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Almojil D, Diawara A, Soulama I, Dieng MM, Manikandan V, Sermé SS, Sombié S, Diarra A, Barry A, Coulibaly SA, Sirima SB, Idaghdour Y. Impact of Plasmodium falciparum infection on DNA methylation of circulating immune cells. Front Genet 2023; 14:1197933. [PMID: 37470040 PMCID: PMC10352500 DOI: 10.3389/fgene.2023.1197933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 06/02/2023] [Indexed: 07/21/2023] Open
Abstract
The regulation of immune cell responses to infection is a complex process that involves various molecular mechanisms, including epigenetic regulation. DNA methylation has been shown to play central roles in regulating gene expression and modulating cell response during infection. However, the nature and extent to which DNA methylation is involved in the host immune response in human malaria remains largely unknown. Here, we present a longitudinal study investigating the temporal dynamics of genome-wide in vivo DNA methylation profiles using 189 MethylationEPIC 850 K profiles from 66 children in Burkina Faso, West Africa, sampled three times: before infection, during symptomatic parasitemia, and after malaria treatment. The results revealed major changes in the DNA methylation profiles of children in response to both Plasmodium falciparum infection and malaria treatment, with widespread hypomethylation of CpGs upon infection (82% of 6.8 K differentially methylated regions). We document a remarkable reversal of CpG methylation profiles upon treatment to pre-infection states. These changes implicate divergence in core immune processes, including the regulation of lymphocyte, neutrophil, and myeloid leukocyte function. Integrative DNA methylation-mRNA analysis of a top differentially methylated region overlapping the pro-inflammatory gene TNF implicates DNA methylation of TNF cis regulatory elements in the molecular mechanisms of TNF regulation in human malaria. Our results highlight a central role of epigenetic regulation in mounting the host immune response to P. falciparum infection and in response to malaria treatment.
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Affiliation(s)
- Dareen Almojil
- Program in Biology, Division of Science and Mathematics, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Aïssatou Diawara
- Program in Biology, Division of Science and Mathematics, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Issiaka Soulama
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Mame Massar Dieng
- Program in Biology, Division of Science and Mathematics, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Vinu Manikandan
- Program in Biology, Division of Science and Mathematics, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Samuel S. Sermé
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Salif Sombié
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Amidou Diarra
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Aissata Barry
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | | | - Sodiomon B. Sirima
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Youssef Idaghdour
- Program in Biology, Division of Science and Mathematics, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
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Jackson EE, Janitz AE, Carabin H. A Method to Create Directed Acyclic Graphs from Cycles of Transmission of Zoonotic and Vector-Borne Infectious Agents. Vector Borne Zoonotic Dis 2023; 23:129-135. [PMID: 36847355 PMCID: PMC11074630 DOI: 10.1089/vbz.2022.0040] [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] [Indexed: 03/01/2023] Open
Abstract
Background: The life cycles of zoonotic and vector-borne diseases can be complex. This complexity makes it challenging to identify factors that confound the association between an exposure of interest and infection in one of the susceptible hosts. In epidemiology, directed acyclic graphs (DAGs) can be used to visualize the relationships between exposures and outcomes and also to identify which factors confound the association between exposure and the outcome of interest. However, DAGs can only be used in situations where no cycle exists in the causal relationships being represented. This is problematic for infectious agents that cycle between hosts. Zoonoses and vector-borne diseases pose additional challenges with DAG construction since multiple required or optional hosts of different species may be part of the cycle. Methods: We review the existing examples of DAGs created for nonzoonotic infectious agents. We then demonstrate how to cut the transmission cycle to create DAGs where infection of a specific host species is the outcome of interest. We adapt our method to create DAGs using examples of transmission and host characteristics common to many zoonotic and vector-borne infectious agents. Results: We demonstrate our method using the transmission cycle of West Nile virus to create a simple transmission DAG that lacks a cycle. Conclusions: Using our work, investigators can create DAGs to help identify confounders of the relationships between modifiable risk factors and infection. Ultimately, a better understanding and control of confounding in measuring the impact of such risk factors can be used to inform health policy, guide public health and animal health interventions, and uncover gaps needing further research attention.
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Affiliation(s)
- Ellen E. Jackson
- Département de pathologie et microbiologie, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
- Centre de recherche en santé publique (CReSP), Université de Montréal and Centre intégré universitaire de santé et de services sociaux du Centre-Sud-de-l'Île-de-Montréal, Montréal, Québec, Canada
- Groupe de recherche en épidémiologie des zoonoses et santé publique (GREZOSP), Université de Montréal, Saint-Hyacinthe, Québec, Canada
- Centre de recherche en infectiologie porcine et avicole (CRIPA), Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
| | - Amanda E. Janitz
- Department of Biostatistics and Epidemiology, Hudson College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Hélène Carabin
- Département de pathologie et microbiologie, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
- Centre de recherche en santé publique (CReSP), Université de Montréal and Centre intégré universitaire de santé et de services sociaux du Centre-Sud-de-l'Île-de-Montréal, Montréal, Québec, Canada
- Groupe de recherche en épidémiologie des zoonoses et santé publique (GREZOSP), Université de Montréal, Saint-Hyacinthe, Québec, Canada
- Département de médecine sociale et préventive, École de santé publique, Université de Montréal, Montréal, Québec, Canada
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Hospital-based surveillance of severe paediatric malaria in two malaria transmission ecological zones of Burkina Faso. Malar J 2023; 22:6. [PMID: 36609299 PMCID: PMC9817371 DOI: 10.1186/s12936-022-04433-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 12/24/2022] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND In the current context of tailoring interventions to maximize impact, it is important that current data of clinical epidemiology guide public health programmes and health workers in the management of severe disease. This study aimed at describing the burden of severe malaria at hospital level in two areas with distinct malaria transmission intensity. METHODS A hospital-based surveillance was established in two regional hospitals located in two areas exposed to different malaria transmission. Data on paediatric severe malaria admissions were recorded using standardized methods from August 2017 to August 2018 with an interruption during the dry season from April to June 2018. RESULTS In total, 921 children with severe malaria cases were enrolled in the study. The mean age was 33.9 (± 1.3) and 36.8 (± 1.6) months in lower malaria transmission (LMT) and higher malaria transmission (HMT) areas (p = 0.15), respectively. The geometric mean of asexual P. falciparum density was significantly higher in the LMT area compared to the HMT area: 22,861 trophozoites/µL (95% CI 17,009.2-30,726.8) vs 11,291.9 trophozoites/µL (95% CI 8577.9-14,864.5). Among enrolled cases, coma was present in 70 (9.2%) participants. 196 patients (21.8%) presented with two or more convulsions episodes prior to admission. Severe anaemia was present in 448 children (49.2%). Other clinical features recorded included 184 (19.9%) cases of lethargy, 99 (10.7%) children with incoercible vomiting, 80 (8.9%) patients with haemoglobinuria, 43 (4.8%) children with severe hypoglycaemia, 37 (4.0%) cases where child was unable to drink/suck, 11 (1.2%) cases of patients with circulatory collapse/shock, and 8 cases (0.9%) of abnormal bleeding (epistaxis). The adjusted odds of presenting with coma, respiratory distress, haemoglobinuria, circulatory collapse/shock and hypoglycaemia were significantly higher (respectively 6.5 (95%CI 3.4-12.1); 1.8 (95%CI 1.0-3.2); 2.7 (95%CI 1.6-4.3); 5.9 (95%CI 1.3-27.9); 1.9 (95%CI 1.0-3.6)) in children living in the HMT area compared to those residing in the LMT area. Overall, forty-four children died during hospitalization (case fatality rate 5.0%) with the highest fatalities in children admitted with respiratory distress (26.0%) and those with hypoglycaemia (25.0%). CONCLUSION The study showed that children in the HMT area have a higher risk of presenting with coma, shock/dehydration, haemoglobinuria, hypoglycaemia, and respiratory distress. Case-fatality rate is higher among patients with respiratory distress or hypoglycaemia. Hospital surveillance provides a reliable and sustainable means to monitor the clinical presentation of severe malaria and tailor the training needs and resources allocation for case management.
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Nankabirwa JI, Arinaitwe E, Briggs J, Rek J, Rosenthal PJ, Kamya MR, Olwoch P, Smith DL, Rodriguez-Barraquer I, Dorsey G, Greenhouse B. Simulating the Impacts of Augmenting Intensive Vector Control with Mass Drug Administration or Test-and-Treat Strategies on the Malaria Infectious Reservoir. Am J Trop Med Hyg 2022; 107:1028-1035. [PMID: 36191870 PMCID: PMC9709029 DOI: 10.4269/ajtmh.21-0953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 06/29/2022] [Indexed: 12/24/2022] Open
Abstract
Highly effective vector control can reduce malaria burden significantly, but individuals with parasitemia provide a potential reservoir for onward transmission. We performed an empirical, non-parametric simulation based on cohort data from Tororo District, Uganda-an area with historically high but recently reduced malaria transmission-to estimate the effects of mass drug administration (MDA) and test-and-treat on parasite prevalence. We estimate that a single round of MDA would have accelerated declines in parasite prevalence dramatically over 2 years (cumulative parasite prevalence ratio [PPR], 0.34). This decline was mostly during the first year of administration (PPR, 0.23) and waned by 23 months (PPR, 0.74). Test-and-treat using a highly sensitive diagnostic had nearly the same effect as MDA at 1 year (PPR, 0.27) and required many fewer treatments. The impact of test-and-treat using a standard diagnostic was modest (PPR, 0.58 at 1 year). Our analysis suggests that in areas experiencing a dramatic reduction in malaria prevalence, MDA or test-and-treat with a highly sensitive diagnostic may be an effective way of reducing or eliminating the infectious reservoir temporarily. However, for sustained benefits, repeated rounds of the intervention or additional interventions are required.
