Backgroung : Onchocerca volvulus, the causal agent of river blindness, is transmitted by the blackfly Simulium damnosum s.l., which breeds in turbulent river waters. This study focused on the nuisance, biting rates and transmission potential of S. damnosum s.l. on the hydro-agricultural scheme site in the commune of Giembe in northern Côte d'Ivoire.

Methods : Blackflies were collected using the human landing catch collection method on two consecutive days of each month during the rainy season from September to October 2023. Samples from each site were dissected monthly for estimation of parity and O. volvulus infection rates.

Results : A total of 3714 blackflies of the species S. damnosum s.l. were captured during the study period, of which 1795 (48.3%) were caught at site A and 1919 (51.7%) at site B. These were species from the savannah group (3688; 99.3%) and species from the forest group (26; 0.7%). Of the 3703 flies dissected, 1029 (27.6%) were parous, while the remainder were nulliparous female flies 2674 (72.4%) and no black flies were found harbouring O. volvulus parasites. It composed The daily cycle of aggression showed two peaks : one between 7 and 9 a.m. and the other between 2 and 6 p.m. Monthly bite rates were very high, ranging from 13800 to 3975 bites/person/month and the average daily aggression rate in the study area was 168.8 bites/person/day.