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Nguetsa GC, Elanga-Ndille E, Essangui Same EG, Nganso Keptchouang T, Mandeng SE, Ekoko Eyisap W, Binyang JA, Fogang B, Nouage L, Piameu M, Ayong L, Etang J, Wanji S, Eboumbou Moukoko CE. Utility of plasma anti-gSG6-P1 IgG levels in determining changes in Anopheles gambiae bite rates in a rural area of Cameroon. Sci Rep 2024; 14:14294. [PMID: 38906949 PMCID: PMC11192751 DOI: 10.1038/s41598-024-58337-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Accepted: 03/27/2024] [Indexed: 06/23/2024] Open
Abstract
The applicability of the specific human IgG antibody response to Anopheles gambiae salivary Gland Protein-6 peptide 1 (gSG6-P1 salivary peptide) as a biomarker able to distinguish the level of exposure to mosquito bites according to seasonal variations has not yet been evaluated in Central African regions. The study aimed to provide the first reliable data on the IgG anti-gSG6-P1 response in rural area in Cameroon according to the dry- and rainy-season. Between May and December 2020, dry blood samples were collected from people living in the Bankeng village in the forest area of the Centre region of Cameroon. Malaria infection was determined by thick-blood smear microscopy and multiplex PCR. The level of IgG anti-gSG6-P1 response, was assessed by enzyme-linked immunosorbent assay. Anopheles density and aggressiveness were assessed using human landing catches. The prevalence of malaria infection remains significantly higher in the rainy season than in the dry season (77.57% vs 61.44%; p = 0.0001). The specific anti-gSG6-P1 IgG response could be detected in individuals exposed to few mosquito bites and showed inter-individual heterogeneity even when living in the same exposure area. In both seasons, the level of anti-gSG6-P1 IgG response was not significantly different between Plasmodium infected and non-infected individuals. Mosquito bites were more aggressive in the rainy season compared to the dry season (human biting rate-HBR of 15.05 b/p/n vs 1.5 b/p/n) where mosquito density was very low. Infected mosquitoes were found only during the rainy season (sporozoite rate = 10.63% and entomological inoculation rate-EIR = 1.42 ib/p/n). The level of IgG anti-gSG6-P1 response was significantly higher in the rainy season and correlated with HBR (p ˂ 0.0001). This study highlights the high heterogeneity of individual's exposure to the Anopheles gambiae s.l vector bites depending on the transmission season in the same area. These findings reinforce the usefulness of the anti-gSG6-P1 IgG response as an accurate immunological biomarker for detecting individual exposure to Anopheles gambiae s.l. bites during the low risk period of malaria transmission in rural areas and for the differentiating the level of exposure to mosquitoes.
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Affiliation(s)
- Glwadys Cheteug Nguetsa
- Malaria Research Unit, Centre Pasteur Cameroon, P.O. Box 1274, Yaoundé, Cameroon.
- Department of Microbiology and Parasitology, Faculty of Sciences, The University of Buea, P.O. Box 63, Buea, Cameroon.
| | - Emmanuel Elanga-Ndille
- Department of Animal Biology, Faculty of Sciences, The University of Dschang, P.O. Box 96, Dschang, Cameroon
- Department of Medical Entomology, Centre for Research in Infectious Diseases, P.O. Box 13591, Yaoundé, Cameroon
| | - Estelle Géraldine Essangui Same
- Malaria Research Unit, Centre Pasteur Cameroon, P.O. Box 1274, Yaoundé, Cameroon
- Department of Biological Sciences, Faculty of Medicine and Pharmaceutical Sciences, The University of Douala, P.O. Box 2701, Douala, Cameroon
| | - Tatiana Nganso Keptchouang
- Malaria Research Unit, Centre Pasteur Cameroon, P.O. Box 1274, Yaoundé, Cameroon
- Department of Biological Sciences, Faculty of Medicine and Pharmaceutical Sciences, The University of Douala, P.O. Box 2701, Douala, Cameroon
| | - Stanilas Elysée Mandeng
- Department of Animal Biology and Physiology, Faculty of Sciences, The University of Yaoundé, P.O. Box 337, Yaounde 1, Cameroon
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroon
| | - Wolfgang Ekoko Eyisap
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroon
| | - Jérome Achille Binyang
- Department of Medical Entomology, Centre for Research in Infectious Diseases, P.O. Box 13591, Yaoundé, Cameroon
- Department of Animal Biology and Physiology, Faculty of Sciences, The University of Yaoundé, P.O. Box 337, Yaounde 1, Cameroon
| | - Balotin Fogang
- Malaria Research Unit, Centre Pasteur Cameroon, P.O. Box 1274, Yaoundé, Cameroon
- Department of Animal Biology and Physiology, Faculty of Sciences, The University of Yaoundé, P.O. Box 337, Yaounde 1, Cameroon
| | - Lynda Nouage
- Department of Medical Entomology, Centre for Research in Infectious Diseases, P.O. Box 13591, Yaoundé, Cameroon
- Department of Animal Biology and Physiology, Faculty of Sciences, The University of Yaoundé, P.O. Box 337, Yaounde 1, Cameroon
| | - Micheal Piameu
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroon
- Ecole des Sciences de La Santé, Université Catholique d'Afrique Centrale, P.O. Box 1110, Yaoundé, Cameroon
| | - Lawrence Ayong
- Malaria Research Unit, Centre Pasteur Cameroon, P.O. Box 1274, Yaoundé, Cameroon
| | - Josiane Etang
- Department of Biological Sciences, Faculty of Medicine and Pharmaceutical Sciences, The University of Douala, P.O. Box 2701, Douala, Cameroon
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroon
| | - Samuel Wanji
- Department of Microbiology and Parasitology, Faculty of Sciences, The University of Buea, P.O. Box 63, Buea, Cameroon
| | - Carole Else Eboumbou Moukoko
- Malaria Research Unit, Centre Pasteur Cameroon, P.O. Box 1274, Yaoundé, Cameroon.
