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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Zhao N, Sesay I, Tu H, Yamba F, Lu L, Guo Y, Song X, Wang J, Liu X, Yue Y, Wu H, Liu Q. Entomological and Molecular Surveillance of Anopheles Mosquitoes in Freetown, Sierra Leone, 2019. Front Public Health 2021; 9:649672. [PMID: 34222167 PMCID: PMC8247763 DOI: 10.3389/fpubh.2021.649672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 05/26/2021] [Indexed: 11/23/2022] Open
Abstract
Background: Malaria is endemic in Sierra Leone, with stable and perennial transmission in all parts of the country. At present, the main prevention and control measures for mosquito vectors here involve insecticide treated nets (ITN) and indoor residual spraying (IRS). The most recent entomological surveillance was conducted prior to the civil war, between 1990 and 1994. Therefore, a new entomological surveillance required to support targeted malaria control strategies. Methods:Anopheles mosquitoes were collected between June and December 2019 using the light trap method. On these, we conducted species identification, analyzed seasonal fluctuation and Plasmodium infection rate, and monitored insecticide resistance. Results: Surveillance of seasonal fluctuation showed that there were two peak of Anopheles density in July (mean 13.67 mosquitoes/trap/night) and October (mean 13.00 mosquitoes/trap/night). Meanwhile, the lowest Anopheles density was seen in early September. Ninety-one representatives of Anopheles gambiae s.l. were selected and identified as An. coluzzii (n = 35) and An. gambiae s.s. (n = 56) using PCR. An. coluzzii and An. gambiae s.s. were found to be heterozygous resistant to the knockdown resistance (kdr) L1014F mutation (100%). Meanwhile, the East African mutation (kdr L1014S) was absent in the tested mosquitoes. Three mosquitoes that tested positive for the parasite, had an individual Plasmodium falciparum infection rate of 12.50, 16.67, and 14.29%. The sampling dates of positive mosquitoes were distributed in the two periods of peak Anopheles mosquito density. Conclusion: This study identified the dominant Anopheles species in Freetown as An. gambiae while the predominant species within the An. gambiae complex was An. gambiae sensu stricto. Surveillance of seasonal fluctuations and high P. falciparum infection rates in Anopheles indicate that the alternation of drought and rainy seasons from June to July, and from October to November, are the key periods for malaria control and prevention in Freetown, Sierra Leone. The high frequency of kdr allele mutations in An. gambiae calls for close monitoring of vector susceptibility to insecticides and tracing of resistance mechanisms in order to develop more effective vector control measures and strategies.
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Affiliation(s)
- Ning Zhao
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China.,Sierra Leone-China Friendship Biosafety Laboratory, Freetown, Sierra Leone
| | - Ishaq Sesay
- Sierra Leone-China Friendship Biosafety Laboratory, Freetown, Sierra Leone
| | - Hong Tu
- Sierra Leone-China Friendship Biosafety Laboratory, Freetown, Sierra Leone.,Chinese Center for Disease Control and Prevention, National Institute of Parasitic Diseases, Shanghai, China
| | - Frederick Yamba
- Ministry of Health and Sanitation of Sierra Leone, Freetown, Sierra Leone
| | - Liang Lu
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China.,Sierra Leone-China Friendship Biosafety Laboratory, Freetown, Sierra Leone
| | - Yuhong Guo
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
| | - Xiuping Song
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
| | - Jun Wang
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
| | - Xiaobo Liu
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
| | - Yujuan Yue
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
| | - Haixia Wu
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
| | - Qiyong Liu
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
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Caputo B, Pichler V, Bottà G, De Marco C, Hubbart C, Perugini E, Pinto J, Rockett KA, Miles A, Della Torre A. Novel genotyping approaches to easily detect genomic admixture between the major Afrotropical malaria vector species, Anopheles coluzzii and An. gambiae. Mol Ecol Resour 2021; 21:1504-1516. [PMID: 33590707 PMCID: PMC8252489 DOI: 10.1111/1755-0998.13359] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 02/05/2021] [Accepted: 02/11/2021] [Indexed: 11/28/2022]
Abstract
