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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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Cherif MS, Dahal P, Beavogui AH, Delamou A, Lama EK, Camara A, Diallo MP. Malaria epidemiology and anti-malarial drug efficacy in Guinea: a review of clinical and molecular studies. Malar J 2021; 20:272. [PMID: 34134728 PMCID: PMC8206902 DOI: 10.1186/s12936-021-03809-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 06/08/2021] [Indexed: 12/13/2022] Open
Abstract
Malaria is one of the leading causes of mortality and morbidity in Guinea. The entire country is considered at risk of the disease. Transmission occurs all year round with peaks occurring from July through October with Plasmodium falciparum as the primary parasite species. Chloroquine (CQ) was the first-line drug against uncomplicated P. falciparum in Guinea until 2005, prior to the adoption of artemisinin-based combination therapy (ACT). In this review, data on therapeutic efficacy of CQ and artemisinin-based combinations reported in published literature is summarized. Against CQ, a failure rate of 27% (12/44) was reported in a study in 1992; a median failure rate of 15.6% [range: 7.7–28.3; 8 studies] was observed during 1996–2001, and 81% (17/21) of the patients failed to clear parasitaemia in a study conducted in 2007. For artemisinin-based combinations, three published studies were identified (1495 patients; 2004–2016); all three studies demonstrated day 28 polymerase chain reaction corrected efficacy > 95%. One study characterized kelch-13 mutations (389 tested; samples collected in 2016) with no evidence of mutations currently known to be associated with artemisinin resistance. The impact of the ongoing COVID-19 pandemic and widespread usage of counterfeit medicines are immediate challenges to malaria control activities in Guinea.
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Affiliation(s)
- Mahamoud Sama Cherif
- Faculty of Sciences and Health Technics, Gamal Abdel Nasser University of Conakry, Conakry, Guinea. .,Centre National de Formation et Recherche en Sante Rurale de Maferinyah, Maferinyah, Guinea.
| | - Prabin Dahal
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Abdoul Habib Beavogui
- Faculty of Sciences and Health Technics, Gamal Abdel Nasser University of Conakry, Conakry, Guinea.,Centre National de Formation et Recherche en Sante Rurale de Maferinyah, Maferinyah, Guinea
| | - Alexandre Delamou
- Faculty of Sciences and Health Technics, Gamal Abdel Nasser University of Conakry, Conakry, Guinea.,Centre National de Formation et Recherche en Sante Rurale de Maferinyah, Maferinyah, Guinea
| | | | - Alioune Camara
- National Malaria Control Programme (NMCP), Conakry, Guinea
| | - Mamadou Pathe Diallo
- Faculty of Sciences and Health Technics, Gamal Abdel Nasser University of Conakry, Conakry, Guinea
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Cansado-Utrilla C, Jeffries CL, Kristan M, Brugman VA, Heard P, Camara G, Sylla M, Beavogui AH, Messenger LA, Irish SR, Walker T. An assessment of adult mosquito collection techniques for studying species abundance and diversity in Maferinyah, Guinea. Parasit Vectors 2020; 13:150. [PMID: 32209116 PMCID: PMC7092564 DOI: 10.1186/s13071-020-04023-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 03/16/2020] [Indexed: 01/10/2024] Open
Abstract
Background Several mosquito collection methods are routinely used in vector control programmes. However, they target different behaviours causing bias in estimation of species diversity and abundance. Given the paucity of mosquito trap data in West Africa, we compared the performance of five trap-lure combinations and Human Landing Catches (HLCs) in Guinea. Methods CDC light traps (LT), BG sentinel 2 traps (BG2T), gravid traps (GT) and Stealth traps (ST) were compared in a 5 × 5 Latin Square design in three villages in Guinea between June and July 2018. The ST, a portable trap which performs similarly to a LT but incorporates LEDs and incandescent light, was included since it has not been widely tested. BG2T were used with BG and MB5 lures instead of CO2 to test the efficacy of these attractants. HLCs were performed for 5 nights, but not as part of the Latin Square. A Generalised Linear Mixed Model was applied to compare the effect of the traps, sites and collection times on mosquito abundance. Species identification was confirmed using PCR-based analysis and Sanger sequencing. Results A total of 10,610 mosquitoes were captured across five traps. ST collected significantly more mosquitoes (7096) than the rest of the traps, but resulted in a higher number of damaged specimens. ST and BG2T collected the highest numbers of Anopheles gambiae (s.l.) and Aedes aegypti mosquitoes, respectively. HLCs captured predominantly An. coluzzii (41%) and hybrids of An. gambiae and An. coluzzii (36%) in contrast to the five traps, which captured predominantly An. melas (83%). The rural site (Senguelen) presented the highest abundance of mosquitoes and overall diversity in comparison with Fandie (semi-rural) and Maferinyah Centre I (semi-urban). Our results confirm the presence of four species for the first time in Guinea. Conclusions ST collected the highest number of mosquitoes suggesting this trap may play an important role for mosquito surveillance in Guinea and similar sites in West Africa. We recommend the incorporation of molecular tools in entomological studies since they have helped to identify 25 mosquito species in this area.![]()
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Affiliation(s)
- Cintia Cansado-Utrilla
- Department of Disease Control, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Claire L Jeffries
- Department of Disease Control, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Mojca Kristan
- Department of Disease Control, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Victor A Brugman
- Department of Disease Control, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Patrick Heard
- Department of Disease Control, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Gnepou Camara
- Centre de Formation et de Recherche en Sante Rurale de Maferinyah, Conakry, Republic of Guinea
| | - Moussa Sylla
- Centre de Formation et de Recherche en Sante Rurale de Maferinyah, Conakry, Republic of Guinea
| | - Abdoul H Beavogui
- Centre de Formation et de Recherche en Sante Rurale de Maferinyah, Conakry, Republic of Guinea
| | - Louisa A Messenger
- Department of Disease Control, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.,Entomology Branch, Centers for Disease Control and Prevention, Atlanta, GA, 30329-4027, USA.,American Society for Microbiology, 1752 N Street, NW, Washington, DC, 20036, USA
| | - Seth R Irish
- Entomology Branch, Centers for Disease Control and Prevention, Atlanta, GA, 30329-4027, USA.,The US President's Malaria Initiative and Entomology Branch, Centers for Disease Control and Prevention, Atlanta, GA, 30329-4027, USA
| | - Thomas Walker
- Department of Disease Control, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.
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Mishra P, Tyagi BK, Chandrasekaran N, Mukherjee A. Biological nanopesticides: a greener approach towards the mosquito vector control. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:10151-10163. [PMID: 28721618 DOI: 10.1007/s11356-017-9640-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 06/26/2017] [Indexed: 06/07/2023]
Abstract
Mosquitoes, being a vector for some potentially dreadful diseases, pose a considerable threat to people all around the world. The control over the growth and propagation of mosquitoes comprises conventional pesticides, insect growth regulators and other microbial control agents. However, the usage of these common chemicals and conventional pesticides eventually has a negative impact on human health as well as the environment, which therefore becomes a major concern. The lacuna allows nanotechnology to come into action and exploit nanopesticides. Nanopesticides are majorly divided into two categories-synthetic and biological. Several nanoformulations serve as a promising nanopesticide viz. nanoparticles, e.g. biologically synthesised nanoparticles through plant extracts, nanoemulsions prepared using the essential oils like neem oil and citronella oil and nanoemulsion of conventional pesticides like pyrethroids. These green approaches of synthesising nanopesticides make use of non-toxic and biologically derived compounds and hence are eco-friendly with a better target specificity. Even though there are numerous evidences to show the effectiveness of these nanopesticides, very few efforts have been made to study the possible non-target effects on other organisms prevalent in the aquatic ecosystem. This study focuses on the role of these nanopesticides towards the vector control and its eco-safe property against the other non-target species.
