Vector resistance to pyrethroids and impact on the efficacy of insecticide-treated mosquito nets in Southern Benin

The use of Long Lasting Insecticidal Nets (LLINs) to protect population from malaria is one of the main strategies which decline the malaria morbidity and mortality in several trials carried out in different countries. However, resistance to pyrethroids is one of some problems which compromise the LLINs effectiveness. This study compares the effectiveness of LLINs in two areas, low and high resistance areas. Mosquitoes were collected in 8 clusters of Plateau department from July 2011 to June 2013 using human landing catch. The heads and thorax of Anopheles gambiae collected were analyzed using the ELISA Circum- Sporozoite Protein test. The human biting rates and entomological inoculation rate (EIR) were compared between areas. On the total of 4228 vectors tested, 220 were positive for Plasmodium falciparum. The EIR obtained in the high resistance zones were not significantly higher (p >0.05) than those obtained in the low resistance zones. In fact, the EIR ranged from 66.69 infected bites/human/6months to 89.67 infected bites/h/24 months in the high resistance zones compared to 184.89 infected bites/h/6 months to 357.53 infected bites/h/24 months in the low resistance zones. This study has not shown evidence of an impact of resistance on the efficacy of LLINs. Key words: Resistance, long lasting insecticidal nets effectiveness, malaria, An. gambiae.