Insecticide resistance in malaria vector mosquitoes at 5 selected districts in Ghana, West Africa

Abstract

Background: The application of insecticides targeted at vector mosquitoes through Indoor Residual Spraying has been adopted as one of the most effective ways of reducing the burden of malaria. However, key to the success of such a strategy is baseline information about local vector population and their profiles to any of the chemicals applied. This paper presents baseline resistance and susceptibility profiles of mosquitoes collected from 5 districts in Ghana earmarked for Indoor Residual Spraying.
Methods: We collected mosquitoes using hand-held aspirators and determined their susceptibility to the four classes of insecticides approved by the WHO for IRS. We further used morphological identification tools to identify the species of the mosquitoes collected.
Results: Out of the total of 5500 mosquitoes collected, 5113 (93.0%) and 387 (7.0%) belonged to the Anopheles gambiae and An. funestus complexes respectively. Overall, mosquitoes collected showed susceptibilities ranging from 97-100% to the Organophosphates and the Carbamates (94.3-100%) but were highly resistant to the Organochlorides (32.2-57.8%) and Pyrethroids (27.7-72.3%).
Conclusion: Our data clearly highlights the importance of prior knowledge of local mosquito populations to any of the recommended classes of insecticides before IRS is incorporated as part of any intended or existing malaria vector control strategy.

Key words: Anopheles gambiae, resistance, susceptibility, Indoor residual spraying