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Andrianinarivomanana TM, Randrianaivo FT, Andriamiarimanana MR, Razafimamonjy MR, Velonirina HJ, Puchot N, Girod R, Bourgouin C. Colonization of Anopheles coustani, a neglected malaria vector in Madagascar. Parasite 2024; 31:31. [PMID: 38896103 PMCID: PMC11186460 DOI: 10.1051/parasite/2024032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Accepted: 05/24/2024] [Indexed: 06/21/2024] Open
Abstract
Anopheles coustani has long been recognized as a secondary malaria vector in Africa. It has recently been involved in the transmission of both Plasmodium falciparum and P. vivax in Madagascar. As most secondary malaria vectors, An. coustani mainly bites outdoors, which renders the control of this mosquito species difficult using classical malaria control measures, such as the use of bed nets or indoor residual spraying of insecticides. For a better understanding of the biology and vector competence of a vector species, it is useful to rear the species in the laboratory. The absence of a colony hinders the assessment of the bionomics of a species and the development of adapted control strategies. Here, we report the first successful establishment of an An. coustani colony from mosquitoes collected in Madagascar. We used a forced copulation procedure as this mosquito species will not mate in cages. We describe our mosquito colonization procedure with detailed biological features concerning larval to adult development and survival, recorded over the first six critical generations. The procedure should be easily applicable to An. coustani from different African countries, facilitating local investigation of An. coustani vector competence and insecticide resistance using the colony as a reference.
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Affiliation(s)
| | | | | | | | | | - Nicolas Puchot
- Institut Pasteur, Université de Paris Cité, Biology of Host-Parasite Interactions Paris France
| | - Romain Girod
- Institut Pasteur de Madagascar, Medical Entomology Unit Antananarivo Madagascar
| | - Catherine Bourgouin
- Institut Pasteur, Université de Paris Cité, Biology of Host-Parasite Interactions Paris France
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Okunlola O, Oloja S, Ebiwonjumi A, Oyeyemi O. Vegetation index and livestock practices as predictors of malaria transmission in Nigeria. Sci Rep 2024; 14:9565. [PMID: 38671079 PMCID: PMC11053042 DOI: 10.1038/s41598-024-60385-z] [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: 02/16/2024] [Accepted: 04/22/2024] [Indexed: 04/28/2024] Open
Abstract
Nigeria is the most malaria-endemic country in the world. Vegetation and livestock practices have been linked to malaria transmission but little is known about these in Nigeria. The study aimed to evaluate the influence of vegetation and livestock as predictors of malaria transmission in Nigeria. Secondary data obtained from the Nigerian Demographic and Health Survey's Geospatial Covariate Datasets Manual were used for the analysis. The survey was carried out successfully in 1389 clusters of thirty (30) households each using a two-stage stratified random sampling design. Hierarchical beta regression models were used to model the associations between malaria incidence, enhanced vegetation index (EVI), and livestock practices. The correlation coefficients for vegetation index and livestock-related variables ranged from - 0.063 to 0.074 and varied significantly with the incidence of malaria in Nigeria (P < 0.001). The model showed vegetation index, livestock goats, and sheep as positive predictors of malaria transmission. Conversely, livestock chicken and pigs were observed to reduce the risk of malaria. The study recommends the need to take into account local differences in transmission when developing malaria early warning systems that utilize environmental and livestock predictors.
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Affiliation(s)
- Oluyemi Okunlola
- Department of Mathematics and Statistics, Redeemer's University, Ede, Osun State, Nigeria
- Department of Mathematical and Computer Sciences, University of Medical Sciences, Ondo City, Ondo State, Nigeria
| | - Segun Oloja
- Department of Mathematical and Computer Sciences, University of Medical Sciences, Ondo City, Ondo State, Nigeria
| | - Ayooluwade Ebiwonjumi
- Department of Mathematical Sciences, Adekunle Ajasin University, Akungba-Akoko, Ondo State, Nigeria
| | - Oyetunde Oyeyemi
- Department of Biosciences and Biotechnology, University of Medical Sciences, Ondo City, Ondo State, Nigeria.
