Background Updated information on the distribution and abundance of Aedes aegypti and Aedes albopictus is crucial to prepare African countries like Benin for possible arbovirus outbreaks. This study aims to evaluate the geographical... more
Background Updated information on the distribution and abundance of Aedes aegypti and Aedes albopictus is crucial to prepare African countries like Benin for possible arbovirus outbreaks. This study aims to evaluate the geographical distribution, the abundance, and the biting behaviors of these two vectors in Benin. Methods Three sampling techniques (Human Landing Catch (HLC), Larval sampling, and Ovitrapping) were used to collect both immature and adult stages of Aedes spp in 23 communes located along the North-South and East-West transect of Benin. Adult Aedes mosquitoes were collected indoors and outdoors using HLC. Mosquito eggs, larvae, and pupae were collected from containers and ovitraps and morphologically identified, then confirmed by Polymerase Chain Reaction (PCR). Results Overall, 12,428 adult specimens of Aedes spp, out of which 76.53% (n = 9508) and 19.32% (n = 2400) were morphologically identified as Ae. aegypti, and Ae. albopictus respectively. Geographically, Ae. ae...
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The efficacy of a vector control tool in reducing mosquito biting is crucial for its acceptability. The present study compared the vector density of Culex spp. And Mansonia spp. across clusters, which received two dual-active ingredient... more
The efficacy of a vector control tool in reducing mosquito biting is crucial for its acceptability. The present study compared the vector density of Culex spp. And Mansonia spp. across clusters, which received two dual-active ingredient (a.i.) long-lasting insecticidal nets (LLINs) and a standard pyrethroid-only LLIN, and assessed the seasonality of these mosquito genera. A total of 85,723 Culex spp. and 144,025 Mansonia spp. were caught over the study period. The density of Culex and Mansonia was reduced in all three arms over the study period. There was no evidence of a significant reduction in the indoor or outdoor density of Culex spp. in either dual-a.i. LLIN arm as compared to the standard pyrethroid-only net arm. A similar trend was observed with Mansonia spp. A high density of Culex spp. was found both in rainy and dry seasons, while for Mansonia spp., this was mainly observed during the rainy season. These results suggest that the novel insecticides in the dual-a.i. LLINs d...
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Current diagnostic and surveillance systems in Benin are not designed to accurately identify or report non-Plasmodium falciparum (Pf) human malaria infections. This study aims to assess and compare the prevalence of circumsporozoite... more
Current diagnostic and surveillance systems in Benin are not designed to accurately identify or report non-Plasmodium falciparum (Pf) human malaria infections. This study aims to assess and compare the prevalence of circumsporozoite protein (CSP) antibodies of Pf and P. vivax (Pv) in Anopheles gambiae s.l. in Benin. For that, mosquito collections were performed through human landing catches (HLC) and pyrethrum spray catches (PSC). The collected mosquitoes were morphologically identified, and Pf, Pv 210, and Pv 247 CSP antibodies were sought in An. gambiae s.l. through the ELISA and polymerase chain reaction (PCR) techniques. Of the 32,773 collected mosquitoes, 20.9% were An. gambiae s.l., 3.9% An. funestus gr., and 0.6% An. nili gr. In An. gambiae s.l., the sporozoite rate was 2.6% (95% CI: 2.1–3.1) for Pf, against 0.30% (95% CI: 0.1–0.5) and 0.2% (95% CI: 0.1–0.4), respectively, for Pv 210 and Pv 247. P. falciparum sporozoite positive mosquitoes were mostly An. gambiae (64.35%), fo...
