseases Research Collaboration, Kampala, Uganda
- Makerere University College of Health Sciences, Kampala, Uganda
| | - Chris J. Drakeley
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Moses Kamya
- Infectious Diseases Research Collaboration, Kampala, Uganda
- Makerere University College of Health Sciences, Kampala, Uganda
| | - Grant Dorsey
- University of California, San Francisco, San Francisco, CA, United States
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13
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Sherrard-Smith E, Ngufor C, Sanou A, Guelbeogo MW, N'Guessan R, Elobolobo E, Saute F, Varela K, Chaccour CJ, Zulliger R, Wagman J, Robertson ML, Rowland M, Donnelly MJ, Gonahasa S, Staedke SG, Kolaczinski J, Churcher TS. Inferring the epidemiological benefit of indoor vector control interventions against malaria from mosquito data. Nat Commun 2022; 13:3862. [PMID: 35790746 PMCID: PMC9256631 DOI: 10.1038/s41467-022-30700-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 05/11/2022] [Indexed: 12/03/2022] Open
Abstract
The cause of malaria transmission has been known for over a century but it is still unclear whether entomological measures are sufficiently reliable to inform policy decisions in human health. Decision-making on the effectiveness of new insecticide-treated nets (ITNs) and the indoor residual spraying of insecticide (IRS) have been based on epidemiological data, typically collected in cluster-randomised control trials. The number of these trials that can be conducted is limited. Here we use a systematic review to highlight that efficacy estimates of the same intervention may vary substantially between trials. Analyses indicate that mosquito data collected in experimental hut trials can be used to parameterize mechanistic models for Plasmodium falciparum malaria and reliably predict the epidemiological efficacy of quick-acting, neuro-acting ITNs and IRS. Results suggest that for certain types of ITNs and IRS using this framework instead of clinical endpoints could support policy and expedite the widespread use of novel technologies.
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Affiliation(s)
| | - Corine Ngufor
- Centre de Recherches Entomologiques de Cotonou, Cotonou, Benin
- London School of Hygiene and Tropical Medicine, London, UK
| | - Antoine Sanou
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Moussa W Guelbeogo
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Raphael N'Guessan
- London School of Hygiene and Tropical Medicine, London, UK
- Institut Pierre Richet, Bouake, Côte d'Ivoire
| | - Eldo Elobolobo
- Centro de Investigação em Saúde de Manhiça, Manhiça, Mozambique
| | - Francisco Saute
- Centro de Investigação em Saúde de Manhiça, Manhiça, Mozambique
| | | | | | - Rose Zulliger
- US President's Malaria Initiative, USAID, Washington, DC, USA
| | | | | | - Mark Rowland
- London School of Hygiene and Tropical Medicine, London, UK
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14
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Loeffel M, Ross A. The relative impact of interventions on sympatric Plasmodium vivax and Plasmodium falciparum malaria: A systematic review. PLoS Negl Trop Dis 2022; 16:e0010541. [PMID: 35767578 PMCID: PMC9242512 DOI: 10.1371/journal.pntd.0010541] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Accepted: 05/27/2022] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND In areas with both Plasmodium vivax and Plasmodium falciparum malaria, interventions can reduce the burden of both species but the impact may vary due to their different biology. Knowing the expected relative impact on the two species over time for vector- and drug-based interventions, and the factors affecting this, could help plan and evaluate intervention strategies. METHODS For three interventions (treated bed nets (ITN), mass drug administration (MDA) and indoor residual spraying (IRS)), we identified studies providing information on the proportion of clinical illness and patent infections attributed to P. vivax over time using a literature search. The change in the proportion of malaria attributed to P. vivax up to two years since implementation was estimated using logistic regression accounting for clustering with random effects. Potential factors (intervention type, coverage, relapse pattern, transmission intensity, seasonality, initial proportion of P. vivax and round of intervention) were assessed. RESULTS In total there were 55 studies found that led to 72 series of time-points for clinical case data and 69 series for patent infection data. The main reason of study exclusion was insufficient information on interventions. There was considerable variation in the proportion of malaria attributed to P. vivax over time by study and location for all of the interventions. Overall, there was an increase apart from MDA in the short-term. The potential factors could not be ruled in or out. Although not consistently significant, coverage, transmission intensity and relapse pattern are possible factors that explain some of the variation found. CONCLUSION While there are reports of an increase in the proportion of malaria due to P. vivax following interventions in the long-term, there was substantial variation for the shorter time-scales considered in this study (up to 24 months for IRS and ITN, and up to six months for MDA). The large variability points to the need for the monitoring of both species after an intervention. Studies should report intervention timing and characteristics to allow inclusion in systematic reviews.
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Affiliation(s)
- Melanie Loeffel
- Swiss Tropical and Public Health Institute, Allschwil, Switzerland
- University of Basel, Basel, Switzerland
| | - Amanda Ross
- Swiss Tropical and Public Health Institute, Allschwil, Switzerland
- University of Basel, Basel, Switzerland
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15
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Asale A, Kassie M, Abro Z, Enchalew B, Belay A, Sangoro PO, Tchouassi DP, Mutero CM. The combined impact of LLINs, house screening, and pull-push technology for improved malaria control and livelihoods in rural Ethiopia: study protocol for household randomised controlled trial. BMC Public Health 2022; 22:930. [PMID: 35538444 PMCID: PMC9088127 DOI: 10.1186/s12889-022-12919-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 03/04/2022] [Indexed: 11/23/2022] Open
Abstract
Background The combined application of long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are commonly used malaria interventions that target indoor Anopheles vectors. Recent studies on the effects of house screening (HS) and LLINs have demonstrated a reduction in indoor vector densities and malaria when the interventions are combined. In addition, complementary interventions are needed to curb co-occurring pest populations which pose menace to agricultural crop productivity and food security. However, interventions that impact malaria mainly centre on public health strategies, overlooking subtle but important component of agricultural measures. Addressing the coexisting risks of malaria and crop pests could contribute to improved livelihood of communities. Methods A four-armed household, cluster-randomized, controlled study will be conducted to assess the combined impact of HS, LLINs and push-pull agricultural technology (PPT) against clinical malaria in children in Ethiopia. The unit of randomization will be the household, which includes a house and its occupants. A total of 838 households will be enrolled in this study. In this trial 246 households will receive LLINs and HS, 250 will receive LLINs, HS and PPT, 175 households will receive LLINs and PPT. The remaining 167 houses which receive LLINs only will be used as control. One child aged ≤14 years will be enrolled per household in each treatment and followed for clinical malaria using active case detection to estimate malaria incidence for two malaria transmission seasons. Discussion Episodes of clinical malaria, density of indoor biting malaria vectors, sporozoite infection rate, improved crop infestation rate, crop yield gain, livestock productivity and cost effectiveness analysis will be the end points of this study. Socio-economic, social demographic, cost-effectiveness analysis will be conducted using qualitative and participatory methods to explore the acceptability of HS and PPT. Documenting the combined impact of LLINs, HS and PPT on the prevalence of clinical malaria and crop pest damage will be the first of its kind. Trial registration Pan African Clinical Trials Registry, PACTR202006878245287. 24/06/2020. https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=11101. Supplementary Information The online version contains supplementary material available at 10.1186/s12889-022-12919-1.
