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Odjo EM, Akpodji CST, Djènontin A, Salako AS, Padonou GG, Adoha CJ, Yovogan B, Adjottin B, Tokponnon FT, Osse R, Agbangla C, Akogbeto MC. Did the prolonged residual efficacy of clothianidin products lead to a greater reduction in vector populations and subsequent malaria transmission compared to the shorter residual efficacy of pirimiphos-methyl? Malar J 2024; 23:119. [PMID: 38664703 PMCID: PMC11047034 DOI: 10.1186/s12936-024-04949-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Accepted: 04/13/2024] [Indexed: 04/28/2024] Open
Abstract
BACKGROUND The residual activity of a clothianidin + deltamethrin mixture and clothianidin alone in IRS covered more than the period of malaria transmission in northern Benin. The aim of this study was to show whether the prolonged residual efficacy of clothianidin-based products resulted in a greater reduction in vector populations and subsequent malaria transmission compared with the shorter residual efficacy of pirimiphos-methyl. METHODS Human bait mosquito collections by local volunteers and pyrethrum spray collections were used in 6 communes under IRS monitoring and evaluation from 2019 to 2021. ELISA/CSP and species PCR tests were performed on Anopheles gambiae sensu lato (s.l.) to determine the infectivity rate and subspecies by commune and year. The decrease in biting rate, entomological inoculation rate, incidence, inhibition of blood feeding, resting density of An. gambiae s.l. were studied and compared between insecticides per commune. RESULTS The An. gambiae complex was the major vector throughout the study area, acounting for 98.71% (19,660/19,917) of all Anopheles mosquitoes collected. Anopheles gambiae s.l. collected was lower inside treated houses (45.19%: 4,630/10,245) than outside (54.73%: 5,607/10,245) after IRS (p < 0.001). A significant decrease (p < 0.001) in the biting rate was observed after IRS in all departments except Donga in 2021 after IRS with clothianidin 50 WG. The impact of insecticides on EIR reduction was most noticeable with pirimiphos-methyl 300 CS, followed by the clothianidin + deltamethrin mixture and finally clothianidin 50 WG. A reduction in new cases of malaria was observed in 2020, the year of mass distribution of LLINs and IRS, as well as individual and collective protection measures linked to COVID-19. Anopheles gambiae s.l. blood-feeding rates and parous were high and similar for all insecticides in treated houses. CONCLUSION To achieve the goal of zero malaria, the optimal choice of vector control tools plays an important role. Compared with pirimiphos-methyl, clothianidin-based insecticides induced a lower reductions in entomological indicators of malaria transmission.
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Affiliation(s)
- Esdras Mahoutin Odjo
- Centre de Recherche Entomologique de Cotonou, Cotonou, Bénin.
- Faculté des Sciences et Techniques, Université d'Abomey- Calavi, Calavi, Bénin.
| | - Christian S T Akpodji
- Centre de Recherche Entomologique de Cotonou, Cotonou, Bénin
- Faculté des Sciences et Techniques, Université d'Abomey- Calavi, Calavi, Bénin
| | - Armel Djènontin
- Centre de Recherche Entomologique de Cotonou, Cotonou, Bénin
- Faculté des Sciences et Techniques, Université d'Abomey- Calavi, Calavi, Bénin
| | | | - Gil Germain Padonou
- Centre de Recherche Entomologique de Cotonou, Cotonou, Bénin
- Faculté des Sciences et Techniques, Université d'Abomey- Calavi, Calavi, Bénin
| | - Constantin Jésukèdè Adoha
- Centre de Recherche Entomologique de Cotonou, Cotonou, Bénin
- Faculté des Sciences et Techniques, Université d'Abomey- Calavi, Calavi, Bénin
| | - Boulais Yovogan
- Centre de Recherche Entomologique de Cotonou, Cotonou, Bénin
- Faculté des Sciences et Techniques, Université d'Abomey- Calavi, Calavi, Bénin
| | - Bruno Adjottin
- Centre de Recherche Entomologique de Cotonou, Cotonou, Bénin
- Faculté des Sciences et Techniques, Université d'Abomey- Calavi, Calavi, Bénin
| | - Filémon T Tokponnon
- Centre de Recherche Entomologique de Cotonou, Cotonou, Bénin
- Faculté des Sciences et Techniques, Université d'Abomey- Calavi, Calavi, Bénin
| | - Razaki Osse
- Centre de Recherche Entomologique de Cotonou, Cotonou, Bénin
- Université Nationale d'Agriculture de Porto-Novo, Porto-Novo, Bénin
| | - Clement Agbangla
- Centre de Recherche Entomologique de Cotonou, Cotonou, Bénin
- Direction Générale de la Recherche Scientifique, Ministère de l'Enseignement Supérieur et de la Recherche Scientifique, Cotonou, Bénin
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Lukubwe O, Mwema T, Joseph R, Maliti D, Iitula I, Katokele S, Uusiku P, Walusimbi D, Ogoma SB, Gueye CS, Vajda E, Tatarsky A, Thomsen E, Tambo M, Mumbengegwi D, Lobo NF. Baseline characterization of entomological drivers of malaria transmission in Namibia: a targeted operational entomological surveillance strategy. Parasit Vectors 2023; 16:220. [PMID: 37408058 DOI: 10.1186/s13071-023-05822-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 05/28/2023] [Indexed: 07/07/2023] Open
Abstract
BACKGROUND Namibia's focus on the elimination of malaria requires an evidence-based strategy directed at understanding and targeting the entomological drivers of malaria transmission. In 2018 and 2019, the Namibia National Vector-borne Diseases Control Program (NVDCP) implemented baseline entomological surveillance based on a question-based approach outlined in the Entomological Surveillance Planning Tool (ESPT). In the present study, we report on the findings of the ESPT-based NVDCP on baseline vector species composition and bionomic traits in malaria endemic regions in northern Namibia, which has the aim of generating an evidence base for programmatic decision-making. METHODS Nine representative sentinel sites were included in the 2018 entomological surveillance program (Kunene, Omusati, Oshana, Ohangwena, Oshikoto, Otjozondjupa, Kavango West, Kavango East and Zambezi); the number was reduced to four sites in 2019 due to limited funding (Ohangwena, Kavango West, Kavango East, and Zambezi). In the 2018 baseline collections, multiple sampling methods (human landing catches, pyrethroid spray catches, U.S. Centers for Disease Control and Prevention light traps [CDC-LTs], resting boxes [RBs] and larval sampling) were utilized to evaluate indoor/outdoor human biting rates, resting behaviors and insecticide resistance (IR). CDC-LTs and RBs were not used in 2019 due to low and non-representative sampling efficacies. RESULTS Overall, molecular evidence demonstrated the presence of three primary mosquito vectors, namely Anopheles arabiensis, rediscovered Anopheles gambiae sensu stricto and Anopheles funestus sensu stricto, alongside Anopheles squamosus and members of the Anopheles coustani complex. Vectors were found to bite throughout the night (1800 hours 0600 hours) both indoors and outdoors, with An. arabiensis having the highest biting rates outdoors. Low numbers of indoor resting Anopheles point to possible low indoor residual spraying (IRS) efficacy-with An. arabiensis found to be the major vector species resting indoors. The IR tests demonstrated varying country-wide resistance levels to the insecticide deltamethrin, with the resistance levels confirmed to have increased in 2019, evidence that impacts national programmatic decision-making. Vectors demonstrated susceptibility to the insecticides dichlorodiphenyltrichloroethane, bendiocarb and Actellic 300CS in 2018, with mosquitoes from only one site (Kavango West) demonstrating possible resistance to DDT. Targeted and question-based entomological surveillance enabled a rapid and focused evidence base to be built, showing where and when humans were being bitten and providing entomological data on long-lasting insecticidal nets, IRS efficacy and insecticide resistance, which the Ministry of Health and Social Services-Namibia can use to further build a monitoring and evaluation framework for understanding the drivers of transmission. CONCLUSION Identification and characterization of species-specific bionomic traits allows for an understanding of where and when vector human contact may occur as well as the potential impact of interventions. Low indoor resting rates as well as the presence of insecticide resistance (and the increase in its frequency) point to the need for mosquito-behavior-directed and appropriate interventions as well as the requirement for a resistance mitigation strategy. The ESPT-based question- and minimal essential indicator-based operational research strategy provides programs with directed and focused data for facilitating decision-making while requiring limited funding and capacity.
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Affiliation(s)
- Ophilia Lukubwe
- University of Science and Technology, Health and Applied Sciences, Windhoek, Namibia.
| | - Tabeth Mwema
- Multidisciplinary Research Center, University of Namibia, Windhoek, Namibia
| | - Rosalia Joseph
- Multidisciplinary Research Center, University of Namibia, Windhoek, Namibia
| | - Deodatus Maliti
- National Vector Borne Disease Control Program, Ministry of Health and Social Services, Windhoek, Namibia
| | - Iitula Iitula
- National Vector Borne Disease Control Program, Ministry of Health and Social Services, Windhoek, Namibia
| | - Stark Katokele
- National Vector Borne Disease Control Program, Ministry of Health and Social Services, Windhoek, Namibia
| | - Petrina Uusiku
- National Vector Borne Disease Control Program, Ministry of Health and Social Services, Windhoek, Namibia
| | | | - Sheila B Ogoma
- Clinton Health Access Initiative, Boston, Massachusetts, USA
| | - Cara Smith Gueye
- Malaria Elimination Initiative, UCSF Institute for Global Health Sciences, University of California, San Francisco, San Francisco, California, USA
| | - Elodie Vajda
- Malaria Elimination Initiative, UCSF Institute for Global Health Sciences, University of California, San Francisco, San Francisco, California, USA
| | - Allison Tatarsky
- Malaria Elimination Initiative, UCSF Institute for Global Health Sciences, University of California, San Francisco, San Francisco, California, USA
| | - Edward Thomsen
- Malaria Elimination Initiative, UCSF Institute for Global Health Sciences, University of California, San Francisco, San Francisco, California, USA
| | - Munya Tambo
- National Vector Borne Disease Control Program, Ministry of Health and Social Services, Windhoek, Namibia
| | - Davis Mumbengegwi
- National Vector Borne Disease Control Program, Ministry of Health and Social Services, Windhoek, Namibia
| | - Neil F Lobo
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, USA
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Mawejje HD, Weetman D, Epstein A, Lynd A, Opigo J, Maiteki-Sebuguzi C, Lines J, Kamya MR, Rosenthal PJ, Donnelly MJ, Dorsey G, Staedke SG. Characterizing pyrethroid resistance and mechanisms in Anopheles gambiae ( s.s.) and Anopheles arabiensis from 11 districts in Uganda. CURRENT RESEARCH IN PARASITOLOGY & VECTOR-BORNE DISEASES 2023; 3:100106. [PMID: 36590346 PMCID: PMC9798136 DOI: 10.1016/j.crpvbd.2022.100106] [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: 06/30/2022] [Revised: 11/09/2022] [Accepted: 12/01/2022] [Indexed: 12/14/2022]
Abstract
Insecticide resistance threatens recent progress on malaria control in Africa. To characterize pyrethroid resistance in Uganda, Anopheles gambiae (s.s.) and Anopheles arabiensis were analyzed from 11 sites with varied vector control strategies. Mosquito larvae were collected between May 2018 and December 2020. Sites were categorized as receiving no indoor-residual spraying ('no IRS', n = 3); where IRS was delivered from 2009 to 2014 and in 2017 and then discontinued ('IRS stopped', n = 4); and where IRS had been sustained since 2014 ('IRS active', n = 4). IRS included bendiocarb, pirimiphos methyl and clothianidin. All sites received long-lasting insecticidal nets (LLINs) in 2017. Adult mosquitoes were exposed to pyrethroids; with or without piperonyl butoxide (PBO). Anopheles gambiae (s.s.) and An. arabiensis were identified using PCR. Anopheles gambiae (s.s.) were genotyped for Vgsc-995S/F, Cyp6aa1, Cyp6p4-I236M, ZZB-TE, Cyp4j5-L43F and Coeae1d, while An. arabiensis were examined for Vgsc-1014S/F. Overall, 2753 An. gambiae (s.l.), including 1105 An. gambiae (s.s.) and 1648 An. arabiensis were evaluated. Species composition varied by site; only nine An. gambiae (s.s.) were collected from 'IRS active' sites, precluding species-specific comparisons. Overall, mortality following exposure to permethrin and deltamethrin was 18.8% (148/788) in An. gambiae (s.s.) and 74.6% (912/1222) in An. arabiensis. Mortality was significantly lower in An. gambiae (s.s.) than in An. arabiensis in 'no IRS' sites (permethrin: 16.1 vs 67.7%, P < 0.001; deltamethrin: 24.6 vs 83.7%, P < 0.001) and in 'IRS stopped' sites (permethrin: 11.3 vs 63.6%, P < 0.001; deltamethrin: 25.6 vs 88.9%, P < 0.001). When PBO was added, mortality increased for An. gambiae (s.s.) and An. arabiensis. Most An. gambiae (s.s.) had the Vgsc-995S/F mutation (95% frequency) and the Cyp6p4-I236M resistance allele (87%), while the frequency of Cyp4j5 and Coeae1d were lower (52% and 55%, respectively). Resistance to pyrethroids was widespread and higher in An. gambiae (s.s.). Where IRS was active, An. arabiensis dominated. Addition of PBO to pyrethroids increased mortality, supporting deployment of PBO LLINs. Further surveillance of insecticide resistance and assessment of associations between genotypic markers and phenotypic outcomes are needed to better understand mechanisms of pyrethroid resistance and to guide vector control.
