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Insecticide resistance

Malaria Control in Somalia. Photo credit: WHO Somalia

Insecticides form an essential part of vector control and is the most widely used and effective strategy to reduce the burden of vector-borne diseases. Knowledge of vector resistance to insecticides is thus crucial to the selection of effective vector control activities.

A situation analysis of 15 countries in the Eastern Mediterranean Region was carried out in 2022. This examined, for each country, the resistance status of vectors to available insecticides commonly used for public health, and the barriers to effective insecticide resistance management. The situation analysis also guided these countries to develop or update their insecticide resistance monitoring and management plans.

Data show that vector resistance to pyrethroids, organochlorines, organophosphates and carbamates is widespread in malaria and dengue-endemic countries. The Anopheles and Aedes mosquito vectors have been found to be resistant to multiple classes of insecticides.

In high burden countries, better monitoring of insecticide resistance in primary vectors of malaria and dengue/chikungunya is needed, as well as plans for managing and monitoring insecticide resistance.

Insecticide resistance monitoring and management plans are:

an integral part of the vector control aspect of national strategic plans for control of vector-borne diseases;
an up-to-date situation analysis for insecticide resistance monitoring and management;
a structure for planning future insecticide susceptibility testing;
a structured plan, which facilitates the collection and analysis of insecticide susceptibility data for decision-making on the use of vector control interventions;
a detailed and accurate plan to assist with resource mobilization; and
a clear record of country-specific challenges and needs to enable effective implementation of insecticide resistance monitoring and management.

Insecticide resistance is one of the major challenges in combating vector-borne diseases and is rapidly spreading among the main mosquito and sandfly vectors that transmit malaria, dengue and leishmaniasis, reducing the effectiveness of core insecticide-based tools such as insecticide-treated nets, indoor residual spraying, and larval control. This challenge is further exacerbated by the high cost of the newly prequalified alternative insecticides.