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Affiliation(s)
- Abebe Asale
- International Centre of Insect Physiology and Ecology, Addis Ababa, Ethiopia.
| | - Menale Kassie
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | - Zewdu Abro
- International Centre of Insect Physiology and Ecology, Addis Ababa, Ethiopia
| | - Bayu Enchalew
- International Centre of Insect Physiology and Ecology, Addis Ababa, Ethiopia
| | - Aklilu Belay
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya.,University of Pretoria Institute for Sustainable Malaria Control, School of Health Systems and Public Health, University of Pretoria, Pretoria, South Africa
| | - Peter O Sangoro
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | - David P Tchouassi
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | - Clifford M Mutero
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya.,University of Pretoria Institute for Sustainable Malaria Control, School of Health Systems and Public Health, University of Pretoria, Pretoria, South Africa
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16
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Detection of temporal, spatial and spatiotemporal clustering of malaria incidence in northwest Ethiopia, 2012–2020. Sci Rep 2022; 12:3635. [PMID: 35256698 PMCID: PMC8901673 DOI: 10.1038/s41598-022-07713-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Accepted: 02/21/2022] [Indexed: 11/25/2022] Open
Abstract
Malaria is one of Ethiopia's most targeted communicable diseases for elimination. Malaria transmission varies significantly across space and time; and Ethiopia had space–time disparity in its transmission intensities. Considering heterogeneity and transmission intensity at the district level could play a crucial role in malaria prevention and elimination. This study aimed to explore temporal, spatial, and spatiotemporal clusters of malaria incidence in northwest Ethiopia. The analysis is based on monthly malaria surveillance data of districts and collected from the Amhara public health institute. The Kulldorff's retrospective space–time scan statistics using a discrete Poisson model were used to detect temporal, spatial, and space–time clusters of malaria incidence with and without adjusting the altitude + LLIN arm. Monthly malaria incidence had seasonal variations, and higher seasonal indices occurred in October and November. The temporal cluster occurred in the higher transmission season between September and December annually. The higher malaria incidence risk occurred between July 2012 and December 2013 (LLR = 414,013.41, RR = 2.54, P < 0.05). The purely spatial clustering result revealed that the most likely cluster occurred in the north and northwest parts of the region while secondary clusters varied in years. The space–time clusters were detected with and without considering altitude + LLIN arm. The most likely space–time cluster was concentrated in northwestern and western parts of the region with a high-risk period between July 2012 and December 2013 (LLR = 880,088.3, RR = 5.5, P < 0.001). We found eight significant space–time clusters using the altitude + LLIN arm. The most likely space–time cluster occurred in the western and northwestern parts of the region in July 2012–December 2013 (LLR = 886,097.7, RR = 5.55, P < 0.05). However, secondary clusters were located in eastern, northwestern, western parts of regions, which had different cases and relative risks in each cluster. Malaria transmission had temporal, spatial, and space–time variation in the region at the district level. Hence, considering these variations and factors contributing to malaria stratification would play an indispensable role in preventing and controlling practices that ultimately leads to malaria eliminations.
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17
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Pryce J, Medley N, Choi L. Indoor residual spraying for preventing malaria in communities using insecticide-treated nets. Cochrane Database Syst Rev 2022; 1:CD012688. [PMID: 35038163 PMCID: PMC8763033 DOI: 10.1002/14651858.cd012688.pub3] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Insecticide-treated nets (ITNs) and indoor residual spraying (IRS) are used to prevent malaria transmission. Both interventions use insecticides to kill mosquitoes that bite and rest indoors. Adding IRS to ITNs may improve malaria control simply because two interventions can be better than one. Furthermore, IRS may improve malaria control where ITNs are failing due to insecticide resistance. Pyrethroid insecticides are the predominant class of insecticide used for ITNs, as they are more safe than other insecticide classes when in prolonged contact with human skin. While many mosquito populations have developed some resistance to pyrethroid insecticides, a wider range of insecticides can be used for IRS. This review is an update of the previous Cochrane 2019 edition. OBJECTIVES To summarize the effect on malaria of additionally implementing IRS, using non-pyrethroid-like or pyrethroid-like insecticides, in communities currently using ITNs. SEARCH METHODS We searched the Cochrane Infectious Diseases Group Specialized Register; CENTRAL; MEDLINE; and five other databases for records from 1 January 2000 to 8 November 2021, on the basis that ITN programmes did not begin to be implemented as policy before the year 2000. SELECTION CRITERIA We included cluster-randomized controlled trials (cRCTs), interrupted time series (ITS), or controlled before-after studies (CBAs) comparing IRS plus ITNs with ITNs alone. We included studies with at least 50% ITN ownership (defined as the proportion of households owning one or more ITN) in both study arms. DATA COLLECTION AND ANALYSIS Two review authors independently assessed studies for eligibility, analyzed risk of bias, and extracted data. We used risk ratio (RR) and 95% confidence intervals (CI). We stratified by type of insecticide, 'pyrethroid-like' and 'non-pyrethroid-like'; the latter could improve malaria control better than adding IRS insecticides that have the same way of working as the insecticide on ITNs ('pyrethroid-like'). We used subgroup analysis of ITN usage in the studies to explore heterogeneity. We assessed the certainty of evidence using the GRADE approach. MAIN RESULTS Eight cRCTs (10 comparisons), one CBA, and one ITS study, all conducted since 2008 in sub-Saharan Africa, met our inclusion criteria. The primary vectors in all sites were mosquitoes belonging to the Anopheles gambiae s.l. complex species; five studies in Benin, Mozambique, Ghana, Sudan, and Tanzania also reported the vector Anopheles funestus. Five cRCTs and both quasi-experimental design studies used insecticides with targets different to pyrethroids (two used bendiocarb, three used pirimiphos-methyl, and one used propoxur. Each of these studies were conducted in areas where the vectors were described as resistant or highly resistant to pyrethroids. Two cRCTs used dichloro-diphenyl-trichlorethane (DDT), an insecticide with the same target as pyrethroids. The remaining cRCT used both types of insecticide (pyrethroid deltamethrin in the first year, switching to bendiocarb for the second year). Indoor residual spraying using 'non-pyrethroid-like' insecticides Six studies were included (four cRCTs, one CBA, and one ITS). Our main analysis for prevalence excluded a study at high risk of bias due to repeated sampling of the same population. This risk did not apply to other outcomes. Overall, the addition of IRS reduced malaria parasite prevalence (RR 0.61, 95% CI 0.42 to 0.88; 4 cRCTs, 16,394 participants; high-certainty evidence). IRS may also reduce malaria incidence on average (rate ratio 0.86, 95% CI 0.61 to 1.23; 4 cRCTs, 323,631 child-years; low-certainty evidence) but the effect was absent in two studies. Subgroup analyses did not explain the qualitative heterogeneity between studies. One cRCT reported no effect on malaria incidence or parasite prevalence in the first year, when a pyrethroid-like insecticide was used for IRS, but showed an effect on both outcomes in the second year, when a non-pyrethroid-like IRS was used. The addition of IRS may also reduce anaemia prevalence (RR 0.71, 95% CI 0.38 to 1.31; 3 cRCTs, 4288 participants; low-certainty evidence). Four cRCTs reported the impact of IRS on entomological inoculation rate (EIR), with variable results; overall, we do not know if IRS had any effect on the EIR in communities using ITNs (very low-certainty evidence). Studies also reported the adult mosquito density and the sporozoite rate, but we could not summarize or pool these entomological outcomes due to differences in the reported data. Three studies measured the prevalence of pyrethroid resistance before and after IRS being introduced: there was no difference detected, but these data are limited. Indoor residual spraying using 'pyrethroid-like' insecticides Adding IRS using a pyrethroid-like insecticide did not appear to markedly alter malaria incidence (rate ratio 1.07, 95% CI 0.80 to 1.43; 2 cRCTs, 15,717 child-years; moderate-certainty evidence), parasite prevalence (RR 1.11, 95% CI 0.86 to 1.44; 3 cRCTs, 10,820 participants; moderate-certainty evidence), or anaemia prevalence (RR 1.12, 95% CI 0.89 to 1.40; 1 cRCT, 4186 participants; low-certainty evidence). Data on EIR were limited so no conclusion was made (very low-certainty evidence). AUTHORS' CONCLUSIONS in communities using ITNs, the addition of IRS with 'non-pyrethroid-like' insecticides was associated with reduced malaria prevalence. Malaria incidence may also be reduced on average, but there was unexplained qualitative heterogeneity, and the effect may therefore not be observed in all settings. When using 'pyrethroid-like' insecticides, there was no detectable additional benefit of IRS in communities using ITNs.