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Affiliation(s)
- Joaniter I. Nankabirwa
- Department of Internal Medicine, Makerere University College of Health Sciences, Kampala, Uganda
- Infectious Disease Research Collaboration, Kampala, Uganda
| | | | - Jessica Briggs
- Department of Infectious Diseases, School of Medicine, University of California, San Francisco, California
| | - John Rek
- Infectious Disease Research Collaboration, Kampala, Uganda
| | - Philip J. Rosenthal
- Department of Infectious Diseases, School of Medicine, University of California, San Francisco, California
| | - Moses R. Kamya
- Department of Internal Medicine, Makerere University College of Health Sciences, Kampala, Uganda
- Infectious Disease Research Collaboration, Kampala, Uganda
| | - Peter Olwoch
- Infectious Disease Research Collaboration, Kampala, Uganda
| | - David L. Smith
- Department of Health Metrics Sciences, University of Washington, Seattle, Washington
| | - Isabel Rodriguez-Barraquer
- Department of Infectious Diseases, School of Medicine, University of California, San Francisco, California
| | - Grant Dorsey
- Department of Infectious Diseases, School of Medicine, University of California, San Francisco, California
| | - Bryan Greenhouse
- Department of Infectious Diseases, School of Medicine, University of California, San Francisco, California
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Yaro JB, Tiono AB, Ouedraogo A, Lambert B, Ouedraogo ZA, Diarra A, Traore A, Lankouande M, Soulama I, Sanou A, Worrall E, Agboraw E, Sagnon N, Ranson H, Churcher TS, Lindsay SW, Wilson AL. Risk of Plasmodium falciparum infection in south-west Burkina Faso: potential impact of expanding eligibility for seasonal malaria chemoprevention. Sci Rep 2022; 12:1402. [PMID: 35082312 PMCID: PMC8791962 DOI: 10.1038/s41598-022-05056-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 12/10/2021] [Indexed: 11/10/2022] Open
Abstract
Burkina Faso has one of the highest malaria burdens in sub-Saharan Africa despite the mass deployment of insecticide-treated nets (ITNs) and use of seasonal malaria chemoprevention (SMC) in children aged up to 5 years. Identification of risk factors for Plasmodium falciparum infection in rural Burkina Faso could help to identify and target malaria control measures. A cross-sectional survey of 1,199 children and adults was conducted during the peak malaria transmission season in the Cascades Region of south-west Burkina Faso in 2017. Logistic regression was used to identify risk factors for microscopically confirmed P. falciparum infection. A malaria transmission dynamic model was used to determine the impact on malaria cases averted of administering SMC to children aged 5-15 year old. P. falciparum prevalence was 32.8% in the study population. Children aged 5 to < 10 years old were at 3.74 times the odds (95% CI = 2.68-5.22, P < 0.001) and children aged 10 to 15 years old at 3.14 times the odds (95% CI = 1.20-8.21, P = 0.02) of P. falciparum infection compared to children aged less than 5 years old. Administration of SMC to children aged up to 10 years is predicted to avert an additional 57 malaria cases per 1000 population per year (9.4% reduction) and administration to children aged up to 15 years would avert an additional 89 malaria cases per 1000 population per year (14.6% reduction) in the Cascades Region, assuming current coverage of pyrethroid-piperonyl butoxide ITNs. Malaria infections were high in all age strata, although highest in children aged 5 to 15 years, despite roll out of core malaria control interventions. Given the burden of infection in school-age children, extension of the eligibility criteria for SMC could help reduce the burden of malaria in Burkina Faso and other countries in the region.
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Affiliation(s)
- Jean Baptiste Yaro
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
- Department of Biosciences, Durham University, Durham, UK
| | - Alfred B Tiono
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Alphonse Ouedraogo
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Ben Lambert
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Faculty of Medicine, Imperial College London, London, UK
| | - Z Amidou Ouedraogo
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Amidou Diarra
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Adama Traore
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Malik Lankouande
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Issiaka Soulama
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
- Institut de Recherche en Sciences de la Santé, Ouagadougou, Burkina Faso
| | - Antoine Sanou
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
- Institute of Biodiversity, Animal Health & Comparative Medicine, Glasgow University, Glasgow, UK
| | - Eve Worrall
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Efundem Agboraw
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - N'Fale Sagnon
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Hilary Ranson
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Thomas S Churcher
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Faculty of Medicine, Imperial College London, London, UK
| | | | - Anne L Wilson
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK.
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6
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Yaro JB, Tiono AB, Sanou A, Toe HK, Bradley J, Ouedraogo A, Ouedraogo ZA, Guelbeogo MW, Agboraw E, Worrall E, Sagnon N'F, Lindsay SW, Wilson AL. Risk factors associated with house entry of malaria vectors in an area of Burkina Faso with high, persistent malaria transmission and high insecticide resistance. Malar J 2021; 20:397. [PMID: 34629053 PMCID: PMC8504047 DOI: 10.1186/s12936-021-03926-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 09/26/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In rural Burkina Faso, the primary malaria vector Anopheles gambiae sensu lato (s.l.) primarily feeds indoors at night. Identification of factors which influence mosquito house entry could lead to development of novel malaria vector control interventions. A study was therefore carried out to identify risk factors associated with house entry of An. gambiae s.l. in south-west Burkina Faso, an area of high insecticide resistance. METHODS Mosquitoes were sampled monthly during the malaria transmission season using CDC light traps in 252 houses from 10 villages, each house sleeping at least one child aged five to 15 years old. Potential risk factors for house entry of An. gambiae s.l. were measured, including socio-economic status, caregiver's education and occupation, number of people sleeping in the same part of the house as the child, use of anti-mosquito measures, house construction and fittings, proximity of anopheline aquatic habitats and presence of animals near the house. Mosquito counts were compared using a generalized linear mixed-effect model with negative binomial and log link function, adjusting for repeated collections. RESULTS 20,929 mosquitoes were caught, of which 16,270 (77.7%) were An. gambiae s.l. Of the 6691 An. gambiae s.l. identified to species, 4101 (61.3%) were An. gambiae sensu stricto and 2590 (38.7%) Anopheles coluzzii. Having a metal-roof on the child's sleeping space (IRR = 0.55, 95% CI 0.32-0.95, p = 0.03) was associated with fewer malaria vectors inside the home. CONCLUSION This study demonstrated that the rate of An. gambiae s.l. was 45% lower in sleeping spaces with a metal roof, compared to those with thatch roofs. Improvements in house construction, including installation of metal roofs, should be considered in endemic areas of Africa to reduce the burden of malaria.
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Affiliation(s)
- Jean Baptiste Yaro
- Centre National de Recherche Et de Formation Sur Le Paludisme, Ouagadougou, Burkina Faso.,Department of Biosciences, Durham University, Durham, UK
| | - Alfred B Tiono
- Centre National de Recherche Et de Formation Sur Le Paludisme, Ouagadougou, Burkina Faso
| | - Antoine Sanou
- Centre National de Recherche Et de Formation Sur Le Paludisme, Ouagadougou, Burkina Faso
| | - Hyacinthe K Toe
- Centre National de Recherche Et de Formation Sur Le Paludisme, Ouagadougou, Burkina Faso
| | - John Bradley
- MRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
| | - Alphonse Ouedraogo
- Centre National de Recherche Et de Formation Sur Le Paludisme, Ouagadougou, Burkina Faso
| | - Z Amidou Ouedraogo
- 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
| | - Efundem Agboraw
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Eve Worrall
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - N 'Fale Sagnon
- Centre National de Recherche Et de Formation Sur Le Paludisme, Ouagadougou, Burkina Faso
| | | | - Anne L Wilson
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK.
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Kosasih A, Koepfli C, Dahlan MS, Hawley WA, Baird JK, Mueller I, Lobo NF, Sutanto I. Gametocyte carriage of Plasmodium falciparum (pfs25) and Plasmodium vivax (pvs25) during mass screening and treatment in West Timor, Indonesia: a longitudinal prospective study. Malar J 2021; 20:177. [PMID: 33836772 PMCID: PMC8034167 DOI: 10.1186/s12936-021-03709-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 03/23/2021] [Indexed: 11/21/2022] Open
Abstract
Background A goal of malaria epidemiological interventions is the detection and treatment of parasite reservoirs in endemic areas—an activity that is expected to reduce local transmission. Since the gametocyte is the only transmissible stage from human host to mosquito vector, this study evaluated the pre and post presence of gametocytes during a mass screening and treatment (MST) intervention conducted during 2013 in East Nusa Tenggara, Indonesia. Methods RT-qPCR targeting pfs25 and pvs25 transcripts—gametocyte molecular markers for Plasmodium falciparum and Plasmodium vivax, respectively, was performed to detect and quantify gametocytes in blood samples of P. falciparum and P. vivax-infected subjects over the course of the MST study. The presence of both asexual and sexual parasites in microscopic and submicroscopic infections was compared from the start and end of the MST, using proportion tests as well as parametric and non-parametric tests. Results Parasite prevalence remained unchanged for P. falciparum (6% = 52/811 versus 7% = 50/740, p = 0.838), and decreased slightly for P. vivax (24% = 192/811 versus 19% = 142/740, p = 0.035) between the MST baseline and endpoint. No significant difference was observed in gametocyte prevalence for either P. falciparum (2% = 19/803 versus 3% = 23/729, p = 0.353, OR = 1.34, 95%CI = 0.69–2.63), or P. vivax (7% = 49/744 versus 5% = 39/704, p = 0.442, OR = 0.83, 95%CI = 0.52–1.31). Even though there was an insignificant difference between the two time points, the majority of parasite positive subjects at the endpoint had been negative at baseline (P. falciparum: 66% = 29/44, P. vivax: 60% = 80/134). This was similarly demonstrated for the transmissible stage—where the majority of gametocyte positive subjects at the endpoint were negative at baseline (P. falciparum: 95% = 20/21, P. vivax: 94% = 30/32). These results were independent of treatment provided during MST activities. No difference was demonstrated in parasite and gametocyte density between both time points either in P. falciparum or P. vivax. Conclusion In this study area, similar prevalence rates of P. falciparum and P. vivax parasites and gametocytes before and after MST, although in different individuals, points to a negligible impact on the parasite reservoir. Treatment administration based on parasite positivity as implemented in the MST should be reevaluated for the elimination strategy in the community. Trial registration Clinical trials registration NCT01878357. Registered 14 June 2013, https://www.clinicaltrials.gov/ct2/show/NCT01878357. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03709-y.
