Baseline Entomological Indicators of Malaria Transmission Prior to the Implementation of Indoor Residual Spraying in Malanville District, Northern of Benin.

Abstract

Background : To assess malaria transmission in the district of Malanville in northern Benin, an entomological study was carried out in two sites from January to December 2016. Methods : Adults mosquitoes were collected monthly by human landing catches (HLC) over two consecutive nights (8:00 PM - 6:00AM) in four compounds randomly selected from each study site. These collections were completed by indoor pyrethrum spray catches (PSC) in 10 additional compounds in each study site. The sampling method used in each compound was consistent during the study period. Head-thoraces of female mosquitoes captured by HLC were tested for the presence of circumsporozoite protein (CSP). Mosquitoes captured by PSC were preserved for species identification using polymerase chain reaction (PCR). Results : i)– Overall, 9,019 female mosquitoes were caught by PSC and 21,474 by HLC; ii) – In Malanville, Plasmodium falciparum was mainly transmitted by An. gambiae s.s where malaria transmission was high from June to November during the rainy season and declined during the dry season (December-May); iii) – The average entomological inoculation rate (EIR) was significantly higher during the rainy season(0.8 infectious bites/person/night) compared to the dry season (0.1 infectious bites/person/month) (P<0.05). Conclusion : These findings showed malaria transmission is unimodal in the city of Malanville. The main malaria parasite, Plasmodium falciparum , was transmitted by An. gambiae s.s . Results from this study will be useful for National Malaria Control Program authorities in the choice of vector control strategies to prevent malaria transmission in the district of Malanville.