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Affiliation(s)
- Joseph Pryce
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Nancy Medley
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Leslie Choi
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
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18
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Nchama VUNN, Said AH, Mtoro A, Bidjimi GO, Owono MA, Maye ERM, Mangue MEO, Okomo GNN, Pasialo BEN, Ondo DM, Lopez MSA, Mochomuemue FL, Obono MO, Besaha JCM, Chuquiyauri R, Jongo SA, Kamaka K, Kibondo UA, Athuman T, Falla CC, Eyono JNM, Smith JM, García GA, Raso J, Nyakarungu E, Mpina M, Schindler T, Daubenberger C, Lemiale L, Billingsley PF, Sim BKL, Richie TL, Church LWP, Olotu A, Tanner M, Hoffman SL, Abdulla S. Incidence of Plasmodium falciparum malaria infection in 6-month to 45-year-olds on selected areas of Bioko Island, Equatorial Guinea. Malar J 2021; 20:322. [PMID: 34284778 PMCID: PMC8290541 DOI: 10.1186/s12936-021-03850-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 07/11/2021] [Indexed: 11/10/2022] Open
Abstract
Background Extensive malaria control measures have been implemented on Bioko Island, Equatorial Guinea over the past 16 years, reducing parasite prevalence and malaria-related morbidity and mortality, but without achieving elimination. Malaria vaccines offer hope for reducing the burden to zero. Three phase 1/2 studies have been conducted successfully on Bioko Island to evaluate the safety and efficacy of whole Plasmodium falciparum (Pf) sporozoite (SPZ) malaria vaccines. A large, pivotal trial of the safety and efficacy of the radiation-attenuated Sanaria® PfSPZ Vaccine against P. falciparum is planned for 2022. This study assessed the incidence of malaria at the phase 3 study site and characterized the influence of socio-demographic factors on the burden of malaria to guide trial design. Methods A cohort of 240 randomly selected individuals aged 6 months to 45 years from selected areas of North Bioko Province, Bioko Island, was followed for 24 weeks after clearance of parasitaemia. Assessment of clinical presentation consistent with malaria and thick blood smears were performed every 2 weeks. Incidence of first and multiple malaria infections per person-time of follow-up was estimated, compared between age groups, and examined for associated socio-demographic risk factors. Results There were 58 malaria infection episodes observed during the follow up period, including 47 first and 11 repeat infections. The incidence of malaria was 0.25 [95% CI (0.19, 0.32)] and of first malaria was 0.23 [95% CI (0.17, 0.30)] per person per 24 weeks (0.22 in 6–59-month-olds, 0.26 in 5–17-year-olds, 0.20 in 18–45-year-olds). Incidence of first malaria with symptoms was 0.13 [95% CI (0.09, 0.19)] per person per 24 weeks (0.16 in 6–59-month-olds, 0.10 in 5–17-year-olds, 0.11 in 18–45-year-olds). Multivariate assessment showed that study area, gender, malaria positivity at screening, and household socioeconomic status independently predicted the observed incidence of malaria. Conclusion Despite intensive malaria control efforts on Bioko Island, local transmission remains and is spread evenly throughout age groups. These incidence rates indicate moderate malaria transmission which may be sufficient to support future larger trials of PfSPZ Vaccine. The long-term goal is to conduct mass vaccination programmes to halt transmission and eliminate P. falciparum malaria.
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Affiliation(s)
- Vicente Urbano Nsue Ndong Nchama
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Ali Hamad Said
- Medical Care Development International (MCDI), Silver Spring, USA. .,Ifakara Health Institute, Dar es Salaam, Tanzania.
| | - Ali Mtoro
- Medical Care Development International (MCDI), Silver Spring, USA.,Ifakara Health Institute, Dar es Salaam, Tanzania
| | - Gertrudis Owono Bidjimi
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Marta Alene Owono
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Escolastica Raquel Mansogo Maye
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Martin Eka Ondo Mangue
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Genaro Nsue Nguema Okomo
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Beltran Ekua Ntutumu Pasialo
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Dolores Mbang Ondo
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Maria-Silvia Angue Lopez
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Fortunata Lobede Mochomuemue
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Mariano Obiang Obono
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Juan Carlos Momo Besaha
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Raul Chuquiyauri
- Medical Care Development International (MCDI), Silver Spring, USA.,Sanaria Inc., Rockville, USA
| | | | - Kassim Kamaka
- Medical Care Development International (MCDI), Silver Spring, USA.,Ifakara Health Institute, Dar es Salaam, Tanzania
| | | | | | | | | | | | | | - José Raso
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Elizabeth Nyakarungu
- Medical Care Development International (MCDI), Silver Spring, USA.,Ifakara Health Institute, Dar es Salaam, Tanzania
| | - Maxmillian Mpina
- Ifakara Health Institute, Dar es Salaam, Tanzania.,Swiss Tropical and Public Health Institute (Swiss TPH), Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Tobias Schindler
- Swiss Tropical and Public Health Institute (Swiss TPH), Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Claudia Daubenberger
- Swiss Tropical and Public Health Institute (Swiss TPH), Basel, Switzerland.,University of Basel, Basel, Switzerland
| | | | | | | | | | | | - Ally Olotu
- Medical Care Development International (MCDI), Silver Spring, USA.,Ifakara Health Institute, Dar es Salaam, Tanzania
| | - Marcel Tanner
- Swiss Tropical and Public Health Institute (Swiss TPH), Basel, Switzerland.,University of Basel, Basel, Switzerland
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19
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Threats to the effectiveness of insecticide-treated bednets for malaria control: thinking beyond insecticide resistance. LANCET GLOBAL HEALTH 2021; 9:e1325-e1331. [PMID: 34216565 DOI: 10.1016/s2214-109x(21)00216-3] [Citation(s) in RCA: 73] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 04/03/2021] [Accepted: 04/23/2021] [Indexed: 12/22/2022]
Abstract
From 2004 to 2019, insecticide-treated bednets (ITNs) have been the most effective tool for reducing malaria morbidity and mortality in sub-Saharan Africa. Recently, however, the decline in malaria cases and deaths has stalled. Some suggest that this inertia is due to increasing resistance in malaria vectors to the pyrethroid insecticides used for treating ITNs. However, there is presently little evidence to reach this conclusion and we therefore recommend that a broader perspective to evaluate ITN effectiveness in terms of access to nets, use of nets, bioefficacy, and durability should be taken. We argue that a single focus on insecticide resistance misses the bigger picture. To improve the effects of ITNs, net coverage should increase by increasing funding for programmes, adopting improved strategies for increasing ITN uptake, and enhancing the longevity of the active ingredients and the physical integrity of nets, while simultaneously accelerating the development and evaluation of novel vector control tools.
