[Atypical activity rhythm in Aedes aegypti in a sub-sudanian savannah zone of Côte d'Ivoire]

Ae. aegypti is vector of many arboviruses of medical and/or economical importance. It transmits the yellow fever, dengue and Chikungunya viruses. Small water collections constitute its potential breeding sites. Three different populations of Ae. aegypti are known in Africa: a selvatic population breeding in tree holes and rock holes, a population breeding in discarded containers in peri-domestic area and a third population which breeds in drinking water containers and various receptacles inside habitations. The biting activity of this vector is diurnal in East Africa, but it occurs usually at sun set in West Africa. An entomological survey was carried out in a village situated in Sudan savannah zone of Côte d'Ivoire to appreciate Aedini populations in dry season. Mosquito collections were organized from 4 p.m. to 6 a.m. The results showed an atypical biting activity rhythm in dry season, characterized by a permanent activity during the whole night up to 6 a.m., a pronounced tendency to endophagy and a peak biting aggressivity at midnight inside as well as outside houses. The epidemiological implications of such an atypical rhythm of biting activity are analysed. It is suggested to appreciate the extent of this phenomenon through some more investigations in the villages of the area and determine the induced stegomyian focus.