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Affiliation(s)
- Ayleen Kosasih
- PhD Programme in Biomedical Sciences, Medical Faculty, Universitas Indonesia, Jakarta, Indonesia.,Eijkman-Oxford Clinical Research Unit, Jakarta, Indonesia.,Indonesian Medical Education and Research Institute, Jakarta, Indonesia
| | - Cristian Koepfli
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA.,Infection & Immunity Division, Walter & Eliza Hall Institute, Melbourne, Australia
| | | | | | - J Kevin Baird
- Center for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Ivo Mueller
- Infection & Immunity Division, Walter & Eliza Hall Institute, Melbourne, Australia
| | - Neil F Lobo
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA
| | - Inge Sutanto
- Indonesian Medical Education and Research Institute, Jakarta, Indonesia. .,Department of Parasitology, Medical Faculty, Universitas Indonesia, Jakarta, Indonesia.
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Yaro JB, Ouedraogo A, Ouedraogo ZA, Diarra A, Lankouande M, Agboraw E, Worrall E, Toe KH, Sanou A, Guelbeogo WM, Sagnon N, Ranson H, Tiono AB, Lindsay SW, Wilson AL. A cohort study to identify risk factors for Plasmodium falciparum infection in Burkinabe children: implications for other high burden high impact countries. Malar J 2020; 19:371. [PMID: 33066799 PMCID: PMC7565747 DOI: 10.1186/s12936-020-03443-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 10/07/2020] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Progress in controlling malaria has stalled in recent years. Today the malaria burden is increasingly concentrated in a few countries, including Burkina Faso, where malaria is not declining. A cohort study was conducted to identify risk factors for malaria infection in children in southwest Burkina Faso, an area with high insecticide-treated net (ITN) coverage and insecticide-resistant vectors. METHODS Incidence of Plasmodium falciparum infection was measured in 252 children aged 5 to 15 years, using active and passive detection, during the 2017 transmission season, following clearance of infection. Demographic, socio-economic, environmental, and entomological risk factors, including use of ITNs and insecticide resistance were monitored. RESULTS During the six-month follow-up period, the overall incidence of P. falciparum infection was 2.78 episodes per child (95% CI = 2.66-2.91) by microscopy, and 3.11 (95% CI = 2.95-3.28) by polymerase chain reaction (PCR). The entomological inoculation rate (EIR) was 80.4 infective bites per child over the six-month malaria transmission season. At baseline, 80.6% of children were reported as sleeping under an ITN the previous night, although at the last survey, 23.3% of nets were in poor condition and considered no longer protective. No association was found between the rate of P. falciparum infection and either EIR (incidence rate ratio (IRR): 1.00, 95% CI: 1.00-1.00, p = 0.08) or mortality in WHO tube tests when vectors were exposed to 0.05% deltamethrin (IRR: 1.05, 95% CI: 0.73-1.50, p = 0.79). Travel history (IRR: 1.52, 95% CI: 1.45-1.59, p < 0.001) and higher socio-economic status were associated with an increased risk of P. falciparum infection (IRR: 1.05, 95% CI: 1.00-1.11, p = 0.04). CONCLUSIONS Incidence of P. falciparum infection remains overwhelmingly high in the study area. The study findings suggest that because of the exceptionally high levels of malaria transmission in the study area, malaria elimination cannot be achieved solely by mass deployment of ITNs and additional control measures are needed.
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Affiliation(s)
- Jean Baptiste Yaro
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
- Department of Biosciences, Durham University, Durham, UK
| | - Alphonse Ouedraogo
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Z Amidou Ouedraogo
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Amidou Diarra
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Malik Lankouande
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Efundem Agboraw
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Eve Worrall
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Kobié Hyacinthe Toe
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Antoine Sanou
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
- Institute of Biodiversity Animal Health & Comparative Medicine, Glasgow University, Glasgow, UK
| | - W Moussa Guelbeogo
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - N'Fale Sagnon
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Hilary Ranson
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Alfred B Tiono
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | | | - Anne L Wilson
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK.
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9
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Hartley MA, Hofmann N, Keitel K, Kagoro F, Antunes Moniz C, Mlaganile T, Samaka J, Masimba J, Said Z, Temba H, Gonzalez I, Felger I, Genton B, D’Acremont V. Clinical relevance of low-density Plasmodium falciparum parasitemia in untreated febrile children: A cohort study. PLoS Med 2020; 17:e1003318. [PMID: 32956354 PMCID: PMC7505590 DOI: 10.1371/journal.pmed.1003318] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 08/13/2020] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Low-density (LD) Plasmodium infections are missed by standard malaria rapid diagnostic tests (standard mRDT) when the blood antigen concentration is below the detection threshold. The clinical impact of these LD infections is unknown. This study investigates the clinical presentation and outcome of untreated febrile children with LD infections attending primary care facilities in a moderately endemic area of Tanzania. METHODS/FINDINGS This cohort study includes 2,801 febrile pediatric outpatients (median age 13.5 months [range 2-59], female:male ratio 0.8:1.0) recruited in Dar es Salaam, Tanzania between 01 December 2014 and 28 February 2016. Treatment decisions were guided by a clinical decision support algorithm run on a mobile app, which also collected clinical data. Only standard mRDT+ cases received antimalarials. Outcomes (clinical failure, secondary hospitalization, and death) were collected in follow-up visits or interviews on days 3, 7, and 28. After patient recruitment had ended, frozen blood from all 2,801 patients was tested for Plasmodium falciparum (Pf) by ultrasensitive-quantitative polymerase chain reaction (qPCR), standard mRDT, and "ultrasensitive" mRDT. As the latter did not improve sensitivity beyond standard mRDT, it is hereafter excluded. Clinical features and outcomes in LD patients (standard mRDT-/ultrasensitive-qPCR+, not given antimalarials) were compared with those with no detectable (ND) parasitemia (standard mRDT-/ultrasensitive-qPCR-) or high-density (HD) infections (standard mRDT+/ultrasensitive-qPCR+, antimalarial-treated). Pf positivity rate was 7.1% (n = 199/2,801) and 9.8% (n = 274/2,801) by standard mRDT and ultrasensitive qPCR, respectively. Thus, 28.0% (n = 76/274) of ultrasensitive qPCR+ cases were not detected by standard mRDT and labeled "LD". LD patients were, on average, 10.6 months younger than those with HD infections (95% CI 7.0-14.3 months, p < 0.001). Compared with ND, LD patients more frequently had the diagnosis of undifferentiated fever of presumed viral origin (risk ratio [RR] = 2.0, 95% CI 1.3-3.1, p = 0.003) and were more often suffering from severe malnutrition (RR = 3.2, 95% CI 1.1-7.5, p = 0.03). Despite not receiving antimalarials, outcomes for the LD group did not differ from ND regarding clinical failures (2.6% [n = 2/76] versus 4.0% [n = 101/2,527], RR = 0.7, 95% CI 0.2-3.5, p = 0.7) or secondary hospitalizations (2.6% [n = 2/76] versus 2.8% [n = 72/2,527], RR = 0.7,95% CI 0.2-3.2, p = 0.9), and no deaths were reported in any Pf-positive groups. HD patients experienced more secondary hospitalizations (10.1% [n = 20/198], RR = 0.3, 95% CI 0.1-1.0, p = 0.005) than LD patients. All the patients in this cohort were febrile children; thus, the association between parasitemia and fever cannot be investigated, nor can the conclusions be extrapolated to neonates and adults. CONCLUSIONS During a 28-day follow-up period, we did not find evidence of a difference in negative outcomes between febrile children with untreated LD Pf parasitemia and those without Pf parasitemia. These findings suggest LD parasitemia may either be a self-resolving fever or an incidental finding in children with other infections, including those of viral origin. These findings do not support a clinical benefit nor additional risk (e.g. because of missed bacterial infections) to using ultrasensitive malaria diagnostics at a primary care level.