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20
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Gari T, Solomon T, Lindtjørn B. Older children are at increased risk of Plasmodium vivax in south-central Ethiopia: a cohort study. Malar J 2021; 20:251. [PMID: 34092235 PMCID: PMC8183059 DOI: 10.1186/s12936-021-03790-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 05/29/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Better understanding of the distribution of Plasmodium vivax and its risk factors could be used to prevent and control malaria infection. Therefore, the aim of this study was to characterize the distribution and risk factors of P. vivax, and to compare them with Plasmodium falciparum occurrence in south-central Ethiopia. METHODS A cohort of 34,548 individuals were followed for 121 weeks between 2014 and 2016 as part of larger cluster randomized controlled trial to evaluate the effect of long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) on malaria prevention in Ethiopia. Weekly home visit (active search) and patient self- report to health post (passive search) between the weekly home visits were used to register malaria cases. A blood sample was collected by finger prick and malaria was diagnosed using rapid diagnostic test (RDT). Generalized estimating equation (GEE) Poisson model that accounts for repeated measure of malaria episodes was applied to assess the risk factors of P. vivax episode. RESULTS The overall incidence rate of P. vivax was 7.4 episodes per 1000 person-years of observation. The study showed households closer to the lake Zeway and Bulbula river (potential mosquito breeding sites) were more at risk of P. vivax infection (incidence rate ratio (IRR): 1.33; 95% CI = 1.23-1.45). Furthermore, the age group under 5 years (IRR: 1.40, 95% CI = 1.10-1.79), the age group 5-14 years (IRR: 1.27, 95% CI = 1.03-1.57), households with less educated household head (IRR: 1.63, 95% CI = 1.10-2.44) and house roof made of thatch/leaf (IRR: 1.35, 95% CI = 1.11-1.65) were at higher risk for P. vivax. Similar explanatory variables such as distance from the breeding sites, age group (under 5 years but not 5-14 years old), educational status and type of housing were also found to be the predictors of P. falciparum incidence. CONCLUSION Households living closer to a mosquito breeding site, age group under 15 years, less educated household heads and thatch/leaf roof housing were the risk factor for P. vivax. The result of this study can be used for tailored interventions for malaria control and prevention by prioritizing those living close to potential mosquito breeding site, enhancing bed net use of children less than 15 years of age, and improving housing.
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Affiliation(s)
- Taye Gari
- School of Public Health, College of Medicine and Health Sciences, Hawassa University, Hawassa, Ethiopia.
| | - Tarekegn Solomon
- School of Public Health, College of Medicine and Health Sciences, Hawassa University, Hawassa, Ethiopia
| | - Bernt Lindtjørn
- School of Public Health, College of Medicine and Health Sciences, Hawassa University, Hawassa, Ethiopia.,Centre for International Health, University of Bergen, Bergen, Norway
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21
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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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22
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Chaccour C, Zulliger R, Wagman J, Casellas A, Nacima A, Elobolobo E, Savaio B, Saifodine A, Fornadel C, Richardson J, Candrinho B, Robertson M, Saute F. Incremental impact on malaria incidence following indoor residual spraying in a highly endemic area with high standard ITN access in Mozambique: results from a cluster-randomized study. Malar J 2021; 20:84. [PMID: 33568137 PMCID: PMC7877039 DOI: 10.1186/s12936-021-03611-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 01/28/2021] [Indexed: 11/17/2022] Open
Abstract
Background Attaining the goal of reducing the global malaria burden is threatened by recent setbacks in maintaining the effectiveness of vector control interventions partly due to the emergence of pyrethroid resistant vectors. One potential strategy to address these setbacks could be combining indoor residual spraying (IRS) with non-pyrethroids and standard insecticide-treated nets (ITNs). This study aimed to provide evidence on the incremental epidemiological benefit of using third-generation IRS product in a highly endemic area with high ITN ownership. Methods A cluster-randomized, open-label, parallel-arms, superiority trial was conducted in the Mopeia district in Zambezia, Mozambique from 2016 to 2018. The district had received mass distribution of alphacypermethrin ITNs two years before the trial and again mid-way. 86 clusters were defined, stratified and randomized to receive or not receive IRS with pirimiphos-methyl (Actellic®300 CS). Efficacy of adding IRS was assessed through malaria incidence in a cohort of children under five followed prospectively for two years, enhanced passive surveillance at health facilities and by community health workers, and yearly cross-sectional surveys at the peak of the transmission season. Findings A total of 1536 children were enrolled in the cohort. Children in the IRS arm experienced 4,801 cases (incidence rate of 3,532 per 10,000 children-month at risk) versus 5,758 cases in the no-IRS arm (incidence rate of 4,297 per 10,000 children-month at risk), resulting in a crude risk reduction of 18% and an incidence risk ratio of 0.82 (95% CI 0.79–0.86, p-value < 0.001). Facility and community passive surveillance showed a malaria incidence of 278 per 10,000 person-month in the IRS group (43,974 cases over 22 months) versus 358 (95% CI 355–360) per 10,000 person-month at risk in the no-IRS group (58,030 cases over 22 months), resulting in an incidence rate ratio of 0.65 (95% CI 0.60–0.71, p < 0.001). In the 2018 survey, prevalence in children under five in the IRS arm was significantly lower than in the no-IRS arm (OR 0.54, 95% CI, 0.31–0.92, p = 0.0241). Conclusion In a highly endemic area with high ITN access and emerging pyrethroid resistance, adding IRS with pirimiphos-methyl resulted in significant additional protection for children under five years of age. Trial registration: ClinicalTrials.gov identifier NCT02910934, registered 22 September 2016, https://clinicaltrials.gov/ct2/show/NCT02910934?term=NCT02910934&draw=2&rank=1.