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Affiliation(s)
- Henry Ddumba Mawejje
- Infectious Diseases Research Collaboration, Kampala, Uganda.,London School of Hygiene and Tropical Medicine, London, UK
| | - David Weetman
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Adrienne Epstein
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Amy Lynd
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Jimmy Opigo
- National Malaria Control Division, Uganda Ministry of Health, Kampala, Uganda
| | - Catherine Maiteki-Sebuguzi
- Infectious Diseases Research Collaboration, Kampala, Uganda.,National Malaria Control Division, Uganda Ministry of Health, Kampala, Uganda
| | - Jo Lines
- London School of Hygiene and Tropical Medicine, London, UK
| | - Moses R Kamya
- Infectious Diseases Research Collaboration, Kampala, Uganda.,Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | | | - Martin J Donnelly
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Grant Dorsey
- Department of Medicine, University of California, San Francisco, USA
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Govoetchan R, Fongnikin A, Syme T, Small G, Gbegbo M, Todjinou D, Rowland M, Nimmo D, Padonou GG, Ngufor C. VECTRON™ T500, a new broflanilide insecticide for indoor residual spraying, provides prolonged control of pyrethroid-resistant malaria vectors. Malar J 2022; 21:324. [DOI: 10.1186/s12936-022-04336-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 10/26/2022] [Indexed: 11/13/2022] Open
Abstract
Abstract
Background
Broflanilide is a newly discovered insecticide with a novel mode of action targeting insect γ-aminobutyric acid receptors. The efficacy of VECTRON™ T500, a wettable powder formulation of broflanilide, was assessed for IRS against wild pyrethroid-resistant malaria vectors in experimental huts in Benin.
Methods
VECTRON™ T500 was evaluated at 100 mg/m2 in mud and cement-walled experimental huts against wild pyrethroid-resistant Anopheles gambiae sensu lato (s.l.) in Covè, southern Benin, over 18 months. A direct comparison was made with Actellic® 300CS, a WHO-recommended micro-encapsulated formulation of pirimiphos-methyl, applied at 1000 mg/m2. The vector population at Covè was investigated for susceptibility to broflanilide and other classes of insecticides used for vector control. Monthly wall cone bioassays were performed to assess the residual efficacy of VECTRON™ T500 using insecticide susceptible An. gambiae Kisumu and pyrethroid-resistant An. gambiae s.l. Covè strains. The study complied with OECD principles of good laboratory practice.
Results
The vector population at Covè was resistant to pyrethroids and organochlorines but susceptible to broflanilide and pirimiphos-methyl. A total of 23,171 free-flying wild pyrethroid-resistant female An. gambiae s.l. were collected in the experimental huts over 12 months. VECTRON™ T500 induced 56%-60% mortality in wild vector mosquitoes in both cement and mud-walled huts. Mortality with VECTRON™ T500 was 62%-73% in the first three months and remained > 50% for 9 months on both substrate-types. By comparison, mortality with Actellic® 300CS was very high in the first three months (72%-95%) but declined sharply to < 40% after 4 months. Using a non-inferiority margin defined by the World Health Organization, overall mortality achieved with VECTRON™ T500 was non-inferior to that observed in huts treated with Actellic® 300CS with both cement and mud wall substrates. Monthly in situ wall cone bioassay mortality with VECTRON™ T500 also remained over 80% for 18 months but dropped below 80% with Actellic® 300CS at 6–7 months post spraying.
Conclusion
VECTRON™ T500 shows potential to provide substantial and prolonged control of malaria transmitted by pyrethroid-resistant mosquito vectors when applied for IRS. Its addition to the current list of WHO-approved IRS insecticides will provide a suitable option to facilitate rotation of IRS products with different modes of action.
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Evolution of the Ace-1 and Gste2 Mutations and Their Potential Impact on the Use of Carbamate and Organophosphates in IRS for Controlling Anopheles gambiae s.l., the Major Malaria Mosquito in Senegal. Pathogens 2022; 11:pathogens11091021. [PMID: 36145453 PMCID: PMC9504234 DOI: 10.3390/pathogens11091021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Revised: 08/31/2022] [Accepted: 09/02/2022] [Indexed: 11/17/2022] Open
Abstract
Widespread of insecticide resistance amongst the species of the Anopheles gambiae complex continues to threaten vector control in Senegal. In this study, we investigated the presence and evolution of the Ace-1 and Gste2 resistance genes in natural populations of Anopheles gambiae s.l., the main malaria vector in Senegal. Using historical samples collected from ten sentinel health districts, this study focused on three different years (2013, 2017, and 2018) marking the periods of shift between the main public health insecticides families (pyrethroids, carbamates, organophosphates) used in IRS to track back the evolutionary history of the resistance mutations on the Ace-1 and Gste2 loci. The results revealed the presence of four members of the Anopheles gambiae complex, with the predominance of An. arabiensis followed by An. gambiae, An. coluzzii, and An. gambiae–coluzzii hybrids. The Ace-1 mutation was only detected in An. gambiae and An. gambiae–coluzzii hybrids at low frequencies varying between 0.006 and 0.02, while the Gste2 mutation was found in all the species with a frequency ranging between 0.02 and 0.25. The Ace-1 and Gste2 genes were highly diversified with twenty-two and thirty-one different haplotypes, respectively. The neutrality tests on each gene indicated a negative Tajima’s D, suggesting the abundance of rare alleles. The presence and spread of the Ace-1 and Gste2 resistance mutations represent a serious threat to of the effectiveness and the sustainability of IRS-based interventions using carbamates or organophosphates to manage the widespread pyrethroids resistance in Senegal. These data are of the highest importance to support the NMCP for evidence-based vector control interventions selection and targeting.
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Ngangue-Siewe IN, Ndjeunia-Mbiakop P, Kala-Chouakeu NA, Bamou R, Talipouo A, Djamouko-Djonkam L, Vontas J, Mavridis K, Tombi J, Tchuinkam T, Mbida-Mbida JA, Antonio-Nkondjio C. Bendiocarb and Malathion Resistance in Two Major Malaria Vector Populations in Cameroon Is Associated with High Frequency of the G119S Mutation (Ace-1) and Overexpression of Detoxification Genes. Pathogens 2022; 11:pathogens11080824. [PMID: 35894047 PMCID: PMC9330212 DOI: 10.3390/pathogens11080824] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 07/19/2022] [Accepted: 07/21/2022] [Indexed: 12/10/2022] Open
Abstract
The spread of pyrethroid resistance in malaria vectors is a major threat affecting the performance of current control measures. However, there is still not enough information on the resistance profile of mosquitoes to carbamates and organophosphates which could be used as alternatives. The present study assessed the resistance profile of Anopheles gambiae s.l. to bendiocarb and malathion, at the phenotypic and molecular levels, in different eco-epidemiological settings in Cameroon. Anopheles gambiae s.l. mosquitoes were collected from four eco-epidemiological settings across the country and their susceptibility level to bendiocarb and malathion was determined using WHO tubes bioassays. The ace-1 target site G119S mutation was screened by PCR. Reverse Transcription quantitative PCR 3-plex TaqMan assays were used to quantify the level of expression of eight genes associated with metabolic resistance. Resistance to malathion and/or bendiocarb was recorded in all study sites except in mosquitoes collected in Kaélé and Njombé. The Ace-1 (G119S) mutation was detected in high frequencies (>40%) in Kékem and Santchou. Both An. gambiae and An. coluzzii were detected carrying this mutation. The cytochrome P450s gene Cyp6p3 associated with carbamate resistance and the glutathione S-transferase gene Gste2 associated with organophosphate resistance were found to be overexpressed. Genes associated with pyrethroid (Cyp6m2, Cyp9k1, Cyp6p3) and organochlorine (Gste2, Cyp6z1, Cyp6m2) and cuticle resistance (Cyp4g16) were also overexpressed. The rapid spread of resistance to organophosphates and carbamates could seriously compromise future control strategies based on IRS. It is therefore becoming important to assess the magnitude of bendiocarb and malathion resistance countrywide.
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Affiliation(s)
- Idriss Nasser Ngangue-Siewe
- Laboratory of Animal Biology and Physiology, University of Douala, Douala P.O. Box 24157, Cameroon; (I.N.N.-S.); (J.A.M.-M.)
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), Yaoundé P.O. Box 288, Cameroon; (P.N.-M.); (N.A.K.-C.); (R.B.); (A.T.); (L.D.-D.)
| | - Paulette Ndjeunia-Mbiakop
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), Yaoundé P.O. Box 288, Cameroon; (P.N.-M.); (N.A.K.-C.); (R.B.); (A.T.); (L.D.-D.)
- Faculty of Sciences, University of Yaoundé I, Yaoundé P.O. Box 812, Cameroon;
| | - Nelly Armanda Kala-Chouakeu
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), Yaoundé P.O. Box 288, Cameroon; (P.N.-M.); (N.A.K.-C.); (R.B.); (A.T.); (L.D.-D.)
- Vector-Borne Diseases Laboratory of the Applied Biology and Ecology Research Unit (VBID-URBEA), Department of Animal Biology, Faculty of Science of the University of Dschang, Dschang P.O. Box 067, Cameroon;
| | - Roland Bamou
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), Yaoundé P.O. Box 288, Cameroon; (P.N.-M.); (N.A.K.-C.); (R.B.); (A.T.); (L.D.-D.)
- Vector-Borne Diseases Laboratory of the Applied Biology and Ecology Research Unit (VBID-URBEA), Department of Animal Biology, Faculty of Science of the University of Dschang, Dschang P.O. Box 067, Cameroon;
| | - Abdou Talipouo
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), Yaoundé P.O. Box 288, Cameroon; (P.N.-M.); (N.A.K.-C.); (R.B.); (A.T.); (L.D.-D.)
- Faculty of Sciences, University of Yaoundé I, Yaoundé P.O. Box 812, Cameroon;
| | - Landre Djamouko-Djonkam
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), Yaoundé P.O. Box 288, Cameroon; (P.N.-M.); (N.A.K.-C.); (R.B.); (A.T.); (L.D.-D.)