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Affiliation(s)
- Mary-Anne Hartley
- Centre for Primary Care and Public Health, University of Lausanne, Lausanne Switzerland
- EPFL, Machine Learning and Optimization Laboratory, Lausanne, Switzerland
| | - Natalie Hofmann
- Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland
| | - Kristina Keitel
- Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland
| | - Frank Kagoro
- Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
| | - Clara Antunes Moniz
- Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland
| | - Tarsis Mlaganile
- Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
| | - Josephine Samaka
- Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
- Amana hospital, Dar es Salaam, United Republic of Tanzania
| | - John Masimba
- Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
| | - Zamzam Said
- Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
| | - Hosiana Temba
- Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
| | - Iveth Gonzalez
- Foundation for Innovative New Diagnostics (FIND), Geneva, Switzerland
| | - Ingrid Felger
- Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland
| | - Blaise Genton
- Centre for Primary Care and Public Health, University of Lausanne, Lausanne Switzerland
- Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland
| | - Valérie D’Acremont
- Centre for Primary Care and Public Health, University of Lausanne, Lausanne Switzerland
- Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland
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10
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Millar J, Toh KB, Valle D. To screen or not to screen: an interactive framework for comparing costs of mass malaria treatment interventions. BMC Med 2020; 18:149. [PMID: 32552743 PMCID: PMC7304173 DOI: 10.1186/s12916-020-01609-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 04/28/2020] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Mass drug administration and mass-screen-and-treat interventions have been used to interrupt malaria transmission and reduce burden in sub-Saharan Africa. Determining which strategy will reduce costs is an important challenge for implementers; however, model-based simulations and field studies have yet to develop consensus guidelines. Moreover, there is often no way for decision-makers to directly interact with these data and/or models, incorporate local knowledge and expertise, and re-fit parameters to guide their specific goals. METHODS We propose a general framework for comparing costs associated with mass drug administrations and mass screen and treat based on the possible outcomes of each intervention and the costs associated with each outcome. We then used publicly available data from six countries in western Africa to develop spatial-explicit probabilistic models to estimate intervention costs based on baseline malaria prevalence, diagnostic performance, and sociodemographic factors (age and urbanicity). In addition to comparing specific scenarios, we also develop interactive web applications which allow managers to select data sources and model parameters, and directly input their own cost values. RESULTS The regional-level models revealed substantial spatial heterogeneity in malaria prevalence and diagnostic test sensitivity and specificity, indicating that a "one-size-fits-all" approach is unlikely to maximize resource allocation. For instance, urban communities in Burkina Faso typically had lower prevalence rates compared to rural communities (0.151 versus 0.383, respectively) as well as lower diagnostic sensitivity (0.699 versus 0.862, respectively); however, there was still substantial regional variation. Adjusting the cost associated with false negative diagnostic results to included additional costs, such as delayed treated and potential lost wages, undermined the overall costs associated with MSAT. CONCLUSIONS The observed spatial variability and dependence on specified cost values support not only the need for location-specific intervention approaches but also the need to move beyond standard modeling approaches and towards interactive tools which allow implementers to engage directly with data and models. We believe that the framework demonstrated in this article will help connect modeling efforts and stakeholders in order to promote data-driven decision-making for the effective management of malaria, as well as other diseases.
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Affiliation(s)
- Justin Millar
- School of Forest Resources and Conservation, University of Florida, Gainesville, USA.
- Emerging Pathogens Institute, University of Florida, Gainesville, USA.
| | - Kok Ben Toh
- Emerging Pathogens Institute, University of Florida, Gainesville, USA
- School of Natural Resources and Environment, University of Florida, Gainesville, USA
| | - Denis Valle
- School of Forest Resources and Conservation, University of Florida, Gainesville, USA
- Emerging Pathogens Institute, University of Florida, Gainesville, USA
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11
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Desai MR, Samuels AM, Odongo W, Williamson J, Odero NA, Otieno K, Shi YP, Kachur SP, Hamel MJ, Kariuki S, Lindblade KA. Impact of Intermittent Mass Testing and Treatment on Incidence of Malaria Infection in a High Transmission Area of Western Kenya. Am J Trop Med Hyg 2020; 103:369-377. [PMID: 32342846 DOI: 10.4269/ajtmh.19-0735] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Progress with malaria control in western Kenya has stagnated since 2007. Additional interventions to reduce the high burden of malaria in this region are urgently needed. We conducted a two-arm, community-based, cluster-randomized, controlled trial of active case detection and treatment of malaria infections in all residents mass testing and treatment (MTaT) of 10 village clusters (intervention clusters) for two consecutive years to measure differences in the incidence of clinical malaria disease and malaria infections compared with 20 control clusters where MTaT was not implemented. All residents of intervention clusters, irrespective of history of fever or other malaria-related symptoms, were tested three times per year before the peak malaria season using malaria rapid diagnostic tests. All positive cases were treated with dihydroartemisinin-piperaquine. The incidence of clinical malaria was measured through passive surveillance, whereas the cumulative incidence of malaria infection was measured using active surveillance in a cohort comprising randomly selected residents. The incidence of clinical malaria was 0.19 cases/person-year (p-y, 95% CI: 0.13-0.28) in the intervention arm and 0.24 cases/p-y (95% CI: 0.15-0.39) in the control arm (incidence rate ratio [IRR] 0.79, 95% CI: 0.61-1.02). The cumulative incidence of malaria infections was similar between the intervention (2.08 infections/p-y, 95% CI: 1.93-2.26) and control arms (2.19 infections/p-y, 95% CI: 2.02-2.37) with a crude IRR of 0.95 (95% CI: 0.87-1.04). Six rounds of MTaT over 2 years did not have a significant impact on the incidence of clinical malaria or the cumulative incidence of malaria infection in this area of high malaria transmission.
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Affiliation(s)
- Meghna R Desai
- Division of Parasitic Diseases and Malaria, Malaria Branch, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Aaron M Samuels
- Division of Parasitic Diseases and Malaria, Malaria Branch, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Wycliffe Odongo
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - John Williamson
- Division of Parasitic Diseases and Malaria, Malaria Branch, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Nobert Awino Odero
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Kephas Otieno
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Ya Ping Shi
- Division of Parasitic Diseases and Malaria, Malaria Branch, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Stephen Patrick Kachur
- Division of Parasitic Diseases and Malaria, Malaria Branch, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Mary J Hamel
- Division of Parasitic Diseases and Malaria, Malaria Branch, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Simon Kariuki
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Kim A Lindblade
- Division of Parasitic Diseases and Malaria, Malaria Branch, Centers for Disease Control and Prevention, Atlanta, Georgia
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12
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Wamae K, Wambua J, Nyangweso G, Mwambingu G, Osier F, Ndung'u F, Bejon P, Ochola-Oyier LI. Transmission and Age Impact the Risk of Developing Febrile Malaria in Children with Asymptomatic Plasmodium falciparum Parasitemia. J Infect Dis 2020; 219:936-944. [PMID: 30307567 PMCID: PMC6386809 DOI: 10.1093/infdis/jiy591] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 10/10/2018] [Indexed: 11/13/2022] Open
Abstract
Background Plasmodium falciparum infections lead to febrile illness unless the host has sufficient immunity, in which case infection may cause no immediate symptoms (ie, “asymptomatic parasitemia”). Previous studies are conflicting on the role of asymptomatic parasitemia in determining the risk of developing febrile malaria. Methods We monitored 2513 children (living in Kilifi, Kenyan Coast) by blood smears in 17 cross-sectional surveys to identify asymptomatic parasitemia and used active surveillance over 11325 child-years of follow-up to detect febrile malaria. We evaluated the interaction between transmission intensity, age, and asymptomatic parasitemia in determining the risk of developing febrile malaria. Results In the moderate and high transmission intensity settings, asymptomatic parasitemia was associated with a reduced risk of febrile malaria in older children (> 3 years), while in the lower transmission setting, asymptomatic parasitemia was associated with an increased risk of febrile malaria in children of all ages. Additionally, the risk associated with asymptomatic parasitemia was limited to the first 90 days of follow-up. Conclusions Asymptomatic parasitemia is modified by transmission intensity and age, altering the risk of developing febrile episodes and suggesting that host immunity plays a prominent role in mediating this process.
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Affiliation(s)
- Kevin Wamae
- Kenya Medical Research Institute Wellcome Trust Research Programme, Kilifi, Kenya
| | - Juliana Wambua
- Kenya Medical Research Institute Wellcome Trust Research Programme, Kilifi, Kenya
| | - George Nyangweso
- Kenya Medical Research Institute Wellcome Trust Research Programme, Kilifi, Kenya
| | - Gabriel Mwambingu
- Kenya Medical Research Institute Wellcome Trust Research Programme, Kilifi, Kenya
| | - Faith Osier
- Kenya Medical Research Institute Wellcome Trust Research Programme, Kilifi, Kenya
| | - Francis Ndung'u
- Kenya Medical Research Institute Wellcome Trust Research Programme, Kilifi, Kenya.,Nuffield Department of Medicine, Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, University of Oxford, United Kingdom
| | - Philip Bejon
- Kenya Medical Research Institute Wellcome Trust Research Programme, Kilifi, Kenya.,Nuffield Department of Medicine, Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, University of Oxford, United Kingdom
| | - Lynette Isabella Ochola-Oyier
- Kenya Medical Research Institute Wellcome Trust Research Programme, Kilifi, Kenya.,Centre for Biotechnology and Bioinformatics, University of Nairobi, Kenya
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13
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Sutanto I, Kosasih A, Elyazar IRF, Simanjuntak DR, Larasati TA, Dahlan MS, Wahid I, Mueller I, Koepfli C, Kusriastuti R, Surya A, Laihad FJ, Hawley WA, Collins FH, Baird JK, Lobo NF. Negligible Impact of Mass Screening and Treatment on Mesoendemic Malaria Transmission at West Timor in Eastern Indonesia: A Cluster-Randomized Trial. Clin Infect Dis 2019; 67:1364-1372. [PMID: 29579195 PMCID: PMC6186863 DOI: 10.1093/cid/ciy231] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 03/21/2018] [Indexed: 01/09/2023] Open
Abstract
Background Mass screening and treatment (MST) aims to reduce malaria risk in communities by identifying and treating infected persons without regard to illness. Methods A cluster-randomized trial evaluated malaria incidence with and without MST. Clusters were randomized to 3, 2, or no MST interventions: MST3, 6 clusters (156 households/670 individuals); MST2, 5 clusters (89 households/423 individuals); and MST0, 5 clusters (174 households/777 individuals). All clusters completed the study with 14 residents withdrawing. In a cohort of 324 schoolchildren (MST3, n = 124; MST2, n = 57; MST0, n = 143) negative by microscopy at enrollment, we evaluated the incidence density of malaria during 3 months of MST and 3 months following. The MST intervention involved community-wide expert malaria microscopic screening and standard therapy with dihydroartemisinin-piperaquine and primaquine for glucose-6 phosphate dehydrogenase–normal subjects. All blood examinations included polymerase chain reaction assays, which did not guide on-site treatment. Results The risk ratios for incidence density of microscopically patent malaria in MST3 or MST2 relative to that in MST0 clusters were 1.00 (95% confidence interval [CI], .53–1.91) and 1.22 (95% CI, .42–3.55), respectively. Similar results were obtained with molecular analysis and species-specific (P. falciparum and P. vivax) infections. Microscopically subpatent, untreated infections accounted for 72% of those infected. Conclusions Two or 3 rounds of MST within 3 months did not impact the force of anopheline mosquito-borne infection in these communities. The high rate of untreated microscopically subpatent infections likely explains the observed poor impact. Clinical Trials Registration NCT01878357.