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Affiliation(s)
- Carlos Chaccour
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain. .,Centro de Investigação em Saúde de Manhiça, Maputo, Mozambique.
| | - Rose Zulliger
- President's Malaria Initiative, US Centers for Disease Control and Prevention, Maputo, Mozambique
| | | | - Aina Casellas
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain
| | - Amilcar Nacima
- Centro de Investigação em Saúde de Manhiça, Maputo, Mozambique
| | - Eldo Elobolobo
- Centro de Investigação em Saúde de Manhiça, Maputo, Mozambique
| | | | - Abuchahama Saifodine
- President's Malaria Initiative, United States Agency for International Development, Maputo, Mozambique
| | | | | | | | | | - Francisco Saute
- Centro de Investigação em Saúde de Manhiça, Maputo, Mozambique
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23
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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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Syme T, Fongnikin A, Todjinou D, Govoetchan R, Gbegbo M, Rowland M, Akogbeto M, Ngufor C. Which indoor residual spraying insecticide best complements standard pyrethroid long-lasting insecticidal nets for improved control of pyrethroid resistant malaria vectors? PLoS One 2021; 16:e0245804. [PMID: 33507978 PMCID: PMC7842967 DOI: 10.1371/journal.pone.0245804] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 01/07/2021] [Indexed: 11/18/2022] Open
Abstract
Background Where resources are available, non-pyrethroid IRS can be deployed to complement standard pyrethroid LLINs with the aim of achieving improved vector control and managing insecticide resistance. The impact of the combination may however depend on the type of IRS insecticide deployed. Studies comparing combinations of pyrethroid LLINs with different types of non-pyrethroid IRS products will be necessary for decision making. Methods The efficacy of combining a standard pyrethroid LLIN (DuraNet®) with IRS insecticides from three chemical classes (bendiocarb, chlorfenapyr and pirimiphos-methyl CS) was evaluated in an experimental hut trial against wild pyrethroid-resistant Anopheles gambiae s.l. in Cové, Benin. The combinations were also compared to each intervention alone. WHO cylinder and CDC bottle bioassays were performed to assess susceptibility of the local An. gambiae s.l. vector population at the Cové hut site to insecticides used in the combinations. Results Susceptibility bioassays revealed that the vector population at Cové, was resistant to pyrethroids (<20% mortality) but susceptible to carbamates, chlorfenapyr and organophosphates (≥98% mortality). Mortality of wild free-flying pyrethroid resistant An. gambiae s.l. entering the hut with the untreated net control (4%) did not differ significantly from DuraNet® alone (8%, p = 0.169). Pirimiphos-methyl CS IRS induced the highest mortality both on its own (85%) and in combination with DuraNet® (81%). Mortality with the DuraNet® + chlorfenapyr IRS combination was significantly higher than each intervention alone (46% vs. 33% and 8%, p<0.05) demonstrating an additive effect. The DuraNet® + bendiocarb IRS combination induced significantly lower mortality compared to the other combinations (32%, p<0.05). Blood-feeding inhibition was very low with the IRS treatments alone (3–5%) but increased significantly when they were combined with DuraNet® (61% - 71%, p<0.05). Blood-feeding rates in the combinations were similar to the net alone. Adding bendiocarb IRS to DuraNet® induced significantly lower levels of mosquito feeding compared to adding chlorfenapyr IRS (28% vs. 37%, p = 0.015). Conclusions Adding non-pyrethroid IRS to standard pyrethroid-only LLINs against a pyrethroid-resistant vector population which is susceptible to the IRS insecticide, can provide higher levels of vector mosquito control compared to the pyrethroid net alone or IRS alone. Adding pirimiphos-methyl CS IRS may provide substantial improvements in vector control while adding chlorfenapyr IRS can demonstrate an additive effect relative to both interventions alone. Adding bendiocarb IRS may show limited enhancements in vector control owing to its short residual effect.
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Affiliation(s)
- Thomas Syme
- London School of Hygiene and Tropical Medicine (LSHTM), London, United Kingdom
- Centre de Recherches Entomologiques de Cotonou (CREC), Benin, West Africa
- Panafrican Malaria Vector Research Consortium (PAMVERC), Benin, West Africa
| | - Augustin Fongnikin
- Centre de Recherches Entomologiques de Cotonou (CREC), Benin, West Africa
- Panafrican Malaria Vector Research Consortium (PAMVERC), Benin, West Africa
| | - Damien Todjinou
- Centre de Recherches Entomologiques de Cotonou (CREC), Benin, West Africa
- Panafrican Malaria Vector Research Consortium (PAMVERC), Benin, West Africa
| | - Renaud Govoetchan
- London School of Hygiene and Tropical Medicine (LSHTM), London, United Kingdom
- Centre de Recherches Entomologiques de Cotonou (CREC), Benin, West Africa
- Panafrican Malaria Vector Research Consortium (PAMVERC), Benin, West Africa
| | - Martial Gbegbo
- Centre de Recherches Entomologiques de Cotonou (CREC), Benin, West Africa
- Panafrican Malaria Vector Research Consortium (PAMVERC), Benin, West Africa
| | - Mark Rowland
- London School of Hygiene and Tropical Medicine (LSHTM), London, United Kingdom
- Panafrican Malaria Vector Research Consortium (PAMVERC), Benin, West Africa
| | - Martin Akogbeto
- Centre de Recherches Entomologiques de Cotonou (CREC), Benin, West Africa
- Panafrican Malaria Vector Research Consortium (PAMVERC), Benin, West Africa
| | - Corine Ngufor
- London School of Hygiene and Tropical Medicine (LSHTM), London, United Kingdom
- Centre de Recherches Entomologiques de Cotonou (CREC), Benin, West Africa
- Panafrican Malaria Vector Research Consortium (PAMVERC), Benin, West Africa
- * E-mail:
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Sharma RK, Rajvanshi H, Bharti PK, Nisar S, Jayswar H, Mishra AK, Saha KB, Shukla MM, Das A, Kaur H, Wattal SL, Lal AA. Socio-economic determinants of malaria in tribal dominated Mandla district enrolled in Malaria Elimination Demonstration Project in Madhya Pradesh. Malar J 2021; 20:7. [PMID: 33402186 PMCID: PMC7786971 DOI: 10.1186/s12936-020-03540-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 12/07/2020] [Indexed: 02/07/2023] Open
Abstract
Background Malaria is known as a disease of poverty because of its dominance in poverty-stricken areas. Madhya Pradesh state in central India is one of the most vulnerable states for malaria morbidity and mortality. Socio-economic, environmental and demographic factors present challenges in malaria control and elimination. As part of the Malaria Elimination Demonstration Project in the tribal district of Mandla in Madhya Pradesh, this study was undertaken to assess the role of different social-economic factors contributing to malaria incidence. Methods The study was conducted in the 1233 villages of district Mandla, where 87% population resides in rural areas. The data was collected using the android based mobile application—SOCH for a period of 2 years (September 2017 to August 2019). A wealth index was computed along with analysis of the socio-economic characteristics of houses with malaria cases. Variables with significant variation in malaria cases were used in logistic regression. Results More than 70% of houses in Mandla are Kuccha (made of thatched roof or mud), 20% do not have any toilet facilities, and only 11% had an annual income of more than 50,000 INR, which converts to about $700 per year. Households with younger heads, male heads, more number of family members were more likely to have malaria cases. Kuccha construction, improper water supply, low household income houses were also more likely to have a malaria case and the odds doubled in houses with no toilet facilities. Conclusion Based on the results of the study, it has been found that there is an association between the odds of having malaria cases and different household variables such as age, gender, number of members, number of rooms, caste, type of house, toilet facilities, water supply, cattle sheds, agricultural land, income, and vector control interventions. Therefore, a better understanding of the association of various risk factors that influence the incidence of malaria is required to design and/or deploy effective policies and strategies for malaria elimination. The results of this study suggest that appropriate economic and environmental interventions even in low-income and poverty-stricken tribal areas could have huge impact on the success of the national malaria elimination goals.