- Vector-Borne Diseases Laboratory of the Applied Biology and Ecology Research Unit (VBID-URBEA), Department of Animal Biology, Faculty of Science of the University of Dschang, Dschang P.O. Box 067, Cameroon;
| | - John Vontas
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, 70013 Heraklion, Greece; (J.V.); (K.M.)
- Pesticide Science Laboratory, Department of Crop Science, Agricultural University of Athens, 11855 Athens, Greece
| | - Konstantinos Mavridis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, 70013 Heraklion, Greece; (J.V.); (K.M.)
| | - Jeannette Tombi
- Faculty of Sciences, University of Yaoundé I, Yaoundé P.O. Box 812, Cameroon;
| | - Timoléon Tchuinkam
- Vector-Borne Diseases Laboratory of the Applied Biology and Ecology Research Unit (VBID-URBEA), Department of Animal Biology, Faculty of Science of the University of Dschang, Dschang P.O. Box 067, Cameroon;
| | - Jean Arthur Mbida-Mbida
- Laboratory of Animal Biology and Physiology, University of Douala, Douala P.O. Box 24157, Cameroon; (I.N.N.-S.); (J.A.M.-M.)
| | - Christophe Antonio-Nkondjio
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), Yaoundé P.O. Box 288, Cameroon; (P.N.-M.); (N.A.K.-C.); (R.B.); (A.T.); (L.D.-D.)
- Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
- Correspondence: ; Tel.: +237-699-53-86-56
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An evidence synthesis approach for combining different data sources illustrated using entomological efficacy of insecticides for indoor residual spraying. PLoS One 2022; 17:e0263446. [PMID: 35324929 PMCID: PMC8947499 DOI: 10.1371/journal.pone.0263446] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 01/19/2022] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Prospective malaria public health interventions are initially tested for entomological impact using standardised experimental hut trials. In some cases, data are collated as aggregated counts of potential outcomes from mosquito feeding attempts given the presence of an insecticidal intervention. Comprehensive data i.e. full breakdowns of probable outcomes of mosquito feeding attempts, are more rarely available. Bayesian evidence synthesis is a framework that explicitly combines data sources to enable the joint estimation of parameters and their uncertainties. The aggregated and comprehensive data can be combined using an evidence synthesis approach to enhance our inference about the potential impact of vector control products across different settings over time. METHODS Aggregated and comprehensive data from a meta-analysis of the impact of Pirimiphos-methyl, an indoor residual spray (IRS) product active ingredient, used on wall surfaces to kill mosquitoes and reduce malaria transmission, were analysed using a series of statistical models to understand the benefits and limitations of each. RESULTS Many more data are available in aggregated format (N = 23 datasets, 4 studies) relative to comprehensive format (N = 2 datasets, 1 study). The evidence synthesis model had the smallest uncertainty at predicting the probability of mosquitoes dying or surviving and blood-feeding. Generating odds ratios from the correlated Bernoulli random sample indicates that when mortality and blood-feeding are positively correlated, as exhibited in our data, the number of successfully fed mosquitoes will be under-estimated. Analysis of either dataset alone is problematic because aggregated data require an assumption of independence and there are few and variable data in the comprehensive format. CONCLUSIONS We developed an approach to combine sources from trials to maximise the inference that can be made from such data and that is applicable to other systems. Bayesian evidence synthesis enables inference from multiple datasets simultaneously to give a more informative result and highlight conflicts between sources. Advantages and limitations of these models are discussed.
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Runge M, Thawer SG, Molteni F, Chacky F, Mkude S, Mandike R, Snow RW, Lengeler C, Mohamed A, Pothin E. Sub-national tailoring of malaria interventions in Mainland Tanzania: simulation of the impact of strata-specific intervention combinations using modelling. Malar J 2022; 21:92. [PMID: 35300707 PMCID: PMC8929286 DOI: 10.1186/s12936-022-04099-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 02/23/2022] [Indexed: 11/21/2022] Open
Abstract
Background To accelerate progress against malaria in high burden countries, a strategic reorientation of resources at the sub-national level is needed. This paper describes how mathematical modelling was used in mainland Tanzania to support the strategic revision that followed the mid-term review of the 2015–2020 national malaria strategic plan (NMSP) and the epidemiological risk stratification at the council level in 2018. Methods Intervention mixes, selected by the National Malaria Control Programme, were simulated for each malaria risk strata per council. Intervention mixes included combinations of insecticide-treated bed nets (ITN), indoor residual spraying, larval source management, and intermittent preventive therapies for school children (IPTsc). Effective case management was either based on estimates from the malaria indicator survey in 2016 or set to a hypothetical target of 85%. A previously calibrated mathematical model in OpenMalaria was used to compare intervention impact predictions for prevalence and incidence between 2016 and 2020, or 2022. Results For each malaria risk stratum four to ten intervention mixes were explored. In the low-risk and urban strata, the scenario without a ITN mass campaign in 2019, predicted high increase in prevalence by 2020 and 2022, while in the very-low strata the target prevalence of less than 1% was maintained at low pre-intervention transmission intensity and high case management. In the moderate and high strata, IPTsc in addition to existing vector control was predicted to reduce the incidence by an additional 15% and prevalence by 22%. In the high-risk strata, all interventions together reached a maximum reduction of 76%, with around 70% of that reduction attributable to high case management and ITNs. Overall, the simulated revised NMSP was predicted to achieve a slightly lower prevalence in 2020 compared to the 2015–2020 NMSP (5.3% vs 6.3%). Conclusion Modelling supported the choice of intervention per malaria risk strata by providing impact comparisons of various alternative intervention mixes to address specific questions relevant to the country. The use of a council-calibrated model, that reproduces local malaria trends, represents a useful tool for compiling available evidence into a single analytical platform, that complement other evidence, to aid national programmes with decision-making processes. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04099-5.
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Affiliation(s)
- Manuela Runge
- Swiss Tropical and Public Health Institute, Basel, Switzerland. .,University of Basel, Basel, Switzerland.
| | - Sumaiyya G Thawer
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Fabrizio Molteni
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Frank Chacky
- National Malaria Control Programme, Dodoma, Tanzania.,Ministry of Health, Community Development, Gender, Elderly, and Children, Dodoma, Tanzania
| | - Sigsbert Mkude
- National Malaria Control Programme, Dodoma, Tanzania.,Ministry of Health, Community Development, Gender, Elderly, and Children, Dodoma, Tanzania
| | - Renata Mandike
- National Malaria Control Programme, Dodoma, Tanzania.,Ministry of Health, Community Development, Gender, Elderly, and Children, Dodoma, Tanzania
| | - Robert W Snow
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK.,Population Health Unit, Kenya Medical Research Institute-Wellcome Trust Research Programme, Nairobi, Kenya
| | - Christian Lengeler
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Ally Mohamed
- National Malaria Control Programme, Dodoma, Tanzania.,Ministry of Health, Community Development, Gender, Elderly, and Children, Dodoma, Tanzania
| | - Emilie Pothin
- Swiss Tropical and Public Health Institute, Basel, Switzerland. .,University of Basel, Basel, Switzerland. .,CHAI, Clinton Health Access Initiative, New York, USA.
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9
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Sagbohan HW, Kpanou CD, Osse R, Dagnon F, Padonou GG, Sominahouin AA, Salako AS, Sidick A, Sewade W, Akinro B, Ahmed S, Impoinvil D, Agbangla C, Akogbeto M. Intensity and mechanisms of deltamethrin and permethrin resistance in Anopheles gambiae s.l. populations in southern Benin. Parasit Vectors 2021; 14:202. [PMID: 33853655 PMCID: PMC8048290 DOI: 10.1186/s13071-021-04699-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 03/22/2021] [Indexed: 11/24/2022] Open
Abstract
Background Insecticide resistance is threatening the effectiveness of efforts to control malaria vectors in Benin. This study explores the levels and mechanisms of insecticide resistance in An. gambiae s.l. to pyrethroids. Methods Larvae were collected from August 2017 to July 2018 in five communes in southern Benin (Adjohoun, Allada, Bohicon, Cotonou, and Porto-Novo) representing diverse ecological regions, and were reared in Benin’s insectary. Two- to five-day-old female mosquitoes from each district were exposed to multiple doses of deltamethrin and permethrin (1×, 2×, 5×, and 10×) using the WHO insecticide resistance intensity bioassay. The effect of pre-exposure to the synergist, piperonyl butoxide (PBO), was also tested at different pyrethroid doses. Molecular allele frequencies of kdr (1014F) and ace-1R (119S) insecticide resistance mutations and levels of detoxification enzymes were determined for mosquitoes sampled from each study area. Results An. gambiae s.l. were resistant to pyrethroid-only exposure up to 10× the diagnostic doses in all the study sites for both deltamethrin and permethrin. Mortality was significantly higher in An. gambiae s.l. pre-exposed to PBO followed by exposure to deltamethrin or permethrin compared to mosquitoes exposed to deltamethrin or permethrin only (p < 0.001). The difference in mortality between deltamethrin only and PBO plus deltamethrin was the smallest in Cotonou (16–64%) and the greatest in Bohicon (12–93%). The mortality difference between permethrin only and PBO plus permethrin was the smallest in Cotonou (44–75%) and the greatest in Bohicon (22–72%). In all the study sites, the kdr resistance allele (1014F) frequency was high (75–100%), while the ace-1 resistance allele (G119S) frequency was low (0–3%). Analysis of the metabolic enzymatic activity of An. gambiae s.l. showed overexpression of nonspecific esterases and glutathione S-transferases (GST) in all study sites. In contrast to the PBO results, oxidase expression was low and was similar to the susceptible An. gambiae s.s. Kisumu strain in all sites. Conclusion There is high-intensity resistance to pyrethroids in southern Benin. However, pre-exposure to PBO significantly increased susceptibility to the pyrethroids in the different An. gambiae s.l. populations sampled. The use of PBO insecticide-treated bed nets may help maintain the gains in An. gambiae (s.l.) control in southern Benin. Graphical Abstract ![]()
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Affiliation(s)
- Hermann Watson Sagbohan
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin. .,Faculty of Science and Technology of the University of Abomey-Calavi, Godomey, Benin.
| | - Casimir D Kpanou
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin.,Faculty of Science and Technology of the University of Abomey-Calavi, Godomey, Benin
| | - Razaki Osse
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin.,National University of Agriculture of Porto-Novo, Porto-Novo, Benin
| | | | - Germain G Padonou
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin.,Faculty of Science and Technology of the University of Abomey-Calavi, Godomey, Benin
| | | | - Albert Sourou Salako
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin.,Faculty of Science and Technology of the University of Abomey-Calavi, Godomey, Benin
| | | | - Wilfried Sewade
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
| | - Bruno Akinro
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
| | - Saadani Ahmed
- US President's Malaria Initiative, US Agency for International Development, Cotonou, Benin
| | - Daniel Impoinvil
- US President's Malaria Initiative, Centers for Disease Control and Prevention (CDC), Atlanta, USA
| | - Clément Agbangla
- Faculty of Science and Technology of the University of Abomey-Calavi, Godomey, Benin.,Genetics and Biotechnology Laboratory of the UAC, Godomey, Benin
| | - Martin Akogbeto
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
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Deguenon JM, Riegel C, Cloherty-Duvernay ER, Chen K, Stewart DA, Wang B, Gittins D, Tihomirov L, Apperson CS, McCord MG, Roe RM. New Mosquitocide Derived From Volcanic Rock. JOURNAL OF MEDICAL ENTOMOLOGY 2021; 58:458-464. [PMID: 32808667 DOI: 10.1093/jme/tjaa141] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Indexed: 06/11/2023]
Abstract
Malaria, dengue, yellow fever, and the Zika and West Nile Viruses are major vector-borne diseases of humans transmitted by mosquitoes. According to the World Health Organization, over 80% of the world's population is at risk of contacting these diseases. Insecticides are critical for mosquito control and disease prevention, and insect insecticide resistance is on the increase; new alternatives with potentially different modes of action from current chemistry are needed. During laboratory screening of industrial minerals for insecticide activity against Anopheles gambiae (Giles) (Diptera: Culicidae) we discovered a novel mechanical insecticide derived from volcanic rock (MIVR) with potential use as a residual spray. In modified WHO cone tests, the time to 50% mortality was 5 h under high-humidity conditions. MIVR treated surfaces demonstrated no mosquito repellency. In field studies where the mechanical insecticide was applied to wood using standard spray equipment and then placed under stilt homes in New Orleans, LA, the residual activity was >80% after 9 wk against Aedes aegypti (L.) (Diptera: Culicidae), Aedes albopictus (Skuse) (Diptera: Culicidae) and Culex quinquefasciatus (Say) (Diptera: Culicidae) (with similar efficacy to a positive chemical insecticide control). In scanning electron microcopy studies, the MIVR was transferred as particles mostly to the legs of the mosquito. This wettable powder made from volcanic rock is a mechanical insecticide representing a potential new mode of action different from current chemistry for mosquito control and is in commercial development under the trade name Imergard™WP as an indoor and outdoor residual spray.
