Distribution and ecological aspects of sand fly species from Kousseri, an endemic focus of visceral leishmaniasis in Northern Cameroon

Abstract

IntroductionKousseri in the Far North Region of Cameroon has long been known as an endemic focus of visceral leishmaniasis (VL), although the study on sand flies in this focus is scarce. The present study investigates the spatial distribution, seasonality, and ecological aspects of sand flies from Kousseri. This study is based on the need to optimize the effectiveness of leishmaniasis control programs in the northern part of the country. MethodsSand flies were sampled monthly over 12 months in five selected sites using CDC light traps. Only captured females were morphologically identified at species level based on valid keys. Results and discussionOverall, 4,214 sand fly specimens were collected during 360 trapping nights. The male/female sex ratio slightly favored females (1:1.04). The eudominant Sergentomyia antennata followed by both dominant Sergentomyia schwetzi and Sergentomyia squamipleuris were the most common and abundant species, accounting for 76.1% of the collection. Phlebotomus duboscqi, the confirmed vector of cutaneous leishmaniasis (CL) in West African foci, although rare in the collection, was found in four of the five surveyed sites. This sand fly species with Se. schwetzi abounded in peri-urban areas and, respectively, in animal shed and in uninhabited house biotopes, while Se. antennata and Se. squamipleuris prevailed in rural areas and, respectively, in animal shelter biotopes and outside dwellings. All caught sand fly species except Se. schwetzi, Sergentomyia clydei, Sergentomyia inermis, and Sergentomyia adleri prevailed during the dry season. The highest Shannon–Wiener index of sand flies due to the maximal richness and evenness was found in the urban area, in outdoor biotopes, and during the rainy season (H′ = 1.68, 1.80, and 1.74, respectively). These data provide evidence that less urbanized areas, animal shelters around the compounds, and the absence of precipitation (dry season) favored the dispersion of abundant sand fly species in Kousseri. Based on previous reports on Leishmania transmission, a surveillance plan is required to prevent an outbreak of VL or an establishment of CL or canine leishmaniasis (CnL) in this focus. Further research identifying the blood meal source and the Leishmania parasites in these insects is critical for providing insightful data to fight leishmaniasis in Northern Cameroon.