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Affiliation(s)
- Ravendra K Sharma
- Indian Council of Medical Research-National Institute of Research in Tribal Health, (ICMR-NIRTH), Jabalpur, Madhya Pradesh, India.
| | - Harsh Rajvanshi
- Malaria Elimination Demonstration Project, Mandla, Madhya Pradesh, India
| | - Praveen K Bharti
- Indian Council of Medical Research-National Institute of Research in Tribal Health, (ICMR-NIRTH), Jabalpur, Madhya Pradesh, India
| | - Sekh Nisar
- Malaria Elimination Demonstration Project, Mandla, Madhya Pradesh, India
| | - Himanshu Jayswar
- Directorate of Health Services, Government of Madhya Pradesh, Bhopal, India
| | - Ashok K Mishra
- Indian Council of Medical Research-National Institute of Research in Tribal Health, (ICMR-NIRTH), Jabalpur, Madhya Pradesh, India
| | - Kalyan B Saha
- Indian Council of Medical Research-National Institute of Research in Tribal Health, (ICMR-NIRTH), Jabalpur, Madhya Pradesh, India
| | - Man Mohan Shukla
- Indian Council of Medical Research-National Institute of Research in Tribal Health, (ICMR-NIRTH), Jabalpur, Madhya Pradesh, India
| | - Aparup Das
- Indian Council of Medical Research-National Institute of Research in Tribal Health, (ICMR-NIRTH), Jabalpur, Madhya Pradesh, India
| | - Harpreet Kaur
- Indian Council of Medical Research, Department of Health Research, Ministry of Health and Family Welfare, New Delhi, India
| | - Suman L Wattal
- National Vector Borne Disease Control Program, Ministry of Health and Family Welfare, New Delhi, India
| | - Altaf A Lal
- Malaria Elimination Demonstration Project, Mandla, Madhya Pradesh, India.,Foundation for Disease Elimination and Control of India, Mumbai, Maharashtra, India
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Spatio-temporal trends in anaemia among pregnant women, adolescents and preschool children in sub-Saharan Africa. Public Health Nutr 2020; 24:3648-3661. [PMID: 33190664 DOI: 10.1017/s1368980020004620] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
OBJECTIVE We investigated the spatiotemporal trends in the burden of maternal, adolescent and child anaemia in sub-Saharan Africa (SSA) and evaluated some individual and household predictors of anaemia. DESIGN Average Hb concentrations and anaemia prevalence were estimated, plotted over time and mapped by country and sub-region. Multilevel linear regression models were used to evaluate individual and household predictors of Hb concentration. PARTICIPANTS Data from Demographic and Health Surveys (DHS) spanning 2000-2018 were merged into data sets for 37 623 pregnant women, 89 815 older adolescent girls and 401 438 preschool children. SETTING The merged DHS represent nationally representative samples from thirty-three countries. RESULTS Prevalence of anaemia remains high in SSA, affecting 60, 36 and 44 % of children, adolescents and pregnant women, respectively. Anaemia prevalence among children did not materially improve from 2000 to 2018. Anaemia prevalence among older adolescent girls and pregnant women did not also improve, but this masks a period of improvement followed by depreciation in population anaemia status. Pregnant adolescents had 12·5 g/l (95 % CI: 11·3, 13·6) lower Hb concentration compared with non-pregnant adolescents and 1·7 g/l (95 % CI: 0·7, 2·6) lower Hb concentration compared with pregnant women > 40 years, respectively. Stunting and wasting were associated with 1·3-3·3 g/l lower Hb concentration among children. Other significant predictors of Hb concentration were educational attainment, wealth quintiles, source of drinking water, number of children < 5 years in the household and possession of bed-nets. CONCLUSION Anaemia in SSA has not improved remarkably since year 2000 and remains excessive among children.
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Mutero CM, Okoyo C, Girma M, Mwangangi J, Kibe L, Ng'ang'a P, Kussa D, Diiro G, Affognon H, Mbogo CM. Evaluating the impact of larviciding with Bti and community education and mobilization as supplementary integrated vector management interventions for malaria control in Kenya and Ethiopia. Malar J 2020; 19:390. [PMID: 33143707 PMCID: PMC7607826 DOI: 10.1186/s12936-020-03464-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 10/26/2020] [Indexed: 12/04/2022] Open
Abstract
Background Malaria prevention in Africa is mainly through the use of long-lasting insecticide treated nets (LLINs). The objective of the study was to assess the effect of supplementing LLINs with either larviciding with Bacillus thuringiensis israelensis (Bti) or community education and mobilization (CEM), or with both interventions in the context of integrated vector management (IVM). Methods The study involved a factorial, cluster-randomized, controlled trial conducted in Malindi and Nyabondo sites in Kenya and Tolay site in Ethiopia, to assess the impact of the following four intervention options on mosquitoes and malaria prevalence: LLINs only (arm 1); LLINs and Bti (arm 2); LLINs and CEM (arm 3); and, LLINs combined with Bti and CEM (arm 4). Between January 2013 and December 2015, CDC light traps were used to sample adult mosquitoes during the second, third and fourth quarter of each year in 10 houses in each of 16 villages at each of the three study sites. Larvae were sampled once a fortnight from potential mosquito-breeding habitats using standard plastic dippers. Cross-sectional malaria parasite prevalence surveys were conducted involving a total of 11,846 primary school children during the 3-year period, including 4800 children in Tolay, 3000 in Malindi and 4046 in Nyabondo study sites. Results Baseline relative indoor anopheline density was 0.11, 0.05 and 0.02 mosquitoes per house per night in Malindi, Tolay and Nyabondo sites, respectively. Nyabondo had the highest recorded overall average malaria prevalence among school children at 32.4%, followed by Malindi with 5.7% and Tolay 1.7%. There was no significant reduction in adult anopheline density at each of the three sites, which could be attributed to adding of the supplementary interventions to the usage of LLINs. Malaria prevalence was significantly reduced by 50% in Tolay when using LLINs coupled with application of Bti, community education and mobilization. The two other sites did not reveal significant reduction of prevalence as a result of combining LLINs with any of the other supplementary interventions. Conclusion Combining LLINs with larviciding with Bti and CEM further reduced malaria infection in a low prevalence setting in Ethiopia, but not at sites with relatively higher prevalence in Kenya. More research is necessary at the selected sites in Kenya to periodically determine the suite of vector control interventions and broader disease management strategies, which when integrated would further reduce adult anopheline populations and malaria prevalence beyond what is achieved with LLINs.