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Affiliation(s)
- Prabhakar Mishra
- Centre for Nanobiotechnology, VIT University, Vellore, Tamil Nadu, 632014, India
| | - Brij Kishore Tyagi
- Department of Zoology & Environment Science, Punjabi University, Patiala, Punjab, 147002, India
| | | | - Amitava Mukherjee
- Centre for Nanobiotechnology, VIT University, Vellore, Tamil Nadu, 632014, India.
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Keita K, Camara D, Barry Y, Ossè R, Wang L, Sylla M, Miller D, Leite L, Schopp P, Lawrence GG, Akogbéto M, Dotson EM, Guilavogui T, Keita M, Irish SR. Species Identification and Resistance Status of Anopheles gambiae s.l. (Diptera: Culicidae) Mosquitoes in Guinea. JOURNAL OF MEDICAL ENTOMOLOGY 2017; 54:677-681. [PMID: 28399224 DOI: 10.1093/jme/tjw228] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Indexed: 06/07/2023]
Abstract
Insecticide resistance is one of the primary threats to the recent gains in malaria control. This is especially true in Guinea, where long-lasting insecticidal nets are currently the primary vector control intervention. To better inform the national malaria control program on the current status of insecticide resistance in Guinea, resistance bioassays were conducted, using Anopheles gambiae s.l. Giles, in three sites. Molecular analyses were also done on An. gambiae s.l. to determine the species and find whether the target-site mutations kdr and Ace1R were present. Susceptibility tests revealed resistance to DDT and pyrethroids, although mosquitoes were susceptible to deltamethrin in two of the three sites tested. Mosquitoes were susceptible to bendiocarb, except in Kissidougou, Guinea. The kdr-west mutation was widespread and the frequency was 60% or more in all sites. However, the Ace1R mutation was present in low levels. Insecticide susceptibility should continue to be monitored in Guinea to ensure insecticide-based vector control methods remain effective.
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Affiliation(s)
- K Keita
- Programme Nationale de Lutte contre le Paludisme, Ministère de la Santé, BP. 595, Conakry, Guinea (; ; ; ; )
| | - D Camara
- Programme Nationale de Lutte contre le Paludisme, Ministère de la Santé, BP. 595, Conakry, Guinea (; ; ; ; )
| | - Y Barry
- Programme Nationale de Lutte contre le Paludisme, Ministère de la Santé, BP. 595, Conakry, Guinea (; ; ; ; )
| | - R Ossè
- Centre de Recherche Entomologique de Cotonou, 06?BP 2604, Cotonou, Bénin (; )
| | - L Wang
- Entomology Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, 1600 Clifton Rd., G-49, Atlanta, GA 30329 (; ; ; ; ; ; )
| | - M Sylla
- Centre National de Formation et de Recherche en Santé Rurale de Maferinyah, Maferinyah, Guinea
| | - D Miller
- Entomology Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, 1600 Clifton Rd., G-49, Atlanta, GA 30329 (; ; ; ; ; ; )
| | - L Leite
- Entomology Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, 1600 Clifton Rd., G-49, Atlanta, GA 30329 (; ; ; ; ; ; )
| | - P Schopp
- Entomology Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, 1600 Clifton Rd., G-49, Atlanta, GA 30329 (; ; ; ; ; ; )
| | - G G Lawrence
- Entomology Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, 1600 Clifton Rd., G-49, Atlanta, GA 30329 (; ; ; ; ; ; )
| | - M Akogbéto
- Centre de Recherche Entomologique de Cotonou, 06?BP 2604, Cotonou, Bénin (; )
| | - E M Dotson
- Entomology Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, 1600 Clifton Rd., G-49, Atlanta, GA 30329 (; ; ; ; ; ; )
| | - T Guilavogui
- Programme Nationale de Lutte contre le Paludisme, Ministère de la Santé, BP. 595, Conakry, Guinea (; ; ; ; )
| | - M Keita
- Programme Nationale de Lutte contre le Paludisme, Ministère de la Santé, BP. 595, Conakry, Guinea (; ; ; ; )
| | - S R Irish
- Entomology Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, 1600 Clifton Rd., G-49, Atlanta, GA 30329 (; ; ; ; ; ; )
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Olé Sangba ML, Sidick A, Govoetchan R, Dide-Agossou C, Ossè RA, Akogbeto M, Ndiath MO. Evidence of multiple insecticide resistance mechanisms in Anopheles gambiae populations in Bangui, Central African Republic. Parasit Vectors 2017; 10:23. [PMID: 28086840 PMCID: PMC5237250 DOI: 10.1186/s13071-016-1965-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 12/31/2016] [Indexed: 11/30/2022] Open
Abstract
Background Knowledge of insecticide resistance status in the main malaria vectors is an essential component of effective malaria vector control. This study presents the first evaluation of the status of insecticide resistance in Anopheles gambiae populations from Bangui, the Central African Republic. Methods Anopheles mosquitoes were reared from larvae collected in seven districts of Bangui between September to November 2014. The World Health Organisation’s bioassay susceptibility tests to lambda-cyhalothrin (0.05%), deltamethrin (0.05%), DDT (4%), malathion (5%), fenitrothion (1%) and bendiocarb (0.1%) were performed on adult females. Species and molecular forms as well as the presence of L1014F kdr and Ace-1R mutations were assessed by PCR. Additional tests were conducted to assess metabolic resistance status. Results After 1 h exposure, a significant difference of knockdown effect was observed between districts in all insecticides tested except deltamethrin and malathion. The mortality rate (MR) of pyrethroids group ranging from 27% (CI: 19–37.5) in Petevo to 86% (CI: 77.6–92.1) in Gbanikola; while for DDT, MR ranged from 5% (CI: 1.6–11.3) in Centre-ville to 39% (CI: 29.4–49.3) in Ouango. For the organophosphate group a MR of 100% was observed in all districts except Gbanikola where a MR of 96% (CI: 90–98.9) was recorded. The mortality induced by bendiocarb was very heterogeneous, ranging from 75% (CI: 62.8–82.8) in Yapele to 99% (CI: 84.5–100) in Centre-ville. A high level of kdr-w (L1014F) frequency was observed in all districts ranging from 93 to 100%; however, no kdr-e (L1014S) and Ace-1R mutation were found in all tested mosquitoes. Data of biochemical analysis showed significant overexpression activities of cytochrome P450, GST and esterases in Gbanikola and Yapele (χ2 = 31.85, df = 2, P < 0.001). By contrast, esterases activities using α and β-naphthyl acetate were significantly low in mosquitoes from PK10 and Ouango in comparison to Kisumu strain (χ2 = 17.34, df = 2, P < 0.005). Conclusions Evidence of resistance to DDT and pyrethroids as well as precocious emergence of resistance to carbamates were detected among A. gambiae mosquitoes from Bangui, including target-site mutations and metabolic mechanisms. The co-existence of these resistance mechanisms in A. gambiae may be a serious obstacle for the future success of malaria control programmes in this region. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1965-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Marina Lidwine Olé Sangba
- G4 Malaria Group, Institut Pasteur of Bangui, BP 926, Bangui, Central African Republic.,Faculté des Sciences et Techniques, Université d'Abomey Calavi, Cotonou, Benin.,Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, 06 BP 2604, Benin
| | - Aboubakar Sidick
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, 06 BP 2604, Benin
| | - Renaud Govoetchan
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, 06 BP 2604, Benin.,Ecole Nationale des Sciences et Techniques Agricole de Djougou (ENSTA), Université des Sciences Arts et Techniques de Natitingou (USATN), Natitingou, Benin
| | - Christian Dide-Agossou
- University of Colorado Denver Anschutz Medical Campus, 13001 E 17th Pl, Aurora, CO, 80045, USA
| | - Razaki A Ossè
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, 06 BP 2604, Benin.,Ecole de Gestion et d'Exploitation des Systèmes d'Elevage (EGESE), Université d'Agriculture de Kétou (UAK), Kétou, Benin
| | - Martin Akogbeto
- Faculté des Sciences et Techniques, Université d'Abomey Calavi, Cotonou, Benin.,Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, 06 BP 2604, Benin
| | - Mamadou Ousmane Ndiath
- G4 Malaria Group, Institut Pasteur of Bangui, BP 926, Bangui, Central African Republic. .,G4 Malaria Group, Institut Pasteur of Madagascar BP 1274, Ambatofotsikely Avaradoha 101, Antananarivo, Madagascar.
