Daily and seasonal variation of the nuisance caused by Simulium damnosum s.l. in three epidemiological facies of onchocerciasis (Soubré, Bouaflé and Touba) in Côte d'Ivoire

Abstract

The stings of the blackflies create a nuisance that hinders the agricultural and fishing activities of rural populations. In order to respond to the concern of the latter, this study was carried out in three epidemiological facies of onchocerciasis in Côte d’Ivoire. The aim of the study was to determine the daily and seasonal variation of blackfly nuisance. To do this, blackflies were captured on humans, identified and dissected. The entomological data revealed a total of 4244 blackflies captured. The comparison between the daily periods and the blackfly nuisance reveals averages of 42.4; 2.03; 22.3 bites/man/ hour and 5.04; 10.06; 27.1 bites/man/hour recorded in the morning, afternoon and evening respectively in Soubré and Bouaflé. In Touba the respective averages of 12.06 and 83.06 bites/man/hour were recorded in the morning and evening. A significant difference was observed between the bite density received during the rainy and dry seasons (χ2 = 4.81; p = 0.022). The bite density recorded in the rainy season was about twice as high as in the dry season (OR=1.87). A significant nuisance due to blackflies appeared in the divisions of Soubré, Bouaflé and Touba and varied seasonally between localities. In order to eradicate this blackflies nuisance, the onchocerciasis control system should eliminate blackflies by various means such as the destruction of breeding sites.