- Department of Biological Sciences, Faculty of Medicine and Pharmaceutical Sciences, The University of Douala, P.O. Box 2701, Douala, Cameroon.
- Laboratory of Parasitology, Mycology and Virology, Postgraduate Training Unit for Health Sciences, Postgraduate School for Pure and Applied Sciences, The University of Douala, P.O. Box 2701, Douala, Cameroon.
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Lapidus S, Goheen MM, Sy M, Deme AB, Ndiaye IM, Diedhiou Y, Mbaye AM, Hagadorn KA, Sene SD, Pouye MN, Thiam LG, Ba A, Guerra N, Mbengue A, Raduwan H, Vigan-Womas I, Parikh S, Ko AI, Ndiaye D, Fikrig E, Chuang YM, Bei AK. Two mosquito salivary antigens demonstrate promise as biomarkers of recent exposure to P. falciparum infected mosquito bites. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2024.04.20.24305430. [PMID: 38712295 PMCID: PMC11071555 DOI: 10.1101/2024.04.20.24305430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Background Measuring malaria transmission intensity using the traditional entomological inoculation rate is difficult. Antibody responses to mosquito salivary proteins such as SG6 have previously been used as biomarkers of exposure to Anopheles mosquito bites. Here, we investigate four mosquito salivary proteins as potential biomarkers of human exposure to mosquitoes infected with P. falciparum: mosGILT, SAMSP1, AgSAP, and AgTRIO. Methods We tested population-level human immune responses in longitudinal and cross-sectional plasma samples from individuals with known P. falciparum infection from low and moderate transmission areas in Senegal using a multiplexed magnetic bead-based assay. Results AgSAP and AgTRIO were the best indicators of recent exposure to infected mosquitoes. Antibody responses to AgSAP, in a moderate endemic area, and to AgTRIO in both low and moderate endemic areas, were significantly higher than responses in a healthy non-endemic control cohort (p-values = 0.0245, 0.0064, and <0.0001 respectively). No antibody responses significantly differed between the low and moderate transmission area, or between equivalent groups during and outside the malaria transmission seasons. For AgSAP and AgTRIO, reactivity peaked 2-4 weeks after clinical P. falciparum infection and declined 3 months after infection. Discussion Reactivity to both AgSAP and AgTRIO peaked after infection and did not differ seasonally nor between areas of low and moderate transmission, suggesting reactivity is likely reflective of exposure to infectious mosquitos or recent biting rather than general mosquito exposure. Kinetics suggest reactivity is relatively short-lived. AgSAP and AgTRIO are promising candidates to incorporate into multiplexed assays for serosurveillance of population-level changes in P. falciparum-infected mosquito exposure.
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Affiliation(s)
- Sarah Lapidus
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA
| | - Morgan M Goheen
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA
- Division of Infectious Diseases, Yale School of Medicine, New Haven, CT, USA
| | - Mouhamad Sy
- Laboratory of Parasitology and Mycology, Cheikh Anta Diop University, Aristide le Dantec Hospital, Dakar, Senegal
- International Research and Training Center for Applied Genomics and Health Surveillance (CIGASS) at UCAD, Dakar, Senegal
| | - Awa B Deme
- Laboratory of Parasitology and Mycology, Cheikh Anta Diop University, Aristide le Dantec Hospital, Dakar, Senegal
- International Research and Training Center for Applied Genomics and Health Surveillance (CIGASS) at UCAD, Dakar, Senegal
| | - Ibrahima Mbaye Ndiaye
- Laboratory of Parasitology and Mycology, Cheikh Anta Diop University, Aristide le Dantec Hospital, Dakar, Senegal
- International Research and Training Center for Applied Genomics and Health Surveillance (CIGASS) at UCAD, Dakar, Senegal
| | - Younous Diedhiou
- Laboratory of Parasitology and Mycology, Cheikh Anta Diop University, Aristide le Dantec Hospital, Dakar, Senegal
- International Research and Training Center for Applied Genomics and Health Surveillance (CIGASS) at UCAD, Dakar, Senegal
| | - Amadou Moctar Mbaye
- Laboratory of Parasitology and Mycology, Cheikh Anta Diop University, Aristide le Dantec Hospital, Dakar, Senegal
- International Research and Training Center for Applied Genomics and Health Surveillance (CIGASS) at UCAD, Dakar, Senegal
| | - Kelly A Hagadorn
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA
| | - Seynabou Diouf Sene
- G4 - Malaria Experimental Genetic Approaches & Vaccines, Pôle Immunophysiopathologie et Maladies Infectieuses, Institut Pasteur de Dakar, Dakar, Senegal
| | - Mariama Nicole Pouye
- G4 - Malaria Experimental Genetic Approaches & Vaccines, Pôle Immunophysiopathologie et Maladies Infectieuses, Institut Pasteur de Dakar, Dakar, Senegal
| | - Laty Gaye Thiam
- G4 - Malaria Experimental Genetic Approaches & Vaccines, Pôle Immunophysiopathologie et Maladies Infectieuses, Institut Pasteur de Dakar, Dakar, Senegal
| | - Aboubacar Ba