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Coulibaly B, Kone R, Barry MS, Emerson B, Coulibaly MB, Niare O, Beavogui AH, Traore SF, Vernick KD, Riehle MM. Malaria vector populations across ecological zones in Guinea Conakry and Mali, West Africa. Malar J 2016; 15:191. [PMID: 27059057 PMCID: PMC4826509 DOI: 10.1186/s12936-016-1242-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 03/30/2016] [Indexed: 11/12/2022] Open
Abstract
Background Malaria remains a pervasive public health problem in sub-Saharan West Africa. Here mosquito vector populations were explored across four sites in Mali and the Republic of Guinea (Guinea Conakry). The study samples the major ecological zones of malaria-endemic regions in West Africa within a relatively small distance. Methods Mosquito vectors were sampled from larval pools, adult indoor resting sites, and indoor and outdoor human-host seeking adults. Mosquitoes were collected at sites spanning 350 km that represented arid savannah, humid savannah, semi-forest and deep forest ecological zones, in areas where little was previously known about malaria vector populations. 1425 mosquito samples were analysed by molecular assays to determine species, genetic attributes, blood meal sources and Plasmodium infection status. Results Anopheles gambiae and Anopheles coluzzii were the major anophelines represented in all collections across the ecological zones, with A. coluzzii predominant in the arid savannah and A. gambiae in the more humid sites. The use of multiple collection methodologies across the sampling sites allows assessment of potential collection bias of the different methods. The L1014F kdr insecticide resistance mutation (kdr-w) is found at high frequency across all study sites. This mutation appears to have swept almost to fixation, from low frequencies 6 years earlier, despite the absence of widespread insecticide use for vector control. Rates of human feeding are very high across ecological zones, with only small fractions of animal derived blood meals in the arid and humid savannah. About 30 % of freshly blood-fed mosquitoes were positive for Plasmodium falciparum presence, while the rate of mosquitoes with established infections was an order of magnitude lower. Conclusions The study represents detailed vector characterization from an understudied area in West Africa with endemic malaria transmission. The deep forest study site includes the epicenter of the 2014 Ebola virus epidemic. With new malaria control interventions planned in Guinea, these data provide a baseline measure and an opportunity to assess the outcome of future interventions. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1242-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Boubacar Coulibaly
- Malaria Research and Training Centre, Faculty of Medicine and Dentistry, University of Mali, Bamako, Mali
| | - Raymond Kone
- Centre de Formation et de Recherche en Santé Rurale de Mafèrinyah, Conakry, Republic of Guinea
| | - Mamadou S Barry
- Centre de Formation et de Recherche en Santé Rurale de Mafèrinyah, Conakry, Republic of Guinea
| | - Becky Emerson
- Department of Microbiology, University of Minnesota, Minneapolis, MN, USA
| | - Mamadou B Coulibaly
- Malaria Research and Training Centre, Faculty of Medicine and Dentistry, University of Mali, Bamako, Mali
| | - Oumou Niare
- Malaria Research and Training Centre, Faculty of Medicine and Dentistry, University of Mali, Bamako, Mali
| | - Abdoul H Beavogui
- Centre de Formation et de Recherche en Santé Rurale de Mafèrinyah, Conakry, Republic of Guinea
| | - Sekou F Traore
- Malaria Research and Training Centre, Faculty of Medicine and Dentistry, University of Mali, Bamako, Mali
| | - Kenneth D Vernick
- Department of Microbiology, University of Minnesota, Minneapolis, MN, USA. .,Department of Parasites and Insect Vectors, Unit of Genetics and Genomics of Insect Vectors, Institut Pasteur, Paris, France. .,CNRS Unit of Hosts, Vectors and Pathogens (URA3012), Paris, France.
| | - Michelle M Riehle
- Department of Microbiology, University of Minnesota, Minneapolis, MN, USA
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Kouassi BL, de Souza DK, Goepogui A, Balde SM, Diakité L, Sagno A, Djameh GI, Chammartin F, Vounatsou P, Bockarie MJ, Utzinger J, Koudou BG. Low prevalence of Plasmodium and absence of malaria transmission in Conakry, Guinea: prospects for elimination. Malar J 2016; 15:175. [PMID: 26987480 PMCID: PMC4797167 DOI: 10.1186/s12936-016-1230-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 03/11/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Over the past 15 years, mortality and morbidity due to malaria have been reduced substantially in sub-Saharan Africa and local elimination has been achieved in some settings. This study addresses the bio-ecology of larval and adult stages of malaria vectors, Plasmodium infection in Anopheles gambiae s.l. in the city of Conakry, Guinea, and discusses the prospect for malaria elimination. METHODS Water bodies were prospected to identify potential mosquito breeding sites for 6 days each in the dry season (January 2013) and in the rainy season (August 2013), using the dipping method. Adult mosquitoes were collected in 15 communities in the five districts of Conakry using exit traps and indoor spraying catches over a 1-year period (November 2012 to October 2013). Molecular approaches were employed for identification of Anopheles species, including An. coluzzii and An. gambiae s.s. Individual An. gambiae mosquitoes were tested for Plasmodium falciparum and P. vivax sporozoites using the VecTest™ malaria panel assay and an enzyme-linked immunosorbent assay. A systematic research of Ministry of Health statistical yearbooks was performed to determine malaria prevalence in children below the age of 5 years. RESULTS Culex larval breeding sites were observed in large numbers throughout Conakry in both seasons. While Anopheles larval breeding sites were less frequent than Culex breeding sites, there was a high odds of finding An. gambiae mosquito larvae in agricultural sites during the rainy season. Over the 1-year study period, a total of 14,334 adult mosquitoes were collected; 14,135 Culex (98.6%) and 161 (1.1%) from the An. gambiae complex. One-hundred and twelve Anopheles mosquitoes, mainly collected from rice fields and gardens, were subjected to molecular analysis. Most of the mosquitoes were An. gambiae s.s. (n = 102; 91.1%) while the remaining 10 (8.9%) were An. melas. The molecular M form of An. gambiae s.s. was predominant (n = 89; 79.5%). The proportions of kdr genotype in the An. gambiae s.s. M and S form were 65.2 and 81.8% (n = 9), respectively. No sporozoite infection were detected in any of the mosquitoes tested. The prevalence of Plasmodium recorded in children aged below 5 years was relatively low and varied between 2.2 and 7.6% from 2009 to 2012. CONCLUSIONS The low density of larval and adult stages of Anopheles mosquitoes, the absence of infected An. gambiae species and the low prevalence of Plasmodium in under 5-year-old children are important features that might facilitate malaria elimination in Conakry. The heterogeneity in species composition and resistance profiles call for vector control interventions that are tailored to the local bio-ecological setting.