The two most efficient and most recently radiated Afrotropical vectors of human malaria - Anopheles coluzzii and An. gambiae - are identified by single-locus diagnostic PCR assays based on species-specific markers in a 4 Mb region on chromosome-X centromere. Inherently, these diagnostic assays cannot detect interspecific autosomal admixture shown to be extensive at the westernmost and easternmost extremes of the species range. The main aim of this study was to develop novel, easy-to-implement tools for genotyping An. coluzzii and An. gambiae-specific ancestral informative markers (AIMs) identified from the Anopheles gambiae 1000 genomes (Ag1000G) project. First, we took advantage of this large set of data in order to develop a multilocus approach to genotype 26 AIMs on all chromosome arms valid across the species range. Second, we tested the multilocus assay on samples from Guinea Bissau, The Gambia and Senegal, three countries spanning the westernmost hybridization zone, where conventional species diagnostic is problematic due to the putative presence of a novel "hybrid form". The multilocus assay was able to capture patterns of admixture reflecting those revealed by the whole set of AIMs and provided new original data on interspecific admixture in the region. Third, we developed an easy-to-use, cost-effective PCR approach for genotyping two AIMs on chromosome-3 among those included in the multilocus approach, opening the possibility for advanced identification of species and of admixed specimens during routine large scale entomological surveys, particularly, but not exclusively, at the extremes of the range, where WGS data highlighted unexpected autosomal admixture.
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Affiliation(s)
- Beniamino Caputo
- Dipartimento di Sanità Pubblica e Malattie Infettive, Istituto Pasteur Italia-Fondazione Cenci-Bolognetti, Università di Roma "Sapienza", Rome, Italy
| | - Verena Pichler
- Dipartimento di Sanità Pubblica e Malattie Infettive, Istituto Pasteur Italia-Fondazione Cenci-Bolognetti, Università di Roma "Sapienza", Rome, Italy
| | - Giordano Bottà
- Dipartimento di Sanità Pubblica e Malattie Infettive, Istituto Pasteur Italia-Fondazione Cenci-Bolognetti, Università di Roma "Sapienza", Rome, Italy.,Wellcome Centre for Human Genetics, University of Oxford, Headington, Oxford, UK
| | - Carlo De Marco
- Dipartimento di Sanità Pubblica e Malattie Infettive, Istituto Pasteur Italia-Fondazione Cenci-Bolognetti, Università di Roma "Sapienza", Rome, Italy
| | - Christina Hubbart
- Wellcome Centre for Human Genetics, University of Oxford, Headington, Oxford, UK
| | - Eleonora Perugini
- Dipartimento di Sanità Pubblica e Malattie Infettive, Istituto Pasteur Italia-Fondazione Cenci-Bolognetti, Università di Roma "Sapienza", Rome, Italy
| | - Joao Pinto
- Global Health & Tropical Medicine, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Lisbon, Portugal
| | - Kirk A Rockett
- Wellcome Centre for Human Genetics, University of Oxford, Headington, Oxford, UK
| | - Alistair Miles
- Malaria Programme, Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK.,MRC Centre for Genomics and Global Health, University of Oxford, Oxford, UK
| | - Alessandra Della Torre
- Dipartimento di Sanità Pubblica e Malattie Infettive, Istituto Pasteur Italia-Fondazione Cenci-Bolognetti, Università di Roma "Sapienza", Rome, Italy
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Murindahabi MM, Takken W, Misago X, Niyituma E, Umupfasoni J, Hakizimana E, van Vliet AJH, Poortvliet PM, Mutesa L, Murindahabi NK, Koenraadt CJM. Monitoring mosquito nuisance for the development of a citizen science approach for malaria vector surveillance in Rwanda. Malar J 2021; 20:36. [PMID: 33423679 PMCID: PMC7798336 DOI: 10.1186/s12936-020-03579-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Accepted: 12/31/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Many countries, including Rwanda, have mosquito monitoring programmes in place to support decision making in the fight against malaria. However, these programmes can be costly, and require technical (entomological) expertise. Involving citizens in data collection can greatly support such activities, but this has not yet been thoroughly investigated in a rural African context. METHODS Prior to the implementation of such a citizen-science approach, a household entomological survey was conducted in October-November 2017 and repeated one year later in Busoro and Ruhuha sectors, in southern and eastern province of Rwanda, respectively. The goal was to evaluate the perception of mosquito nuisance reported by citizens as a potential indicator for malaria vector hotspots. Firstly, mosquito abundance and species composition were determined using Centers for Disease Control and Prevention (CDC) light traps inside the houses. Secondly, household members were interviewed about malaria risk factors and their perceived level of mosquito nuisance. RESULTS Tiled roofs, walls made of mud and wood, as well as the number of occupants