Entomological Surveillance of Aedes mosquitoes, vectors of arboviruses in a peri-urban area of Yaounde, Centre, Cameroon

Introduction: Vector surveillance is essential to control several infectious vector-borne diseases. Aedes Mosquitoes are the main vectors of arboviruses diseases affecting humans such as Dengue, Chikungunya, yellow fever and Zika represent a serious concern in tropical/subtropical countries and are considered emerging or re-emerging. Due to the absence of effective treatments and vaccines against most arboviruses diseases, vector control remains the most effective measure to prevent further resurgence. It is important to measure variation in their population to predict the environmental conditions promoting their development. In this line, a large-scale surveillance was undertaken in a peri-urban area of Yaounde, Cameroon to study the spatio-temporal distribution of Aedes population. Methods: The study was conducted in Nkolbisson, a peri-urban district of Yaounde over one year. A total of 100 ovitraps were placed in 14 randomly selected stations across the study site, they were fixed to supports such as banana tree trunks, stakes and tree trunks (height: 1m) around dwellings. Those ovitraps containing filter paper soaked in spring water to collect Aedes eggs. Seven days later, ovitraps were checked and ovitrap-related indices were estimated. The filter paper was replaced each time the sites were visited. Immature stages were counted, kept and raised until the adult stage and morphologically identified after emergence using the identification keys. Results: A total of 51,499 mosquitoes belonging to 3 genus namely Aedes, Culex and Eretmapodites and 14 species were collected. Aedes genus was predominant (n=51,146; 99.31%). Morphological identification of the collected species mostly reveals the presence of Aedes albopictus (88.14%), followed by Aedes simpsoni (5.97%) and Aedes aegypti (5.12%) and we see that the main vector in this site was Aedes albopictus and there was no significant difference in the adult mosquito's numbers Aedes simpsoni and Aedes aegypti (P˃0.05). The highest values for Aedes egg density and positive ovitraps percentage were recorded in Mai 2023 and April 2023 respectively. High densities recorded in ovitraps through the study site highlights a potentially high-risk area for dengue epidemics. Discussion: The eggs abundance and density per traps indicates a high level of infestation at the study site. The widespread distribution of Ae. albopictus highlights its adaptability and competitive advantage over Ae. aegypti and native species. The presence of other mosquito species alongside Aedes points to competition and potential co-transmission of diseases. This finding highlights the utility of ovitraps for broader vector surveillance. Conclusion: The implementation of surveillance and control programs for arboviruses vectors is urgent required in view of the increase in cases of arboviruses. Ovitraps can therefore be an effective tool for arboviruses surveillance. These data provide important entomological information that could be useful in designing an effective integrated program to control Aedes vectors in the city of Yaounde.