- G4 - Malaria Experimental Genetic Approaches & Vaccines, Pôle Immunophysiopathologie et Maladies Infectieuses, Institut Pasteur de Dakar, Dakar, Senegal
| | - Noemi Guerra
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA
| | - Alassane Mbengue
- G4 - Malaria Experimental Genetic Approaches & Vaccines, Pôle Immunophysiopathologie et Maladies Infectieuses, Institut Pasteur de Dakar, Dakar, Senegal
| | - Hamidah Raduwan
- Division of Infectious Diseases, Yale School of Medicine, New Haven, CT, USA
| | - Inés Vigan-Womas
- G4 - Malaria Experimental Genetic Approaches & Vaccines, Pôle Immunophysiopathologie et Maladies Infectieuses, Institut Pasteur de Dakar, Dakar, Senegal
| | - Sunil Parikh
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA
- Division of Infectious Diseases, Yale School of Medicine, New Haven, CT, USA
| | - Albert I Ko
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA
- Division of Infectious Diseases, Yale School of Medicine, New Haven, CT, USA
| | - Daouda Ndiaye
- Laboratory of Parasitology and Mycology, Cheikh Anta Diop University, Aristide le Dantec Hospital, Dakar, Senegal
- International Research and Training Center for Applied Genomics and Health Surveillance (CIGASS) at UCAD, Dakar, Senegal
| | - Erol Fikrig
- Division of Infectious Diseases, Yale School of Medicine, New Haven, CT, USA
| | - Yu-Min Chuang
- Division of Infectious Diseases, Yale School of Medicine, New Haven, CT, USA
| | - Amy K Bei
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA
- Laboratory of Parasitology and Mycology, Cheikh Anta Diop University, Aristide le Dantec Hospital, Dakar, Senegal
- G4 - Malaria Experimental Genetic Approaches & Vaccines, Pôle Immunophysiopathologie et Maladies Infectieuses, Institut Pasteur de Dakar, Dakar, Senegal
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Beke OAH, Assi SB, Kokrasset APH, Dibo KJD, Tanoh MA, Danho M, Remoué F, Koudou GB, Poinsignon A. Implication of agricultural practices in the micro-geographic heterogeneity of malaria transmission in Bouna, Côte d'Ivoire. Malar J 2023; 22:313. [PMID: 37848895 PMCID: PMC10583306 DOI: 10.1186/s12936-023-04748-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 10/10/2023] [Indexed: 10/19/2023] Open
Abstract
BACKGROUND Wetlands and irrigated agricultural crops create potential breeding sites for Anopheles mosquitoes, leading to a heterogeneity in malaria transmission. In agricultural areas, heterogeneity of malaria transmission is often associated with the presence of hotspots consisting of localized clusters of higher transmission intensity. This study aims to identify micro-geographic hotspots of malaria transmission in an agricultural setting using a multidisciplinary approach. METHODS Two cross-sectional surveys were conducted at the end of the dry season and at the peak of the rainy season in rural and urban sites in Bouna, northeastern Côte d'Ivoire. A total of 296 individuals from 148 farming households were randomly selected and sociological, geographical, entomological, and clinical data as well as blood samples were collected during each visit. Parasitological data and Anopheles exposure (measured using entomological and immunological methods) were compared with demographic, agricultural, and geographic data to identify drivers of malaria transmission. Heat maps combining these data were used to identify households with ongoing malaria transmission throughout the year. RESULTS In rural areas, Plasmodium prevalence was consistent between the dry and the rainy seasons, with roughly half of the population infected. In urban areas, malaria transmission indicators were lower, with a parasite prevalence of less than 20%, which remained comparable between the dry and the rainy season. The presence of irrigated crops and proximity to wetlands were associated with increased Anopheles exposure. By mapping Plasmodium infection and Anopheles exposure, two different types of hotspots of malaria transmission were identified: micro-geographical scale and local scale hotspots. CONCLUSIONS The presence of wetlands in urban areas and irrigated agriculture in rural areas resulted in heterogeneity in malaria transmission on a micro-geographical scale. These specific households present particular risk of malaria transmission and could fuel malaria transmission in surrounding households. The identification of micro-geographical areas using heat maps combining several epidemiological parameters can help to identify hotspots of malaria transmission. The implementation of malaria control measures, such as seasonal chemoprophylaxis or vector control, in these areas could help to reduce the incidence of malaria and facilitate its elimination.
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Affiliation(s)
- Obo Armel-Hermann Beke
- National Malaria Control Programme, Abidjan, Côte d'Ivoire.
- Swiss Center of Scientific Research, Abidjan, Côte d'Ivoire.
- Institut National Polytechnique Houphouët Boigny, Yamoussoukro, Côte d'Ivoire.
- Institut National de Santé Publique / Institut Pierre Richet, Bouaké, Côte d'Ivoire.