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Affiliation(s)
- Bernard L Kouassi
- UFR Science de la Nature, Université Alassane Ouattara, 02 BP 801, Abidjan, 01, Côte d'Ivoire.,Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, 01 BP 1303, Abidjan, 01, Côte d'Ivoire.,Swiss Tropical and Public Health Institute, P.O. Box, CH-4002, Basel, Switzerland.,University of Basel, P.O. Box, CH-4003, Basel, Switzerland
| | - Dziedzom K de Souza
- Noguchi Memorial Institute for Medical Research, P.O. Box LG 581, Legon-Accra, Ghana.
| | - Andre Goepogui
- Programmes National de Lutte contre l'Onchocercoses et les autres Maladies Tropicales Négligées, Ministère de la Sante, Conakry, Guinea
| | - Siradiou M Balde
- Programmes National de Lutte contre l'Onchocercoses et les autres Maladies Tropicales Négligées, Ministère de la Sante, Conakry, Guinea
| | - Lamia Diakité
- Programmes National de Lutte contre l'Onchocercoses et les autres Maladies Tropicales Négligées, Ministère de la Sante, Conakry, Guinea
| | - Arsène Sagno
- Programmes National de Lutte contre l'Onchocercoses et les autres Maladies Tropicales Négligées, Ministère de la Sante, Conakry, Guinea
| | - Georgina I Djameh
- Noguchi Memorial Institute for Medical Research, P.O. Box LG 581, Legon-Accra, Ghana
| | - Frédérique Chammartin
- Swiss Tropical and Public Health Institute, P.O. Box, CH-4002, Basel, Switzerland.,University of Basel, P.O. Box, CH-4003, Basel, Switzerland
| | - Penelope Vounatsou
- Swiss Tropical and Public Health Institute, P.O. Box, CH-4002, Basel, Switzerland.,University of Basel, P.O. Box, CH-4003, Basel, Switzerland
| | - Moses J Bockarie
- Filariasis Programme Support Unit, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Jürg Utzinger
- Swiss Tropical and Public Health Institute, P.O. Box, CH-4002, Basel, Switzerland.,University of Basel, P.O. Box, CH-4003, Basel, Switzerland
| | - Benjamin G Koudou
- UFR Science de la Nature, Université Alassane Ouattara, 02 BP 801, Abidjan, 01, Côte d'Ivoire.,Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, 01 BP 1303, Abidjan, 01, Côte d'Ivoire.,Swiss Tropical and Public Health Institute, P.O. Box, CH-4002, Basel, Switzerland
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Tene Fossog B, Ayala D, Acevedo P, Kengne P, Ngomo Abeso Mebuy I, Makanga B, Magnus J, Awono-Ambene P, Njiokou F, Pombi M, Antonio-Nkondjio C, Paupy C, Besansky NJ, Costantini C. Habitat segregation and ecological character displacement in cryptic African malaria mosquitoes. Evol Appl 2015; 8:326-45. [PMID: 25926878 PMCID: PMC4408144 DOI: 10.1111/eva.12242] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 12/08/2014] [Indexed: 01/09/2023] Open
Abstract
Understanding how divergent selection generates adaptive phenotypic and population diversification provides a mechanistic explanation of speciation in recently separated species pairs. Towards this goal, we sought ecological gradients of divergence between the cryptic malaria vectors Anopheles coluzzii and An. gambiae and then looked for a physiological trait that may underlie such divergence. Using a large set of occurrence records and eco-geographic information, we built a distribution model to predict the predominance of the two species across their range of sympatry. Our model predicts two novel gradients along which the species segregate: distance from the coastline and altitude. Anopheles coluzzii showed a ‘bimodal’ distribution, predominating in xeric West African savannas and along the western coastal fringe of Africa. To test whether differences in salinity tolerance underlie this habitat segregation, we assessed the acute dose–mortality response to salinity of thirty-two larval populations from Central Africa. In agreement with its coastal predominance, Anopheles coluzzii was overall more tolerant than An. gambiae. Salinity tolerance of both species, however, converged in urban localities, presumably reflecting an adaptive response to osmotic stress from anthropogenic pollutants. When comparing degree of tolerance in conjunction with levels of syntopy, we found evidence of character displacement in this trait.
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Affiliation(s)
- Billy Tene Fossog
- Institut de Recherche pour le Développement (IRD), UMR MIVEGEC (UM1, UM2, CNRS 5290, IRD 224) Montpellier, France ; Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC) Yaoundé, Cameroon ; Department of Animal Biology, Faculty of Sciences, University of Yaoundé I Yaoundé, Cameroon
| | - Diego Ayala
- Institut de Recherche pour le Développement (IRD), UMR MIVEGEC (UM1, UM2, CNRS 5290, IRD 224) Montpellier, France ; Eck Institute for Global Health & Department of Biological Sciences, University of Notre Dame Notre Dame, IN, USA ; Centre International de Recherches Médicales de Franceville (CIRMF) Franceville, Gabon
| | - Pelayo Acevedo
- SaBio, Instituto de Investigación en Recursos Cinegéticos (IREC), CSIC-UCLM-JCCM Ciudad Real, Spain
| | - Pierre Kengne
- Institut de Recherche pour le Développement (IRD), UMR MIVEGEC (UM1, UM2, CNRS 5290, IRD 224) Montpellier, France ; Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC) Yaoundé, Cameroon
| | | | - Boris Makanga
- Institut de Recherche pour le Développement (IRD), UMR MIVEGEC (UM1, UM2, CNRS 5290, IRD 224) Montpellier, France ; Centre International de Recherches Médicales de Franceville (CIRMF) Franceville, Gabon ; Institut de Recherche en Ecologie Tropicale (IRET) Libreville, Gabon
| | - Julie Magnus
- Centre International de Recherches Médicales de Franceville (CIRMF) Franceville, Gabon
| | - Parfait Awono-Ambene
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC) Yaoundé, Cameroon
| | - Flobert Njiokou
- Department of Animal Biology, Faculty of Sciences, University of Yaoundé I Yaoundé, Cameroon
| | - Marco Pombi
- Sezione di Parassitologia, Dipartimento di Sanità Pubblica e Malattie Infettive, Università di Roma 'La Sapienza' Rome, Italy
| | - Christophe Antonio-Nkondjio
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC) Yaoundé, Cameroon
| | - Christophe Paupy
- Institut de Recherche pour le Développement (IRD), UMR MIVEGEC (UM1, UM2, CNRS 5290, IRD 224) Montpellier, France ; Centre International de Recherches Médicales de Franceville (CIRMF) Franceville, Gabon
| | - Nora J Besansky
- Eck Institute for Global Health & Department of Biological Sciences, University of Notre Dame Notre Dame, IN, USA
| | - Carlo Costantini
- Institut de Recherche pour le Développement (IRD), UMR MIVEGEC (UM1, UM2, CNRS 5290, IRD 224) Montpellier, France ; Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC) Yaoundé, Cameroon
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Mashauri FM, Kinung'hi SM, Kaatano GM, Magesa SM, Kishamawe C, Mwanga JR, Nnko SE, Malima RC, Mero CN, Mboera LEG. Impact of indoor residual spraying of lambda-cyhalothrin on malaria prevalence and anemia in an epidemic-prone district of Muleba, north-western Tanzania. Am J Trop Med Hyg 2013; 88:841-9. [PMID: 23458959 DOI: 10.4269/ajtmh.12-0412] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The Government of Tanzania introduced indoor residual spraying (IRS) in Muleba district in north-western Tanzania after frequent malaria epidemics. Malaria parasitological baseline and two cross-sectional follow-up surveys were conducted in villages under the IRS program and those not under IRS to assess the impact of IRS intervention. After two rounds of IRS intervention there was a significant reduction of malaria parasitological indices in both two villages. In IRS villages overall, parasitemia prevalence was reduced by 67.2%, splenomegaly was reduced by 75.8%, whereas anemia was reduced by 50.5%. There was also a decline of malaria parasite density from 896.4 at baseline to 128.8 at second follow-up survey. Similarly, there was also a reduction of malaria parasitological indices in non-IRS villages; however, parasitological indices in IRS villages remained far below the levels in non-IRS villages. The reduction of malaria parasitological indices in non-IRS villages might have been contributed by interventions other than IRS.
