Razaki Ossè

Dengue is a viral infection transmitted by mosquitoes of the Aedes genus, responsible for millions of cases each year. In Benin, several outbreaks have been reported, particularly in Abomey-Calavi, where the first dengue-related death was recorded in 2019. In the absence of a specific treatment, vector control remains the primary preventive measure. However, the emergence of insecticide resistance, notably through kdr mutations, could compromise its effectiveness. This study aims to identify the dengue virus serotypes circulating in the commune of Abomey-Calavi and to assess the frequency of kdr mutations V410L , V1016G , V1016I , F1534C , and S989P in Aedes aegypti and Aedes albopictus mosquitoes. Mosquitoes were collected in August 2024 from four arrondissement Togba, Calavi, Akassato, and Godomey through morning and afternoon spraying. After morphological identification, molecular analyses were conducted to detect the viral serotypes and kdr mutations. A total of 218 Aedes mosquitoes were collected, with a predominance of Aedes aegypti (68.8%) compared to Aedes albopictus (31.2%). The overall dengue positivity rate was 23.39% (95% CI: 17.9–29.6). The most frequent serotype was DENV-3 (12.4%), followed by DENV-2 (6.9%), DENV-1 (5%), and DENV-4 (0.09%). Six mosquitoes were co-infected with two serotypes. Kdr mutations were detected in both species, with frequencies of 45% for V1016G , 44% for S989P , 40% for F1534C , 22% for V410L , and 19% for V1016I. Four mosquitoes carried three simultaneous mutations, while twenty-two carried two. These results highlight the active circulation of the dengue virus and the presence of kdr mutations in Aedes mosquitoes in Abomey-Calavi. However, no significant association was observed between dengue infection and kdr mutations, and their distribution was independent of the viral serotype. These findings emphasize the need for regular monitoring of kdr mutations to adapt vector control strategies and limit the spread of dengue.

Pyrethroid resistance in Anopheles gambiae s.l. compromises malaria vector control in sub-Saharan Africa. In Benin, resistance has been documented for over

Introduction: Ticks, particularly Rhipicephalus microplus , are major blood‐sucking ectoparasites of livestock, causing considerable economic losses both through their direct pathogenic effects and their role as vectors of infectious agents. However, tick diversity, host association and pathogen carriage remain insufficiently documented in Southern Benin. This study investigated tick species composition, anatomical attachment preferences, host breed associations and the molecular detection of selected bacterial pathogens in six municipalities of Southern Benin. Methods: Ticks were collected from cattle and morphologically identified. Community structure was explored using multivariate analysis. A subset of engorged R. microplus specimens was screened for Bartonella spp. and Rickettsia spp. using conventional PCR. Results: The tick fauna was dominated by R. microplus , with additional detection of Amblyomma variegatum and other Hyalomma , Haemaphysalis and Rhipicephalus species. Ticks were mainly attached to ears, axillae and trunk. Spatial variation was observed but should be considered exploratory given the limited number of sampling sites. Molecular analysis detected Bartonella spp. and Rickettsia spp. DNA in tested ticks. Species proportions reflect relative abundance rather than true prevalence, and pathogen detection was based on genus‐level PCR without sequencing confirmation. Conclusion: These findings contribute to the understanding of tick ecology and pathogen circulation in Southern Benin and highlight the need for probabilistic sampling and sequencing‐based confirmation in future epidemiological studies.