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Affiliation(s)
- Jean M Deguenon
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC
| | - Claudia Riegel
- New Orleans Mosquito, Termite and Rodent Control Board Laboratory, New Orleans, LA
| | | | - Kaiying Chen
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC
| | | | - Bo Wang
- Imerys Filtration Minerals, Inc., Roswell, GA
| | | | | | - Charles S Apperson
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC
| | - Marian G McCord
- College of Natural Resources, North Carolina State University, Raleigh, NC
| | - R Michael Roe
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC
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11
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Deguenon JM, Azondekon R, Agossa FR, Padonou GG, Anagonou R, Ahoga J, N’dombidje B, Akinro B, Stewart DA, Wang B, Gittins D, Tihomirov L, Apperson CS, McCord MG, Akogbeto MC, Roe RM. Imergard TMWP: A Non-Chemical Alternative for an Indoor Residual Spray, Effective against Pyrethroid-Resistant Anopheles gambiae (s.l.) in Africa. INSECTS 2020; 11:E322. [PMID: 32456154 PMCID: PMC7290382 DOI: 10.3390/insects11050322] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 04/29/2020] [Accepted: 05/18/2020] [Indexed: 11/17/2022]
Abstract
Malaria is the deadliest mosquito-borne disease and kills predominantly people in sub-Saharan Africa (SSA). The now widespread mosquito resistance to pyrethroids, with rapidly growing resistance to other insecticide classes recommended by the World Health Organization (WHO), may overturn the successes gained in mosquito control in recent years. It is of utmost importance to search for new, inexpensive, and safe alternatives, with new modes of action, that might improve the efficacy of current insecticides. The efficacy of a novel mechanical insecticidal mineral derived from volcanic rock, ImergardTMWP, was investigated to determine its efficacy as a stand-alone residual wall spray and as a mixture with deltamethrin (K-Othrine® Polyzone) in experimental huts in Cove, Benin. The evaluation was conducted with susceptible (Kisumu) and wild-type Anopheles gambiae (s.l.). Deltamethrin applied alone demonstrated 40-45% mortality (at 72 h post-exposure) during the first four months, which declined to 25% at six months for wild An. gambiae from Cove. ImergardTMWP alone and mixed with deltamethrin, under the same assay conditions, produced 79-82% and 73-81% mortality, respectively, during the same six-month period. ImergardTMWP met the 80% WHO bio-efficacy threshold for residual activity for the first five months with 78% residual activity at six months. ImergardTMWP can be used as a mixture with chemical insecticides or as a stand-alone pesticide for mosquito control in Africa.
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Affiliation(s)
- Jean M. Deguenon
- Department of Entomology and Plant Pathology, Campus Box 7647, 3230 Ligon Street, North Carolina State University, Raleigh, NC 27695, USA; (J.M.D.); (C.S.A.)
| | - Roseric Azondekon
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou 06BP2604, Benin; (R.A.); (F.R.A.); (G.G.P.); (R.A.); (J.A.); (B.N.); (B.A.); (M.C.A.)
| | - Fiacre R. Agossa
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou 06BP2604, Benin; (R.A.); (F.R.A.); (G.G.P.); (R.A.); (J.A.); (B.N.); (B.A.); (M.C.A.)
| | - Gil G. Padonou
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou 06BP2604, Benin; (R.A.); (F.R.A.); (G.G.P.); (R.A.); (J.A.); (B.N.); (B.A.); (M.C.A.)
| | - Rodrigue Anagonou
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou 06BP2604, Benin; (R.A.); (F.R.A.); (G.G.P.); (R.A.); (J.A.); (B.N.); (B.A.); (M.C.A.)
| | - Juniace Ahoga
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou 06BP2604, Benin; (R.A.); (F.R.A.); (G.G.P.); (R.A.); (J.A.); (B.N.); (B.A.); (M.C.A.)
| | - Boris N’dombidje
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou 06BP2604, Benin; (R.A.); (F.R.A.); (G.G.P.); (R.A.); (J.A.); (B.N.); (B.A.); (M.C.A.)
| | - Bruno Akinro
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou 06BP2604, Benin; (R.A.); (F.R.A.); (G.G.P.); (R.A.); (J.A.); (B.N.); (B.A.); (M.C.A.)
| | - David A. Stewart
- Imerys Filtration Minerals, Inc., Roswell, GA 30076, USA; (D.A.S.); (B.W.); (D.G.); (L.T.)
| | - Bo Wang
- Imerys Filtration Minerals, Inc., Roswell, GA 30076, USA; (D.A.S.); (B.W.); (D.G.); (L.T.)
| | - David Gittins
- Imerys Filtration Minerals, Inc., Roswell, GA 30076, USA; (D.A.S.); (B.W.); (D.G.); (L.T.)
| | - Larissa Tihomirov
- Imerys Filtration Minerals, Inc., Roswell, GA 30076, USA; (D.A.S.); (B.W.); (D.G.); (L.T.)
| | - Charles S. Apperson
- Department of Entomology and Plant Pathology, Campus Box 7647, 3230 Ligon Street, North Carolina State University, Raleigh, NC 27695, USA; (J.M.D.); (C.S.A.)
| | - Marian G. McCord
- College of Natural Resources, Campus Box 8001, 2820 Faucette Drive, North Carolina State University, Raleigh, NC 27695, USA;
| | - Martin C. Akogbeto
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou 06BP2604, Benin; (R.A.); (F.R.A.); (G.G.P.); (R.A.); (J.A.); (B.N.); (B.A.); (M.C.A.)
| | - R. Michael Roe
- Department of Entomology and Plant Pathology, Campus Box 7647, 3230 Ligon Street, North Carolina State University, Raleigh, NC 27695, USA; (J.M.D.); (C.S.A.)
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12
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Akogbéto MC, Dagnon F, Aïkpon R, Ossé R, Salako AS, Ahogni I, Akinro B, Sominahouin A, Sidick A, Tokponnon F, Padonou GG. Lessons learned, challenges and outlooks for decision-making after a decade of experience monitoring the impact of indoor residual spraying in Benin, West Africa. Malar J 2020; 19:45. [PMID: 31992318 PMCID: PMC6986099 DOI: 10.1186/s12936-020-3131-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 01/18/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Since 2008, Indoor Residual Spraying (IRS) has been performed in Benin in 19 districts, including 4 in southern Benin, 9 in Atacora, and 8 in Atacora, Alibori and Donga in northern Benin. However, Benin still struggles with questions about IRS cost-benefit and epidemiological impact. Lessons learned and challenges from 10 years of IRS in Benin to be shared with the stakeholders involved in vector control implementation for decision-making. METHODS Entomological parameters have been assessed entomological parameters in IRS communes since 2008. In all IRS intervention communes, decreases in human biting rate (HBR) of Anopheles gambiae, blood feeding inhibition and entomological inoculation rate (EIR) as compared to control district have been measured. RESULTS EIR was reduced by 80-90%, which is encouraging, but should be observed with caution because: (i) the reduction may be insufficient to decrease epidemiological indicators given that the residual EIR in IRS districts is still higher than it is in some regions of stable malaria; (ii) the reduction in EIR is based on comparisons with control communes, but it is difficult to select control areas with the same environmental characteristics as intervention areas; (iii) despite the reduction, half of all mosquitoes that entered IRS-treated houses succeeded in taking human blood meals. Further, there are behaviours among Benin's population that limit IRS efficacy, including recent data showing that > 90% of people are not protected by IRS between 7 and 10 p.m. This is due to the fact that they remain outdoors and that most people are not protected from mosquito bites after 10 p.m. because they either sleep outdoors without IRS protection or indoors without an ITN. Moreover, people have large amounts of clothing hanging on walls where mosquitoes can rest instead of IRS-treated walls. Finally, other components are important to consider in implementing IRS among which: (i) Vector resistance management strategies are sometimes poorly understood; this is actually different from the need to replace one insecticide with another after the emergence of resistance; (ii) African countries should prepare to finance IRS themselves. CONCLUSION To curtail residual malaria transmission, additional interventions able to target vectors escaping IRS should be prioritized.
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Affiliation(s)
- Martin C Akogbéto
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Benin.,Faculté des Sciences et Techniques, de l' Université d'Abomey-Calavi, Cotonou, Benin
| | - Fortuné Dagnon
- US President's Malaria Initiative, US Agency for International Development, Cotonou, Benin
| | - Rock Aïkpon
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Benin.,Technologies, Ingénierie et Mathématiques, Université Nationale des Sciences, Abomey, Bénin
| | - Razaki Ossé
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Benin.,Université Nationale d'Agriculture, de Porto-Novo, Bénin
| | - Albert S Salako
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Benin. .,Faculté des Sciences et Techniques, de l' Université d'Abomey-Calavi, Cotonou, Benin.
| | - Idelphonse Ahogni
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Benin.,Faculté des Sciences et Techniques, de l' Université d'Abomey-Calavi, Cotonou, Benin
| | - Bruno Akinro
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Benin
| | - André Sominahouin
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Benin.,Faculté des Sciences Humaines et Sociales, de l' Université d'Abomey-Calavi, Cotonou, Benin
| | - Aboubakar Sidick
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Benin
| | | | - Germain G Padonou
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Benin.,Faculté des Sciences et Techniques, de l' Université d'Abomey-Calavi, Cotonou, Benin
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13
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Salako AS, Dagnon F, Sovi A, Padonou GG, Aïkpon R, Ahogni I, Syme T, Govoétchan R, Sagbohan H, Sominahouin AA, Akinro B, Iyikirenga L, Agossa F, Akogbeto MC. Efficacy of Actellic 300 CS-based indoor residual spraying on key entomological indicators of malaria transmission in Alibori and Donga, two regions of northern Benin. Parasit Vectors 2019; 12:612. [PMID: 31888730 PMCID: PMC6937814 DOI: 10.1186/s13071-019-3865-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 12/19/2019] [Indexed: 11/25/2022] Open
Abstract
Background The current study shows the results of three years of IRS entomological monitoring (2016, before intervention; 2017 and 2018, after intervention) performed in Alibori and Donga, northern Benin. Methods Mosquito collections were performed on a monthly basis using human landing catches and pyrethrum spray catches in six districts including four treated with Actellic 300 CS (Kandi, Gogounou, Djougou and Copargo) and two untreated (Bembèrèkè and Kouandé) which served as control sites. Key transmission indicators of Anopheles gambiae (s.l.) as well as the residual activity of Actellic 300 CS assessed through WHO cone tests, were determined. Results The residual efficacy duration of Actellic 300 CS after the two IRS campaigns (2017 and 2018) was 4–5 months (May–September). The parity rate and the sporozoite index of An. gambiae (s.l.) were 36.62% and 0.71%, respectively, after the first spray round in treated areas compared to 57.24% and 3.7%, respectively, in the control areas (P < 0.0001). The same trend was observed after the second spray round. After the first spray round, each person received 1.6 infective bites/month (ib/m) in the treated areas against 12.11 ib/m in the control areas, resulting in a reduction rate of 86.78%. Similarly, the entomological inoculation rate was 1.5 ib/m after the second spray round in the treated areas vs 9.75 ib/m in the control areas, corresponding to a reduction of 84.61%. A decrease in the parity rate (46.26%), sporozoite index (85.75%) and EIR (87.27%) was observed for An. gambiae (s.l.) after the first round of IRS (June–October 2017) compared to the pre-intervention period (June–October 2016). The density of An. gambiae (s.l.) ranged between 0.38–0.48 per house in treated areas vs 1.53–1.76 An. gambiae (s.l.) per house respectively after the first and second IRS rounds. Conclusions This study showed the positive impact of IRS in reducing key entomological parameters of malaria transmission in Alibori and Donga. However, the considerable blood-feeding rate of An. gambiae (s.l.) in spray areas, stress the need for the population to sleep under long-lasting insecticidal nets (LLINs) in addition, to prevent from mosquito bites which did not succeed in resting on sprayed walls.