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Background Following agricultural use and large-scale distribution of insecticide-treated nets (ITNs), malaria vector resistance to pyrethroids is widespread in sub-Saharan Africa. Interceptor® G2 is a new dual active ingredient (AI) ITN... more
Background Following agricultural use and large-scale distribution of insecticide-treated nets (ITNs), malaria vector resistance to pyrethroids is widespread in sub-Saharan Africa. Interceptor® G2 is a new dual active ingredient (AI) ITN treated with alpha-cypermethrin and chlorfenapyr for the control of pyrethroid-resistant malaria vectors. In anticipation of these new nets being more widely distributed, testing was conducted to develop a chlorfenapyr susceptibility bioassay protocol and gather susceptibility information. Methods Bottle bioassay tests were conducted using five concentrations of chlorfenapyr at 12.5, 25, 50, 100, and 200 µg AI/bottle in 10 countries in sub-Saharan Africa using 13,639 wild-collected Anopheles gambiae sensu lato (s.l.) (56 vector populations per dose) and 4,494 pyrethroid-susceptible insectary mosquitoes from 8 colonized strains. In parallel, susceptibility tests were conducted using a provisional discriminating concentration of 100 µg AI/bottle in 16...
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Malaria remains the main cause of morbidity and mortality in Benin despite the scale-up of long-lasting insecticidal nets (LLINs), indoor residual spraying, and malaria case management. This study aimed to determine the malaria burden and... more
Malaria remains the main cause of morbidity and mortality in Benin despite the scale-up of long-lasting insecticidal nets (LLINs), indoor residual spraying, and malaria case management. This study aimed to determine the malaria burden and its associated risk factors in a rural area of Benin characterized by high net coverage and pyrethroid-resistant mosquito vectors. A community-based cross-sectional survey was conducted in three districts in southern Benin. Approximately 4,320 randomly selected participants of all ages were tested for malaria using rapid diagnostic tests within 60 clusters. Risk factors for malaria infection were evaluated using mixed-effect logistic regression models. Despite high population net use (96%), malaria infection prevalence was 43.5% (cluster range: 15.1-72.7%). Children (58.7%) were more likely to be infected than adults (31.2%), with a higher malaria prevalence among older children (5-10 years: 69.1%; 10-15 years: 67.9%) compared to young children (&l...
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Background Long-lasting insecticidal nets (LLINs) are currently the primary method of malaria control in sub-Saharan Africa and have contributed to a significant reduction in malaria burden over the past 15 years. However, this progress... more
Background Long-lasting insecticidal nets (LLINs) are currently the primary method of malaria control in sub-Saharan Africa and have contributed to a significant reduction in malaria burden over the past 15 years. However, this progress is threatened by the wide-scale selection of insecticide-resistant malaria vectors. It is, therefore, important to accelerate the generation of evidence for new classes of LLINs. Methods This protocol presents a three-arm superiority, single-blinded, cluster randomized controlled trial to evaluate the impact of 2 novel dual-active ingredient LLINs on epidemiological and entomological outcomes in Benin, a malaria-endemic area with highly pyrethroid-resistant vector populations. The study arms consist of (i) Royal Guard® LLIN, a net combining a pyrethroid (alpha-cypermethrin) plus an insect growth regulator (pyriproxyfen), which in the adult female is known to disrupt reproduction and egg fertility; (ii) Interceptor G2® LLIN, a net incorporating two ad...
Background Long-lasting insecticidal nets (LLINs) are currently the primary method of malaria control in sub-Saharan Africa and have contributed to a significant reduction in malaria burden over the past 15 years. However, this progress... more
Background Long-lasting insecticidal nets (LLINs) are currently the primary method of malaria control in sub-Saharan Africa and have contributed to a significant reduction in malaria burden over the past 15 years. However, this progress is threatened by the wide-scale selection of insecticide-resistant malaria vectors. It is, therefore, important to accelerate the generation of evidence for new classes of LLINs. Methods This protocol presents a three-arm superiority, single-blinded, cluster randomized controlled trial to evaluate the impact of 2 novel dual-active ingredient LLINs on epidemiological and entomological outcomes in Benin, a malaria-endemic area with highly pyrethroid-resistant vector populations. The study arms consist of (i) Royal Guard® LLIN, a net combining a pyrethroid (alpha-cypermethrin) plus an insect growth regulator (pyriproxyfen), which in the adult female is known to disrupt reproduction and egg fertility; (ii) Interceptor G2® LLIN, a net incorporating two ad...