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Affiliation(s)
- Fabian M Mashauri
- National Institute for Medical Research, Mwanza Research Centre, Mwanza, Tanzania.
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11
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Abstract
Understanding genetic causes and effects of speciation in sympatric populations of sexually reproducing eukaryotes is challenging, controversial, and of practical importance for controlling rapidly evolving pests and pathogens. The major African malaria vector mosquito Anopheles gambiae sensu stricto (s.s.) is considered to contain two incipient species with strong reproductive isolation, hybrids between the M and S molecular forms being very rare. Following recent observations of higher proportions of hybrid forms at a few sites in West Africa, we conducted new surveys of 12 sites in four contiguous countries (The Gambia, Senegal, Guinea-Bissau, and Republic of Guinea). Identification and genotyping of 3499 A. gambiae s.s. revealed high frequencies of M/S hybrid forms at each site, ranging from 5 to 42%, and a large spectrum of inbreeding coefficient values from 0.11 to 0.76, spanning most of the range expected between the alternative extremes of panmixia and assortative mating. Year-round sampling over 2 years at one of the sites in The Gambia showed that M/S hybrid forms had similar relative frequencies throughout periods of marked seasonal variation in mosquito breeding and abundance. Genome-wide scans with an Affymetrix high-density single-nucleotide polymorphism (SNP) microarray enabled replicate comparisons of pools of different molecular forms, in three separate populations. These showed strong differentiation between M and S forms only in the pericentromeric region of the X chromosome that contains the molecular form-specific marker locus, with only a few other loci showing minor differences. In the X chromosome, the M/S hybrid forms were more differentiated from M than from S forms, supporting a hypothesis of asymmetric introgression and backcrossing.
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12
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Ahoua Alou LP, Koffi AA, Adja MA, Assi SB, Kouassi PK, N'Guessan R. Status of pyrethroid resistance in Anopheles gambiae s. s. M form prior to the scaling up of Long Lasting Insecticidal Nets (LLINs) in Adzopé, Eastern Côte d'Ivoire. Parasit Vectors 2012; 5:289. [PMID: 23232083 PMCID: PMC3534552 DOI: 10.1186/1756-3305-5-289] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Accepted: 12/04/2012] [Indexed: 11/20/2022] Open
Abstract
Background The growing development of pyrethroid resistance constitutes a serious threat to malaria control programmes and if measures are not taken in time, resistance may compromise control efforts in the foreseeable future. Prior to Long Lasting Insecticidal Nets (LLINs) distribution in Eastern Cote d’Ivoire, we conducted bioassays to inform the National Malaria Control Programme of the resistance status of the main malaria vector, Anopheles gambiae s. s. and the need for close surveillance of resistance. Methods Larvae of An. gambiae s. s. were collected in two areas of Adzopé (Port-Bouët and Tsassodji) and reared to adults. WHO susceptibility tests with impregnated filter papers were carried out to detect resistance to three pyrethroids commonly used to develop LLINs: permethrin 1%, deltamethrin 0.05% and lambda-cyhalothrin 0.05%. Molecular assays were conducted to detect M and S forms and the L1014F kdr allele in individual mosquitoes. Results Resistance, at various degrees was detected in both areas of Adzopé. Overall, populations of An. gambiae at both sites surveyed showed equivalent frequency of the L1014F kdr allele (0.67) but for all tested pyrethroids, there were significantly higher survival rates for mosquitoes from Tsassodji (32–58%) than those from Port-Bouët (3–32%) (p < 0.001), indicating the implication of resistance mechanisms other than kdr alone. During the survey period (May–June) in this forested area of Côte d’Ivoire, An. gambiae s. s. found were exclusively of the M form and were apparently selected for pyrethroid resistance through agricultural and household usage of insecticides. Conclusion Prior to LLINs scaling up in Eastern Côte d’Ivoire, resistance was largely present at various levels in An. gambiae. Underlying mechanisms included the high frequency of the L1014F kdr mutation and other unidentified components, probably metabolic detoxifiers. Their impact on the efficacy of the planned strategy (LLINs) in the area should be investigated alongside careful monitoring of the trend in that resistance over time. The need for alternative insecticides to supplement or replace pyrethroids on nets must be stressed.
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13
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Yewhalaw D, Asale A, Tushune K, Getachew Y, Duchateau L, Speybroeck N. Bio-efficacy of selected long-lasting insecticidal nets against pyrethroid resistant Anopheles arabiensis from South-Western Ethiopia. Parasit Vectors 2012; 5:159. [PMID: 22871143 PMCID: PMC3485103 DOI: 10.1186/1756-3305-5-159] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Accepted: 08/02/2012] [Indexed: 11/24/2022] Open
Abstract
Background The emergence and spread of insecticide resistance in the major African malaria vectors Anopheles gambiae s.s. and Anopheles arabiensis may compromise control initiatives based on insecticide-treated nets (ITNs) or indoor residual spraying (IRS), and thus threaten the global malaria elimination strategy. Methods We investigated pyrethroid resistance in four populations of An. arabiensis from south-western Ethiopia and then assessed the bio-efficacy of six World Health Organization recommended long lasting insecticidal nets (LLINs) using these populations. Results For all four populations of An. arabiensis, bottle bioassays indicated low to moderate susceptibility to deltamethrin (mortality at 30 minutes ranged between 43 and 80%) and permethrin (mortality ranged between 16 and 76%). Pre-exposure to the synergist piperonylbutoxide (PBO) significantly increased the susceptibility of all four populations to both deltamethrin (mortality increased between 15.3 and 56.8%) and permethrin (mortality increased between 11.6 and 58.1%), indicating the possible involvement of metabolic resistance in addition to the previously identified kdr mutations. There was reduced susceptibility of all four An. arabiensis populations to the five standard LLINs tested (maximum mortality 81.1%; minimum mortality 13.9%). Bio-efficacy against the four populations varied by net type, with the largest margin of difference observed with the Jimma population (67.2% difference). Moreover, there were differences in the bio-efficacy of each individual standard LLIN against the four mosquito populations; for example there was a difference of 40% in mortality of Yorkool against two populations. Results from standard LLINs indicated reduced susceptibility to new, unused nets that was likely due to observed pyrethroid resistance. The roof of the combination LLIN performed optimally (100% mortality) against all the four populations of An. arabiensis, indicating that observed reductions in susceptibility could be ameliorated with the combination of PBO with deltamethrin, as used in PermaNet® 3.0. Conclusion Our results suggest that bio-efficacy evaluations using local mosquito populations should be conducted where possible to make evidence-based decisions on the most suitable control products, and that those combining multiple chemicals such as PBO and deltamethrin should be considered for maintaining a high level of efficacy in vector control programmes.