| | - Serge-Brice Assi
- National Malaria Control Programme, Abidjan, Côte d'Ivoire
- Institut National de Santé Publique / Institut Pierre Richet, Bouaké, Côte d'Ivoire
| | | | | | | | - Mathias Danho
- Institut National Polytechnique Houphouët Boigny, Yamoussoukro, Côte d'Ivoire
| | - Franck Remoué
- MIVEGEC, University of Montpellier, IRD, CNRS, Montpellier, France
| | | | - Anne Poinsignon
- MIVEGEC, University of Montpellier, IRD, CNRS, Montpellier, France
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Sedda L, McCann RS, Kabaghe AN, Gowelo S, Mburu MM, Tizifa TA, Chipeta MG, van den Berg H, Takken W, van Vugt M, Phiri KS, Cain R, Tangena JAA, Jones CM. Hotspots and super-spreaders: Modelling fine-scale malaria parasite transmission using mosquito flight behaviour. PLoS Pathog 2022; 18:e1010622. [PMID: 35793345 PMCID: PMC9292116 DOI: 10.1371/journal.ppat.1010622] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 07/18/2022] [Accepted: 05/27/2022] [Indexed: 11/19/2022] Open
Abstract
Malaria hotspots have been the focus of public health managers for several years due to the potential elimination gains that can be obtained from targeting them. The identification of hotspots must be accompanied by the description of the overall network of stable and unstable hotspots of malaria, especially in medium and low transmission settings where malaria elimination is targeted. Targeting hotspots with malaria control interventions has, so far, not produced expected benefits. In this work we have employed a mechanistic-stochastic algorithm to identify clusters of super-spreader houses and their related stable hotspots by accounting for mosquito flight capabilities and the spatial configuration of malaria infections at the house level. Our results show that the number of super-spreading houses and hotspots is dependent on the spatial configuration of the villages. In addition, super-spreaders are also associated to house characteristics such as livestock and family composition. We found that most of the transmission is associated with winds between 6pm and 10pm although later hours are also important. Mixed mosquito flight (downwind and upwind both with random components) were the most likely movements causing the spread of malaria in two out of the three study areas. Finally, our algorithm (named MALSWOTS) provided an estimate of the speed of malaria infection progression from house to house which was around 200-400 meters per day, a figure coherent with mark-release-recapture studies of Anopheles dispersion. Cross validation using an out-of-sample procedure showed accurate identification of hotspots. Our findings provide a significant contribution towards the identification and development of optimal tools for efficient and effective spatio-temporal targeted malaria interventions over potential hotspot areas.
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Affiliation(s)
- Luigi Sedda
- Lancaster Ecology and Epidemiology Group, Lancaster Medical School, Lancaster University, United Kingdom
| | - Robert S. McCann
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Alinune N. Kabaghe
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Steven Gowelo
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
- MAC Communicable Diseases Action Centre, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Monicah M. Mburu
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Tinashe A. Tizifa
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
- Center for Tropical Medicine and Travel Medicine, University of Amsterdam, The Netherlands
| | - Michael G. Chipeta
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi
| | - Henk van den Berg
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Willem Takken
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Michèle van Vugt
- Center for Tropical Medicine and Travel Medicine, University of Amsterdam, The Netherlands
| | - Kamija S. Phiri
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Russell Cain
- Lancaster Ecology and Epidemiology Group, Lancaster Medical School, Lancaster University, United Kingdom
| | - Julie-Anne A. Tangena
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Christopher M. Jones
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
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Kearney EA, Agius PA, Chaumeau V, Cutts JC, Simpson JA, Fowkes FJI. Anopheles salivary antigens as serological biomarkers of vector exposure and malaria transmission: A systematic review with multilevel modelling. eLife 2021; 10:e73080. [PMID: 34939933 PMCID: PMC8860437 DOI: 10.7554/elife.73080] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 12/21/2021] [Indexed: 12/25/2022] Open
Abstract
Background Entomological surveillance for malaria is inherently resource-intensive and produces crude population-level measures of vector exposure which are insensitive in low-transmission settings. Antibodies against Anopheles salivary proteins measured at the individual level may serve as proxy biomarkers for vector exposure and malaria transmission, but their relationship is yet to be quantified. Methods A systematic review of studies measuring antibodies against Anopheles salivary antigens (PROSPERO: CRD42020185449). Multilevel modelling (to account for multiple study-specific observations [level 1], nested within study [level 2], and study nested within country [level 3]) estimated associations between seroprevalence with Anopheles human biting rate (HBR) and malaria transmission measures. Results From 3981 studies identified in literature searches, 42 studies across 16 countries were included contributing 393 study-specific observations of anti-Anopheles salivary antibodies determined in 42,764 samples. A positive association between HBR (log transformed) and seroprevalence was found; overall a twofold (100% relative) increase in HBR was associated with a 23% increase in odds of seropositivity (OR: 1.23, 95% CI: 1.10-1.37; p<0.001). The association between HBR and Anopheles salivary antibodies was strongest with concordant, rather than discordant, Anopheles species. Seroprevalence was also significantly positively associated with established epidemiological measures of malaria transmission: entomological inoculation rate, Plasmodium spp. prevalence, and malarial endemicity class. Conclusions Anopheles salivary antibody biomarkers can serve as a proxy measure for HBR and malaria transmission, and could monitor malaria receptivity of a population to sustain malaria transmission. Validation of Anopheles species-specific biomarkers is important given the global heterogeneity in the distribution of Anopheles species. Salivary biomarkers have the potential to transform surveillance by replacing impractical, inaccurate entomological investigations, especially in areas progressing towards malaria elimination. Funding Australian National Health and Medical Research Council, Wellcome Trust.
