Detection of DENV-1, DENV-3, and DENV-4 Serotypes in and , and Epidemic Risk in the Departments of Oueme and Plateau, South-Eastern Benin.

This study conducted in the departments of Oueme and Plateau aims to assess the presence of the dengue virus and its different serotypes in and , as well as the epidemic risk incurred by the populations. Collections of adult mosquitoes using human landing catches (HLC) were carried out in six communes, three (Porto-Novo, Adjarra, and Avrankou) in the Oueme department and the rest (Ifangni, Kétou, and Pobè) in the Plateau department. Pools of ten mosquitoes were formed, and stored at -80°C in RNA later. RT-PCR was used to detect dengue virus, and conventional PCR for the different serotypes. Inspection of water containers and collection of larvae was performed inside and around each house to calculate the stegomyan indices. In the six communes, the dengue virus was present both in and . Combined data of the two species at the communes level revealed infection rates ranging from 80.00% (95% CI: 61.43-92.29) to 96.67% (95% CI: 82.78-99.92). In all the communes, the values of stegomyan indices reached the WHO threshold, which indicates the existence of the risk of an arbovirus epidemic. In addition, the infection rates were similar for [88.19% (95% CI: 81.27-93.24)] and [86.79% (95% CI: 74.66-94.52)]. The three virus serotypes detected in the pools of were DENV-1, DENV-3, and DENV-4, with a high prevalence for the first two. This study revealed that three serotypes (DENV-1, DENV-3, and DENV-4) of dengue virus circulate in and in the departments of Oueme and Plateau. Moreover, the risk of transmission of arboviruses was globally high and variable from commune to commune. This information is essential for informed decision-making in the preventive control of the disease.