in the house were predictors for the number of mosquitoes (Culicidae) in the houses, while the presence of eaves plus walls made of mud and wood were predictors for malaria vector abundance. Perception of mosquito nuisance reported indoors tended to be significantly correlated with the number of Anopheles gambiae sensu lato (s.l.) and Culicidae collected indoors, but this varied across years and sectors. At the village level, nuisance also significantly correlated with An. gambiae s.l. and total mosquito density, but only in 2018 while not in 2017. CONCLUSIONS Perception of mosquito nuisance denoted in a questionnaire survey could be used as a global indicator of malaria vector hotspots. Hence, involving citizens in such activities can complement malaria vector surveillance and control.
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Affiliation(s)
- Marilyn Milumbu Murindahabi
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands.,College of Sciences and Technology, University of Rwanda, Kigali, Rwanda
| | - Willem Takken
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Xavier Misago
- Malaria and Other Parasitic Diseases Division, Rwanda Biomedical Center, Kigali, Rwanda
| | - Elias Niyituma
- Malaria and Other Parasitic Diseases Division, Rwanda Biomedical Center, Kigali, Rwanda
| | - Jackie Umupfasoni
- Malaria and Other Parasitic Diseases Division, Rwanda Biomedical Center, Kigali, Rwanda
| | - Emmanuel Hakizimana
- Malaria and Other Parasitic Diseases Division, Rwanda Biomedical Center, Kigali, Rwanda
| | - Arnold J H van Vliet
- Environmental Systems Analysis Group, Wageningen University & Research, Wageningen, The Netherlands
| | - P Marijn Poortvliet
- Strategic Communication Group, Wageningen University & Research, Wageningen, the Netherlands
| | - Leon Mutesa
- College of Medicine and Health Sciences, University of Rwanda, Kigali, Rwanda
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Ant T, Foley E, Tytheridge S, Johnston C, Goncalves A, Ceesay S, Ndiath MO, Affara M, Martinez J, Pretorius E, Grundy C, Rodrigues A, Djata P, d'Alessandro U, Bailey R, Mabey D, Last A, Logan JG. A survey of Anopheles species composition and insecticide resistance on the island of Bubaque, Bijagos Archipelago, Guinea-Bissau. Malar J 2020; 19:27. [PMID: 31941507 PMCID: PMC6964033 DOI: 10.1186/s12936-020-3115-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 01/10/2020] [Indexed: 11/10/2022] Open
Abstract
Background Bubaque is the most populous island of the Bijagos archipelago, a group of malaria-endemic islands situated off the coast of Guinea-Bissau, West Africa. Malaria vector control on Bubaque relies almost exclusively on the use of long-lasting insecticidal nets (LLINs). However, there is little information on local vector bionomics and insecticide resistance. Methods A survey of mosquito species composition was performed at the onset of the wet season (June/July) and the beginning of the dry season (November/December). Sampling was performed using indoor adult light-traps and larval dipping. Anopheles mosquitoes were identified to species level and assessed for kdr allele frequency by TaqMan PCR. Females were analysed for sporozoite positivity by CSP-ELISA. Resistance to permethrin and α-cypermethrin was measured using the CDC-bottle bioassay incorporating the synergist piperonyl-butoxide. Results Several Anopheles species were found on the island, all belonging to the Anopheles gambiae sensu lato (s.l.) complex, including An. gambiae sensu stricto, Anopheles coluzzii, Anopheles melas, and An. gambiae/An. coluzzii hybrids. Endophagic Anopheles species composition and abundance showed strong seasonal variation, with a majority of An. gambiae (50% of adults collected) caught in June/July, while An. melas was dominant in November/December (83.9% of adults collected). Anopheles gambiae had the highest sporozoite rate in both seasons, with infection rates of 13.9% and 20% in June/July and November/December, respectively. Moderate frequencies of the West African kdr allele were found in An. gambiae (36%), An. coluzzii (35%), An. gambiae/An. coluzzii hybrids (42%). Bioassays suggest moderate resistance to α-cypermethrin, but full susceptibility to permethrin. Conclusions The island of Bubaque maintained an An. gambiae s.l. population in both June/July and November/December. Anopheles gambiae was the primary vector at the onset of the wet season, while An. melas is likely to be responsible for most dry season transmission. There was moderate kdr allele frequency and synergist assays suggest likely metabolic resistance, which could reduce the efficacy of LLINs. Future control of malaria on the islands should consider the seasonal shift in mosquito species, and should employ continuous monitoring for insecticide resistance.