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Msugupakulya BJ, Urio NH, Jumanne M, Ngowo HS, Selvaraj P, Okumu FO, Wilson AL. Changes in contributions of different Anopheles vector species to malaria transmission in east and southern Africa from 2000 to 2022. Parasit Vectors 2023; 16:408. [PMID: 37936155 PMCID: PMC10631025 DOI: 10.1186/s13071-023-06019-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 10/18/2023] [Indexed: 11/09/2023] Open
Abstract
BACKGROUND Malaria transmission in Africa is facilitated by multiple species of Anopheles mosquitoes. These vectors have different behaviors and vectorial capacities and are affected differently by vector control interventions, such as insecticide-treated nets and indoor residual spraying. This review aimed to assess changes in the contribution of different vector species to malaria transmission in east and southern Africa over 20 years of widespread insecticide-based vector control. METHODS We searched PubMed, Global Health, and Web of Science online databases for articles published between January 2000 and April 2023 that provided species-specific sporozoite rates for different malaria vectors in east and southern Africa. We extracted data on study characteristics, biting rates, sporozoite infection proportions, and entomological inoculation rates (EIR). Using EIR data, the proportional contribution of each species to malaria transmission was estimated. RESULTS Studies conducted between 2000 and 2010 identified the Anopheles gambiae complex as the primary malaria vector, while studies conducted from 2011 to 2021 indicated the dominance of Anopheles funestus. From 2000 to 2010, in 57% of sites, An. gambiae demonstrated higher parasite infection prevalence than other Anopheles species. Anopheles gambiae also accounted for over 50% of EIR in 76% of the study sites. Conversely, from 2011 to 2021, An. funestus dominated with higher infection rates than other Anopheles in 58% of sites and a majority EIR contribution in 63% of sites. This trend coincided with a decline in overall EIR and the proportion of sporozoite-infected An. gambiae. The main vectors in the An. gambiae complex in the region were Anopheles arabiensis and An. gambiae sensu stricto (s.s.), while the important member of the An. funestus group was An. funestus s.s. CONCLUSION The contribution of different vector species in malaria transmission has changed over the past 20 years. As the role of An. gambiae has declined, An. funestus now appears to be dominant in most settings in east and southern Africa. Other secondary vector species may play minor roles in specific localities. To improve malaria control in the region, vector control should be optimized to match these entomological trends, considering the different ecologies and behaviors of the dominant vector species.
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Affiliation(s)
- Betwel J Msugupakulya
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania.
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK.
| | - Naomi H Urio
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania
- School of Life Science and Bioengineering, The Nelson Mandela African Institution of Sciences & Technology, Arusha, Tanzania
| | - Mohammed Jumanne
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania
| | - Halfan S Ngowo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, UK
| | - Prashanth Selvaraj
- Institute for Disease Modeling, Bill and Melinda Gates Foundation, Seattle, USA
| | - Fredros O Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania.
- School of Life Science and Bioengineering, The Nelson Mandela African Institution of Sciences & Technology, Arusha, Tanzania.
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, UK.
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Park Town, Johannesburg, Republic of South Africa.
| | - Anne L Wilson
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK.