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Affiliation(s)
- Inge Sutanto
- Department of Parasitology, Faculty of Medicine, University of Indonesia, Indonesia
| | - Ayleen Kosasih
- Department of Parasitology, Faculty of Medicine, University of Indonesia, Indonesia
| | | | - Deddy R Simanjuntak
- Department of Parasitology, Faculty of Medicine, University of Indonesia, Indonesia
| | - Tri A Larasati
- Department of Parasitology, Faculty of Medicine, University of Indonesia, Indonesia
| | | | - Isra Wahid
- Department of Parasitology, Faculty of Medicine, University of Hasanudin, Makasar, Indonesia
| | - Ivo Mueller
- Population Health and Immunity Division, Walter and Eliza Hall Institute, Melbourne, Victoria, Australia
| | - Cristian Koepfli
- Population Health and Immunity Division, Walter and Eliza Hall Institute, Melbourne, Victoria, Australia
| | - Rita Kusriastuti
- Communicable Disease Control, Ministry of Health, Jakarta, Indonesia
| | - Asik Surya
- Communicable Disease Control, Ministry of Health, Jakarta, Indonesia
| | | | | | - Frank H Collins
- Eck Institute for Global Health, University of Notre Dame, Indiana
| | - J Kevin Baird
- Eijkman-Oxford Clinical Research Unit, Indonesia.,Center for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, United Kingdom
| | - Neil F Lobo
- Eck Institute for Global Health, University of Notre Dame, Indiana
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14
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Barry A, Behet MC, Nébié I, Lanke K, Grignard L, Ouedraogo A, Soulama I, Drakeley C, Sauerwein R, Bolscher JM, Dechering KJ, Bousema T, Tiono AB, Gonçalves BP. Functional antibodies against Plasmodium falciparum sporozoites are associated with a longer time to qPCR-detected infection among schoolchildren in Burkina Faso. Wellcome Open Res 2019; 3:159. [PMID: 30828645 PMCID: PMC6381444 DOI: 10.12688/wellcomeopenres.14932.2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/23/2019] [Indexed: 11/23/2022] Open
Abstract
Background: Individuals living in malaria-endemic regions develop immunity against severe malaria, but it is unclear whether immunity against pre-erythrocytic stages that blocks initiation of blood-stage infection after parasite inoculation develops following continuous natural exposure. Methods: We cleared schoolchildren living in an area (health district of Saponé, Burkina Faso) with highly endemic seasonal malaria of possible sub-patent infections and examined them weekly for incident infections by nested PCR. Plasma samples collected at enrolment were used to quantify antibodies to the pre-eryhrocytic-stage antigens circumsporozoite protein (CSP) and Liver stage antigen 1 (LSA-1).
In vitro sporozoite gliding inhibition and hepatocyte invasion inhibition by naturally acquired antibodies were assessed using
Plasmodium falciparum NF54 sporozoites. Associations between antibody responses, functional pre-erythrocytic immunity phenotypes and time to infection detected by
18S quantitative PCR were studied. Results: A total of 51 children were monitored. Anti-CSP antibody titres showed a positive association with sporozoite gliding motility inhibition (P<0.0001, Spearman’s ρ=0.76).
In vitro hepatocyte invasion was inhibited by naturally acquired antibodies (median inhibition, 19.4% [IQR 15.2-40.9%]), and there were positive correlations between invasion inhibition and gliding inhibition (P=0.005, Spearman’s ρ=0.67) and between invasion inhibition and CSP-specific antibodies (P=0.002, Spearman’s ρ=0.76). Survival analysis indicated longer time to infection in individuals displaying higher-than-median sporozoite gliding inhibition activity (P=0.01), although this association became non-significant after adjustment for blood-stage immunity (P = 0.06). Conclusions: In summary, functional antibodies against the pre-erythrocytic stages of malaria infection are acquired in children who are repeatedly exposed to
Plasmodium parasites. This immune response does not prevent them from becoming infected during a malaria transmission season, but might delay the appearance of blood stage parasitaemia. Our approach could not fully separate the effects of pre-erythrocytic-specific and blood-stage-specific antibody-mediated immune responses
in vivo; epidemiological studies powered and designed to address this important question should become a research priority.
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Affiliation(s)
- Aissata Barry
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso.,Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Marije C Behet
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Issa Nébié
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Kjerstin Lanke
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Lynn Grignard
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Alphonse Ouedraogo
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Issiaka Soulama
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Robert Sauerwein
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | | | | | - Teun Bousema
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.,Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Alfred B Tiono
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Bronner P Gonçalves
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
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15
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Barry A, Behet MC, Nébié I, Lanke K, Grignard L, Ouedraogo A, Soulama I, Drakeley C, Sauerwein R, Bolscher JM, Dechering KJ, Bousema T, Tiono AB, Gonçalves BP. Functional antibodies against Plasmodium falciparum sporozoites are associated with a longer time to qPCR-detected infection among schoolchildren in Burkina Faso. Wellcome Open Res 2019; 3:159. [PMID: 30828645 DOI: 10.12688/wellcomeopenres.14932.1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/03/2018] [Indexed: 01/29/2023] Open
Abstract
Background: Individuals living in malaria-endemic regions develop immunity against severe malaria, but it is unclear whether immunity against pre-erythrocytic stages that blocks initiation of blood-stage infection after parasite inoculation develops following continuous natural exposure. Methods: We cleared schoolchildren living in an area (health district of Saponé, Burkina Faso) with highly endemic seasonal malaria of possible sub-patent infections and examined them weekly for incident infections by nested PCR. Plasma samples collected at enrolment were used to quantify antibodies to the pre-eryhrocytic-stage antigens circumsporozoite protein (CSP) and Liver stage antigen 1 (LSA-1). In vitro sporozoite gliding inhibition and hepatocyte invasion inhibition by naturally acquired antibodies were assessed using Plasmodium falciparum NF54 sporozoites. Associations between antibody responses, functional pre-erythrocytic immunity phenotypes and time to infection detected by 18S quantitative PCR were studied. Results: A total of 51 children were monitored. Anti-CSP antibody titres showed a positive association with sporozoite gliding motility inhibition (P<0.0001, Spearman's ρ=0.76). In vitro hepatocyte invasion was inhibited by naturally acquired antibodies (median inhibition, 19.4% [IQR 15.2-40.9%]), and there were positive correlations between invasion inhibition and gliding inhibition (P=0.005, Spearman's ρ=0.67) and between invasion inhibition and CSP-specific antibodies (P=0.002, Spearman's ρ=0.76). Survival analysis indicated longer time to infection in individuals displaying higher-than-median sporozoite gliding inhibition activity (P=0.01), although this association became non-significant after adjustment for blood-stage immunity (P = 0.06). Conclusions: In summary, functional antibodies against the pre-erythrocytic stages of malaria infection are acquired in children who are repeatedly exposed to Plasmodium parasites. This immune response does not prevent them from becoming infected during a malaria transmission season, but might delay the appearance of blood stage parasitaemia. Our approach could not fully separate the effects of pre-erythrocytic-specific and blood-stage-specific antibody-mediated immune responses in vivo; epidemiological studies powered and designed to address this important question should become a research priority.