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Affiliation(s)
- Thomas Ant
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Erin Foley
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Scott Tytheridge
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Colin Johnston
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Adriana Goncalves
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Sainey Ceesay
- Disease Control & Elimination Theme, Medical Research Council Unit, London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Mamadou Ousmane Ndiath
- Disease Control & Elimination Theme, Medical Research Council Unit, London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Muna Affara
- Disease Control & Elimination Theme, Medical Research Council Unit, London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Julien Martinez
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Elizabeth Pretorius
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Chris Grundy
- Department of Infectious Disease Epidemiology, Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | | | - Paulo Djata
- Ministério da saude chez Ministério da saude de Guinea-Bissau, Bissau, Guinea-Bissau
| | - Umberto d'Alessandro
- MRC The Gambia at the London School of Hygiene & Tropical Medicine, Fajara, Gambia
| | - Robin Bailey
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - David Mabey
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Anna Last
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - James G Logan
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. .,ARCTEC, Chariot Innovations Ltd, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.
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Prussing C, Emerson KJ, Bickersmith SA, Sallum MAM, Conn JE. Minimal genetic differentiation of the malaria vector Nyssorhynchus darlingi associated with forest cover level in Amazonian Brazil. PLoS One 2019; 14:e0225005. [PMID: 31725789 DOI: 10.1371/journal.pone.0225005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 10/25/2019] [Indexed: 12/05/2022] Open
Abstract
The relationship between deforestation and malaria in Amazonian Brazil is complex, and a deeper understanding of this relationship is required to inform effective control measures in this region. Here, we are particularly interested in characterizing the impact of land use and land cover change on the genetics of the major regional vector of malaria, Nyssorhynchus darlingi (Root). We used nextera-tagmented, Reductively Amplified DNA (nextRAD) genotyping-by-sequencing to genotype 164 Ny. darlingi collected from 16 collection sites with divergent forest cover levels in seven municipalities in four municipality groups that span the state of Amazonas in northwestern Amazonian Brazil: São Gabriel da Cachoeira, Presidente Figueiredo, four municipalities in the area around Cruzeiro do Sul, and Lábrea. Using a dataset of 5,561 Single Nucleotide Polymorphisms (SNPs), we investigated the genetic structure of these Ny. darlingi populations with a combination of model- and non-model-based analyses. We identified weak to moderate genetic differentiation among the four municipality groups. There was no evidence for microgeographic genetic structure of Ny. darlingi among forest cover levels within the municipality groups, indicating that there may be gene flow across areas of these municipalities with different degrees of deforestation. Additionally, we conducted an environmental association analysis using two outlier detection methods to determine whether individual SNPs were associated with forest cover level without affecting overall population genetic structure. We identified 14 outlier SNPs, and investigated functions associated with their proximal genes, which could be further characterized in future studies.
