Distribution and trends of insecticide resistance in malaria vectors in Ethiopia (1986 -2017): a review

Introduction: Malaria vector control intervention relies mainly on long-lasting insecticidal nets and indoor residual spraying. The distribution and frequency of insecticide resistance have increased dramatically and are now threatening the global success of the control program. Resistance to the public health insecticides has been frequently reported in Ethiopia. This review aimed at mapping the spatial and temporal distribution, and the trend of insecticide resistance to different insecticides used for vector control in the Ethiopian populations of Anopheles arabiensis.Objective: To assess the distribution and trends of insecticide resistance, which could help the implementation of Insecticide Resistant Management strategy in the country.Methods: Relevant published articles and reports on malaria mosquito resistance management were reviewed. The obtained data were organized and the geographical distribution resistance was mapped. For those sites where resistance was reported, but had no GPS coordinates, the coordinates were obtained from Google Earth.Results: Since 1986, resistance increased from time to time even after the country stopped DDT spraying. The Anopheles arabiensis population has developed resistance to pyrethirods and organochlorine class insecticides in most parts of the country. Few vector populations also developed resistance to carbamate insecticides. However, most populations surveyed were fully susceptible to primiphos–methyl and fenthrithion.Conclusions: Wild populations of An. arabiensis were found resistant to pyrethroid insecticides used for treating nets, therefore there is a need to condsider new generation nets to improve the protective effect of nets. As the vector was fully susceptible to primiphos–methyl, it can be used as an alternative insecticide for indoor residual spraying. Moreover, insecticide resistance management strategies should be implemented in the country in such a way that a change in insecticide pattern is ensured before the resistance to a certain insecticide reaches its tipping point