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Affiliation(s)
- Ellen A Kearney
- The McFarlane Burnet Institute of Medical Research and Public HealthMelbourneAustralia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of MelbourneMelbourneAustralia
| | - Paul A Agius
- The McFarlane Burnet Institute of Medical Research and Public HealthMelbourneAustralia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of MelbourneMelbourneAustralia
- Department of Epidemiology and Preventive Medicine, Monash UniversityMelbourneAustralia
| | - Victor Chaumeau
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol UniversityMae SotThailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of OxfordOxfordUnited Kingdom
| | - Julia C Cutts
- The McFarlane Burnet Institute of Medical Research and Public HealthMelbourneAustralia
- Department of Medicine at the Doherty Institute, The University of MelbourneMelbourneAustralia
| | - Julie A Simpson
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of MelbourneMelbourneAustralia
| | - Freya JI Fowkes
- The McFarlane Burnet Institute of Medical Research and Public HealthMelbourneAustralia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of MelbourneMelbourneAustralia
- Department of Epidemiology and Preventive Medicine, Monash UniversityMelbourneAustralia
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Use of anti-gSG6-P1 IgG as a serological biomarker to assess temporal exposure to Anopheles' mosquito bites in Lower Moshi. PLoS One 2021; 16:e0259131. [PMID: 34705869 PMCID: PMC8550589 DOI: 10.1371/journal.pone.0259131] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 10/13/2021] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Malaria prevalence in the highlands of Northern Tanzania is currently below 1% making this an elimination prone setting. As climate changes may facilitate increasing distribution of Anopheles mosquitoes in such settings, there is a need to monitor changes in risks of exposure to ensure that established control tools meet the required needs. This study explored the use of human antibodies against gambiae salivary gland protein 6 peptide 1 (gSG6-P1) as a biomarker of Anopheles exposure and assessed temporal exposure to mosquito bites in populations living in Lower Moshi, Northern Tanzania. METHODS Three cross-sectional surveys were conducted in 2019: during the dry season in March, at the end of the rainy season in June and during the dry season in September. Blood samples were collected from enrolled participants and analysed for the presence of anti-gSG6-P1 IgG. Mosquitoes were sampled from 10% of the participants' households, quantified and identified to species level. Possible associations between gSG6-P1 seroprevalence and participants' characteristics were determined. RESULTS The total number of Anopheles mosquitoes collected was highest during the rainy season (n = 1364) when compared to the two dry seasons (n = 360 and n = 1075, respectively). The gSG6-P1 seroprevalence increased from 18.8% during the dry season to 25.0% during the rainy season (χ2 = 2.66; p = 0.103) followed by a significant decline to 11.0% during the next dry season (χ2 = 12.56; p = 0.001). The largest number of mosquitoes were collected in one village (Oria), but the seroprevalence was significantly lower among the residents as compared to the rest of the villages (p = 0.039), explained by Oria having the highest number of participants owning and using bed nets. Both individual and household gSG6-P1 IgG levels had no correlation with numbers of Anopheles mosquitoes collected. CONCLUSION Anti-gSG6-P1 IgG is a potential tool in detecting and distinguishing temporal and spatial variations in exposure to Anopheles mosquito bites in settings of extremely low malaria transmission where entomological tools may be obsolete. However studies with larger sample size and extensive mosquito sampling are warranted to further explore the association between this serological marker and abundance of Anopheles mosquito.
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Influence of Host-Related Factors and Exposure to Mosquito Bites on the Dynamics of Antibody Response to Plasmodium falciparum Antigens. Trop Med Infect Dis 2021; 6:tropicalmed6040185. [PMID: 34698307 PMCID: PMC8544703 DOI: 10.3390/tropicalmed6040185] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 09/30/2021] [Accepted: 10/11/2021] [Indexed: 11/24/2022] Open
Abstract
Humoral immunity to Plasmodium falciparum is acquired after repeated infections, and can lead to clinical protection. This study aimed to evaluate how human-, parasite-, and environment-related determinants can modulate the dynamics of IgG responses to Plasmodium falciparum after an infection. Individuals (n = 68, average age = 8.2 years) with uncomplicated malaria were treated with ACT and followed up for 42 days. IgG responses to P. falciparum merozoite antigens (PfMSP1, PfMSP3, PfAMA1, PfGLURP-R0), to whole schizont extract (PfSchz), and to Anopheles gSG6-P1 and Aedes Nterm–34 kDa salivary peptides were measured. Regression analyses were used to identify factors that influence the dynamics of IgG response to P. falciparum antigen between D0 and D42, including demographic and biological factors and the level of exposure to mosquito bites. The dynamics of IgG response to P. falciparum differed according to the antigen. According to multivariate analysis, IgG responses to PfSchz and to PfGLURP-R0 appear to be affected by exposure to Aedes saliva and are associated with age, parasite density, and anti-Plasmodium pre-existing immune response at study inclusion. The present work shows that human exposure to Aedes saliva may contribute, in addition to other factors, to the regulation of anti-Plasmodium immune responses during a natural infection.
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8
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Doumbe-Belisse P, Kopya E, Ngadjeu CS, Sonhafouo-Chiana N, Talipouo A, Djamouko-Djonkam L, Awono-Ambene HP, Wondji CS, Njiokou F, Antonio-Nkondjio C. Urban malaria in sub-Saharan Africa: dynamic of the vectorial system and the entomological inoculation rate. Malar J 2021; 20:364. [PMID: 34493280 PMCID: PMC8424958 DOI: 10.1186/s12936-021-03891-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 08/20/2021] [Indexed: 12/11/2022] Open
Abstract
Sub-Saharan Africa is registering one of the highest urban population growth across the world. It is estimated that over 75% of the population in this region will be living in urban settings by 2050. However, it is not known how this rapid urbanization will affect vector populations and disease transmission. The present study summarizes findings from studies conducted in urban settings between the 1970s and 2020 to assess the effects of urbanization on the entomological inoculation rate pattern and anopheline species distribution. Different online databases such as PubMed, ResearchGate, Google Scholar, Google were screened. A total of 90 publications were selected out of 1527. Besides, over 200 additional publications were consulted to collate information on anopheline breeding habitats and species distribution in urban settings. The study confirms high malaria transmission in rural compared to urban settings. The study also suggests that there had been an increase in malaria transmission in most cities after 2003, which could also be associated with an increase in sampling, resources and reporting. Species of the Anopheles gambiae complex were the predominant vectors in most urban settings. Anopheline larvae were reported to have adapted to different aquatic habitats. The study provides updated information on the distribution of the vector population and the dynamic of malaria transmission in urban settings. The study also highlights the need for implementing integrated control strategies in urban settings.