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Ginsberg HS, Couret J. Nonlinearities in transmission dynamics and efficient management of vector-borne pathogens. Ecol Appl 2019; 29:e01892. [PMID: 30929298 DOI: 10.1002/eap.1892] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 02/15/2019] [Accepted: 03/04/2019] [Indexed: 06/09/2023]
Abstract
Integrated Pest Management (IPM) is an approach to minimizing economic and environmental harm caused by pests, and Integrated Vector Management (IVM) uses similar methods to minimize pathogen transmission by vectors. The risk of acquiring a vector-borne infection is often quantified using the density of infected vectors. The relationship between vector numbers and risk of human infection is more or less linear when both vector numbers and pathogen prevalence in vectors are low, but the relationship is nonlinear when vector density and/or infection prevalence are high. Therefore, the density of infected vectors often does not accurately predict risk of human exposure to pathogens, and traditional estimates of the percent control often overestimate the level of protection from infection resulting from management programs. We suggest a modified estimator, percent protection, which more accurately quantifies protection against human infection resulting from a management intervention. Cost-effectiveness of a management program is critical to protection of both public health and the environment, because the more efficiently available resources and funding are used, the fewer people get sick, and well-targeted efficient management programs minimize the need for poorly targeted, expensive environmental interventions (e.g., broadscale pesticide applications) that tend to damage nontarget organisms and natural systems. Design of an efficient, cost-effective IVM program requires knowledge of the cost-effectiveness functions (the effectiveness of control methods at lowering vector bites and/or infection prevalence with different levels of application) of the various control methods to be applied. Alternative programs can be designed that optimize percent protection by integrating different control methods at different levels of investment, and environmental effects of these alternatives can be compared, allowing environmental considerations to be included explicitly in the decision process. IPM, IVM, and Adaptive Management share the characteristic that management decisions must be made with incomplete knowledge of the functioning of natural systems or the efficacies of interventions. IVM surveillance programs that assess the effects of individual control methods and of combinations of control methods on the numbers of vector bites and on infection prevalence in vectors can increase knowledge of pathogen transmission dynamics and provide information to improve program effectiveness in subsequent applications.
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Affiliation(s)
- Howard S Ginsberg
- U.S. Geological Survey, Patuxent Wildlife Research Center, Rhode Island Field Station, Department of Plant Sciences and Entomology, University of Rhode Island, Kingston, Rhode Island, 02881, USA
| | - Jannelle Couret
- Department of Biological Sciences, University of Rhode Island, Kingston, Rhode Island, 02881, USA
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Riveron JM, Watsenga F, Irving H, Irish SR, Wondji CS. High Plasmodium Infection Rate and Reduced Bed Net Efficacy in Multiple Insecticide-Resistant Malaria Vectors in Kinshasa, Democratic Republic of Congo. J Infect Dis 2019; 217:320-328. [PMID: 29087484 PMCID: PMC5853898 DOI: 10.1093/infdis/jix570] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Accounting for approximately 11% of all malaria cases, the Democratic Republic of the Congo (DRC) is central to malaria elimination efforts. To support vector control interventions in DRC, we characterized the dynamics and impact of insecticide resistance in major malaria vectors in 2015. High Plasmodium infection rates were recorded in Anopheles gambiae and Anopheles funestus, with Plasmodium falciparum predominant over Plasmodium malariae. Both mosquito species exhibited high and multiple resistance to major public health insecticide classes. The extremely high resistance to permethrin and DDT (dichlorodiphenyltrichloroethane) in An. gambiae (low mortalities after 6 hours exposure) is worrisome, and is supported by a reduced insecticidal effect of bed nets against both mosquito species in laboratory tests. Metabolic and target site insensitivity mechanisms are driving this resistance in An. gambiae, but only the former was observed in An. funestus. These findings highlight the urgent need for actions to prolong the effectiveness of insecticide-based interventions in DRC.
