Mosquitoes of the genus Aedes are the most important arthropod disease vector. Dengue virus (DENV) and Chikungunya virus (CHIKV) are the main arboviruses distributed throughout the world. Based on entomo-virological surveillance, appropriate public health strategies can be adopted to contain cases and control outbreaks. This study aims to show the potential performance of two new molecular methods for detecting DENV serotypes and CHIKV in mosquitoes. Mosquitoes were collected in urban and sylvatic areas of Bobo-Dioulasso, Burkina Faso, between July and August 2023. DENV and CHIKV were screened using new multiplex RT-PCR and RT-qPCR methods. A total of 2150 mosquitoes were trapped, consisting of 976 Aedes (959 Ae. aegypti, 6 Ae. furcifer, and 11 Ae. vittatus) and 1174 Culex sp. These were grouped into 39 pools, with each pool containing a maximum of 30 mosquitoes. Molecular screening revealed that 7.7% (3/39) of the pools were positive for DENV. Specifically, DENV-1 was detected in one pool (1/3), and DENV-3 was found in two pools (2/3). All pools tested negative for CHIKV. The overall minimum infection rate (MIR) of DENV in this study was 3.07 (95% CI: 2.24–19.86). This study shows the usefulness of our new molecular tools for the surveillance of DENV serotypes and CHIKV.

Arboviral diseases are emerging public health challenges in Burkina Faso, largely driven by the proliferation of Aedes aegypti mosquitoes in the environment. Effective surveillance of arbovirus circulation is critical to inform interventions. From August 2022 to June 2023, we implemented a comprehensive entomological surveillance platform in five sectors of Bobo-Dioulasso. Surveillance methods included oviposition traps to collect eggs, larval surveys in some concessions per sector conducted bimonthly, and adult mosquito collections using BG-Sentinel traps and Prokopack aspirators. Mosquito samples colonized by Ae. aegypti were identified morphologically, confirmed by conventional PCR, and screened by RT-PCR for dengue (DENV), chikungunya (CHIKV), yellow fever (YFV), and Zika (ZIKV) viruses. Molecular analysis detected dengue virus and yellow fever virus in mosquito pools from sector 22 and chikungunya virus in sectors 9 and 26; no Zika virus was found. This study demonstrates the successful establishment of an integrated entomological surveillance platform capable of capturing the spatial and temporal dynamics of arboviral vectors and virus circulation in Bobo-Dioulasso. The identification of active dengue and chikungunya transmission underlines the urgent need for sustained vector monitoring and targeted control strategies. Our approach provides a scalable model for arboviral disease surveillance and epidemic preparedness in West African urban settings.

Background: One of the alternatives for controlling malaria is using mosquito symbiotic bacteria to reduce Plasmodium transmission. Species of Serratia , a genus of the Enterobacteriaceae family, have been isolated from the midgut of mosquitoes and are commonly found in water, soil and plant surfaces. These bacteria have shown great promise in blocking the transmission of Plasmodium in mosquitoes. The aim of this study was to isolate and characterize the genus Serratia within the Anopheles gambiae complex from Burkina Faso. Methods: Mosquitoes were collected in three field sites located in Houet Province in western Burkina Faso (Dioulassoba, Vallée du Kou and Soumousso), transported to the laboratory and identified morphologically. The salivary gland, midgut, spermatheca, ovary of females and testis of males were dissected and their contents ground up. Different species of Serratia were identified by PCR targeting of the luxS gene of Serratia, followed by 16S ribosomal RNA (rRNA) sequencing. Results: Molecular analyses identified the isolates as belonging to the genus Serratia , and phylogenetic reconstruction revealed that these strains are highly similar to one another but distinct from Serratia strains previously reported in neighboring countries such as Ghana and Nigeria. The overall prevalence of Serratia among malaria vectors was 13.3%. This prevalence varied according to the development stage of mosquitoes, locality of origin and mosquito organ. Only one Anopheles coluzzii mosquito was co-infected with Serratia and Plasmodium falciparum . Conclusions: The results of this study support the presence of Serratia spp. in wild mosquitoes from Burkina Faso, we well as their potential use in malaria control. Graphical

Mosquitoes genus Aedes are the most important arthropod disease vector. Dengue Virus (DENV) and Chikungunya Virus (CHIKV) are the main arboviruses distributed in the world. Based on entomo-virological surveillance, appropriating public health strategies can be addressed to contain cases and control outbreaks. This study aims to show the potential performance of two new molecular methods for detecting DENV serotypes and CHIKV in mosquitoes. Mosquitoes were collected in urban areas and sylvatic areas between July to August 2023, DENV and CHIKV were screened using new multiplex RT-PCR and RT-q PCR. A total of 2150 mosquitoes were trapped including 976 Aedes (959 Ae. egypti, 6 Ae. furcifer and 11 Ae. Vittatus) and 1174 Culex from 39 pools of a maximum of 30 mosquitoes each, tested by molecular screening, 7.7% (3/39) were positive for DENV, DENV-1 was detected in one pool (1/3), and DENV-3 in two pools (2/3). All the pools were negative for CHIKV. The overall minimum infection rate (MIR) of DENV in this study was 3.07 (95% CI: 2.24 —19.86). This study shows the usefulness of our new molecular tools in DENV serotypes and CHIKV surveillance.

The endosymbiotic bacterium Wolbachia, which is widely distributed among terrestrial arthropods, represents a promising tool for vector control. Its interest lies in its ability to block the transmission of arboviruses from vectors to humans and to promote the spread of infected individuals through various mechanisms affecting host reproduction. At the molecular level, Wolbachia exhibits considerable diversity structured into several phylogroups. The present study aimed to identify the phylogroups of Wolbachia infecting Aedes aegypti in Côte d’Ivoire. Larvae of Aedes aegypti were collected in Korhogo, Bouaké, Abidjan, and Bingerville in 2022 and 2024 and reared in the laboratory. After adult emergence, female mosquitoes were identified morphologically and confirmed by molecular identification using a species-specific PCR targeting the ITS2 gene. Wolbachia detection was performed by quantitative PCR (qPCR) targeting the 16S rRNA gene, followed by nested PCR amplification of positive samples. The resulting amplicons were sequenced and subjected to phylogenetic analysis based on the 16S rRNA gene. Overall, 13.43% (6/67) in 2022 and 7.5% (15/200) of the analyzed mosquitoes were infected with Wolbachia. The prevalence of infection differed significantly between sampling sites and sampling periods. Among the identified strains, 83.33% (5/6) belonged to phylogroup B, while 16.67% (1/6) were assigned to phylogroup Q. The studied Aedes aegypti populations thus exhibit a low natural prevalence of Wolbachia infection, associated with the presence of two distinct phylogroups. These findings highlight the need for targeted intervention strategies to promote the establishment and stability of the endosymbiont within natural mosquito populations.