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Affiliation(s)
- Albert Sourou Salako
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin. .,Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Cotonou, Benin.
| | - Fortune Dagnon
- USA President's Malaria Initiative, USA Agency for International Development, Cotonou, Benin
| | - Arthur Sovi
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin.,Faculty of Agronomy, University of Parakou, BP 123, Parakou, Benin.,Disease Control Department, Faculty of Infectious & Tropical Diseases, The London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Gil Germain Padonou
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin.,Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Cotonou, Benin
| | - Rock Aïkpon
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin.,Université Nationale des Sciences, Technologies, Ingénierie et Mathématiques, Abomey, Bénin
| | - Idelphonse Ahogni
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin.,Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Cotonou, Benin
| | - Thomas Syme
- Disease Control Department, Faculty of Infectious & Tropical Diseases, The London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Renaud Govoétchan
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin.,Faculty of Agronomy, University of Parakou, BP 123, Parakou, Benin
| | - Herman Sagbohan
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin.,Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Cotonou, Benin
| | - André Aimé Sominahouin
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin.,Faculté des Sciences Humaines et Sociales de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
| | - Bruno Akinro
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
| | | | - Fiacre Agossa
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin.,PMI VectorLink Project, Abt Associates, Kinshasa, Democratic Republic of Congo
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14
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Barrier bednets target malaria vectors and expand the range of usable insecticides. Nat Microbiol 2019; 5:40-47. [PMID: 31792426 DOI: 10.1038/s41564-019-0607-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 10/11/2019] [Indexed: 11/08/2022]
Abstract
Transmission of Plasmodium falciparum malaria parasites occurs when nocturnal Anopheles mosquito vectors feed on human blood. In Africa, where malaria burden is highest, bednets treated with pyrethroid insecticide were highly effective in preventing mosquito bites and reducing transmission, and essential to achieving unprecedented reductions in malaria until 2015 (ref. 1). Since then, progress has stalled2, and with insecticidal bednets losing efficacy against pyrethroid-resistant Anopheles vectors3,4, methods that restore performance are urgently needed to eliminate any risk of malaria returning to the levels seen before their widespread use throughout sub-Saharan Africa5. Here, we show that the primary malaria vector Anopheles gambiae is targeted and killed by small insecticidal net barriers positioned above a standard bednet in a spatial region of high mosquito activity but zero contact with sleepers, opening the way for deploying many more insecticides on bednets than is currently possible. Tested against wild pyrethroid-resistant A. gambiae in Burkina Faso, pyrethroid bednets with organophosphate barriers achieved significantly higher killing rates than bednets alone. Treated barriers on untreated bednets were equally effective, without significant loss of personal protection. Mathematical modelling of transmission dynamics predicted reductions in clinical malaria incidence with barrier bednets that matched those of 'next-generation' nets recommended by the World Health Organization against resistant vectors. Mathematical models of mosquito-barrier interactions identified alternative barrier designs to increase performance. Barrier bednets that overcome insecticide resistance are feasible using existing insecticides and production technology, and early implementation of affordable vector control tools is a realistic prospect.
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15
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Elanga-Ndille E, Nouage L, Ndo C, Binyang A, Assatse T, Nguiffo-Nguete D, Djonabaye D, Irwing H, Tene-Fossog B, Wondji CS. The G119S Acetylcholinesterase ( Ace-1) Target Site Mutation Confers Carbamate Resistance in the Major Malaria Vector Anopheles gambiae from Cameroon: A Challenge for the Coming IRS Implementation. Genes (Basel) 2019; 10:genes10100790. [PMID: 31614683 PMCID: PMC6826778 DOI: 10.3390/genes10100790] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Revised: 10/06/2019] [Accepted: 10/08/2019] [Indexed: 01/26/2023] Open
Abstract
Growing resistance is reported to carbamate insecticides in malaria vectors in Cameroon. However, the contribution of acetylcholinesterase (Ace-1) to this resistance remains uncharacterised. Here, we established that the G119S mutation is driving resistance to carbamates in Anopheles gambiae populations from Cameroon. Insecticide bioassay on field-collected mosquitoes from Bankeng, a locality in southern Cameroon, showed high resistance to the carbamates bendiocarb (64.8% ± 3.5% mortality) and propoxur (55.71% ± 2.9%) but a full susceptibility to the organophosphate fenitrothion. The TaqMan genotyping of the G119S mutation in field-collected adults revealed the presence of this resistance allele (39%). A significant correlation was observed between the Ace-1R and carbamate resistance at allelic ((bendiocarb; odds ratio (OR) = 75.9; p < 0.0001) and (propoxur; OR = 1514; p < 0.0001)) and genotypic (homozygote resistant vs. homozygote susceptible (bendiocarb; OR = 120.8; p < 0.0001) and (propoxur; OR = 3277; p < 0.0001)) levels. Furthermore, the presence of the mutation was confirmed by sequencing an Ace-1 portion flanking codon 119. The cloning of this fragment revealed a likely duplication of Ace-1 in Cameroon as mosquitoes exhibited at least three distinct haplotypes. Phylogenetic analyses showed that the predominant Ace-1R allele is identical to that from West Africa suggesting a recent introduction of this allele in Central Africa from the West. The spread of this Ace-1R represents a serious challenge to future implementation of indoor residual spraying (IRS)-based interventions using carbamates or organophosphates in Cameroon.
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Affiliation(s)
| | - Lynda Nouage
- Centre for Research in Infectious Diseases (CRID), P.O. BOX 13591, Yaoundé, Cameroon.
- Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, P.O. Box 812, Yaoundé, Cameroon.
| | - Cyrille Ndo
- Centre for Research in Infectious Diseases (CRID), P.O. BOX 13591, Yaoundé, Cameroon.
- Department of Biological Sciences, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, P.O. Box 24157, Douala, Cameroon.
| | - Achille Binyang
- Centre for Research in Infectious Diseases (CRID), P.O. BOX 13591, Yaoundé, Cameroon.
- Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, P.O. Box 812, Yaoundé, Cameroon.
| | - Tatiane Assatse
- Centre for Research in Infectious Diseases (CRID), P.O. BOX 13591, Yaoundé, Cameroon.
- Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, P.O. Box 812, Yaoundé, Cameroon.
| | - Daniel Nguiffo-Nguete
- Centre for Research in Infectious Diseases (CRID), P.O. BOX 13591, Yaoundé, Cameroon.
- Department of Animal Biology, Faculty of Science, University of Dschang, P.O. Box 67, Dschang, Cameroon.
| | - Doumani Djonabaye
- Centre for Research in Infectious Diseases (CRID), P.O. BOX 13591, Yaoundé, Cameroon.
- Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, P.O. Box 812, Yaoundé, Cameroon.
| | - Helen Irwing
- Vector Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK.
| | - Billy Tene-Fossog
- Centre for Research in Infectious Diseases (CRID), P.O. BOX 13591, Yaoundé, Cameroon.
| | - Charles S Wondji
- Centre for Research in Infectious Diseases (CRID), P.O. BOX 13591, Yaoundé, Cameroon.
- Vector Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK.
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16
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Corrêa APSA, Galardo AKR, Lima LA, Câmara DCP, Müller JN, Barroso JFS, Lapouble OMM, Rodovalho CM, Ribeiro KAN, Lima JBP. Efficacy of insecticides used in indoor residual spraying for malaria control: an experimental trial on various surfaces in a "test house". Malar J 2019; 18:345. [PMID: 31601226 PMCID: PMC6785876 DOI: 10.1186/s12936-019-2969-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 09/21/2019] [Indexed: 11/10/2022] Open
Abstract
Background Malaria is a public health problem in the Brazilian Amazon region. In integrated vector management for malaria (anopheline) control, indoor residual spraying (IRS) represents one of the main tools in the basic strategy applied in the Amazonian states. It is essential to understand the residual efficacy of insecticides on different surfaces to determine spray cycles, ensure their rational use, and prevent wastage. This study aimed to evaluate the residual efficacy of six insecticide formulations used in the National Malaria Control Programme on four different types of walls in a field simulation at a “test house”. Methods The tests were performed as a field-simulating evaluation at a “test house” built in the municipality of Macapá. Six insecticide formulations comprising four pyrethroids, a carbamate, and an organophosphate were used, and evaluated when applied on different wall surfaces: painted wood, unpainted wood, plastered cement, and unplastered cement. The insecticides were applied to the interior walls of the “test house” by a trained technician. Results In the bioassays performed with pyrethroids, deltamethrin water-dispersible granules (WG) performed particularly well, presenting residual bioefficacy of 8 months on both wood surfaces after the IRS, whereas alpha-cypermethrin suspension concentrate (SC) and etofenprox wettable powder (WP) demonstrated residual bioefficacy of 4 months on at least one of the wood surfaces; however, the pyrethroid lambda-cyhalothrin WP showed a low residual bioefficacy (< 3 months) on all tested surfaces, demonstrating its inefficiency for areas with a long transmission cycle of malaria. For the carbamate-bendiocarb WP, residual bioefficacy for 3 months was achieved only on wood surfaces. In general, the organophosphate pirimifos-methyl capsule suspension (CS) demonstrated the best result, with a mortality rate < 80% over a period of 6 months on all surfaces tested. Conclusion Insecticide efficiency varies among different types of surface; therefore, a “test house” is a valuable evaluation tool. This work highlights the usefulness of associating the residual efficacy of insecticides on the surfaces commonly found in houses in endemic areas, together with knowledge about the transmission cycle duration of the transmission cycle and the insecticide susceptibility of the vector. This association helps in the decision-making for the malaria control intervention regarding.