Pyrethroid resistance in Anopheles gambiae sensu lato threatens the efficacy of long-lasting insecticidal nets (LLINs) in Benin. District-level resistance

The Plasmodium transmission-blocking endosymbiont Microsporidia MB was previously identified in Anopheles gambiae s.l., but its association with the carria

Background: Animal African trypanosomosis (AAT) remains a major constraint to livestock production across sub‐Saharan Africa despite ongoing control efforts. Although several studies have assessed farmers’ knowledge, attitudes, and practices (KAP) regarding AAT in cattle production systems, little is known about small ruminant and pig farmers, particularly in Benin. This study assessed farmers’ KAP regarding tsetse flies and AAT and identified the sociodemographic factors associated with disease awareness in southern Benin. Methods: A community‐based cross‐sectional survey was conducted between September and December 2024 among 384 randomly selected goat, sheep, and pig farmers from six communes in southern Benin. Data were collected using a structured, pretested questionnaire administered through the KoboCollect platform. Descriptive statistics were used to summarize respondents’ characteristics and KAP outcomes. Associations between sociodemographic variables and knowledge were assessed using chi‐square tests, while multivariable logistic regression identified independent predictors of knowledge. The results are presented as odds ratios (ORs) with 95% confidence intervals (95% CIs). Statistical significance was set at p < 0.05. Results: Among the 384 respondents, 62.24% were men, 45.57% were aged 41–50 years, and 56.77% had no formal education. Although most farmers (83.59%) correctly recognized tsetse flies, only 16.93% identified them as vectors of animal trypanosomosis, and 81.3% had never heard of the disease. Knowledge was significantly associated with sex ( χ ² = 74.527; p < 0.0001), age ( χ ² = 299.04; p < 0.0001), marital status ( χ ² = 873.37; p < 0.0001), educational level ( χ ² = 219.96; p < 0.0001), and occupation ( χ ² = 214.23; p < 0.001). In multivariable analysis, secondary and higher education, male sex, and agricultural occupations remained significant predictors of knowledge. While insecticides were perceived as the most effective control method (44.53%), only 14.1% of respondents reported using them, and two‐thirds implemented no specific vector control measures. Trypanocides were used by only 11.5% of farmers, whereas reliance on traditional plant‐based practices remained uncommon (2.86%). Conclusions: Small ruminant and pig farmers in southern Benin generally recognize tsetse flies but have limited knowledge of their role in AAT transmission and report low adoption of effective prevention and control measures. These findings highlight the need for targeted awareness campaigns, strengthened veterinary extension services, and integrated One Health approaches to improve AAT prevention and sustainable livestock production in Benin.

Insecticide-based interventions continue to serve as the cornerstone of Aedes mosquito control, the primary vectors of arboviruses. This study assessed the insecticide resistance profiles of four Aedes mosquitoes in three rural areas in southern Nigeria, where arbovirus outbreaks recently occurred. Using WHO tube tests and CDC bottle bioassays, four Aedes species (Aedes aegypti, Ae. albopictus, Ae. simpsoni complex and Ae. luteocephalus) were evaluated for susceptibility to commonly used public health insecticides, including deltamethrin, alphacypermethrin, permethrin, pirimiphos-methyl, chlorfenapyr and clothianidin. Biochemical assays were conducted using Ae. albopictus to establish the role of metabolic resistance mechanism. Amplification and sequencing of fragment of Ae. luteocephalus ITS1 gene molecularly confirmed its species identity. Aedes aegypti exhibited possible resistance to pirimiphos-methyl but remained susceptible to all other insecticides across study sites. Aedes albopictus showed resistance to DDT and possible resistance to pirimiphos-methyl, while remaining susceptible to pyrethroids. Aedes luteocephalus was resistant to pirimiphos-methyl but susceptible to all other insecticides. Aedes simpsoni complex was fully susceptible to all insecticides. Biochemical assays revealed elevated 𝛼-esterase and monooxygenase activities (3.4-fold and 2.54-fold, respectively) in exposed females of Ae. albopictus compared to the unexposed cohort. Overall, the low resistance levels observed underscore the need for sustained insecticide resistance monitoring and management to maintain the effectiveness of insecticide-based vector control strategies in Nigeria.

