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06 Jun 2017

The Institut Pasteur in Bangui identifies multiple mechanisms of insecticide resistance in malaria vector mosquitoes

In the Central African Republic (CAR), malaria is a major cause of morbidity and mortality. Vector control remains one of the strategies to reduce the transmission of this infection. Unfortunately, no data on insecticide resistance of malaria vectors is available. Researchers from the Institut Pasteur in Bangui led by Mamadou Osmane Diath working in collaboration with the universities of Denver in the United States and Abomey-Calavi in Benin provide the first assessment of insecticide resistance status in Anopheles gambiae in Bangui.

Their paper, published in Parasites and Vectors (January 2017), shows that the populations of Anopheles gambiae present in Bangui are resistant to DDT and pyrethroids. The coexistence of these mechanisms of resistance constitutes a serious obstacle to the anti-vectorial fight.

(© Institut Pasteur de Bangui)

During the year 2014 in Bangui the capital city of CAR, the scientist collected samples of An. gambiae in seven districts of the city. In the laboratory, they conducted insecticide susceptibility tests to assess the level of sensitivity (or resistance) of mosquitoes to different types of insecticides by measuring mortality rate after 24 hours exposures. Bioassays have shown that all tested An. gambiae populations are resistant to dichlorodiphenyltrichloroethane (DDT) and and pyrethroids. Pyrethroids are the only family of insecticides recommended for impregnated mosquitoe nets. There is an urge for new studies on vector control strategies. On the contrary, they are sensitive to malathion and fenitrothion, suggesting that these insecticides can be used for vector control measures. They subsequently performed biochemical analysis to investigate the mechanisms underlying the resistance to DDT and pyrethroids. They found a common mutation and a high level of detoxification enzymes inhibiting effects of insecticides.

The publication:
Evidence of multiple insecticide resistance mechanisms in Anopheles gambiae populations in Bangui, Central African Republic
, Parasit Vectors. 2017; 10: 23.
Olé-Sangba ML, Sidick A, Govoetchan R, Dide-Agossou C, Ossè RA, Akogbeto M, Ndiath MO

From the Institut Pasteur in Bangui (18 May 2017, in French)