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Affiliation(s)
- Aissata Barry
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso.,Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Marije C Behet
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Issa Nébié
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Kjerstin Lanke
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Lynn Grignard
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Alphonse Ouedraogo
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Issiaka Soulama
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Robert Sauerwein
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | | | | | - Teun Bousema
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.,Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Alfred B Tiono
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Bronner P Gonçalves
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
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16
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Prado CC, Alvarado-Cabrera LA, Camargo-Ayala PA, Garzón-Ospina D, Camargo M, Soto-De León SC, Cubides JR, Celis-Giraldo CT, Patarroyo ME, Patarroyo MA. Behavior and abundance of Anopheles darlingi in communities living in the Colombian Amazon riverside. PLoS One 2019; 14:e0213335. [PMID: 30845198 PMCID: PMC6405047 DOI: 10.1371/journal.pone.0213335] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 02/20/2019] [Indexed: 01/08/2023] Open
Abstract
In the past few years, relative frequencies of malaria parasite species in communities living in the Colombian Amazon riverside have changed, being Plasmodium vivax (61.4%) and Plasmodium malariae (43.8%) the most frequent. Given this epidemiological scenario, it is important to determine the species of anophelines involved in these parasites' transmission. This study was carried out in June 2016 in two indigenous communities living close to the tributaries of the Amazon River using protected human bait. The results of this study showed a total abundance of 1,085 mosquitos, of which 99.2% corresponded to Anopheles darlingi. Additionally, only two anopheline species were found, showing low diversity in the study areas. Molecular confirmation of some individuals was then followed by evolutionary analysis by using the COI gene. Nested PCR was used for identifying the three Plasmodium species circulating in the study areas. Of the two species collected in this study, 21.0% of the An. darlingi mosquitoes were infected with P. malariae, 21.9% with P. vivax and 10.3% with Plasmodium falciparum. It exhibited exophilic and exophagic behavior in both study areas, having marked differences regarding its abundance in each community (Tipisca first sampling 49.4%, Tipisca second sampling 39.6% and Doce de Octubre 10.9%). Interestingly, An. mattogrossensis infected by P. vivax was found for the first time in Colombia (in 50% of the four females collected). Analysis of An. darlingi COI gene diversity indicated a single population maintaining a high gene flow between the study areas. The An. darlingi behavior pattern found in both communities represents a risk factor for the region's inhabitants living/working near these sites. This highlights the need for vector control efforts such as the use of personal repellents and insecticides for use on cattle, which must be made available in order to reduce this Anopheline's abundance.
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Affiliation(s)
- César Camilo Prado
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá, Colombia
| | | | - Paola Andrea Camargo-Ayala
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá, Colombia
| | - Diego Garzón-Ospina
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá, Colombia
- PhD Programme in Biomedical and Biological Sciences, School of Medicine and Health Sciences, Universidad del Rosario, Bogotá, Colombia
| | - Milena Camargo
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá, Colombia
- PhD Programme in Biomedical and Biological Sciences, School of Medicine and Health Sciences, Universidad del Rosario, Bogotá, Colombia
| | - Sara Cecilia Soto-De León
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá, Colombia
| | - Juan Ricardo Cubides
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá, Colombia
| | | | - Manuel Elkin Patarroyo
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá, Colombia
- School of Medicine, Universidad Nacional de Colombia, Bogotá, Colombia
| | - Manuel Alfonso Patarroyo
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá, Colombia
- Basic Sciences Department, School of Medicine and Health Sciences, Universidad del Rosario, Bogotá, Colombia
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17
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Microscopic malaria parasitemia diagnosis and grading on benchmark datasets. Microsc Res Tech 2018; 81:1042-1058. [DOI: 10.1002/jemt.23071] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2017] [Revised: 04/23/2018] [Accepted: 05/10/2018] [Indexed: 12/16/2022]
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18
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Ouédraogo AL, Eckhoff PA, Luty AJF, Roeffen W, Sauerwein RW, Bousema T, Wenger EA. Modeling the impact of Plasmodium falciparum sexual stage immunity on the composition and dynamics of the human infectious reservoir for malaria in natural settings. PLoS Pathog 2018; 14:e1007034. [PMID: 29742161 PMCID: PMC5962096 DOI: 10.1371/journal.ppat.1007034] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 05/21/2018] [Accepted: 04/16/2018] [Indexed: 12/22/2022] Open
Abstract
Malaria transmission remains high in Sub-Saharan Africa despite large-scale implementation of malaria control interventions. A comprehensive understanding of the transmissibility of infections to mosquitoes may guide the design of more effective transmission reducing strategies. The impact of P. falciparum sexual stage immunity on the infectious reservoir for malaria has never been studied in natural settings. Repeated measurements were carried out at start-wet, peak-wet and dry season, and provided data on antibody responses against gametocyte/gamete antigens Pfs48/45 and Pfs230 as anti-gametocyte immunity. Data on high and low-density infections and their infectiousness to anopheline mosquitoes were obtained using quantitative molecular methods and mosquito feeding assays, respectively. An event-driven model for P. falciparum sexual stage immunity was developed and fit to data using an agent based malaria model infrastructure. We found that Pfs48/45 and Pfs230 antibody densities increased with increasing concurrent gametocyte densities; associated with 55–70% reduction in oocyst intensity and achieved up to 44% reduction in proportions of infected mosquitoes. We showed that P. falciparum sexual stage immunity significantly reduces transmission of microscopic (p < 0.001) but not submicroscopic (p = 0.937) gametocyte infections to mosquitoes and that incorporating sexual stage immunity into mathematical models had a considerable impact on the contribution of different age groups to the infectious reservoir of malaria. Human antibody responses to gametocyte antigens are likely to be dependent on recent and concurrent high-density gametocyte exposure and have a pronounced impact on the likelihood of onward transmission of microscopic gametocyte densities compared to low density infections. Our mathematical simulations indicate that anti-gametocyte immunity is an important factor for predicting and understanding the composition and dynamics of the human infectious reservoir for malaria. Submicroscopic gametocyte infections are efficiently transmitted from humans to mosquitoes in settings with efficient malaria vectors and may pose challenges for malaria control and elimination efforts. Our understanding of what mechanisms contribute to submicroscopic gametocytes infectiousness remains limited. Here we assess the impact of naturally acquired anti-gametocyte antibodies on malaria transmission to mosquitoes and on the age-dependent composition of the infectious reservoir and seasonal dynamics. Anti-gametocyte immunity significantly reduces the infectiousness of high gametocyte density infections, contributes to explain the age-related profiles of the infectious reservoir in the study area, whilst submicroscopic gametocyte infections that present with lower anti-Pfs48/45 and anti-Pfs230 antibody responses commonly remain transmissible to mosquitoes. Our findings indicate that sexual stage immunity needs to be incorporated in transmission models to better understand transmission dynamics. Furthermore, tools that boost sexual stage immunity may reduce transmission to mosquitoes and thus aid elimination strategies.
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Affiliation(s)
- André Lin Ouédraogo
- Institute for Disease Modeling, Intellectual Ventures, Bellevue, Washington, United States of America
- Département de Sciences Biomédicales, Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
- * E-mail:
| | - Philip A. Eckhoff
- Institute for Disease Modeling, Intellectual Ventures, Bellevue, Washington, United States of America
| | - Adrian J. F. Luty
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, HB, the Netherlands
- MERIT UMR 216/CERPAGE, Institut de Recherche pour le Développement, Cotonou, Bénin
- UMR 216, Mère et enfant face aux infections tropicales, Institut de Recherche pour le Développement, Paris, France
| | - Will Roeffen
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, HB, the Netherlands
| | - Robert W. Sauerwein
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, HB, the Netherlands
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, HB, the Netherlands
| | - Edward A. Wenger
- Institute for Disease Modeling, Intellectual Ventures, Bellevue, Washington, United States of America
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19
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Tiedje KE, Oduro AR, Agongo G, Anyorigiya T, Azongo D, Awine T, Ghansah A, Pascual M, Koram KA, Day KP. Seasonal Variation in the Epidemiology of Asymptomatic Plasmodium falciparum Infections across Two Catchment Areas in Bongo District, Ghana. Am J Trop Med Hyg 2017; 97:199-212. [PMID: 28719306 DOI: 10.4269/ajtmh.16-0959] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Understanding the epidemiology of asymptomatic Plasmodium falciparum infections is critical for countries to move toward malaria elimination. Using different methods for parasite detection, we evaluated how seasonality, spatial location, and other factors affect the age-specific epidemiology of asymptomatic malaria in Bongo District, Ghana. Asymptomatic prevalence by microscopy decreased significantly from 42.5% at the end of the wet to 27.5% at the end of the dry season (P < 0.001). Using the 18S rRNA polymerase chain reactions (PCRs), all microscopy-negative samples were screened and prevalence of submicroscopic infections also decreased significantly from the wet (55.4%) to the dry (20.7%) season (P < 0.001). Combining detection methods, 74.4% and 42.5% of the population in the wet and dry seasons, respectively, had evidence of a P. falciparum infection. Interestingly in those > 20 years of age, we found evidence of infection in 64.3% of the population in the wet and 27.0% in the dry season. Using both microscopy and PCR, the asymptomatic P. falciparum reservoir peaks at the end of the wet season and infections in all age groups constitute the reservoir of malaria infection. At the end of the wet season, spatial heterogeneity in the prevalence and density of P. falciparum infections was observed between the two catchment areas surveyed in Bongo District. These results indicate that if elimination is to succeed, interventions will need to target not just P. falciparum infections in children but also in adults, and be implemented toward the end of the dry season in this area of West Africa.