Epidemics of arboviruses in general, and dengue fever in particular, are an increasing threat in areas where Aedes (Ae.) aegypti is present. The effectiveness of chemical control of Ae. aegypti is jeopardized by the increasing frequency of insecticide resistance. The aim of this study was to determine the susceptibility status of Ae. aegypti to public health insecticides and assess the underlying mechanisms driving insecticide resistance. Ae. aegypti eggs were collected in two study sites in the vicinity of houses for two weeks using gravid Aedes traps (GATs). After rearing the mosquitoes to adulthood, female Ae. aegypti were exposed to diagnostic doses of permethrin, deltamethrin and bendiocarb, using Centers for Disease Control and Prevention (CDC) bottle bioassays. Unexposed, un-engorged female Ae. aegypti were tested individually for mixed-function oxidase (MFO), glutathione-S-transferase (GST) and α and β esterase activities. Finally, allele-specific PCR (AS-PCR) was used to detect possible kdr mutations (F1534C, S989P, and V1016G) in the voltage-gated sodium channel gene in insecticide-exposed Ae. aegypti. Most traps were oviposition positive; 93.2% and 97% of traps contained Ae. aegypti eggs in the 10^ème arrondissement of Cotonou and in Godomey-Togoudo, respectively. Insecticide bioassays detected resistance to permethrin and deltamethrin in both study sites and complete susceptibility to bendiocarb. By comparison to the insecticide-susceptible Rockefeller strain, field Ae. aegypti populations had significantly higher levels of GSTs and significantly lower levels of α and β esterases; there was no significant difference between levels of MFOs. AS-PCR genotyping revealed the possible presence of 3 kdr mutations (F1534C, S989P, and V1016G) at high frequencies; 80.9% (228/282) of the Ae. aegypti tested had at least 1 mutation, while the simultaneous presence of all 3 kdr mutations was identified in 13 resistant individuals. Study findings demonstrated phenotypic pyrethroid resistance, the over-expression of key detoxification enzymes, and the possible presence of several kdr mutations in Ae. aegypti populations, emphasizing the urgent need to implement vector control strategies targeting arbovirus vector species in Benin.

Epidemics of arboviruses in general, and dengue fever, in particular, are an increasing threat in areas where Aedes (Ae.) aegypti is present. The effectiveness of chemical control of Ae. aegypti is threatened by the increasing frequency of insecticide resistance. The aim of this study was to determine the susceptibility status of Ae. aegypti to public health insecticides and assess the underlying mechanisms driving insecticide resistance. Ae. aegypti eggs were collected in two study sites in the vicinity of houses for two weeks using Gravid Aedes Traps (GATs). After rearing mosquitoes to adulthood, female Ae. aegypti were exposed to the diagnostic doses of permethrin, deltamethrin and bendiocarb, using Centers for Disease Control and Prevention (CDC) bottle bioassays. Unexposed, un-engorged female Ae. aegypti were tested individually for mixed-function oxidase (MFO), glutathione-S-transferase (GST) and esterase activity. Finally, allele-specific PCR (AS-PCR) was used to detect kdr mutations (F1534C, S989P and V1016G) in the voltage-gated sodium channel gene in insecticide-exposed Ae. aegypti. Most traps were oviposition positive; 93.2% and 97% of traps contained Ae. aegypti eggs in the 10ème arrondissement of Cotonou and in Godomey-Togoudo, respectively. Insecticide bioassays assays detected resistance to permethrin and deltamethrin in both study sites and complete susceptibility to bendiocarb. By comparison to the insecticide-susceptibility Rockefeller strain, field Ae. aegypti populations had significantly higher levels of GSTs and significantly lower levels of  and  esterases; there was no significant difference between levels of MFOs. AS-PCR genotyping revealed the presence of the three kdr mutations (F1534C, S989P and V1016G) at high frequencies; 80.9% (228/282) of Ae. aegypti tested had at least one mutation, while the simultaneous presence of all three kdr mutations was identified in 13 resistant individuals. Study findings demonstrated phenotypic pyrethroid resistance, the overexpression of key detoxification enzymes and the presence of several kdr mutations in Ae. aegypti populations, emphasizing the urgent need to implement vector control strategies, targeting arbovirus vector species in Benin.