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Affiliation(s)
- Clifford M Mutero
- International Centre of Insect Physiology and Ecology (ICIPE), P. O. Box 30772, 00100, Nairobi, Kenya. .,Institute for Sustainable Malaria Control, School of Health Systems and Public Health, University of Pretoria, Pretoria, South Africa.
| | - Collins Okoyo
- Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute (KEMRI), Nairobi, Kenya
| | - Melaku Girma
- Zoological Sciences Department, Addis Ababa University, Addis Ababa, Ethiopia
| | - Joseph Mwangangi
- Centre for Geographic Medicine Research, Kenya Medical Research Institute (KEMRI), Kilifi, Kenya
| | - Lydia Kibe
- Centre for Geographic Medicine Research, Kenya Medical Research Institute (KEMRI), Kilifi, Kenya
| | - Peter Ng'ang'a
- International Centre of Insect Physiology and Ecology (ICIPE), P. O. Box 30772, 00100, Nairobi, Kenya
| | - Dereje Kussa
- International Centre of Insect Physiology and Ecology (ICIPE), Addis Ababa, Ethiopia
| | - Gracious Diiro
- International Centre of Insect Physiology and Ecology (ICIPE), P. O. Box 30772, 00100, Nairobi, Kenya
| | - Hippolyte Affognon
- West and Central Africa Council for Agricultural Research and Development, Dakar, Senegal
| | - Charles M Mbogo
- Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute (KEMRI), Nairobi, Kenya.,Centre for Geographic Medicine Research, Kenya Medical Research Institute (KEMRI), Kilifi, Kenya
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Smith RD, Keogh-Brown MR, Chico RM, Bretscher MT, Drakeley C, Jensen HT. Will More of the Same Achieve Malaria Elimination? Results from an Integrated Macroeconomic Epidemiological Demographic Model. Am J Trop Med Hyg 2020; 103:1871-1882. [PMID: 32959760 PMCID: PMC7646798 DOI: 10.4269/ajtmh.19-0472] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 06/22/2020] [Indexed: 12/20/2022] Open
Abstract
Historic levels of funding have reduced the global burden of malaria in recent years. Questions remain, however, as to whether scaling up interventions, in parallel with economic growth, has made malaria elimination more likely today than previously. The consequences of "trying but failing" to eliminate malaria are also uncertain. Reduced malaria exposure decreases the acquisition of semi-immunity during childhood, a necessary phase of the immunological transition that occurs on the pathway to malaria elimination. During this transitional period, the risk of malaria resurgence increases as proportionately more individuals across all age-groups are less able to manage infections by immune response alone. We developed a robust model that integrates the effects of malaria transmission, demography, and macroeconomics in the context of Plasmodium falciparum malaria within a hyperendemic environment. We analyzed the potential for existing interventions, alongside economic development, to achieve malaria elimination. Simulation results indicate that a 2% increase in future economic growth will increase the US$5.1 billion cumulative economic burden of malaria in Ghana to US$7.2 billion, although increasing regional insecticide-treated net coverage rates by 25% will lower malaria reproduction numbers by just 9%, reduce population-wide morbidity by -0.1%, and reduce prevalence from 54% to 46% by 2034. As scaling up current malaria control tools, combined with economic growth, will be insufficient to interrupt malaria transmission in Ghana, high levels of malaria control should be maintained and investment in research and development should be increased to maintain the gains of the past decade and to minimize the risk of resurgence, as transmission drops.
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Affiliation(s)
- Richard D. Smith
- College of Medicine and Health, University of Exeter, Exeter, United Kingdom
- Faculty of Public Health and Policy, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Marcus R. Keogh-Brown
- Faculty of Public Health and Policy, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - R. Matthew Chico
- Faculty of Public Health and Policy, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Michael T. Bretscher
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
- Department of Infectious Disease Epidemiology, MRC Centre for Outbreak Analysis and Modelling, Imperial College, London, United Kingdom
| | - Chris Drakeley
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Henning Tarp Jensen
- Faculty of Public Health and Policy, London School of Hygiene and Tropical Medicine, London, United Kingdom
- Department of Food and Resource Economics, Faculty of Science, University of Copenhagen, Frederiksberg, United Kingdom
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Zerdo Z, Van Geertruyden JP, Massebo F, Biresaw G, Shewangizawu M, Tunje A, Chisha Y, Yohanes T, Bastiaens H, Anthierens S. Parents' perception on cause of malaria and their malaria prevention experience among school-aged children in Kutcha district, Southern Ethiopia; qualitative study. PLoS One 2020; 15:e0239728. [PMID: 33048941 PMCID: PMC7553332 DOI: 10.1371/journal.pone.0239728] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2019] [Accepted: 09/11/2020] [Indexed: 11/19/2022] Open
Abstract
INTRODUCTION School-aged children become a highly vulnerable group for malaria, yet they are less likely to use malaria prevention interventions. Previous studies exploring perception on cause of malaria mainly focused on pregnant mothers or parents of children under age five years. Exploring parent's perception on cause of malaria and their experiences on the prevention of malaria and associated challenges among school-aged children is important to develop a malaria prevention education package for school-aged children to reduce malaria and malaria related morbidities among school-aged children. METHODS A descriptive qualitative study is conducted in Kutcha district by recruiting 19 parents of school-aged children for semi-structured interviews, 6 key informants and 6 focus group discussion which consists of parents, health development army and health extension workers. A semi-structured interview guide is used to guide the interview process. The collected data is analyzed thematically with a focus on the three major areas of concern: perceived cause of malaria, experience of malaria prevention and challenges of bed net use for prevention of malaria. RESULTS Five causes of malaria were identified, namely hunger, mosquito bite, exposure to hot sunshine, poor sanitation and hygiene and eating some sweet foods and unripe maize. Participants perceived that eating sweet foods and unripe maize lead to enlargement of the spleen that ends in malaria while poor hygiene and sanitation leads to either development of the ova of mosquito and the landing of the housefly to contaminate food for consumption. The experiences of malaria prevention were largely influenced by their perceived cause of malaria. The malaria prevention measures undertaken by parents were vectors control measures, homemade herbal remedies and restricting children from eating sweet foods. The challenges of malaria prevention by using bed nets were related to a negative attitude, sleeping behaviors of children; use of bed nets for unintended purposes, shortage of bed nets and delays in the distribution of bed nets. CONCLUSION There were misconceptions about the cause of malaria and associated experiences of malaria prevention. Control of malaria among school-aged children need health education targeting the challenges and correcting identified misconceptions by parents in Kutcha district and in other similar settings.