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Affiliation(s)
- Kathryn E Tiedje
- Department of Microbiology, New York University, New York, New York.,School of BioSciences, Bio21 Institute/University of Melbourne, Melbourne, Australia
| | | | | | | | | | | | - Anita Ghansah
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Mercedes Pascual
- Santa Fe Institute, Sante Fe, New Mexico.,Department of Ecology and Evolution, University of Chicago, Chicago, Illinois
| | - Kwadwo A Koram
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Karen P Day
- Department of Microbiology, New York University, New York, New York.,School of BioSciences, Bio21 Institute/University of Melbourne, Melbourne, Australia
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20
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Iribhogbe OI, Emmanuel I, Odianosen M. Comparative analysis of the safety and tolerability of fixed-dose artesunate/amodiaquine versus artemether/lumefantrine combinations for uncomplicated falciparum malaria in pregnancy: a randomized open label study. Clin Pharmacol 2017; 9:45-54. [PMID: 28533699 PMCID: PMC5431733 DOI: 10.2147/cpaa.s131351] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
A comparative clinical study was conducted to evaluate the safety and tolerability of two commonly used fixed dose artemisinin-based combinations for the treatment of uncomplicated Plasmodium falciparum malaria in the second and third trimester of pregnancy. To achieve this, a total of 155 participants were recruited for the study. Eighty of these were drawn from pregnant women who came for routine antenatal care while 40 nonpregnant participants were recruited from apparently healthy females in the community. Eighty pregnant participants with uncomplicated P. falciparum malaria were randomized into artesunate/amodiaquine (AA) and artemether/lumefantrine (AL) treatment arms while 40 nonpregnant and 35 nonmalarious pregnant women were used as control. The interventional groups received standard fixed dose combinations of AA (100/270 mg) daily or AL (20/120 mg) twice daily for 3 days. Blood samples were collected on day 4 and patients were followed-up closely to ascertain the safety of the drugs. The study showed a significant (p<0.0001) elevation of alkaline phosphatase in the AA and AL group compared to the nonpregnant control and a significant (p<0.05) elevation of alanine transaminase and aspartate transaminase level in the AL combination group when compared with the AA group. The elevated hepatic enzymes were within the normal range for pregnancy and were not clinically significant. Adverse event rate was higher in the AA group (n=28 [70%]) when compared to the AL group (n=4 [10%]) although the drugs were well-tolerated in both treatment arms. In conclusion, the use of these combinations is safe in the second and third trimester of pregnancy. However, we recommend active pharmacovigilance and spontaneous drug reporting of the agents in order to continuously monitor safety in the vastly heterogeneous population.
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Affiliation(s)
| | - Igue Emmanuel
- Department of Human Physiology College of Medicine, Ambrose Alli University Ekpoma, Edo State, Nigeria
| | - Marylove Odianosen
- Department of Human Physiology College of Medicine, Ambrose Alli University Ekpoma, Edo State, Nigeria
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21
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How to Contain Artemisinin- and Multidrug-Resistant Falciparum Malaria. Trends Parasitol 2017; 33:353-363. [DOI: 10.1016/j.pt.2017.01.004] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Revised: 11/18/2016] [Accepted: 01/05/2017] [Indexed: 11/20/2022]
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22
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Nkumama IN, O'Meara WP, Osier FHA. Changes in Malaria Epidemiology in Africa and New Challenges for Elimination. Trends Parasitol 2017; 33:128-140. [PMID: 27939610 PMCID: PMC6995363 DOI: 10.1016/j.pt.2016.11.006] [Citation(s) in RCA: 138] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 10/28/2016] [Accepted: 11/11/2016] [Indexed: 12/20/2022]
Abstract
Although the burden of Plasmodium falciparum malaria is gradually declining in many parts of Africa, it is characterized by spatial and temporal variability that presents new and evolving challenges for malaria control programs. Reductions in the malaria burden need to be sustained in the face of changing epidemiology whilst simultaneously tackling significant pockets of sustained or increasing transmission. Large-scale, robust surveillance mechanisms that measure rather than estimate the actual burden of malaria over time from large areas of the continent where such data are lacking need to be prioritized. We review these fascinating developments, caution against complacency, and make the case that improving the extent and quality of malaria surveillance is vital for Africa as she marches on towards elimination.
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Affiliation(s)
- Irene N Nkumama
- KEMRI-Wellcome Trust Research Programme, P.O. Box 230-80108, Kilifi, Kenya
| | - Wendy P O'Meara
- Duke University, Durham, NC, USA; Moi University College of Health Sciences, Eldoret, Kenya
| | - Faith H A Osier
- KEMRI-Wellcome Trust Research Programme, P.O. Box 230-80108, Kilifi, Kenya.
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23
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Valle D, Millar J, Amratia P. Spatial heterogeneity can undermine the effectiveness of country-wide test and treat policy for malaria: a case study from Burkina Faso. Malar J 2016; 15:513. [PMID: 27760546 PMCID: PMC5070201 DOI: 10.1186/s12936-016-1565-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 10/07/2016] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Considerable debate has arisen regarding the appropriateness of the test and treat malaria policy broadly recommended by the World Health Organization. While presumptive treatment has important drawbacks, the effectiveness of the test and treat policy can vary considerably across regions, depending on several factors such as baseline malaria prevalence and rapid diagnostic test (RDT) performance. METHODS To compare presumptive treatment with test and treat, generalized linear mixed effects models were fitted to data from 6510 children under five years of age from Burkina Faso's 2010 Demographic and Health Survey. RESULTS The statistical model results revealed substantial regional variation in baseline malaria prevalence (i.e., pre-test prevalence) and RDT performance. As a result, a child with a positive RDT result in one region can have the same malaria infection probability as a demographically similar child with a negative RDT result in another region. These findings indicate that a test and treat policy might be reasonable in some settings, but may be undermined in others due to the high proportion of false negatives. CONCLUSIONS High spatial variability can substantially reduce the effectiveness of a national level test and treat malaria policy. In these cases, region-specific guidelines for malaria diagnosis and treatment may need to be formulated. Based on the statistical model results, proof-of-concept, web-based tools were created that can aid in the development of these region-specific guidelines and may improve current malaria-related policy in Burkina Faso.
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Affiliation(s)
- Denis Valle
- School of Forest Resources and Conservation, University of Florida, 136 Newins-Ziegler Hall, Gainesville, FL 32611 USA
| | - Justin Millar
- School of Forest Resources and Conservation, University of Florida, 136 Newins-Ziegler Hall, Gainesville, FL 32611 USA
| | - Punam Amratia
- School of Forest Resources and Conservation, University of Florida, 136 Newins-Ziegler Hall, Gainesville, FL 32611 USA
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24
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Pemberton-Ross P, Smith TA, Hodel EM, Kay K, Penny MA. Age-shifting in malaria incidence as a result of induced immunological deficit: a simulation study. Malar J 2015; 14:287. [PMID: 26206255 PMCID: PMC4513612 DOI: 10.1186/s12936-015-0805-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 07/10/2015] [Indexed: 11/10/2022] Open
Abstract
Effective population-level interventions against Plasmodium falciparum malaria lead to age-shifts, delayed morbidity or rebounds in morbidity and mortality whenever they are deployed in ways that do not permanently interrupt transmission. When long-term intervention programmes target specific age-groups of human hosts, the age-specific morbidity rates ultimately adjust to new steady-states, but it is very difficult to study these rates and the temporal dynamics leading up to them empirically because the changes occur over very long time periods. This study investigates the age and magnitude of age- and time- shifting of incidence induced by either pre-erythrocytic vaccination (PEV) programmes or seasonal malaria chemo-prevention (SMC), using an ensemble of individual-based stochastic simulation models of P. falciparum dynamics. The models made various assumptions about immunity decay, transmission heterogeneity and were parameterized with data on both age-specific infection and disease incidence at different levels of exposure, on the durations of different stages of the parasite life-cycle and on human demography. Effects of transmission intensity, and of levels of access to malaria treatment were considered. While both PEV and SMC programmes are predicted to have overall strongly positive health effects, a shift of morbidity into older children is predicted to be induced by either programme if transmission levels remain static and not reduced by other interventions. Predicted shifting of burden continue into the second decade of the programme. Even if long-term surveillance is maintained it will be difficult to avoid mis-attribution of such long-term changes in age-specific morbidity patterns to other factors. Conversely, short-lived transient changes in incidence measured soon after introduction of a new intervention may give over-positive views of future impacts. Complementary intervention strategies could be designed to specifically protect those age-groups at risk from burden shift.
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Affiliation(s)
- Peter Pemberton-Ross
- Swiss Tropical and Public Health Institute, 4002, Basel, Switzerland.
- Universität Basel, 4003, Basel, Switzerland.
| | - Thomas A Smith
- Swiss Tropical and Public Health Institute, 4002, Basel, Switzerland.
- Universität Basel, 4003, Basel, Switzerland.
| | - Eva Maria Hodel
- Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK.
| | - Katherine Kay
- Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK.
| | - Melissa A Penny
- Swiss Tropical and Public Health Institute, 4002, Basel, Switzerland.
- Universität Basel, 4003, Basel, Switzerland.
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25
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Ouédraogo AL, Gonçalves BP, Gnémé A, Wenger EA, Guelbeogo MW, Ouédraogo A, Gerardin J, Bever CA, Lyons H, Pitroipa X, Verhave JP, Eckhoff PA, Drakeley C, Sauerwein R, Luty AJF, Kouyaté B, Bousema T. Dynamics of the Human Infectious Reservoir for Malaria Determined by Mosquito Feeding Assays and Ultrasensitive Malaria Diagnosis in Burkina Faso. J Infect Dis 2015; 213:90-9. [PMID: 26142435 DOI: 10.1093/infdis/jiv370] [Citation(s) in RCA: 116] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2015] [Accepted: 06/26/2015] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND Plasmodium falciparum gametocytes are essential for malaria transmission. Malaria control measures that aim at reducing transmission require an accurate characterization of the human infectious reservoir. METHODS We longitudinally determined human infectiousness to mosquitoes and P. falciparum carriage by an ultrasensitive RNA-based diagnostics in 130 randomly selected inhabitants of an endemic area. RESULTS At least 1 mosquito was infected by 32.6% (100 of 307) of the blood samples; in total, 7.6% of mosquitoes (916 of 12 079) were infected. The proportion of infectious individuals and infected mosquitoes were negatively associated with age and positively with asexual parasites (P < .001). Human infectiousness was higher at the start of the wet season and subsequently declined at the peak of the wet season (adjusted odds ratio, 0.52; P = .06) and in the dry season (0.23; P < .001). Overall, microscopy-negative individuals were responsible for 28.7% of infectious individuals (25 of 87) and 17.0% of mosquito infections (145 of 855). CONCLUSIONS Our study reveals that the infectious reservoir peaks at the start of the wet season, with prominent roles for infections in children and submicroscopic infections. These findings have important consequences for strategies and the timing of interventions, which need to include submicroscopic infections and be implemented in the dry season.