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Affiliation(s)
- Delenasaw Yewhalaw
- Department of Biology, College of Natural Sciences, Jimma University, Jimma, Ethiopia.
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14
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Touré M, Carnevale P, Chandre F. [Late impact of lambdacyhalothrin-treated nets on kdr allelic frequency in Anopheles gambiae s.s. (Diptera: Culicidae) from northern Côte-d'Ivoire]. ACTA ACUST UNITED AC 2012; 105:305-10. [PMID: 22814881 DOI: 10.1007/s13149-012-0250-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 05/05/2012] [Indexed: 11/28/2022]
Abstract
Nets treated with lambdacyhalothrin 15 mg a.i./m2 were distributed in four villages of Korhogo area in northern Côte-d'Ivoire, and four other villages without nets were followed as controls. Mosquitoes were collected every three months from June 1999 to August 2000 in the villages, and then tested to determine their genotypes for kdr mutation L1014F conferring cross-resistance to pyrethroids and DDT and for M and S molecular forms of Anopheles gambiae s.s. The frequencies of the resistant allele at kdr mutation L1014F locus were very high and they varied from 0.82 to 0.96. Before the trial, the genotypic frequencies of specimens at kdr locus did not show any significant difference. However, they significantly increased in mosquitoes from treated villages (0.94) compared to those from control villages (0.87) on month 14 (P = 0.013). No significant difference was observed between mosquitoes collected outside and inside the houses (P < 0.05). In contrary, a significant difference was observed before and after the trial between mosquitoes from villages with two cycles of rice cultivation per year and those from villages without rice cultivation (P = 0.008 and P = 0.012). Nine out of twelve populations of field mosquitoes showed Hardy-Weinberg disequilibrium at kdr locus (P < 0.05). The S and M molecular forms of An. gambiae s.s. were sympatric in Korhogo area and the S form represents 97%. No hybrid between M and S forms was observed. All individuals of the M form were homozygote susceptible at kdr locus.
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Affiliation(s)
- M Touré
- Laboratoire de génétique, université de Daloa, Daloa, Côte-d'Ivoire.
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15
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Oduola AO, Idowu ET, Oyebola MK, Adeogun AO, Olojede JB, Otubanjo OA, Awolola TS. Evidence of carbamate resistance in urban populations of Anopheles gambiae s.s. mosquitoes resistant to DDT and deltamethrin insecticides in Lagos, South-Western Nigeria. Parasit Vectors 2012; 5:116. [PMID: 22686575 PMCID: PMC3409038 DOI: 10.1186/1756-3305-5-116] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 06/11/2012] [Indexed: 11/10/2022] Open
Abstract
Background Resistance monitoring is essential in ensuring the success of insecticide based vector control programmes. This study was carried out to assess the susceptibility status of urban populations of Anopheles gambiae to carbamate insecticide being considered for vector control in mosquito populations previously reported to be resistant to DDT and permethrin. Methods Two – three day old adult female Anopheles mosquitoes reared from larval collections in 11 study sites from Local Government Areas of Lagos were exposed to test papers impregnated with DDT 4%, deltamethrin 0.05% and propoxur 0.1% insecticides. Additional tests were carried out to determine the susceptibility status of the Anopheles gambiae population to bendiocarb insecticide. Members of the A. gambiae complex, the molecular forms, were identified by PCR assays. The involvement of metabolic enzymes in carbamate resistance was assessed using Piperonyl butoxide (PBO) synergist assays. The presence of kdr-w/e and ace-1R point mutations responsible for DDT-pyrethroid and carbamate resistance mechanisms was also investigated by PCR. Results Propoxur resistance was found in 10 out of the 11 study sites. Resistance to three classes of insecticides was observed in five urban localities. Mortality rates in mosquitoes exposed to deltamethrin and propoxur did not show any significant difference (P > 0.05) but was significantly higher (P < 0.05) in populations exposed to DDT. All mosquitoes tested were identified as A. gambiae s.s (M form). The kdr -w point mutation at allelic frequencies between 45%-77% was identified as one of the resistant mechanisms responsible for DDT and pyrethroid resistance. Ace-1R point mutation was absent in the carbamate resistant population. However, the possible involvement of metabolic resistance was confirmed by synergistic assays conducted. Conclusion Evidence of carbamate resistance in A. gambiae populations already harbouring resistance to DDT and permethrin is a clear indication that calls for the implementation of insecticide resistance management strategies to combat the multiple resistance identified.
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Affiliation(s)
- Adedayo O Oduola
- Molecular Entomology and Vector Control Research Laboratory, Public Health Division, Nigerian Institute of Medical Research, Akoka, Lagos, Nigeria.
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van den Berg H, Zaim M, Yadav RS, Soares A, Ameneshewa B, Mnzava A, Hii J, Dash AP, Ejov M. Global trends in the use of insecticides to control vector-borne diseases. ENVIRONMENTAL HEALTH PERSPECTIVES 2012; 120:577-82. [PMID: 22251458 PMCID: PMC3339467 DOI: 10.1289/ehp.1104340] [Citation(s) in RCA: 149] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Accepted: 01/17/2012] [Indexed: 05/23/2023]
Abstract
BACKGROUND Data on insecticide use for vector control are essential for guiding pesticide management systems on judicious and appropriate use, resistance management, and reduction of risks to human health and the environment. OBJECTIVE We studied the global use and trends of insecticide use for control of vector-borne diseases for the period 2000 through 2009. METHODS A survey was distributed to countries with vector control programs to request national data on vector control insecticide use, excluding the use of long-lasting insecticidal nets (LNs). Data were received from 125 countries, representing 97% of the human populations of 143 targeted countries. RESULTS The main disease targeted with insecticides was malaria, followed by dengue, leishmaniasis, and Chagas disease. The use of vector control insecticides was dominated by organochlorines [i.e., DDT (dichlorodiphenyltrichloroethane)] in terms of quantity applied (71% of total) and by pyrethroids in terms of the surface or area covered (81% of total). Global use of DDT for vector control, most of which was in India alone, was fairly constant during 2000 through 2009. In Africa, pyrethroid use increased in countries that also achieved high coverage for LNs, and DDT increased sharply until 2008 but dropped in 2009. CONCLUSIONS The global use of DDT has not changed substantially since the Stockholm Convention went into effect. The dominance of pyrethroid use has major implications because of the spread of insecticide resistance with the potential to reduce the efficacy of LNs. Managing insecticide resistance should be coordinated between disease-specific programs and sectors of public health and agriculture within the context of an integrated vector management approach.