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Affiliation(s)
- Jacob M Riveron
- Vector Biology Department, Liverpool School of Tropical Medicine, United Kingdom.,Research Unit, Liverpool School of Tropical Medicine (LSTM)/Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC) Research Unit, Yaoundé, Cameroon
| | - Francis Watsenga
- Institut National de Recherche Biomédicale, Kinshasa, Democratic Republic of Congo
| | - Helen Irving
- Vector Biology Department, Liverpool School of Tropical Medicine, United Kingdom
| | - Seth R Irish
- US President's Malaria Initiative, Entomology Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Charles S Wondji
- Vector Biology Department, Liverpool School of Tropical Medicine, United Kingdom.,Research Unit, Liverpool School of Tropical Medicine (LSTM)/Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC) Research Unit, Yaoundé, Cameroon
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9
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Thailayil J, Gabrieli P, Caputo B, Bascuñán P, South A, Diabate A, Dabire R, Della Torre A, Catteruccia F. Analysis of natural female post-mating responses of Anopheles gambiae and Anopheles coluzzii unravels similarities and differences in their reproductive ecology. Sci Rep 2018; 8:6594. [PMID: 29700344 DOI: 10.1038/s41598-018-24923-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 03/20/2018] [Indexed: 11/18/2022] Open
Abstract
Anopheles gambiae and An. coluzzii, the two most important malaria vectors in sub-Saharan Africa, are recently radiated sibling species that are reproductively isolated even in areas of sympatry. In females from these species, sexual transfer of male accessory gland products, including the steroid hormone 20-hydroxyecdysone (20E), induces vast behavioral, physiological, and transcriptional changes that profoundly shape their post-mating ecology, and that may have contributed to the insurgence of post-mating, prezygotic reproductive barriers. As these barriers can be detected by studying transcriptional changes induced by mating, we set out to analyze the post-mating response of An. gambiae and An. coluzzii females captured in natural mating swarms in Burkina Faso. While the molecular pathways shaping short- and long-term mating-induced changes are largely conserved in females from the two species, we unravel significant inter-specific differences that suggest divergent regulation of key reproductive processes such as egg development, processing of seminal secretion, and mating behavior, that may have played a role in reproductive isolation. Interestingly, a number of these changes occur in genes previously shown to be regulated by the sexual transfer of 20E and may be due to divergent utilization of this steroid hormone in the two species.
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10
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Vicente JL, Clarkson CS, Caputo B, Gomes B, Pombi M, Sousa CA, Antao T, Dinis J, Bottà G, Mancini E, Petrarca V, Mead D, Drury E, Stalker J, Miles A, Kwiatkowski DP, Donnelly MJ, Rodrigues A, Torre AD, Weetman D, Pinto J. Massive introgression drives species radiation at the range limit of Anopheles gambiae. Sci Rep 2017; 7:46451. [PMID: 28417969 PMCID: PMC5394460 DOI: 10.1038/srep46451] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 03/17/2017] [Indexed: 12/30/2022] Open
Abstract
Impacts of introgressive hybridisation may range from genomic erosion and species collapse to rapid adaptation and speciation but opportunities to study these dynamics are rare. We investigated the extent, causes and consequences of a hybrid zone between Anopheles coluzzii and Anopheles gambiae in Guinea-Bissau, where high hybridisation rates appear to be stable at least since the 1990s. Anopheles gambiae was genetically partitioned into inland and coastal subpopulations, separated by a central region dominated by A. coluzzii. Surprisingly, whole genome sequencing revealed that the coastal region harbours a hybrid form characterised by an A. gambiae-like sex chromosome and massive introgression of A. coluzzii autosomal alleles. Local selection on chromosomal inversions may play a role in this process, suggesting potential for spatiotemporal stability of the coastal hybrid form and providing resilience against introgression of medically-important loci and traits, found to be more prevalent in inland A. gambiae.