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Affiliation(s)
- Ana Paula S A Corrêa
- Laboratório de Fisiologia e Controle de Artrópodes Vetores-Fundação Oswaldo Cruz, Rio de Janeiro, Brazil. .,Laboratório de Entomologia Médica, Instituto de Pesquisas Científicas e Tecnológicas do Estado de Amapá-IEPA, Macapá, Brazil.
| | - Allan K R Galardo
- Laboratório de Entomologia Médica, Instituto de Pesquisas Científicas e Tecnológicas do Estado de Amapá-IEPA, Macapá, Brazil
| | - Luana A Lima
- Laboratório de Entomologia Médica, Instituto de Pesquisas Científicas e Tecnológicas do Estado de Amapá-IEPA, Macapá, Brazil
| | - Daniel C P Câmara
- Núcleo Operacional Sentinela de Mosquitos Vetores - Laboratório de Mosquitos Transmissores de Hematozoários, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Josiane N Müller
- Laboratório de Fisiologia e Controle de Artrópodes Vetores-Fundação Oswaldo Cruz, Rio de Janeiro, Brazil.,Laboratório de Entomologia Médica, Instituto de Pesquisas Científicas e Tecnológicas do Estado de Amapá-IEPA, Macapá, Brazil
| | - Jéssica Fernanda S Barroso
- Laboratório de Entomologia Médica, Instituto de Pesquisas Científicas e Tecnológicas do Estado de Amapá-IEPA, Macapá, Brazil
| | - Oscar M M Lapouble
- Pan-American Health Organization/World Health Organization (PAHO/WHO), Paramaribo, Suriname.,Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Amazonas, Brazil.,Programa de Pós-Graduação em Medicina Tropical, Universidade do Estado do Amazonas, Manaus, Amazonas, Brazil
| | - Cynara M Rodovalho
- Laboratório de Fisiologia e Controle de Artrópodes Vetores-Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | | | - José Bento P Lima
- Laboratório de Fisiologia e Controle de Artrópodes Vetores-Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
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17
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Susceptibility of Anopheles Mosquito to Agricultural Insecticides in the Adansi North District, Ghana. JOURNAL OF PURE AND APPLIED MICROBIOLOGY 2019. [DOI: 10.22207/jpam.13.2.04] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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18
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Agossa FR, Padonou GG, Fassinou AJYH, Odjo EM, Akuoko OK, Salako A, Koukpo ZC, Nwangwu UC, Akinro B, Sezonlin M, Akogbeto MC. Small-scale field evaluation of the efficacy and residual effect of Fludora ® Fusion (mixture of clothianidin and deltamethrin) against susceptible and resistant Anopheles gambiae populations from Benin, West Africa. Malar J 2018; 17:484. [PMID: 30594207 PMCID: PMC6311023 DOI: 10.1186/s12936-018-2633-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 12/15/2018] [Indexed: 12/02/2022] Open
Abstract
Background In recognition of the threat of insecticide resistance in vectors of malaria, the WHO Global Malaria Programme recommends the development of an appropriate and comprehensive response to insecticide resistance. In principle, good resistance management practice requires the application of multiple insecticides of different modes of action, for example, in rotations and mixtures. Insecticides recommended by the World Health Organization for indoor residual spraying and long-lasting insecticide nets are limited. It is, therefore, judicious to prevent the rapid spread of insecticide resistance by evaluating new insecticides formulations with different modes of action and long residual effect. Methods Fludora® Fusion, a new neonicotinoid IRS formulation (a mixture of 500 g/kg clothianidin and 62.5 g/kg deltamethrin applied 200 mg ai/sqm + 25 mg ai/sqm, respectively) was tested. Small scale field evaluation of this product was conducted in the district of Dangbo in Benin, to compare its efficacy and residual effect on cement and mud walls against those of clothianidin 200 mg ai/sqm (WG 70) alone, and of deltamethrin 25 mg ai/sqm (WG 250) alone. WHO wall cone bioassays were conducted monthly with laboratory susceptible Anopheles “Kisumu” and wild Anopheles gambiae sensu stricto (s.s.) population from Dangbo. The induced mortality by each treatment per wall substrate for 24 h, 48 h, and 72 h post exposure were recorded every month and analysed. Results Fludora® Fusion and clothianidin WG 70 showed mortality rates over 80% WHO bio-efficacy threshold on cement walls either with susceptible or resistant An. gambiae s.s. over a period of 10 and 9 months, respectively. Treatment with Fludora® Fusion and clothianidin WG 70 on the mud walls showed residual effect for 6 months and 5 months respectively against both susceptible and resistant mosquitoes. During the whole evaluation period, deltamethrin WG 250 showed mortality rates below 80% against resistant Anopheles population. Furthermore, the knock down rates observed with the Fludora® Fusion combination were significantly higher (p < 5%) than those induced by Clothiandin WG 70. Conclusion Both the Fludora® Fusion combination and clothianidin alone showed very good and lasting efficacy for IRS against resistant Anopheles with some residual benefit provided by the combination. The residual efficacy of the Fludora® Fusion combination evaluated at 10 months shows this product is a good candidate for IRS interventions. Electronic supplementary material The online version of this article (10.1186/s12936-018-2633-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Fiacre R Agossa
- Centre de Recherche Entomologique de Cotonou (CREC), 06BP2604, Cotonou, Bénin.
| | - Gil G Padonou
- Centre de Recherche Entomologique de Cotonou (CREC), 06BP2604, Cotonou, Bénin.,Laboratoire Evolution, Biodiversité des Arthropodes et Assainissement, FAST-UAC, Abomey-Calavi, Bénin
| | - Arsene Jacques Y H Fassinou
- Centre de Recherche Entomologique de Cotonou (CREC), 06BP2604, Cotonou, Bénin.,Ecole Doctorale Sciences de la Vie et de la Terre, FAST-UAC, Abomey-Calavi, Bénin
| | - Esdras M Odjo
- Centre de Recherche Entomologique de Cotonou (CREC), 06BP2604, Cotonou, Bénin
| | - Osei K Akuoko
- Noguchi Memorial Institute for Medical Research University, Accra, Ghana
| | - Albert Salako
- Centre de Recherche Entomologique de Cotonou (CREC), 06BP2604, Cotonou, Bénin.,Ecole Doctorale Sciences de la Vie et de la Terre, FAST-UAC, Abomey-Calavi, Bénin
| | - Zinsou C Koukpo
- Centre de Recherche Entomologique de Cotonou (CREC), 06BP2604, Cotonou, Bénin.,Ecole Doctorale Sciences de la Vie et de la Terre, FAST-UAC, Abomey-Calavi, Bénin
| | - Udoka C Nwangwu
- National Arbovirus and Vectors Research Centre (NAVRC), Enugu, Nigeria
| | - Bruno Akinro
- Centre de Recherche Entomologique de Cotonou (CREC), 06BP2604, Cotonou, Bénin
| | - Michel Sezonlin
- Centre de Recherche Entomologique de Cotonou (CREC), 06BP2604, Cotonou, Bénin.,Laboratoire Evolution, Biodiversité des Arthropodes et Assainissement, FAST-UAC, Abomey-Calavi, Bénin
| | - Martin C Akogbeto
- Centre de Recherche Entomologique de Cotonou (CREC), 06BP2604, Cotonou, Bénin.,Laboratoire Evolution, Biodiversité des Arthropodes et Assainissement, FAST-UAC, Abomey-Calavi, Bénin
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19
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Systematic review of indoor residual spray efficacy and effectiveness against Plasmodium falciparum in Africa. Nat Commun 2018; 9:4982. [PMID: 30478327 PMCID: PMC6255894 DOI: 10.1038/s41467-018-07357-w] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 10/25/2018] [Indexed: 11/08/2022] Open
Abstract
Indoor residual spraying (IRS) is an important part of malaria control. There is a growing list of insecticide classes; pyrethroids remain the principal insecticide used in bednets but recently, novel non-pyrethroid IRS products, with contrasting impacts, have been introduced. There is an urgent need to better assess product efficacy to help decision makers choose effective and relevant tools for mosquito control. Here we use experimental hut trial data to characterise the entomological efficacy of widely-used, novel IRS insecticides. We quantify their impact against pyrethroid-resistant mosquitoes and use a Plasmodium falciparum transmission model to predict the public health impact of different IRS insecticides. We report that long-lasting IRS formulations substantially reduce malaria, though their benefit over cheaper, shorter-lived formulations depends on local factors including bednet use, seasonality, endemicity and pyrethroid resistance status of local mosquito populations. We provide a framework to help decision makers evaluate IRS product effectiveness.
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20
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Agossa FR, Padonou GG, Koukpo CZ, Zola-Sahossi J, Azondekon R, Akuoko OK, Ahoga J, N'dombidje B, Akinro B, Fassinou AJYH, Sezonlin M, Akogbeto MC. Efficacy of a novel mode of action of an indoor residual spraying product, SumiShield® 50WG against susceptible and resistant populations of Anopheles gambiae (s.l.) in Benin, West Africa. Parasit Vectors 2018; 11:293. [PMID: 29747684 PMCID: PMC5946391 DOI: 10.1186/s13071-018-2869-6] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 04/23/2018] [Indexed: 11/10/2022] Open
Abstract
Background Scale-up of the distribution of long-lasting insecticide-treated bed nets and indoor residual spraying with insecticides over the last decade have contributed to the considerable decrease of malaria morbidity and mortality in sub-Saharan Africa. Due to the increasing pyrethroid resistance intensity and the spread of carbamate resistance in Anopheles gambiae (s.s.) mosquitoes and the limited number of insecticides recommended by the WHO for vector control, alternative insecticide formulations for IRS with long-lasting residual activity are required to sustain the gains obtained in most malaria-endemic countries. Methods SumiShield 50WG (clothianidin 300 mg ai/m2) developed by Sumitomo Chemical was evaluated alongside deltamethrin 25 mg ai/m2 (K-Othrine 250 WG) against a pyrethroid resistant Anopheles gambiae (s.l.) population in experimental huts in Covè, Benin. Residual activity was also tested in cone bioassays with the susceptible An. gambiae “Kisumu” strain and the local wild resistant population. Results The results showed very low toxicity from deltamethrin (mortality rates ranged between 1–40%) against host-seeking resistant Anopheles populations. SumiShield in contrast gave an overall mean mortality of 91.7% at the 120 h observation across the eight- month observation period following spraying. The residual activity measured using cone tests was over the 80% WHO threshold for 24 weeks for resistant wild Anopheles population and 32 weeks for the susceptible strain “Kisumu” after the spraying. Conclusions SumiShield is a good candidate for IRS in areas of permanent malaria transmission and where Anopheles populations are resistant to other conventional insecticides such as pyrethroids. It would be interesting to complete experimental huts studies by assessing the efficacy and residual effect of SumiShield 50WG at community level (small-scale field testing) in an area where vectors are highly resistant to insecticides.
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Affiliation(s)
- Fiacre R Agossa
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin.