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Affiliation(s)
- Henk van den Berg
- Laboratory of Entomology, Wageningen University, Wageningen, the Netherlands
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Ndiath MO, Sougoufara S, Gaye A, Mazenot C, Konate L, Faye O, Sokhna C, Trape JF. Resistance to DDT and pyrethroids and increased kdr mutation frequency in An. gambiae after the implementation of permethrin-treated nets in Senegal. PLoS One 2012; 7:e31943. [PMID: 22384107 PMCID: PMC3285187 DOI: 10.1371/journal.pone.0031943] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Accepted: 01/20/2012] [Indexed: 11/19/2022] Open
Abstract
Introduction The aim of this study was to evaluate the susceptibility to insecticides of An. gambiae mosquitoes sampled in Dielmo (Senegal), in 2010, 2 years after the implementation of Long Lasting Insecticide-treated Nets (LLINs) and to report the evolution of kdr mutation frequency from 2006 to 2010. Methods WHO bioassay susceptibility tests to 6 insecticides were performed on adults F0, issuing from immature stages of An. gambiae s.l., sampled in August 2010. Species and molecular forms as well as the presence of L1014F and L1014S kdr mutations were assessed by PCR. Longitudinal study of kdr mutations was performed on adult mosquitoes sampled monthly by night landing catches from 2006 to 2010. Findings No specimen studied presented the L1014S mutation. During the longitudinal study, L1014F allelic frequency rose from 2.4% in year before the implementation of LLINs to 4.6% 0–12 months after and 18.7% 13–30 months after. In 2010, An. gambiae were resistant to DDT, Lambda-cyhalothrin, Deltamethrin and Permethrin (mortality rates ranging from 46 to 63%) but highly susceptible to Fenitrothion and Bendiocarb (100% mortality). There was significantly more RR genotype among An. gambiae surviving exposure to DDT or Pyrethroids. An. arabiensis represented 3.7% of the sampled mosquitoes (11/300) with no kdr resistance allele detected. An. gambiae molecular form M represented 29.7% of the mosquitoes with, among them, kdr genotypes SR (18%) and SS (82%). An. gambiae molecular form S represented 66% of the population with, among them, kdr genotype SS (33.3%), SR (55.6%) and RR (11.1%). Only 2 MS hybrid mosquitoes were sampled and presented SS kdr genotype. Conclusion Biological evidence of resistance to DDT and pyrethroids was detected among An. gambiae mosquitoes in Dielmo (Senegal) within 24 months of community use of LLINs. Molecular identification of L1014F mutation indicated that target site resistance increased after the implementation of LLINs.
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Affiliation(s)
- Mamadou O. Ndiath
- Institut de Recherche pour le Développement, Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE) UMR 198, Campus commun UCAD-IRD de Hann, BP 1386, CP 18524, Dakar, Sénégal
| | - Seynabou Sougoufara
- Institut de Recherche pour le Développement, Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE) UMR 198, Campus commun UCAD-IRD de Hann, BP 1386, CP 18524, Dakar, Sénégal
| | - Abdoulaye Gaye
- Institut de Recherche pour le Développement, Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE) UMR 198, Campus commun UCAD-IRD de Hann, BP 1386, CP 18524, Dakar, Sénégal
| | - Catherine Mazenot
- Institut de Recherche pour le Développement, Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE) UMR 198, Campus commun UCAD-IRD de Hann, BP 1386, CP 18524, Dakar, Sénégal
| | - Lassana Konate
- Laboratoire Ecologie Vectorielle et Parasitaire, UCAD, Fann Dakar, Sénégal
| | - Oumar Faye
- Laboratoire Ecologie Vectorielle et Parasitaire, UCAD, Fann Dakar, Sénégal
| | - Cheikh Sokhna
- Institut de Recherche pour le Développement, Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE) UMR 198, Campus commun UCAD-IRD de Hann, BP 1386, CP 18524, Dakar, Sénégal
- * E-mail:
| | - Jean-Francois Trape
- Institut de Recherche pour le Développement, Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE) UMR 198, Campus commun UCAD-IRD de Hann, BP 1386, CP 18524, Dakar, Sénégal
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Santolamazza F, Caputo B, Calzetta M, Vicente JL, Mancini E, Petrarca V, Pinto J, della Torre A. Comparative analyses reveal discrepancies among results of commonly used methods for Anopheles gambiaemolecular form identification. Malar J 2011; 10:215. [PMID: 21810255 PMCID: PMC3170251 DOI: 10.1186/1475-2875-10-215] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Accepted: 08/02/2011] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Anopheles gambiae M and S molecular forms, the major malaria vectors in the Afro-tropical region, are ongoing a process of ecological diversification and adaptive lineage splitting, which is affecting malaria transmission and vector control strategies in West Africa. These two incipient species are defined on the basis of single nucleotide differences in the IGS and ITS regions of multicopy rDNA located on the X-chromosome. A number of PCR and PCR-RFLP approaches based on form-specific SNPs in the IGS region are used for M and S identification. Moreover, a PCR-method to detect the M-specific insertion of a short interspersed transposable element (SINE200) has recently been introduced as an alternative identification approach. However, a large-scale comparative analysis of four widely used PCR or PCR-RFLP genotyping methods for M and S identification was never carried out to evaluate whether they could be used interchangeably, as commonly assumed. RESULTS The genotyping of more than 400 A. gambiae specimens from nine African countries, and the sequencing of the IGS-amplicon of 115 of them, highlighted discrepancies among results obtained by the different approaches due to different kinds of biases, which may result in an overestimation of MS putative hybrids, as follows: i) incorrect match of M and S specific primers used in the allele specific-PCR approach; ii) presence of polymorphisms in the recognition sequence of restriction enzymes used in the PCR-RFLP approaches; iii) incomplete cleavage during the restriction reactions; iv) presence of different copy numbers of M and S-specific IGS-arrays in single individuals in areas of secondary contact between the two forms. CONCLUSIONS The results reveal that the PCR and PCR-RFLP approaches most commonly utilized to identify A. gambiae M and S forms are not fully interchangeable as usually assumed, and highlight limits of the actual definition of the two molecular forms, which might not fully correspond to the two A. gambiae incipient species in their entire geographical range. These limits are discussed and operational suggestions on the choice of the most convenient method for large-scale M- and S-form identification are provided, also taking into consideration technical aspects related to the epidemiological characteristics of different study areas.
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Affiliation(s)
- Federica Santolamazza
- Istituto Pasteur-Fondazione Cenci-Bolognetti, Dipartimento di Sanità Pubblica e Malattie Infettive, Università SAPIENZA, Piazzale Aldo Moro 5, 00185, Rome, Italy
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19
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Koekemoer LL, Spillings BL, Christian RN, Lo TCM, Kaiser ML, Norton RA, Oliver SV, Choi KS, Brooke BD, Hunt RH, Coetzee M. Multiple Insecticide Resistance inAnopheles gambiae(Diptera: Culicidae) from Pointe Noire, Republic of the Congo. Vector Borne Zoonotic Dis 2011; 11:1193-200. [DOI: 10.1089/vbz.2010.0192] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Lizette L. Koekemoer
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Belinda L. Spillings
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Riann N. Christian
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Te-Chang M. Lo
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Maria L. Kaiser
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Ryan A.I. Norton
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Shune V. Oliver
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Kwang S. Choi
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Basil D. Brooke
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Richard H. Hunt
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- School of Animal, Plant, and Environmental Sciences, University of Witwatersrand, Johannesburg, South Africa
| | - Maureen Coetzee
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
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20
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Hunt RH, Fuseini G, Knowles S, Stiles-Ocran J, Verster R, Kaiser ML, Choi KS, Koekemoer LL, Coetzee M. Insecticide resistance in malaria vector mosquitoes at four localities in Ghana, West Africa. Parasit Vectors 2011; 4:107. [PMID: 21679391 PMCID: PMC3145582 DOI: 10.1186/1756-3305-4-107] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2011] [Accepted: 06/16/2011] [Indexed: 11/24/2022] Open
Abstract
Background Malaria vector control programmes that rely on insecticide-based interventions such as indoor house spraying with residual insecticides or insecticide treated bed nets, need to base their decision-making process on sound baseline data. More and more commercial entities in Africa, such as mining companies, are realising the value to staff productivity of controlling malaria transmission in their areas of operation. This paper presents baseline entomological data obtained during surveys conducted for four mining operations in Ghana, West Africa. Results The vast majority of the samples were identified as Anopheles gambiae S form with only a few M form specimens being identified from Tarkwa. Plasmodium falciparum infection rates ranged from 4.5 to 8.6% in An. gambiae and 1.81 to 8.06% in An. funestus. High survival rates on standard WHO bioassay tests were recorded for all insecticide classes except the organophosphates that showed reasonable mortality at all locations (i.e. > 90%). The West African kdr mutation was detected and showed high frequencies in all populations. Conclusions The data highlight the complexity of the situation prevailing in southern Ghana and the challenges facing the malaria vector control programmes in this region. Vector control programmes in Ghana need to carefully consider the resistance profiles of the local mosquito populations in order to base their resistance management strategies on sound scientific data.