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Gueye A, Ngom EHM, Diagne A, Ndoye BB, Dione ML, Sambe BS, Sokhna C, Diallo M, Niang M, Dia I. Host feeding preferences of malaria vectors in an area of low malaria transmission. Sci Rep 2023; 13:16410. [PMID: 37775717 PMCID: PMC10542387 DOI: 10.1038/s41598-023-43761-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Accepted: 09/28/2023] [Indexed: 10/01/2023] Open
Abstract
Studying the behaviour and trophic preferences of mosquitoes is an important step in understanding the exposure of vertebrate hosts to vector-borne diseases. In the case of human malaria, transmission increases when mosquitoes feed more on humans than on other animals. Therefore, understanding the spatio-temporal dynamics of vectors and their feeding preferences is essential for improving vector control measures. In this study, we investigated the feeding behaviour of Anopheles mosquitoes at two sites in the Sudanian areas of Senegal where transmission is low following the implementation of vector control measures. Blood-fed mosquitoes were collected monthly from July to November 2022 by pyrethrum spray catches in sleeping rooms of almost all houses in Dielmo and Ndiop villages, and blood meals were identified as from human, bovine, ovine, equine and chicken by ELISA. Species from the An. gambiae complex were identified by PCR. The types and numbers of potential domestic animal hosts were recorded in each village. The Human Blood Index (HBI) and the Manly Selection Ratio (MSR) were calculated to determine whether hosts were selected in proportion to their abundance. Spatio-temporal variation in HBI was examined using the Moran's index. A total of 1251 endophilic Anopheles females were collected in 115 bedrooms, including 864 blood fed females of 6 species. An. arabiensis and An. funestus were predominant in Dielmo and Ndiop, respectively. Of the 864 blood meals tested, 853 gave a single host positive result mainly on bovine, equine, human, ovine and chicken in decreasing order in both villages. Overall, these hosts were not selected in proportion to their abundance. The human host was under-selected, highlighting a marked zoophily for the vectors. Over time and space, the HBI were low with no obvious trend, with higher and lower values observed in each of the five months at different points in each village. These results highlight the zoophilic and exophagic behaviour of malaria vectors. This behaviour is likely to be a consequence of the distribution and use of LLINs in both villages and may increase risk of residual outdoor transmission. This underlines the need to study the feeding host profile of outdoor resting populations and how domestic animals may influence malaria epidemiology in order to tailor effective malaria vector control strategies in the two villages.
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Affiliation(s)
- Assiyatou Gueye
- Pole de Zoologie Medicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - El Hadji Malick Ngom
- Pole de Zoologie Medicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Aissatou Diagne
- Pole Immunophysiopathologie et Maladies Infectieuses, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Baye Bado Ndoye
- Pole de Zoologie Medicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Mamadou Lamine Dione
- Pole de Zoologie Medicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Babacar Souleymane Sambe
- Pole Immunophysiopathologie et Maladies Infectieuses, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Cheikh Sokhna
- UMR Vecteurs Infections Tropicales et Mediterraneennes (VITROME), Campus International UCAD-IRD, Route des Peres Maristes, BP 1386, Dakar, Senegal
| | - Mawlouth Diallo
- Pole de Zoologie Medicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Makhtar Niang
- Pole Immunophysiopathologie et Maladies Infectieuses, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Ibrahima Dia
- Pole de Zoologie Medicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal.
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Habtamu K, Petros B, Yan G. Plasmodium vivax: the potential obstacles it presents to malaria elimination and eradication. Trop Dis Travel Med Vaccines 2022; 8:27. [PMID: 36522671 PMCID: PMC9753897 DOI: 10.1186/s40794-022-00185-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 11/23/2022] [Indexed: 12/23/2022] Open
Abstract
Initiatives to eradicate malaria have a good impact on P. falciparum malaria worldwide. P. vivax, however, still presents significant difficulties. This is due to its unique biological traits, which, in comparison to P. falciparum, pose serious challenges for malaria elimination approaches. P. vivax's numerous distinctive characteristics and its ability to live for weeks to years in liver cells in its hypnozoite form, which may elude the human immune system and blood-stage therapy and offer protection during mosquito-free seasons. Many malaria patients are not fully treated because of contraindications to primaquine use in pregnant and nursing women and are still vulnerable to P. vivax relapses, although there are medications that could radical cure P. vivax. Additionally, due to CYP2D6's highly variable genetic polymorphism, the pharmacokinetics of primaquine may be impacted. Due to their inability to metabolize PQ, some CYP2D6 polymorphism alleles can cause patients to not respond to treatment. Tafenoquine offers a radical treatment in a single dose that overcomes the potentially serious problem of poor adherence to daily primaquine. Despite this benefit, hemolysis of the early erythrocytes continues in individuals with G6PD deficiency until all susceptible cells have been eliminated. Field techniques such as microscopy or rapid diagnostic tests (RDTs) miss the large number of submicroscopic and/or asymptomatic infections brought on by reticulocyte tropism and the low parasitemia levels that accompany it. Moreover, P. vivax gametocytes grow more quickly and are much more prevalent in the bloodstream. P. vivax populations also have a great deal of genetic variation throughout their genome, which ensures evolutionary fitness and boosts adaptation potential. Furthermore, P. vivax fully develops in the mosquito faster than P. falciparum. These characteristics contribute to parasite reservoirs in the human population and facilitate faster transmission. Overall, no genuine chance of eradication is predicted in the next few years unless new tools for lowering malaria transmission are developed (i.e., malaria elimination and eradication). The challenging characteristics of P. vivax that impede the elimination and eradication of malaria are thus discussed in this article.