| | - Gil G Padonou
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin.,Laboratoire Evolution, Biodiversité des Arthropodes et Assainissement, FAST - UAC, Abomey-Calavi, Bénin
| | - Come Z Koukpo
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin.,Ecole Doctorale Sciences de la Vie et de la Terre, FAST - UAC, Abomey-Calavi, Bénin
| | | | | | - Osei K Akuoko
- Noguchi Memorial Institute for Medical Research University, Accra, Ghana
| | - Juniace Ahoga
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin
| | - Boris N'dombidje
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin
| | - Bruno Akinro
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin
| | - Arsene Jacques Y H Fassinou
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin.,Ecole Doctorale Sciences de la Vie et de la Terre, FAST - UAC, Abomey-Calavi, Bénin
| | - Michel Sezonlin
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin.,Laboratoire Evolution, Biodiversité des Arthropodes et Assainissement, FAST - UAC, Abomey-Calavi, Bénin
| | - Martin C Akogbeto
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin.,Laboratoire Evolution, Biodiversité des Arthropodes et Assainissement, FAST - UAC, Abomey-Calavi, Bénin
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21
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Wagman J, Gogue C, Tynuv K, Mihigo J, Bankineza E, Bah M, Diallo D, Saibu A, Richardson JH, Kone D, Fomba S, Bernson J, Steketee R, Slutsker L, Robertson M. An observational analysis of the impact of indoor residual spraying with non-pyrethroid insecticides on the incidence of malaria in Ségou Region, Mali: 2012-2015. Malar J 2018; 17:19. [PMID: 29316917 PMCID: PMC5761159 DOI: 10.1186/s12936-017-2168-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 12/29/2017] [Indexed: 11/10/2022] Open
Abstract
Background Ségou Region in Central Mali is an area of high malaria burden with seasonal transmission, high access to and use of long-lasting insecticidal nets (LLINs), and resistance to pyrethroids and DDT well documented in Anopheles gambiae s.l. (the principal vector of malaria in Mali). Ségou has recently received indoor residual spraying (IRS) supported by Mali’s collaboration with the US President’s Malaria Initiative/Africa Indoor Residual Spraying programme. From 2012 to 2015, two different non-pyrethroid insecticides: bendiocarb in 2012 and 2013 and pirimiphos-methyl in 2014 and 2015, were used for IRS in two districts. This report summarizes the results of observational analyses carried out to assess the impact of these IRS campaigns on malaria incidence rates reported through local and district health systems before and after spraying. Methods A series of retrospective time series analyses were performed on 1,382,202 rapid diagnostic test-confirmed cases of malaria reported by district routine health systems in Ségou Region from January 2012 to January 2016. Malaria testing, treatment, surveillance and reporting activities remained consistent across districts and years during the study period, as did LLIN access and use estimates as well as An. gambiae s.l. insecticide resistance patterns. Districts were stratified by IRS implementation status and all-age monthly incidence rates were calculated and compared across strata from 2012 to 2014. In 2015 a regional but variable scale-up of seasonal malaria chemoprevention complicated the region-wide analysis; however IRS operations were suspended in Bla District that year so a difference in differences approach was used to compare 2014 to 2015 changes in malaria incidence at the health facility level in children under 5-years-old from Bla relative to changes observed in Barouéli, where IRS operations were consistent. Results During 2012–2014, rapid reductions in malaria incidence were observed during the 6 months following each IRS campaign, though most of the reduction in cases (70% of the total) was concentrated in the first 2 months after each campaign was completed. Compared to non-IRS districts, in which normal seasonal patterns of malaria incidence were observed, an estimated 286,745 total fewer cases of all-age malaria were observed in IRS districts. The total cost of IRS in Ségou was around 9.68 million USD, or roughly 33.75 USD per case averted. Further analysis suggests that the timing of the 2012–2014 IRS campaigns (spraying in July and August) was well positioned to maximize public health impact. Suspension of IRS in Bla District after the 2014 campaign resulted in a 70% increase in under-5-years-old malaria incidence rates from 2014 to 2015, significantly greater (p = 0.0003) than the change reported from Barouéli District, where incidence rates remained the same. Conclusions From 2012 to 2015, the annual IRS campaigns in Ségou are associated with several hundred thousand fewer cases of malaria. This work supports the growing evidence that shows that IRS with non-pyrethroid insecticides is a wise public health investment in areas with documented pyrethroid resistance, high rates of LLIN coverage, and where house structures and population densities are appropriate. Additionally, this work highlights the utility of quality-assured and validated routine surveillance and well defined observational analyses to rapidly assess the impact of malaria control interventions in operational settings, helping to empower evidence-based decision making and to further grow the evidence base needed to better understand when and where to utilize new vector control tools as they become available. Electronic supplementary material The online version of this article (10.1186/s12936-017-2168-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Diakalkia Kone
- Programme National de Lutte Contre le Paludisme, Bamako, Mali
| | - Seydou Fomba
- Programme National de Lutte Contre le Paludisme, Bamako, Mali
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Nardini L, Hunt RH, Dahan-Moss YL, Christie N, Christian RN, Coetzee M, Koekemoer LL. Malaria vectors in the Democratic Republic of the Congo: the mechanisms that confer insecticide resistance in Anopheles gambiae and Anopheles funestus. Malar J 2017; 16:448. [PMID: 29115954 PMCID: PMC5678590 DOI: 10.1186/s12936-017-2099-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2017] [Accepted: 10/28/2017] [Indexed: 11/22/2022] Open
Abstract
Background The Democratic Republic of the Congo (DRC) is characterized as a holoendemic malaria area with the main vectors being Anopheles funestus and members of the Anopheles gambiae complex. Due to political instability and socio-economic challenges in the region, knowledge of insecticide resistance status and resistance mechanisms in these vectors is limited. Mosquitoes were collected from a mining site in the north-eastern part of the country and, following identification, were subjected to extensive testing for the target-site and biochemical basis of resistance. Quantitative real-time PCR was used to assess a suite of 10 genes frequently involved in pyrethroid and dichlorodiphenyltrichloroethane (DDT) resistance in An. gambiae females and males. In An. funestus, gene expression microarray analysis was carried out on female mosquitoes. Results In both species, deltamethrin resistance was recorded along with high resistance and suspected resistance to DDT in An. gambiae and An. funestus, respectively. A total of 85% of An. gambiae carried the kdr mutations as either homozygous resistant (RR) (L1014S, L1014F or both) or heterozygous (RS), however only 3% carried the rdl mutant allele (RS) and no ace-1 mutations were recorded. Synergist assays indicated a strong role for P450s in deltamethrin resistance in both species. In An. gambiae, analysis of transcription levels showed that the glutathione-S-transferase, GSTS1-2, produced the highest fold change in expression (7.6-fold in females and 31-fold in males) followed by GSTE2, thioredoxin peroxidase (TPX2), and cytochrome oxidases (CYP6M2 and CYP6P1). All other genes tested produced fold change values below 2. Microarray analysis revealed significant over-transcription of cuticular proteins as well as CYP6M7, CYP6P9a and CYP6P9b in insecticide resistant An. funestus. Conclusions These data show that high levels of deltamethrin resistance in the main malaria vector species, conferred by enzymatic detoxification, are present in the DRC. Electronic supplementary material The online version of this article (10.1186/s12936-017-2099-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Luisa Nardini
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, 2000, South Africa.,Centre for Emerging, Zoonotic & Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, 2131, South Africa
| | - Richard H Hunt
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, 2000, South Africa.,Centre for Emerging, Zoonotic & Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, 2131, South Africa
| | - Yael L Dahan-Moss
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, 2000, South Africa.,Centre for Emerging, Zoonotic & Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, 2131, South Africa
| | - Nanette Christie
- Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria, 0028, South Africa
| | - Riann N Christian
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, 2000, South Africa.,Centre for Emerging, Zoonotic & Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, 2131, South Africa
| | - Maureen Coetzee
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, 2000, South Africa.,Centre for Emerging, Zoonotic & Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, 2131, South Africa
| | - Lizette L Koekemoer
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, 2000, South Africa. .,Centre for Emerging, Zoonotic & Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, 2131, South Africa.
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Randriamaherijaona S, Nepomichene TNJJ, Assoukpa J, Madec Y, Boyer S. Efficacy of Bendiocarb Used for Indoor Residual Spraying for Malaria Control in Madagascar: Results With Local Anopheles Species (Diptera: Culicidae) From Experimental Hut Trials. JOURNAL OF MEDICAL ENTOMOLOGY 2017; 54:1031-1036. [PMID: 28399303 DOI: 10.1093/jme/tjx047] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Indexed: 06/07/2023]
Abstract
To control malaria in Madagascar, two primary vector control interventions are being scaled up: insecticide-treated nets and indoor residual spraying of bendiocarb, which was implemented in the Malagasy Central Highlands in 2009. The current efficacy of bendiocarb against Anopheles species was evaluated in a small-scale field trial. An experimental hut trial comparing the effectiveness of bendiocarb sprayed on five substrates (cement, wood, tin, mud, and vegetative materials) was carried out against Anopheles species in two study sites located in the eastern foothills of Madagascar. No significant difference was detected in either exophily or blood-feeding rates between treated and untreated huts. The mortality rate was significantly greater in treated huts compared to untreated huts. Efficacy up to 80% was found for 5 mo posttreatment. Although effective, bendiocarb has been used for 7 yr, and therefore an alternative insecticide may be needed to avoid the emergence of resistance.
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Affiliation(s)
- Sanjiarizaha Randriamaherijaona
- Unité d'Entomologie Médicale, Institut Pasteur de Madagascar, BP 1274 Antananarivo, Madagascar
- Ecole Doctorale Sciences de la Vie et de l'Environnement, Université d'Antananarivo, Madagascar
| | - Thiery Nirina Jean Jose Nepomichene
- Unité d'Entomologie Médicale, Institut Pasteur de Madagascar, BP 1274 Antananarivo, Madagascar
- Ecole Doctorale Sciences de la Vie et de l'Environnement, Université d'Antananarivo, Madagascar
| | - Jade Assoukpa
- Unité d'Entomologie Médicale, Institut Pasteur de Madagascar, BP 1274 Antananarivo, Madagascar
- Unité d'Epidémiologie des Maladies Emergentes, Institut Pasteur 25-28, rue du Docteur Roux, 75015 Paris, France
| | - Yoann Madec
- Unité d'Epidémiologie des Maladies Emergentes, Institut Pasteur 25-28, rue du Docteur Roux, 75015 Paris, France
| | - Sébastien Boyer
- Unité d'Entomologie Médicale, Institut Pasteur de Madagascar, BP 1274 Antananarivo, Madagascar
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24
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Agossa FR, Gnanguenon V, Anagonou R, Azondekon R, Aïzoun N, Sovi A, Oké-Agbo F, Sèzonlin M, Akogbéto MC. Impact of Insecticide Resistance on the Effectiveness of Pyrethroid-Based Malaria Vectors Control Tools in Benin: Decreased Toxicity and Repellent Effect. PLoS One 2015; 10:e0145207. [PMID: 26674643 PMCID: PMC4682945 DOI: 10.1371/journal.pone.0145207] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2015] [Accepted: 12/01/2015] [Indexed: 11/19/2022] Open
Abstract
Since the first evidence of pyrethroids resistance in 1999 in Benin, mutations have rapidly increased in mosquitoes and it is now difficult to design a study including a control area where malaria vectors are fully susceptible. Few studies have assessed the after effect of resistance on the success of pyrethroid based prevention methods in mosquito populations. We therefore assessed the impact of resistance on the effectiveness of pyrethroids based indoor residual spraying (IRS) in semi-field conditions and long lasting insecticidal nets (LLINs) in laboratory conditions. The results observed showed low repulsion and low toxicity of pyrethroids compounds in the test populations. The toxicity of pyrethroids used in IRS was significantly low with An. gambiae s.l (< 46%) but high for other predominant species such as Mansonia africana (93% to 97%). There were significant differences in terms of the repellent effect expressed as exophily and deterrence compared to the untreated huts (P<0.001). Furthermore, mortality was 23.71% for OlyseNet® and 39.06% for PermaNet®. However, with laboratory susceptible "Kisumu", mortality was 100% for both nets suggesting a resistance within the wild mosquito populations. Thus treatment with pyrethroids at World Health Organization recommended dose will not be effective at reducing malaria in the coming years. Therefore it is necessary to study how insecticide resistance decreases the efficacy of particular pyrethroids used in pyrethroid-based vector control so that a targeted approach can be adopted.