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Affiliation(s)
- Richard H Hunt
- Malaria Entomology Research Unit, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
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Kaiser ML, Koekemoer LL, Coetzee M, Hunt RH, Brooke BD. Staggered larval time-to-hatch and insecticide resistance in the major malaria vector Anopheles gambiae S form. Malar J 2010; 9:360. [PMID: 21156042 PMCID: PMC3020156 DOI: 10.1186/1475-2875-9-360] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Accepted: 12/14/2010] [Indexed: 11/10/2022] Open
Abstract
Background Anopheles gambiae is a major vector of malaria in the West African region. Resistance to multiple insecticides has been recorded in An. gambiae S form in the Ahafo region of Ghana. A laboratory population (GAH) established using wild material from this locality has enabled a mechanistic characterization of each resistance phenotype as well as an analysis of another adaptive characteristic - staggered larval time-to-hatch. Methods Individual egg batches obtained from wild caught females collected from Ghana and the Republic of the Congo were monitored for staggered larval time-to-hatch. In addition, early and late larval time-to-hatch sub-colonies were selected from GAH. These selected sub-colonies were cross-mated and their hybrid progeny were subsequently intercrossed and back-crossed to the parental strains. The insecticide susceptibilities of the GAH base colony and the time-to-hatch selected sub-colonies were quantified for four insecticide classes using insecticide bioassays. Resistance phenotypes were mechanistically characterized using insecticide-synergist bioassays and diagnostic molecular assays for known reduced target-site sensitivity mutations. Results Anopheles gambiae GAH showed varying levels of resistance to all insecticide classes. Metabolic detoxification and reduced target-site sensitivity mechanisms were implicated. Most wild-caught families showed staggered larval time-to-hatch. However, some families were either exclusively early hatching or late hatching. Most GAH larvae hatched early but many egg batches contained a proportion of late hatching larvae. Crosses between the time-to-hatch selected sub-colonies yielded ambiguous results that did not fit any hypothetical models based on single-locus Mendelian inheritance. There was significant variation in the expression of insecticide resistance between the time-to-hatch phenotypes. Conclusions An adaptive response to the presence of multiple insecticide classes necessarily involves the development of multiple resistance mechanisms whose effectiveness may be enhanced by intra-population variation in the expression of resistance phenotypes. The variation in the expression of insecticide resistance in association with selection for larval time-to-hatch may induce this kind of enhanced adaptive plasticity as a consequence of pleiotropy, whereby mosquitoes are able to complete their aquatic life stages in a variable breeding environment using staggered larval time-to-hatch, giving rise to an adult population with enhanced variation in the expression of insecticide resistance.
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Affiliation(s)
- Maria L Kaiser
- Malaria Entomology Research Unit, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
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Choi KS, Spillings BL, Coetzee M, Hunt RH, Koekemoer LL. A comparison of DNA sequencing and the hydrolysis probe analysis (TaqMan assay) for knockdown resistance (kdr) mutations in Anopheles gambiae from the Republic of the Congo. Malar J 2010; 9:278. [PMID: 20937156 PMCID: PMC2959077 DOI: 10.1186/1475-2875-9-278] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Accepted: 10/12/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Knockdown resistance (kdr) caused by a single base pair mutation in the sodium channel gene is strongly associated with pyrethroid insecticide resistance in Anopheles gambiae in West-Central Africa. Recently, various molecular techniques have been developed to screen for the presence of the kdr mutations in vector populations with varying levels of accuracy. In this study, the results of the hydrolysis probe analysis for detecting the kdr mutations in An. gambiae s.s. from the Republic of the Congo were compared with DNA sequence analysis. METHODS A total of 52 pyrethroid and DDT resistant An. gambiae from Pointe-Noire (Congo-Brazzaville) were tested for detection of the two kdr mutations (kdr-e and kdr-w) that are known to occur in this species. Results from the hydrolysis probe analysis were compared to DNA sequencing to verify the accuracy of the probe analysis for this vector population. RESULTS Fifty-one specimens were found to be An. gambiae S-form and one was a M/S hybrid. DNA sequencing revealed that more than half of the specimens (55.8%) carried both the kdr-e and kdr-w resistance mutations, seven specimens (13.5%) were homozygous for the kdr-e mutation, and 14 specimens (26.9%) were homozygous for the kdr-w mutation. A single individual was genotyped as heterozygous kdr-e mutation (1.9%) only and another as heterozygous kdr-w mutation (1.9%) only. Analysis using hydrolysis probe analysis, without adjustment of the allelic discrimination axes on the scatter plots, revealed six specimens (11.5%) carrying both mutations, 30 specimens (57.8%) as homozygous kdr-w, six specimens (11.5%) homozygous for the kdr-e mutation, one specimen (1.9%) heterozygous for the kdr-w mutation and one specimen (1.9%) present in wild type form. Eight of the specimens (15.4%) could not be identified using unadjusted hydrolysis probe analysis values. No heterozygous kdr-e mutations were scored when adjustment for the allelic discrimination axes was omitted. However, when the axes on the scatter plots were adjusted the results were consistent with those of the DNA sequence analysis, barring two individuals that were mis-scored in the hydrolysis probe analysis. CONCLUSION Both the kdr-e and kdr-w mutations were abundant in An. gambiae S-form from Pointe-Noire. The hydrolysis probe analysis can lead to misleading results if adjustment to allelic discrimination axes is not investigated. This is mainly relevant when both kdr-e and kdr-w are present in a population in a high frequency. This report highlights the importance of concurrent screening for both mutations. Therefore, performing routine assay protocols blindly can result in the misinterpretation of results. Although hydrolysis probe analysis of kdr is still held as the gold standard assay, this paper highlights the importance of kdr mutation confirmation via sequencing especially in regions where kdr frequency has never been reported before or where both the kdr-e and kdr-w mutations are present simultaneously.
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Affiliation(s)
- Kwang Shik Choi
- Vector Control Reference Unit, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
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Brooke BD, Koekemoer LL. Major effect genes or loose confederations? The development of insecticide resistance in the malaria vector Anopheles gambiae. Parasit Vectors 2010; 3:74. [PMID: 20716346 PMCID: PMC2930636 DOI: 10.1186/1756-3305-3-74] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Accepted: 08/17/2010] [Indexed: 11/10/2022] Open
Abstract
Insecticide use in public health and agriculture presents a dramatic adaptive challenge to target and non-target insect populations. The rapid development of genetically modulated resistance to insecticides is postulated to develop in two distinct ways: By selection for single major effect genes or by selection for loose confederations in which several factors, not normally associated with each other, inadvertently combine their effects to produce resistance phenotypes. Insecticide resistance is a common occurrence and has been intensively studied in the major malaria vector Anopheles gambiae, providing a useful model for examining how insecticide resistance develops and what pleiotropic effects are likely to emerge as a consequence of resistance. As malaria vector control becomes increasingly reliant on successfully managing insecticide resistance, the characterisation of resistance mechanisms and their pleiotropic effects becomes increasingly important.
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Affiliation(s)
- Basil D Brooke
- Malaria Entomology Research Unit, School of Pathology of the University of the Witwatersrand and the National Health Laboratory Service, Johannesburg, South Africa.
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