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Affiliation(s)
- Zerihun Zerdo
- Department of Medical Laboratory Science, College of Medicine and Health Sciences, Arba Minch University, Arba Minch, Ethiopia
- Global Health Institute, Antwerp University, Antwerp, Belgium
| | | | - Fekadu Massebo
- Department of Biology, College of Natural Sciences, Arba Minch University, Arba Minch, Ethiopia
| | - Gelila Biresaw
- Department of Medical Laboratory Science, College of Medicine and Health Sciences, Arba Minch University, Arba Minch, Ethiopia
| | - Misgun Shewangizawu
- Department of public health, College of Medicine and Health Sciences, Arba Minch University, Arba Minch, Ethiopia
| | - Abayneh Tunje
- Department of public health, College of Medicine and Health Sciences, Arba Minch University, Arba Minch, Ethiopia
| | - Yilma Chisha
- Department of public health, College of Medicine and Health Sciences, Arba Minch University, Arba Minch, Ethiopia
| | - Tsegaye Yohanes
- Department of Medical Laboratory Science, College of Medicine and Health Sciences, Arba Minch University, Arba Minch, Ethiopia
| | - Hilde Bastiaens
- Department of Family Medicine and Population Health, University of Antwerp, Antwerp, Belgium
| | - Sibyl Anthierens
- Department of Family Medicine and Population Health, University of Antwerp, Antwerp, Belgium
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Spatiotemporal clustering of malaria in southern-central Ethiopia: A community-based cohort study. PLoS One 2019; 14:e0222986. [PMID: 31568489 PMCID: PMC6768540 DOI: 10.1371/journal.pone.0222986] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 09/11/2019] [Indexed: 01/08/2023] Open
Abstract
Introduction Understanding the spatiotemporal clustering of malaria transmission would help target interventions in settings of low malaria transmission. The aim of this study was to assess whether malaria infections were clustered in areas with long-lasting insecticidal nets (LLINs) alone, indoor residual spraying (IRS) alone, or a combination of LLINs and IRS interventions, and to determine the risk factors for the observed malaria clustering in southern-central Ethiopia. Methods A cohort of 34,548 individuals residing in 6,071 households was followed for 121 weeks, from October 2014 to January 2017. Both active and passive case detection mechanisms were used to identify clinical malaria episodes, and there were no geographic heterogeneity in data collection methods. Using SaTScan software v 9.4.4, a discrete Poisson model was used to identify high rates of spatial, temporal, and spatiotemporal malaria clustering. A multilevel logistic regression model was fitted to identify predictors of spatial malaria clustering. Results The overall incidence of malaria was 16.5 per 1,000 person-year observations. Spatial, temporal, and spatiotemporal clustering of malaria was detected in all types of malaria infection (P. falciparum, P. vivax, or mixed). Spatial clustering was identified in all study arms: for LLIN + IRS arm, a most likely cluster size of 169 cases in 305 households [relative risk (RR) = 4.54, P<0.001]; for LLIN alone arm a cluster size of 88 cases in 103 households (RR = 5.58, P<0.001); for IRS alone arm a cluster size of 58 cases in 50 households (RR = 7.15, P<0.001), and for control arm a cluster size of 147 cases in 377 households (RR = 2.78, P<0.001). Living 1 km closer to potential vector breeding sites increased the odds of being in spatial clusters by 41.32 fold (adjusted OR = 41.32, 95% CI = 3.79–138.89). Conclusions The risk of malaria infection varied significantly between kebeles, within kebeles, and even among households in areas targeted for different types of malaria control interventions in low malaria transmission setting. The results of this study can be used in planning and implementation of malaria control strategies at micro-geographic scale. Trial registration PACT R2014 11000 882128 (8 September 2014).
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Kenea O, Balkew M, Tekie H, Deressa W, Loha E, Lindtjørn B, Overgaard HJ. Impact of combining indoor residual spraying and long-lasting insecticidal nets on Anopheles arabiensis in Ethiopia: results from a cluster randomized controlled trial. Malar J 2019; 18:182. [PMID: 31126286 PMCID: PMC6534825 DOI: 10.1186/s12936-019-2811-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 05/15/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Indoor residual house spraying (IRS) and long-lasting insecticidal nets (LLINs) are the key front-line malaria vector interventions against Anopheles arabiensis, the sole primary malaria vector in Ethiopia. Universal coverage of both interventions has been promoted and there is a growing demand in combinations of interventions for malaria control and elimination. This study compared the impact on entomological outcomes of combining IRS and LLINs with either intervention alone in Adami Tullu district, south-central Ethiopia. The epidemiological outcomes were recently published on a separate paper. METHODS This factorial, cluster-randomized, controlled trial randomized villages to four study arms: IRS + LLIN, IRS, LLIN, and control. LLINs (PermaNet 2.0) were provided free of charge. IRS with propoxur was applied before the main malaria transmission season in 2014, 2015 and 2016. Adult mosquitoes were collected in randomly selected villages in each arm using CDC light trap catch (LTC) set close to a sleeping person, pyrethrum spray catch (PSC), and artificial pit shelter (PIT), for measuring mosquito host-seeking density (HSD), indoor resting density (IRD), and outdoor resting density (ORD), respectively. Human landing catch (HLC) was performed in a sub-set of villages to monitor An. arabiensis human biting rates (HBR). Mean vector densities and HBR were compared among study arms using incidence rate ratio (IRR) calculated by negative binomial regression. RESULTS There were no significant differences in mean densities (HSD, IRD, ORD) and HBR of An. arabiensis between the IRS + LLIN arm and the IRS arm (p > 0.05). However, mean HSD, IRD, ORD, and HBR were significantly lower in the IRS + LLIN arm than in the LLIN alone arm (p < 0.05). All An. arabiensis tested for malaria infection were negative for Plasmodium species. For this reason, the entomological inoculation rate could not be determined. CONCLUSIONS The IRS + LLIN were as effective as IRS alone in reducing densities and HBR of An. arabiensis. However, the effectiveness of the two interventions combined was higher than LLINs alone in reducing densities and HBR of the vector. Added impact of the combination intervention against malaria infectivity rates of An. arabiensis compared to either intervention alone remains unknown and warrants further research. Trial registration PACTR201411000882128. Registered 8 September 2014, https://trialsjournal.biomedcentral.com/articles/10.1186/s13063-016-1154-2.
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Affiliation(s)
- Oljira Kenea
- Department of Zoological Sciences, Addis Ababa University, Addis Ababa, Ethiopia. .,Department of Biology, Wollega University, Nekemte, Ethiopia.
| | - Meshesha Balkew
- Akililu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
| | - Habte Tekie
- Department of Zoological Sciences, Addis Ababa University, Addis Ababa, Ethiopia
| | - Wakgari Deressa
- Department of Preventive Medicine, School of Public Health, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia
| | - Eskindir Loha
- School of Public and Environmental Health, Hawassa University, Hawassa, Ethiopia
| | - Bernt Lindtjørn
- Centre for International Health, University of Bergen, Bergen, Norway
| | - Hans J Overgaard
- Faculty of Science and Technology, Norwegian University of Life Sciences, Ås, Norway
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