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Affiliation(s)
- Fiacre R. Agossa
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
| | | | | | | | - Nazaire Aïzoun
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
| | - Arthur Sovi
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
| | | | - Michel Sèzonlin
- Laboratoire Evolution, Biodiversité des Arthropodes et Assainissement, FAST—UAC, Abomey-Calavi, Bénin
| | - Martin C. Akogbéto
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
- Laboratoire Evolution, Biodiversité des Arthropodes et Assainissement, FAST—UAC, Abomey-Calavi, Bénin
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25
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Akogbéto MC, Aïkpon RY, Azondékon R, Padonou GG, Ossè RA, Agossa FR, Beach R, Sèzonlin M. Six years of experience in entomological surveillance of indoor residual spraying against malaria transmission in Benin: lessons learned, challenges and outlooks. Malar J 2015; 14:242. [PMID: 26063497 PMCID: PMC4465467 DOI: 10.1186/s12936-015-0757-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 06/02/2015] [Indexed: 11/23/2022] Open
Abstract
Background From 2008 to 2013, a prevention intervention against malaria based on indoor residual spraying (IRS) was implemented in Benin. From 2008 to 2012, Ficam M®, a bendiocarb-containing product was used for house spraying, in association with pirimiphos methyl EC (Actellic EC) in 2013. This operation aimed to strengthen the effectiveness of treated nets so as to expedite the achievement of Millennium Development Goals (MDGs): the reduction of morbidity and mortality due to malaria by 75 % from 2000 to 2015. Methods Monitoring and evaluation (M&E) was implemented in order to evaluate the impact of IRS intervention on malaria transmission. Anopheles gambiae s.l. populations were sampled by human landing catch. In addition, window exit traps and pyrethrum spray catches were performed to assess exophagic behaviour of Anopheles vectors the main malaria vector in the treated areas. The residual activity of insecticide in the treated walls was also assessed using WHO bioassay test. Results The purpose of this project was to draw attention to new challenges and future prospects for the success of IRS in Benin. The main strength of the intervention was a large-scale operation in which more than 80 % of the houses were treated due to the strong adhesion of population. In addition, a significant reduction of the EIR in areas under IRS were observed. However, there were many challenges including the high cost of IRS implementation and the identification of suitable areas to implement IRS. This was because of the low and short residual effect of the insecticides recommended for IRS and the management strategy for vector resistance to insecticides. This indicated that challenges are accompanied by suggested solutions. For the cost of IRS to be accessible to states, then local organizations need to be created in partnership with the National Malaria Control Programme (NMCP) in order to ensure relevant planning and implementation of IRS. Conclusion As an anticipatory measure against vector resistance, this paper proposes various methods, such as periodic IRS based on a combination of two or three insecticides of different classes used in rotation every two or three years.
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Affiliation(s)
- Martin C Akogbéto
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Bénin. .,Faculté des Sciences et Techniques, Université d'Abomey Calavi, Cotonou, Bénin.
| | - Rock Y Aïkpon
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Bénin. .,Faculté des Sciences et Techniques, Université d'Abomey Calavi, Cotonou, Bénin.
| | - Roseric Azondékon
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Bénin. .,Université du Massachusetts Amherst, Amherst, MA, USA.
| | - Gil G Padonou
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Bénin. .,Faculté des Sciences et Techniques, Université d'Abomey Calavi, Cotonou, Bénin.
| | - Razaki A Ossè
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Bénin. .,Université d'Agriculture de Kétou, Kétou, Benin.
| | - Fiacre R Agossa
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Bénin. .,Faculté des Sciences et Techniques, Université d'Abomey Calavi, Cotonou, Bénin.
| | | | - Michel Sèzonlin
- Faculté des Sciences et Techniques, Université d'Abomey Calavi, Cotonou, Bénin.
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26
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Ingabire CM, Rulisa A, Van Kempen L, Muvunyi C, Koenraadt CJM, Van Vugt M, Mutesa L, Van Den Borne B, Alaii J. Factors impeding the acceptability and use of malaria preventive measures: implications for malaria elimination in eastern Rwanda. Malar J 2015; 14:136. [PMID: 25889789 PMCID: PMC4389639 DOI: 10.1186/s12936-015-0659-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 03/20/2015] [Indexed: 11/10/2022] Open
Abstract
Background Long-lasting insecticidal nets (LLIN), indoor residual spraying (IRS) and malaria case treatment with artemisinin-based combination therapy (ACT) have been proven to significantly reduce malaria, but may not necessarily lead to malaria elimination. This study explored factors hindering the acceptability and use of available malaria preventive measures to better inform area specific strategies that can lead to malaria elimination. Methods Nine focus group discussions (FGD) covering a cross-section of 81 lay community members and local leaders were conducted in Ruhuha, Southern Eastern Rwanda in December 2013 to determine: community perceptions on malaria disease, acceptability of LLIN and IRS, health care-seeking behaviours and other malaria elimination strategies deployed at household and environmental levels. Discussions were recorded in Kinyarwanda, transcribed into English and coded using Nvivo 10 software. Results Participants ranked malaria as the top among five common diseases in the Ruhuha sector. Participants expressed comprehensive knowledge and understanding of malaria transmission and symptoms. The concept of malaria elimination was acknowledged, but challenges were reported. Sleeping under a bed net was negatively affected by increase of bedbugs (and the associated irritability) as well as discomfortable warmness particularly during the dry season. These two factors were reported as common hindrances of the use of LLIN. Also, widespread use of LLIN in constructing chicken pens or as fences around vegetable gardens was reported. Participants also reported that IRS appeared to lead to an increase in number of mosquitoes and other household bugs rather than kill them. Prompt health centre utilization among participants with presumed malaria was reported to be common particularly among subscribers to the subsidized community-based health insurance (CBHI) scheme. In contrast, the lack of CBHI and/or perceptions that health centre visits were time consuming were common reasons for the use of over-the-counter medicines for malaria management. Conclusion In this study, identification of behavioural determinants in relation to LLIN use, IRS acceptability and health care seeking is a critical step in the development of effective, targeted interventions aiming to further reduce malaria transmission and elimination in the area.
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Affiliation(s)
- Chantal Marie Ingabire
- Department of Health Education & Promotion, Maastricht University, Maastricht, The Netherlands. .,Medical Research Center, Rwanda Biomedical Center, Kigali, Rwanda.
| | - Alexis Rulisa
- Medical Research Center, Rwanda Biomedical Center, Kigali, Rwanda. .,Radboud University Nijmegen, Nijmegen, The Netherlands.
| | | | - Claude Muvunyi
- College of Medicine and Health Sciences, University of Rwanda, Rwanda, The Netherlands.
| | | | | | - Leon Mutesa
- College of Medicine and Health Sciences, University of Rwanda, Rwanda, The Netherlands.
| | - Bart Van Den Borne
- Department of Health Education & Promotion, Maastricht University, Maastricht, The Netherlands.
| | - Jane Alaii
- Context Factor Solutions, Nairobi, Kenya.
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Tchicaya ES, Nsanzabana C, Smith TA, Donzé J, de Hipsl ML, Tano Y, Müller P, Briët OJT, Utzinger J, Koudou BG. Micro-encapsulated pirimiphos-methyl shows high insecticidal efficacy and long residual activity against pyrethroid-resistant malaria vectors in central Côte d'Ivoire. Malar J 2014; 13:332. [PMID: 25152326 PMCID: PMC4159530 DOI: 10.1186/1475-2875-13-332] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 08/19/2014] [Indexed: 11/10/2022] Open
Abstract
Background The wide-scale implementation of insecticide-treated nets and indoor residual spraying (IRS) has contributed to a considerable decrease of malaria morbidity and mortality in sub-Saharan Africa over the last decade. Due to increasing resistance in Anopheles gambiae sensu lato mosquitoes to dichlorodiphenyl trichloroethane (DDT) and pyrethroids, alternative insecticide formulations for IRS with long-lasting residual activity are required to sustain the gains obtained in most malaria-endemic countries. Methods Three experimental capsule suspension (CS) formulations of the organophosphate pirimiphos-methyl were evaluated together with Actellic 50 EC, an emulsifiable concentrate (EC) of pirimiphos-methyl, and the pyrethroid ICON 10 CS, a lambda-cyhalothrin CS formulation, in an experimental hut trial. The formulations were tested on two types of surfaces: mud and cement. The study with a 12-month follow-up was carried out in Bouaké, central Côte d’Ivoire, where An. gambiae mosquitoes show high levels of resistance against pyrethroids, DDT and carbamates. Residual activity was also tested in cone bioassays with the susceptible An. gambiae KISUMU strain. Results One of the CS formulations of pirimiphos-methyl, CS BM, outperformed all other formulations tested. On cement surfaces, the odds ratios of overall insecticidal effect on An. gambiae s.l. of pirimiphos-methyl CS BM compared to Actellic 50 EC were 1.4 (95% confidence interval (CI): 1.2–1.7) for the first three months, 5.6 (95% CI: 4.4–7.2) for the second three months, and 3.6 (95% CI: 3.0–4.4) for the last six months of follow-up. On mud surfaces, the respective odds ratios were 2.5 (95% CI: 1.9–3.3), 3.5 (95% CI: 2.7–4.5), and 1.7 (95% CI: 1.4–2.2). On cement, the residual activity of pirimiphos-methyl CS BM measured using cone tests was similar to that of lambda-cyhalothrin and for both treatments, mortality of susceptible Kisumu laboratory strain was not significantly below the World Health Organization pre-set threshold of 80% for 30 weeks after spraying. Residual activity was shorter on mud surfaces, mortality falling below 80% on both pirimiphos-methyl CS BM and lambda-cyhalothrin treated surfaces at 25 weeks post-treatment. Conclusion CS formulations of pirimiphos-methyl are promising alternatives for IRS, as they demonstrate prolonged insecticidal effect and residual activity against malaria mosquitoes. Electronic supplementary material The online version of this article (doi:10.1186/1475-2875-13-332) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | | | | | | | | | - Olivier J T Briët
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, CH-4002 Basel, Switzerland.
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Aïkpon R, Sèzonlin M, Tokponon F, Okè M, Oussou O, Oké-Agbo F, Beach R, Akogbéto M. Good performances but short lasting efficacy of Actellic 50 EC Indoor Residual Spraying (IRS) on malaria transmission in Benin, West Africa. Parasit Vectors 2014; 7:256. [PMID: 24886499 PMCID: PMC4049441 DOI: 10.1186/1756-3305-7-256] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Accepted: 05/25/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The National Malaria Control Program (NMCP) has been using pirimiphos methyl for the first time for indoor residual spraying (IRS) in Benin. The first round was a success with a significant decrease of entomological indicators of malaria transmission in the treated districts. We present the results of the entomological impact on malaria transmission. Entomologic parameters in the control area were compared with those in intervention sites. METHODS Mosquito collections were carried out in three districts in the Atacora-Dongo region of which two were treated with pirimiphos methyl (Actellic 50EC) (Tanguiéta and Kouandé) and the untreated (Copargo) served as control. Anopheles gambiae s.l. populations were sampled monthly by human landing catch. In addition, window exit traps and pyrethrum spray catches were performed to assess exophagic behavior of Anopheles vectors. In the three districts, mosquito collections were organized to follow the impact of pirimiphos methyl IRS on malaria transmission and possible changes in the behavior of mosquitoes. The residual activity of pirimiphos methyl in the treated walls was also assessed using WHO bioassay test. RESULTS A significant reduction (94.25%) in human biting rate was recorded in treated districts where an inhabitant received less than 1 bite of An. gambiae per night. During this same time, the entomological inoculation rate (EIR) dramatically declined in the treated area (99.24% reduction). We also noted a significant reduction in longevity of the vectors and an increase in exophily induced by pirimiphos methyl on An. gambiae. However, no significant impact was found on the blood feeding rate. Otherwise, the low residual activity of Actellic 50 EC, which is three months, is a disadvantage. CONCLUSION Pirimiphos methyl was found to be effective for IRS in Benin. However, because of the low persistence of Actellic 50EC used in this study on the treated walls, the recourse to another more residual formulation of pirimiphos methyl is required.
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Affiliation(s)
- Rock Aïkpon
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604 Cotonou, Bénin
- Faculté des Sciences et Techniques, Université d’Abomey Calavi, Abomey Calavi, Bénin
| | - Michel Sèzonlin
- Faculté des Sciences et Techniques, Université d’Abomey Calavi, Abomey Calavi, Bénin
| | - Filémon Tokponon
- National Malaria Control Programm (NMCP), Ministry of Health, Cotonou, Benin
| | - Mariam Okè
- National Malaria Control Programm (NMCP), Ministry of Health, Cotonou, Benin
| | - Olivier Oussou
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604 Cotonou, Bénin
| | - Frédéric Oké-Agbo
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604 Cotonou, Bénin
| | | | - Martin Akogbéto
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604 Cotonou, Bénin
- Faculté des Sciences et Techniques, Université d’Abomey Calavi, Abomey Calavi, Bénin
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