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Affiliation(s)
- André Lin Ouédraogo
- Institute for Disease Modeling, Bellevue, Washington Département de Sciences Biomédicales, Centre National de Recherche et de Formation sur le Paludisme
| | - Bronner P Gonçalves
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, United Kingdom
| | - Awa Gnémé
- Département de Sciences Biomédicales, Centre National de Recherche et de Formation sur le Paludisme Université de Ouagadougou
| | | | - Moussa W Guelbeogo
- Département de Sciences Biomédicales, Centre National de Recherche et de Formation sur le Paludisme
| | - Amathe Ouédraogo
- Département de Sciences Biomédicales, Centre National de Recherche et de Formation sur le Paludisme
| | | | | | - Hil Lyons
- Institute for Disease Modeling, Bellevue, Washington
| | - Xavier Pitroipa
- Département de Sciences Biomédicales, Centre National de Recherche et de Formation sur le Paludisme Africa Indoor Residual Spraying, Abt Associates, Madagascar
| | - Jan Peter Verhave
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | | | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, United Kingdom
| | - Robert Sauerwein
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Adrian J F Luty
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands Institut de Recherche pour le Développement, Mère et Enfant Face aux Infections Tropicales Faculté de Pharmacie, Sorbonne Paris Cité, Université Paris Descartes, France
| | - Bocar Kouyaté
- Département de Sciences Biomédicales, Centre National de Recherche et de Formation sur le Paludisme Ministère de la Santé, Ouagadougou, Burkina Faso
| | - Teun Bousema
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, United Kingdom Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
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26
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The relationship between Plasmodium infection, anaemia and nutritional status in asymptomatic children aged under five years living in stable transmission zones in Kinshasa, Democratic Republic of Congo. Malar J 2015; 14:83. [PMID: 25880427 PMCID: PMC4336722 DOI: 10.1186/s12936-015-0595-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 01/30/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria is preventable and treatable when recommended interventions are properly implemented. Thus, diagnosis and treatment focus on symptomatic individuals while asymptomatic Plasmodium infection (PI) plays a role in the sustainability of the transmission and may also have an impact on the morbidity of the disease in terms of anaemia, nutritional status and even cognitive development of children. The objective of this study was to assess PI prevalence and its relationship with known morbidity factors in a vulnerable but asymptomatic stratum of the population. METHODS A simple random sample, household survey in asymptomatic children under the age of five was conducted from April to September 2012 in two health areas of the health zone of Mont Ngafula 1, Kinshasa, Democratic Republic of Congo. RESULTS The PI prevalence were 30.9% (95% CI: 26.5-35.9) and 14.3% (95% CI: 10.5-18.1) in Cité Pumbu and Kindele health areas, respectively, (OR: 2.7; p <0.001). All were Plasmodium falciparum infected and 4% were co-infected with Plasmodium malariae. In Cité Pumbu and Kindele, the prevalence of anaemia (haemoglobin <11 g/dL) was 61.6% (95% CI: 56.6-66.5) and 39.3% (95% CI: 34.0-44.6), respectively, (OR: 2.5; p <0.001). The health area of Cité Pumbu had 32% (95% CI: 27.5-37.0) of chronic malnutrition (HAZ score ≤ -2SD) compared to 5.1% (95% CI: 2.8-7.6) in Kindele. PI was predictor factor for anaemia (aOR: 3.5, p =0.01) and within infected children, there was an inverse relationship between parasite density and haemoglobin level (β = -5*10(-5), p <0.001). Age older than 12 months (aOR: 3.8, p = 0.01), presence of anaemia (aOR: 3.4, p =0.001), chronic malnutrition (aOR: 1.8, p = 0.01), having a single parent/guardian (aOR: 1.6, p =0.04), and the non-use of insecticide-treated nets (aOR: 1.7, p = 0.04) were all predictors for PI in the overall population. CONCLUSION PI in asymptomatic children was correlated with anaemia and chronic malnutrition and was thus a harmful condition in the study population. Malaria control initiatives should not only focus on treatment of symptomatic infections but also take into consideration asymptomatic but infected children.
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27
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Differences in the malariometric indices of asymptomatic carriers in three communities in ibadan, Nigeria. Adv Prev Med 2014; 2014:509236. [PMID: 25587454 PMCID: PMC4284954 DOI: 10.1155/2014/509236] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Accepted: 12/09/2014] [Indexed: 11/17/2022] Open
Abstract
This study was conducted to determine the malariometric indices of children in three different settings in Ibadan, Nigeria. Children were recruited from an urban slum (Oloomi) and a periurban (Sasa) and a rural community (Igbanda) in Ibadan. Children aged between 2 and 10 years were randomly selected from primary schools in the urban and periurban areas. In the rural community, children were recruited from the centre of the village. A total of 670 (55.0%) out of 1218 children recruited were positive for malaria parasitaemia. The urban population had the highest proportion of children with malaria parasitaemia. Splenomegaly was present in 31.5%, hepatomegaly in 41.5%, hepatosplenomegaly in 27.5%, and anaemia in 25.2% of the children. The parasite density was not significantly different among children in the three communities. Children in the rural community had the highest mean PCV of 34.2% and the lowest rates of splenomegaly (6.1%), hepatomegaly (7.6%), and hepatosplenomegaly (4.6%). The spleen rates, liver rates, and presence of hepatosplenomegaly and anaemia were similar in the urban and periurban communities. The malariometric indices among the asymptomatic carriers were high, especially in the urban slum. This stresses the need for intensified efforts at controlling the disease in the study area.
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Nunes JK, Woods C, Carter T, Raphael T, Morin MJ, Diallo D, Leboulleux D, Jain S, Loucq C, Kaslow DC, Birkett AJ. Development of a transmission-blocking malaria vaccine: progress, challenges, and the path forward. Vaccine 2014; 32:5531-9. [PMID: 25077422 DOI: 10.1016/j.vaccine.2014.07.030] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 06/12/2014] [Accepted: 07/08/2014] [Indexed: 10/25/2022]
Abstract
New interventions are needed to reduce morbidity and mortality associated with malaria, as well as to accelerate elimination and eventual eradication. Interventions that can break the cycle of parasite transmission, and prevent its reintroduction, will be of particular importance in achieving the eradication goal. In this regard, vaccines that interrupt malaria transmission (VIMT) have been highlighted as an important intervention, including transmission-blocking vaccines that prevent human-to-mosquito transmission by targeting the sexual, sporogonic, or mosquito stages of the parasite (SSM-VIMT). While the significant potential of this vaccine approach has been appreciated for decades, the development and licensure pathways for vaccines that target transmission and the incidence of infection, as opposed to prevention of clinical malaria disease, remain ill-defined. This article describes the progress made in critical areas since 2010, highlights key challenges that remain, and outlines important next steps to maximize the potential for SSM-VIMTs to contribute to the broader malaria elimination and eradication objectives.
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Affiliation(s)
- Julia K Nunes
- PATH Malaria Vaccine Initiative, Washington, DC, USA
| | - Colleen Woods
- PATH Malaria Vaccine Initiative, Washington, DC, USA; PATH Malaria Vaccine Initiative, Seattle, WA, USA
| | | | | | | | | | | | - Sanjay Jain
- PATH Malaria Vaccine Initiative, Washington, DC, USA
| | | | - David C Kaslow
- PATH Malaria Vaccine Initiative, Washington, DC, USA; PATH, Seattle, WA, USA
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Lin JT, Saunders DL, Meshnick SR. The role of submicroscopic parasitemia in malaria transmission: what is the evidence? Trends Parasitol 2014; 30:183-90. [PMID: 24642035 DOI: 10.1016/j.pt.2014.02.004] [Citation(s) in RCA: 177] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 02/10/2014] [Accepted: 02/13/2014] [Indexed: 12/18/2022]
Abstract
Achieving malaria elimination requires targeting the human reservoir of infection, including those with asymptomatic infection. Smear-positive asymptomatic infections detectable by microscopy are an important reservoir because they often persist for months and harbor gametocytes, the parasite stage infectious to mosquitoes. However, many asymptomatic infections are submicroscopic and can only be detected by molecular methods. Although there is some evidence that individuals with submicroscopic malaria can infect mosquitoes, transmission is much less likely to occur at submicroscopic gametocyte levels. As malaria elimination programs pursue mass screening and treatment of asymptomatic individuals, further research should strive to define the degree to which submicroscopic malaria contributes to the infectious reservoir and, in turn, what diagnostic detection threshold is needed to effectively interrupt transmission.
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Affiliation(s)
- Jessica T Lin
- Division of Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC, USA.
| | - David L Saunders
- Department of Immunology and Medicine, USAMC Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Steven R Meshnick
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, USA
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