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Affiliation(s)
- P Doumbe-Belisse
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun.,Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - E Kopya
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun.,Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - C S Ngadjeu
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun.,Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - N Sonhafouo-Chiana
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun.,Faculty of Health Sciences, University of Buea, Cameroon, P.O. Box 63, Buea, Cameroon
| | - A Talipouo
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun.,Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - L Djamouko-Djonkam
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun.,Faculty of Sciences, University of Dschang Cameroon, P.O. Box 67, Dschang, Cameroon
| | - H P Awono-Ambene
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun
| | - C S Wondji
- Vector Group Liverpool School of Tropical Medicine Pembroke Place, Liverpool, L3 5QA, UK
| | - F Njiokou
- Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - C Antonio-Nkondjio
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun. .,Vector Group Liverpool School of Tropical Medicine Pembroke Place, Liverpool, L3 5QA, UK.
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9
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Cheteug G, Elanga-Ndille E, Donkeu C, Ekoko W, Oloume M, Essangui E, Nwane P, NSango SE, Etang J, Wanji S, Ayong L, Eboumbou Moukoko CE. Preliminary validation of the use of IgG antibody response to Anopheles gSG6-p1 salivary peptide to assess human exposure to malaria vector bites in two endemic areas of Cameroon in Central Africa. PLoS One 2020; 15:e0242510. [PMID: 33382730 PMCID: PMC7774847 DOI: 10.1371/journal.pone.0242510] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 11/03/2020] [Indexed: 11/25/2022] Open
Abstract
The specific immune response to the Anopheles salivary peptide could be a pertinent and complementary tool to assess the risk of malaria transmission and the effectiveness of vector control strategies. This study aimed to obtain first reliable data on the current state of the Anopheles gSG6-P1 biomarker for assess the level of exposure to Anopheles bites in high malaria endemic areas in Cameroon. Blood smears were collected from people living in the neighborhoods of Youpwe (suburban area, continental) and Manoka (rural area, Island), both areas in the coastal region of Cameroon. Malaria infection was determined using thick blood smear microscopy, whereas the level of specific IgG response to gSG-P1 peptide was assessed by enzyme-linked immunosorbent assay from the dried blood spots. Of 266 (153 from Youpwe, 113 from Manoka) malaria endemic residents (mean age: 22.8±19.8 years, age range: 6 months–94 years, male/female sex ratio: 1/1.2, with Manoka mean age: 23.71±20.53, male/female sex ratio:1/1.13 and Youpwe mean age: 22.12±19.22, male/female sex ratio 1/0.67) randomly included in the study, Plasmodium infection prevalence was significantly higher in Manoka than in Youpwe (64.6% vs 12,4%, p = 0.0001). The anti-gSG6-P1 IgG response showed a high inter-individual heterogeneity and was significantly higher among individuals from Manoka than those from Youpwe (p = 0.023). Malaria infected individuals presented a higher anti-gSG6-P1 IgG antibody response than non-infected (p = 0.0004). No significant difference in the level of specific IgG response to gSG-P1 was observed according to long lasting insecticidal nets use. Taken together, the data revealed that human IgG antibody response to Anopheles gSG-P1 salivary peptide could be also used to assess human exposure to malaria vectors in Central African region. This finding strengthens the relevance of this candidate biomarker to be used for measuring human exposure to malaria vectors worldwide.
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Affiliation(s)
- Glwadys Cheteug
- Malaria Research Unit, Centre Pasteur Cameroon, Yaounde, Cameroon
- Department of Microbiology and Parasitology, Faculty of Sciences, University of Buea, Buea, Cameroon
| | | | - Christiane Donkeu
- Malaria Research Unit, Centre Pasteur Cameroon, Yaounde, Cameroon
- Department of Animal Biology and Physiology, Faculty of Sciences, University of Yaounde, Yaounde, Cameroon
| | - Wolfgang Ekoko
- Parasitology and Entomology Research Unit, Department of Animal Biology and Organisms, Faculty of Sciences, University of Douala, Douala, Cameroon
| | - Martine Oloume
- Department of hematology, Centre Pasteur of Cameroon, Yaoundé, Cameroon
| | - Estelle Essangui
- Malaria Research Unit, Centre Pasteur Cameroon, Yaounde, Cameroon
- Parasitology and Entomology Research Unit, Department of Animal Biology and Organisms, Faculty of Sciences, University of Douala, Douala, Cameroon
| | - Philippe Nwane
- Biological Sciences Department, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala, Cameroon
| | - Sandrine Eveline NSango
- Malaria Research Unit, Centre Pasteur Cameroon, Yaounde, Cameroon
- Laboratory of Parasitology, Mycology and Virology, Postgraduate Training Unit for Health Sciences, Postgraduate School for Pure and Applied Sciences, University of Douala, Douala, Cameroon
| | - Josiane Etang
- Biological Sciences Department, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala, Cameroon
- Organisation de Coordination pour la Lutte contre les Endemies en Afrique Central, Yaounde, Cameroon
| | - Samuel Wanji
- Department of Microbiology and Parasitology, Faculty of Sciences, University of Buea, Buea, Cameroon
| | - Lawrence Ayong
- Malaria Research Unit, Centre Pasteur Cameroon, Yaounde, Cameroon
