INSECTICIDE SUSCEPTIBILITY STATUS OF AEDES AEGYPTI (DIPTERA: CULICIDAE) AND THE RISK OF YELLOW FEVER TRANSMISSION IN THE SAVANNAH, UPPER EAST AND UPPER WEST REGIONS OF GHANA

Aedes-borne diseases such as Yellow Fever and Dengue remain major public health challenges in many countries including Ghana. Ghana reported yellow fever in 2016 and recently in 2021 in the northern regions following an outbreak in neighbouring Burkina Faso. Sampling of Aedes mosquito larvae and adults was done in Damongo, Bolgatanga and Nadowli from 100 houses in each area using a stratified sampling method for 16 months, in the years 2015 and 2016. Standard methods were used to assess the risk of transmission and insecticide susceptibility status of Aedes aegypti mosquitoes. A total of 6,630 Aedes mosquitoes were collected using larval sampling from all the three study areas. Out of this number, 34.0% were from Bolgatanga, 43.3% from Damongo and 22.3% from Nadowli. Among the Aedes species collected, 97% were Aedes aegypti, 2.8% were Aedes vittatus and 0.2% were Aedes simpsoni. All the study sites were identified as high risk by the high larval indices observed in 2015 and 2016. All the Aedes aegypti collected from Bolgatanga showed suspected resistance to deltamethrin, permethrin and propoxur based on WHO criteria (deltamethrin 94%, permethrin 93% and propoxur 96%). Aedes aegypti obtained from Damongo were resistant to pyrethroids but susceptible to carbamates. Out of the 200 Aedes aegypti tested, 130 (65%) had the kdr gene mutation (F1534C). Regular monitoring of insecticide resistance development in the Aedes population is necessary to help improve control strategies and reduce risk of yellow fever transmission in the study sites.