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Affiliation(s)
- Kassahun Habtamu
- Department of Microbial, Cellular & Molecular Biology, Addis Ababa University, Addis Ababa, Ethiopia
- Menelik II Medical & Health Science College, Addis Ababa, Ethiopia
| | - Beyene Petros
- Department of Microbial, Cellular & Molecular Biology, Addis Ababa University, Addis Ababa, Ethiopia
| | - Guiyun Yan
- Program in Public Health, University of California at Irvine, Irvine, CA 92697 USA
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Escobar D, Archaga O, Reyes A, Palma A, Larson RT, Vásquez GM, Fontecha G. A Follow-Up to the Geographical Distribution of Anopheles Species in Malaria-Endemic and Non-Endemic Areas of Honduras. INSECTS 2022; 13:insects13060548. [PMID: 35735885 PMCID: PMC9225189 DOI: 10.3390/insects13060548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 06/09/2022] [Accepted: 06/14/2022] [Indexed: 12/10/2022]
Abstract
Simple Summary Malaria is a tropical disease caused by parasites of the genus Plasmodium. The parasite is transmitted to humans through the bite of the female mosquito Anopheles. Honduras is close to the goal of eliminating malaria, but the region called La Moskitia continues to concentrate almost all of the country’s malaria cases. One of the key factors in achieving malaria elimination is a thorough understanding of the mosquito vectors that transmit the disease. There are few studies related to malaria vectors in Honduras. This study aims to contribute to knowing which are the species of vector mosquitoes, mainly in the Department of Gracias a Dios and in other departments in which cases of malaria occur, in addition to describing molecularly for the first time the anophelines of the Bay Islands. The most abundant species found here were Anopheles albimanus, but seven other species were also identified, some of which may contribute to parasite transmission. Abstract Anopheles species are the vectors of malaria, one of the diseases with the greatest impact on the health of the inhabitants of the tropics. Due to their epidemiological relevance and biological complexity, monitoring of anopheline populations in current and former malaria-endemic areas is critical for malaria risk assessment. Recent efforts have described the anopheline species present in the main malaria foci in Honduras. This study updates and expands knowledge about Anopheles species composition, geographical distribution, and genetic diversity in the continental territory of Honduras as in the Bay Islands. Outdoor insect collections were carried out at 25 sites in eight municipalities in five departments of Honduras between 2018 and 2021. Specimens were identified using taxonomic keys. Partial COI gene sequences were used for molecular species identification and phylogenetic analyses. In addition, detection of Plasmodium DNA was carried out in 255 female mosquitoes. Overall, 288 Anopheles mosquitoes were collected from 8 municipalities. Eight species were morphologically identified. Anopheles albimanus was the most abundant and widely distributed species (79.5%). A subset of 175 partial COI gene sequences from 8 species was obtained. Taxonomic identifications were confirmed via sequence analysis. Anopheles albimanus and An. apicimacula showed the highest haplotype diversity and nucleotide variation, respectively. Phylogenetic clustering was found for An. argyritarsis and An. neomaculipalpus when compared with mosquitoes from other Neotropical countries. Plasmodium DNA was not detected in any of the mosquitoes tested. This report builds upon recent records of the distribution and diversity of Anopheles species in malaria-endemic and non-endemic areas of Honduras. New COI sequences are reported for three anopheline species. This is also the first report of COI sequences of An. albimanus collected on the island of Roatán with apparent gene flow relative to mainland populations.