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Background This study provides detailed characteristics of vector populations in preparation for a three-arm cluster randomized controlled trial (RCT) aiming to compare the community impact of dual active-ingredient (AI) long-lasting... more
Background This study provides detailed characteristics of vector populations in preparation for a three-arm cluster randomized controlled trial (RCT) aiming to compare the community impact of dual active-ingredient (AI) long-lasting insecticidal nets (LLINs) that combine two novel insecticide classes–chlorfenapyr or pyriproxifen–with alpha-cypermethrin to improve the prevention of malaria transmitted by insecticide-resistant vectors compared to standard pyrethroid LLINs. Methods The study was carried out in 60 villages across Cove, Zangnanando and Ouinhi districts, southern Benin. Mosquito collections were performed using human landing catches (HLCs). After morphological identification, a sub-sample of Anopheles gambiae s.l. were dissected for parity, analyzed by PCR for species and presence of L1014F kdr mutation and by ELISA-CSP to identify Plasmodium falciparum sporozoite infection. WHO susceptibility tube tests were performed by exposing adult An. gambiae s.l., collected as lar...
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Background In May 2019, a confirmed dengue fever case was detected at the local hospital of Abomey-Calavi Commune in southern Benin. In Benin, there remains a dearth of literature concerning the distribution and biology of Aedes aegypti,... more
Background In May 2019, a confirmed dengue fever case was detected at the local hospital of Abomey-Calavi Commune in southern Benin. In Benin, there remains a dearth of literature concerning the distribution and biology of Aedes aegypti, the principal vector of dengue fever. This study was initiated by the Ministry of Health to partially fill this gap. The findings allowed us to assess the arboviral transmission risk incurred by the population of Abomey-Calavi to support programmatic decision-making. Methods Entomological assessments were conducted in 5% of the houses, meaning 314 houses selected from 11 boroughs in Abomey-Calavi Centre district and 9 villages in Hêvié district. The surveyed breeding sites were water containers located in (domestic) and around (peri-domestic) the dwellings. When a container was positive (housing larvae), a portion of the immature population was sampled with a larval dipper and poured into labeled jars. Immatures were then reared to adulthood at the ...
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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... more
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...
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Background: Millions of pyrethroid LLINs have been distributed in Mali during the past 20 years which, along with agricultural use, has increased the selection pressure on malaria vector populations. This study investigated pyrethroid... more
Background: Millions of pyrethroid LLINs have been distributed in Mali during the past 20 years which, along with agricultural use, has increased the selection pressure on malaria vector populations. This study investigated pyrethroid resistance intensity and susceptible status of malaria vectors to alternative insecticides to guide choice of insecticides for LLINs and IRS for effective control of malaria vectors. Methods: For 3 years between 2016 and 2018, susceptibility testing was conducted annually in 14-16 sites covering southern and central Mali. Anopheles gambiae s.l. were collected from larval sites and adult mosquitoes exposed in WHO tube tests to diagnostic doses of bendiocarb (0.1%) and pirimiphos-methyl (0.25%). Resistance intensity tests were conducted using CDC bottle bioassays (2016-17) and WHO tube tests (2018) at 1 × , 2 × , 5 × , and 10 × the diagnostic concentration of permethrin, deltamethrin and alpha-cypermethrin. WHO tube tests were conducted with pre-exposure...
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Background Long-lasting insecticidal nets (LLINs) are designed to survive and sustain their physical barrier for 3 years in household conditions. However, studies have shown that most of these nets are usually torn or no longer present in... more
Background Long-lasting insecticidal nets (LLINs) are designed to survive and sustain their physical barrier for 3 years in household conditions. However, studies have shown that most of these nets are usually torn or no longer present in the households in less than 3 years. This study was initiated in Benin to compare the survivorship and physical integrity of seven types of LLINs in a same socio-geographic area. Methods In August 2017, 1890 households were selected in 9 villages in the municipality of Zagnanado in central Benin. Each one of the selected households received one of the seven LLIN products: Aspirational®, DawaPlus® 2.0, OlysetNet®, PermaNet® 2.0, PermaNet® 3.0, Royal Sentry® and Yorkool®. Overall, 270 LLINs of each type were freely distributed in Zagnanado, at a rate of 30 LLINs per type per village. These bed nets have been monitored and evaluated every 6 months to identify the most resilient and preferred LLINs in the community. Net survivorship was assessed using ...