| | - Carole Else Eboumbou Moukoko
- Malaria Research Unit, Centre Pasteur Cameroon, Yaounde, Cameroon
- Biological Sciences Department, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala, Cameroon
- Laboratory of Parasitology, Mycology and Virology, Postgraduate Training Unit for Health Sciences, Postgraduate School for Pure and Applied Sciences, University of Douala, Douala, Cameroon
- * E-mail: ,
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Traoré DF, Sagna AB, Assi SB, Tchiekoi BN, Adja AM, Dagnogo M, Koffi AA, Rogier C, Remoue F. Operational Evaluation of the Effectiveness of Long-lasting Insecticidal Nets on Human-Vector Contact in an African Urban Malaria Context. Open Forum Infect Dis 2020; 8:ofaa635. [PMID: 33553475 PMCID: PMC7850104 DOI: 10.1093/ofid/ofaa635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 12/28/2020] [Indexed: 11/30/2022] Open
Abstract
Background Malaria is still a major public health concern in Côte d’Ivoire despite mass distribution of long-lasting insecticidal nets (LLINs) as a key preventive strategy. This study intended to evaluate the operational effectiveness of LLINs on the level of human-vector contact using 1 antibody-based biomarker of exposure to Anopheles in urban areas. Methods This cross-sectional study collected socio-demographic data and use of LLINs from 9 neighborhoods in the city of Bouaké (Côte d’Ivoire). Dry blood spots performed in children aged >6 months and adults were used to evaluate immunoglobulin G (IgG) responses to the Anopheles gSG6-P1 salivary peptide. Results IgG response levels to the salivary peptide were significantly lower in individuals who declared having “always” (n = 270) slept under an LLIN compared with those who had “often” (n = 2087) and “never” (n = 88) slept under an LLIN (P < .0001). IgG response levels to gSG6-P1 between those who declared having “always” and “not always” slept under an LLIN varied according to neighborhood, socio-professional category, and age group. Conclusions The human IgG level to this gSG6-P1 salivary peptide could be a useful tool to evaluate the actual effectiveness of LLINs and help design behavioral change interventions that are crucial for sustaining universal coverage.
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Affiliation(s)
- Dipomin F Traoré
- Institut Pierre Richet (IPR), Institut National de la Santé Publique (INSP), Bouaké, Côte d'Ivoire.,MIVEGEC, University of Montpellier, IRD, CNRS, Montpellier, France.,Unité de Formation et de Recherche en Sciences de la Nature (UFR SN), Université Nangui Abrogoua, Abidjan, Côte d'Ivoire
| | - André B Sagna
- Institut Pierre Richet (IPR), Institut National de la Santé Publique (INSP), Bouaké, Côte d'Ivoire.,MIVEGEC, University of Montpellier, IRD, CNRS, Montpellier, France
| | - Serge B Assi
- Institut Pierre Richet (IPR), Institut National de la Santé Publique (INSP), Bouaké, Côte d'Ivoire
| | - Bertin N'Cho Tchiekoi
- Institut Pierre Richet (IPR), Institut National de la Santé Publique (INSP), Bouaké, Côte d'Ivoire
| | - Akré M Adja
- Institut Pierre Richet (IPR), Institut National de la Santé Publique (INSP), Bouaké, Côte d'Ivoire.,Unité de Formation et de Recherche en Biosciences (UFR Biosciences), Université Félix Houphouët Boigny, Abidjan, Côte d'Ivoire
| | - Mamadou Dagnogo
- Unité de Formation et de Recherche en Sciences de la Nature (UFR SN), Université Nangui Abrogoua, Abidjan, Côte d'Ivoire
| | - Alphonsine A Koffi
- Institut Pierre Richet (IPR), Institut National de la Santé Publique (INSP), Bouaké, Côte d'Ivoire
| | | | - Franck Remoue
- Institut Pierre Richet (IPR), Institut National de la Santé Publique (INSP), Bouaké, Côte d'Ivoire.,MIVEGEC, University of Montpellier, IRD, CNRS, Montpellier, France
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11
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Sagna AB, Kassié D, Couvray A, Adja AM, Hermann E, Riveau G, Salem G, Fournet F, Remoue F. Spatial Assessment of Contact Between Humans and Anopheles and Aedes Mosquitoes in a Medium-Sized African Urban Setting, Using Salivary Antibody-Based Biomarkers. J Infect Dis 2020; 220:1199-1208. [PMID: 31152664 DOI: 10.1093/infdis/jiz289] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 05/30/2019] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Anarchic and poorly controlled urbanization led to an increased risk of mosquito-borne diseases (MBD) in many African cities. Here, we evaluate the spatial heterogeneity of human exposure to malaria and arboviral disease vectors in an urban area of northern Senegal, using antibody-based biomarkers of exposure to Anopheles and Aedes mosquito bites. METHODS A cross-sectional study was undertaken during the rainy season of 2014 in 4 neighborhoods of Saint-Louis, a city in northern Senegal. Among children aged 6-59 months in each neighborhood, the dried blood spot technique was used to evaluate immunoglobulin G (IgG) responses to both gSG6-P1 (Anopheles) and Nterm-34-kDa (Aedes) salivary peptides as validated biomarkers of respective mosquito bite exposure. RESULTS IgG response levels to gSG6-P1 and Nterm-34-kDa salivary peptides varied significantly between the 4 neighborhoods (P < .0001). The level of exposure to Aedes bites also varied according to household access to sanitation services (P = .027), whereas that of exposure to Anopheles bites varied according to insecticide-treated bed net use (P = .006). In addition, spatial clusters of high contact between humans and mosquitoes were identified inside 3 neighborhoods. CONCLUSIONS Antibody-based biomarkers of exposure to Anopheles and Aedes mosquito bites could be helpful tools for evaluating the heterogeneity of exposure to malaria and arboviral disease vectors by national control programs.