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Affiliation(s)
- Denis Escobar
- Microbiology Research Institute, Universidad Nacional Autónoma de Honduras, Tegucigalpa 11101, Honduras; (D.E.); (O.A.)
| | - Osman Archaga
- Microbiology Research Institute, Universidad Nacional Autónoma de Honduras, Tegucigalpa 11101, Honduras; (D.E.); (O.A.)
| | - Allan Reyes
- Unidad de Entomología, Región Sanitaria de Gracias a Dios, Secretaría de Salud de Honduras, Puerto Lempira, Gracias a Dios 33101, Honduras;
| | - Adalid Palma
- Vysnova Partners, Inc., Landover, MD 20785, USA;
| | - Ryan T. Larson
- Department of Entomology, U.S. Naval Medical Research Unit No. 6 (NAMRU-6), Bellavista 07006, Peru; (R.T.L.); (G.M.V.)
| | - Gissella M. Vásquez
- Department of Entomology, U.S. Naval Medical Research Unit No. 6 (NAMRU-6), Bellavista 07006, Peru; (R.T.L.); (G.M.V.)
| | - Gustavo Fontecha
- Microbiology Research Institute, Universidad Nacional Autónoma de Honduras, Tegucigalpa 11101, Honduras; (D.E.); (O.A.)
- Correspondence: ; Tel.: +504-33935443
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Altahir O, AbdElbagi H, Abubakr M, Siddig EE, Ahmed A, Mohamed NS. Blood meal profile and positivity rate with malaria parasites among different malaria vectors in Sudan. Malar J 2022; 21:124. [PMID: 35428264 PMCID: PMC9013081 DOI: 10.1186/s12936-022-04157-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 04/07/2022] [Indexed: 12/03/2022] Open
Abstract
Background Malaria is a life-threatening public health problem globally with particularly heavy burden in the sub-Saharan Africa including Sudan. The understanding of feeding preference of malaria vectors on different hosts is a major challenge for hindering the transmission cycle of malaria. In this study, blood meals taken by blood-fed Anopheles mosquitoes collected from the field in malaria endemic areas of Sudan were analysed for source of blood meal and malaria parasite presence. Methods Anopheles mosquitoes were collected from different regions in Sudan: Khartoum state, Sennar state, Northern state, and El Gedarif state between September 2020 and February 2021. Anopheles mosquitoes were collected using the standard pyrethrum spray catch and back-pack aspirator. Mosquito samples were sorted and morphologically identified to species level using international identification keys. Morphologically identified mosquito species were also confirmed using PCR. Genomic DNA was extracted from mosquitoes for molecular identification of blood meal source and parasite detection. The presence of Plasmodium species DNA in each mosquito sample was investigated using semi-nested PCR. Frequency of each blood meal source, Anopheles mosquito vector, and malaria parasite detected was calculated. Positivity rate of each fed female Anopheles mosquito was calculated for each species. Results A total of 2132 Anopheles mosquitoes were collected. 571 (26.8%) were males and 1561 (73.2%) were females classified based on their abdominal status into 1048 (67.1%) gravid, 274 (17.6%) fed, and 239 (15.3%) unfed females. Among the blood fed Anopheles mosquitoes, 263 (96.0%) were morphologically identified and confirmed using PCR to Anopheles arabiensis, 9 (3.3%) to Anopheles stephensi, and 2 (0.7%) to Anopheles rufipes. Of 274 blood-fed An. arabiensis, 68 (25.9%) fed on mixed blood meals from human and cattle, 8 (3.0%) fed on cattle and goat, and 13 (4.8%) fed on human, cattle and goat. For single blood meal sources, 70 (26.6%) fed on human, 95 (36.1%) fed on cattle, 8 (3.0%) fed on goat, and 1 (0.4%) fed on dog. While An. rufipes and An. stephensi fed on dog (2; 0.75%) and cattle (9; 3.3%), respectively. Plasmodium parasite detection in the blood meals showed that 25/274 (9.1%) An. arabiensis meals were positive for Plasmodium vivax and 19/274 (6.9%) An. arabiensis meals were positive for Plasmodium falciparum. The rate of positivity of An. arabiensis with any Plasmodium species was 16.7%. However, the positivity rate with P. falciparum only was 7.2%, while P. vivax was 9.5%. Both An. rufipes and An. stephensi were having positivity rates of 0.0% each. Conclusions This study which was mainly on blood-fed Anopheles mosquitoes showed a diversity in the type of diet from human, cattle, and goat. Anopheles mosquitoes especially An. arabiensis in Sudan, are opportunistic blood feeders and can feed broadly on both human and cattle. The application of blood meal identification is not only important in malaria vector epidemiological surveillance but also is very useful in areas where arthropods exhibit zoophilic feeding behaviour for mammals.