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Background In 2011, Benin’s National Malaria Control Programme (NMCP) organized a nationwide mass distribution campaign of LLINs throughout the country. Following this intervention, it was important to assess whether the level of... more
Background In 2011, Benin’s National Malaria Control Programme (NMCP) organized a nationwide mass distribution campaign of LLINs throughout the country. Following this intervention, it was important to assess whether the level of susceptibility of malaria vectors to insecticides had remained the same as compared to the pre-intervention period. The current study investigated this. Methods Larval collections were conducted in Ifangni, Sakété, Pobè and Kétou districts located in Plateau department, Southeastern Benin before (2009) and after (2012–2013) LLIN distribution. Anopheles gambiae sensu lato (s.l.) larvae from the 4 study districts were reared to adulthood and WHO susceptibility tests were conducted. The insecticides tested were deltamethrin (0.05%), permethrin (0.75%), bendiocarb (0.1%) and DDT (4%). Molecular species identification as well as, the characterization of the kdr L1014F mutation were also performed in the An. gambiae s.l. complex using PCR method. Results Overall,...
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Despite the success of indoor residual insecticide spraying (IRS) in Africa, particularly in Benin, some gaps of information need to be filled to optimize the effectiveness of this intervention in the perspective of the country's... more
Despite the success of indoor residual insecticide spraying (IRS) in Africa, particularly in Benin, some gaps of information need to be filled to optimize the effectiveness of this intervention in the perspective of the country's effort to eliminate malaria. In anticipation to the 2018 IRS campaign in two targeted regions of northern Benin, this study aimed, to collect baseline information on vector composition, spatio-temporal variation and peak malaria transmission in the Alibori and Donga, two targeted regions of northern Benin. Information collected will help to better plan the implementation and later on the impact assessment of this IRS campaign. The study was carried out in four districts of the two IRS targeted regions of northern Benin. Human landing catches and pyrethrum spray catches protocols were used to assess the biting rate (HBR) and, biting/resting behaviour of malaria vector populations. After morphological identification of collected Anopheles, the heads and t...
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The spread of Ace-1 R mutation that confers carbamate and organophosphate resistance in Anopheles gambiae s.l. is a critical issue for malaria vector control. The aim of this study was to investigate the seasonal variation of the Ace-1 R... more
The spread of Ace-1 R mutation that confers carbamate and organophosphate resistance in Anopheles gambiae s.l. is a critical issue for malaria vector control. The aim of this study was to investigate the seasonal variation of the Ace-1 R mutation in A. gambiae s. l populations. The mosquitoes analyzed were collected by human landing catches (HLC) in five districts in the department of Atacora from May 2011 to June 2013. The collection was carried out twice a month by adult volunteers. They caught any mosquitoes that landed on their legs with an aspirator from 7.00 p.m to 6.00 a.m. Anopheles mosquitoes were morphologically identified and polymerase chain reaction (PCR) assays were run to determine the members of the A. gambiae complex, as well as phenotypes for insensitive acetylcholinesterase (AChE1) due to the Ace-1 R mutation. This study shows that A. gambiae s. s. and Anopheles coluzzii occurred in sympatry in the Atacora region. However, A. gambiae s. s. was predominant during t...