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Affiliation(s)
- André B Sagna
- MIVEGEC, University of Montpellier, CNRS, IRD
- Institut Pierre Richet/Institut National de Santé Publique, Bouaké, Côte d'Ivoire
- Biomedical Research Center Espoir Pour La Santé, Saint-Louis, Sénégal
| | - Daouda Kassié
- ASTRE, University of Montpellier, CIRAD, INRA, Montpellier
- Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
| | | | - Akré Maurice Adja
- Institut Pierre Richet/Institut National de Santé Publique, Bouaké, Côte d'Ivoire
| | - Emmanuel Hermann
- CIIL, Institut Pasteur de Lille, University of Lille, CNRS UMR, Inserm, Lille, France
| | - Gilles Riveau
- CIIL, Institut Pasteur de Lille, University of Lille, CNRS UMR, Inserm, Lille, France
- Biomedical Research Center Espoir Pour La Santé, Saint-Louis, Sénégal
| | - Gérard Salem
- CEPED, University of Paris Descartes, IRD, Paris
| | - Florence Fournet
- MIVEGEC, University of Montpellier, CNRS, IRD
- Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
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12
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Aka KG, Traoré DF, Sagna AB, Zoh DD, Assi SB, Tchiekoi BN, Adja AM, Remoue F, Poinsignon A. Pattern of antibody responses to Plasmodium falciparum antigens in individuals differentially exposed to Anopheles bites. Malar J 2020; 19:83. [PMID: 32085710 PMCID: PMC7033907 DOI: 10.1186/s12936-020-03160-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 02/12/2020] [Indexed: 11/16/2022] Open
Abstract
Background In malaria-endemic areas, human populations are frequently exposed to immunomodulatory salivary components injected during mosquito blood feeding. The consequences on pathogen-specific immune responses are not well known. This study evaluated and compared the humoral responses specific to merozoite stage vaccine candidates of Plasmodium falciparum, in children differentially exposed to Anopheles bites in a natural setting. Methods The cross-sectional study was carried out in Bouaké (Côte d’Ivoire) where entomological data and blood samples from children (0–14 years) were collected in two sites with similar malaria prevalence. Antibody (IgG, IgG1, IgG3) responses to PfAMA1 and PfMSP1 were evaluated by ELISA. Univariate and multivariate analysis were performed to assess the relationship between the immune responses to P. falciparum antigens and exposure to Anopheles bites in the total cohort and in each site, separately. The individual level of exposure to Anopheles bites was evaluated by quantifying specific IgG response to the Anopheles gSG6-P1 salivary peptide, which represents a proxy of Anopheles exposure. Results The anti-Plasmodium humoral responses were different according to the level of exposure of children, with those highly exposed to Anopheles presenting significantly lower antibody responses to PfMSP1 in total population (IgG and IgG3) and in Petessou village (IgG, IgG1, IgG3). No significant difference was seen for PfAMA1 antigen between children differently exposed to Anopheles. In Dar-es-Salam, a neighbourhood where a high Culex density was reported, children presented very low antibody levels specific to both antigens, and no difference according to the exposure to Anopheles bites was found. Conclusion These findings may suggest that immunomodulatory components of Anopheles saliva, in addition to other factors, may participate to the modulation of the humoral response specific to Plasmodium merozoite stage antigens. This epidemiological observation may form a starting point for additional work to decipher the role of mosquito saliva on the modulation of the anti-Plasmodium acquired immunity and clinical protection in combining both field and ex vivo immunological studies.
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Affiliation(s)
- Kakou G Aka
- Institut Pierre Richet, Institut National de Santé Publique, Bouaké, Côte d'Ivoire. .,MIVEGEC, University of Montpellier, CNRS, IRD, Montpellier, France.
| | - Dipomin F Traoré
- Institut Pierre Richet, Institut National de Santé Publique, Bouaké, Côte d'Ivoire.,MIVEGEC, University of Montpellier, CNRS, IRD, Montpellier, France.,UFR Sciences de la Nature, Université Nangui Abrogoua, Abidjan, Côte d'Ivoire
| | - André B Sagna
- Institut Pierre Richet, Institut National de Santé Publique, Bouaké, Côte d'Ivoire.,MIVEGEC, University of Montpellier, CNRS, IRD, Montpellier, France
| | - Dounin D Zoh
- Institut Pierre Richet, Institut National de Santé Publique, Bouaké, Côte d'Ivoire.,UFR Biosciences, Université Félix Houphouët Boigny, Abidjan, Côte d'Ivoire
| | - Serge B Assi
- Institut Pierre Richet, Institut National de Santé Publique, Bouaké, Côte d'Ivoire
| | | | - Akré M Adja
- Institut Pierre Richet, Institut National de Santé Publique, Bouaké, Côte d'Ivoire.,UFR Biosciences, Université Félix Houphouët Boigny, Abidjan, Côte d'Ivoire
| | - Franck Remoue
- Institut Pierre Richet, Institut National de Santé Publique, Bouaké, Côte d'Ivoire.,MIVEGEC, University of Montpellier, CNRS, IRD, Montpellier, France
| | - Anne Poinsignon
- Institut Pierre Richet, Institut National de Santé Publique, Bouaké, Côte d'Ivoire.,MIVEGEC, University of Montpellier, CNRS, IRD, Montpellier, France
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