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Cross DE, Healey AJE, McKeown NJ, Thomas CJ, Macarie NA, Siaziyu V, Singini D, Liywalii F, Sakala J, Silumesii A, Shaw PW. Temporally consistent predominance and distribution of secondary malaria vectors in the Anopheles community of the upper Zambezi floodplain. Sci Rep 2022; 12:240. [PMID: 34997149 PMCID: PMC8742069 DOI: 10.1038/s41598-021-04314-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 12/10/2021] [Indexed: 11/09/2022] Open
Abstract
Regional optimisation of malaria vector control approaches requires detailed understanding both of the species composition of Anopheles mosquito communities, and how they vary over spatial and temporal scales. Knowledge of vector community dynamics is particularly important in settings where ecohydrological conditions fluctuate seasonally and inter-annually, such as the Barotse floodplain of the upper Zambezi river. DNA barcoding of anopheline larvae sampled in the 2019 wet season revealed the predominance of secondary vector species, with An. coustani comprising > 80% of sampled larvae and distributed ubiquitously across all ecological zones. Extensive larval sampling, plus a smaller survey of adult mosquitoes, identified geographic clusters of primary vectors, but represented only 2% of anopheline larvae. Comparisons with larval surveys in 2017/2018 and a contemporaneous independent 5-year dataset from adult trapping corroborated this paucity of primary vectors across years, and the consistent numerical dominance of An. coustani and other secondary vectors in both dry and wet seasons, despite substantial inter-annual variation in hydrological conditions. This marked temporal consistency of spatial distribution and anopheline community composition presents an opportunity to target predominant secondary vectors outdoors. Larval source management should be considered, alongside prevalent indoor-based approaches, amongst a diversification of vector control approaches to more effectively combat residual malaria transmission.
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Affiliation(s)
- Dónall Eoin Cross
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, SY23 3FG, UK
| | - Amy J E Healey
- Lincoln Centre for Water and Planetary Health, College of Science, University of Lincoln, Brayford Pool Campus, Lincoln, LN6 7TS, UK
| | - Niall J McKeown
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, SY23 3FG, UK
| | - Christopher James Thomas
- Lincoln Centre for Water and Planetary Health, College of Science, University of Lincoln, Brayford Pool Campus, Lincoln, LN6 7TS, UK.
| | - Nicolae Adrian Macarie
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, SY23 3FG, UK
| | - Vincent Siaziyu
- Limulunga District Health Office, P.O. Box 910022, Mongu, Zambia
| | - Douglas Singini
- School of Public Health and Health Systems, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - Francis Liywalii
- Provincial Health Office, Western Province, P.O. Box 910022, Mongu, Zambia
| | - Jacob Sakala
- Provincial Health Office, Western Province, P.O. Box 910022, Mongu, Zambia
| | | | - Paul W Shaw
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, SY23 3FG, UK
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