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lasting insecticidal nets (LLINs) have proved to be an important tool for the malaria control and other vector-borne diseases. Benin, by its National Malaria Control Program, conducted in July, 2011 a universal distribution campaign where... more
lasting insecticidal nets (LLINs) have proved to be an important tool for the malaria control and other vector-borne diseases. Benin, by its National Malaria Control Program, conducted in July, 2011 a universal distribution campaign where approximately 5 million of nets were distributed. But after this mass-distribution, questions arise: Do people effectively use or not use the mosquito nets freely distributed? To clarify these questions, this study was conducted on LLINs coverage, use and physical condition in Benin one year after their distribution. The households were randomly selected from 32 clusters. Data on bed net ownership and usage, physical condition of the nets, other characters and issues related to sourcing were asked of all targets to assess the origins of LLIN found at the household level. Of the total surveyed, 88.96% had at least one LLIN. 87.19% of these nets come from the last campaign, 9.1% were from pregnant women voucher clinic delivery systems and 3.20% were ...
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Research Interests: Parasitology, Geography, Medical Microbiology, Biology, Medicine, and 15 moreHumans, Benin, Female, Animals, Male, Anopheles gambiae, Public health systems and services research, Plasmodium falciparum, Oviposition, Reproducibility of Results, Parity, Insect Vectors, Infectivity, ovum, and Malaria Falciparum
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The implementation of a vector control strategy needs to be adapted to both sociocultural and environmental contexts. The determination of National Malaria Control Program (NMCP) to fight effectively against malaria resulted in their... more
The implementation of a vector control strategy needs to be adapted to both sociocultural and environmental contexts. The determination of National Malaria Control Program (NMCP) to fight effectively against malaria resulted in their decision to implement indoor residual spraying (IRS) in the department of Atacora in the Northwest of Benin. This study assessed community knowledge, perceptions and practices about malaria prevention especially about Indoor Residual Spraying (IRS), as well as data related to the type of human dwellings. Cross-sectional study was conducted between September and October, 2010. The results of a total of 7,878 respondents show little knowledge of populations about malaria. There was however a variety of protective measures against mosquito bites including bednets which are the most used. Moreover, IRS was accepted by 98.74% of respondents. Most (79.84%) of the walls were smooth and lend themselves well to the insecticide treatment.
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To implement indoor residual spraying (IRS), the department of Atacora was selected in Benin. Entomological surveys were performed before IRS implementation. Mosquitoes were sampled by Pyrethrum spray catch and were identified... more
To implement indoor residual spraying (IRS), the department of Atacora was selected in Benin. Entomological surveys were performed before IRS implementation. Mosquitoes were sampled by Pyrethrum spray catch and were identified morphologically and by molecular methods. The Plasmodium falciparum circumsporozoite indices were measured by enzyme linked immunosorbent assay (ELISA). Molecular detection of pyrethroid knock down resistance and that of insensitive acetylcholinesterase were performed. Susceptibility status of Anopheles gambiae was determined using World Health Organization (WHO) bioassay tests to various insecticides. A. gambiae s.l. was the main species harvested in houses (81.71%) and A. gambiae s.s is practically the only member that was found. Both M and S forms were in sympatry, but the molecular S form was predominant (94.42%). A. gambiae s.l were susceptible to bendiocarb but fully resistant to organochlorine (DDT), permethrin and deltamethrin. Entomological inoculatio...
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Although effective malaria control measures such as long lasting insecticidal nets (LLINs) have been promoted, relatively little is known about their coverage dimension. However, usage varies among households, and such variation may... more
Although effective malaria control measures such as long lasting insecticidal nets (LLINs) have been promoted, relatively little is known about their coverage dimension. However, usage varies among households, and such variation may seriously limit the potential impact of nets. Moreover, the efficacy of these measures against Anopheles gambiae in some departments is unknown. The objective of this study was to investigate LLINs coverage and use, and their efficacy against A. gambiae in Ouémé department after a mass free distribution. A post survey campaign was undertaken in January, 2012 to assess the effect of campaign six months after LLINs (Olyset net) free distribution in southern Benin. A questionnaire has been provided to heads of 1,600 households randomly selected from four districts. Despite LLINs use reaching more than 80%, coverage was low at 50.9%. A considerable damage rate (14%) of Olyset nets after only 6 months of use was observed. Bioassays revealed inefficacy of olys...