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Affiliation(s)
- José L Vicente
- Global Health and Tropical Medicine, GHTM, Instituto de Higiene e Medicina Tropical, IHMT, Universidade Nova de Lisboa, UNL, Lisbon, Portugal
| | - Christopher S Clarkson
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Beniamino Caputo
- Istituto Pasteur Italia-Fondazione Cenci-Bolognetti, Dipartimento di Sanità Pubblica e Malattie Infettive, Università di Roma "Sapienza", Rome, Italy
| | - Bruno Gomes
- Global Health and Tropical Medicine, GHTM, Instituto de Higiene e Medicina Tropical, IHMT, Universidade Nova de Lisboa, UNL, Lisbon, Portugal
| | - Marco Pombi
- Istituto Pasteur Italia-Fondazione Cenci-Bolognetti, Dipartimento di Sanità Pubblica e Malattie Infettive, Università di Roma "Sapienza", Rome, Italy
| | - Carla A Sousa
- Global Health and Tropical Medicine, GHTM, Instituto de Higiene e Medicina Tropical, IHMT, Universidade Nova de Lisboa, UNL, Lisbon, Portugal
| | - Tiago Antao
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - João Dinis
- Instituto Nacional de Saúde Pública, Ministério da Saúde Pública, Bissau, Guiné-Bissau
| | - Giordano Bottà
- Istituto Pasteur Italia-Fondazione Cenci-Bolognetti, Dipartimento di Sanità Pubblica e Malattie Infettive, Università di Roma "Sapienza", Rome, Italy.,Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Emiliano Mancini
- Istituto Pasteur Italia-Fondazione Cenci-Bolognetti, Dipartimento di Sanità Pubblica e Malattie Infettive, Università di Roma "Sapienza", Rome, Italy
| | - Vincenzo Petrarca
- Istituto Pasteur Italia-Fondazione Cenci-Bolognetti, Dipartimento di Sanità Pubblica e Malattie Infettive, Università di Roma "Sapienza", Rome, Italy.,Istituto Pasteur Italia-Fondazione Cenci-Bolognetti, Dipartimento di Biologia e Biotecnologie "Charles Darwin", Università di Roma "Sapienza", Rome, Italy
| | - Daniel Mead
- Wellcome Trust Sanger Institute, Hinxton, UK
| | | | | | - Alistair Miles
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.,Medical Research Council Centre for Genomics and Global Health, University of Oxford, Oxford, UK
| | - Dominic P Kwiatkowski
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.,Wellcome Trust Sanger Institute, Hinxton, UK.,Medical Research Council Centre for Genomics and Global Health, University of Oxford, Oxford, UK
| | - Martin J Donnelly
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Amabélia Rodrigues
- Instituto Nacional de Saúde Pública, Ministério da Saúde Pública, Bissau, Guiné-Bissau
| | - Alessandra Della Torre
- Istituto Pasteur Italia-Fondazione Cenci-Bolognetti, Dipartimento di Sanità Pubblica e Malattie Infettive, Università di Roma "Sapienza", Rome, Italy
| | - David Weetman
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - João Pinto
- Global Health and Tropical Medicine, GHTM, Instituto de Higiene e Medicina Tropical, IHMT, Universidade Nova de Lisboa, UNL, Lisbon, Portugal
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11
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Stevenson JC, Norris DE. Implicating Cryptic and Novel Anophelines as Malaria Vectors in Africa. Insects 2016; 8:E1. [PMID: 28025486 PMCID: PMC5371929 DOI: 10.3390/insects8010001] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/06/2016] [Revised: 12/09/2016] [Accepted: 12/12/2016] [Indexed: 11/24/2022]
Abstract
Entomological indices and bionomic descriptions of malaria vectors are essential to accurately describe and understand malaria transmission and for the design and evaluation of appropriate control interventions. In order to correctly assign spatio-temporal distributions, behaviors and responses to interventions to particular anopheline species, identification of mosquitoes must be accurately made. This paper reviews the current methods and their limitations in correctly identifying anopheline mosquitoes in sub-Saharan Africa, and highlights the importance of molecular methods to discriminate cryptic species and identify lesser known anophelines. The increasing number of reports of Plasmodium infections in assumed "minor", non-vector, and cryptic and novel species is reviewed. Their importance in terms of evading current control and elimination strategies and therefore maintaining malaria transmission is emphasized.
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Affiliation(s)
- Jennifer C Stevenson
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
- Macha Research Trust, Choma P.O. Box 630166, Southern Province, Zambia.
| | - Douglas E Norris
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
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