High Plasmodium Infection Rate and Reduced Bed Net Efficacy in Multiple Insecticide-Resistant Malaria Vectors in Kinshasa, Democratic Republic of Congo

Accounting for approximately 11% of all malaria cases, the Democratic Republic of Congo (DRC) is central to malaria elimination efforts. To support vector control interventions in DRC, we characterized the dynamics and impact of insecticide resistance in major malaria vectors in 2015. High Plasmodium infection rates were recorded in An. gambiae and An. funestus with P. falciparum predominant over P. malariae. Both mosquito species exhibited high and multiple resistance to major public health insecticide classes. The extremely high resistance to permethrin and DDT in An. gambiae (low mortalities after 6 hours exposure) is worrisome, and is supported by a reduced insecticidal effect of bednets against both mosquito species in laboratory tests. Metabolic and target site insensitivity mechanisms are driving this resistance in An. gambiae but only the former was observed in An. funestus. These findings highlight the urgent need for actions to prolong the effectiveness of insecticide-based interventions in DRC.