Re-emergence of Crimean Congo hemorrhagic fever virus in Kedougou, south-eastern Senegal in 2023: Epidemiological and zoological investigations of the first symptomatic human case.

Crimean-Congo hemorrhagic fever (CCHF) is a zoonosis transmitted mainly by ticks. In Senegal, the CCHF virus has been circulating since at least 2003. However, the first symptomatic human case was detected and confirmed only in 2023 in the southeastern part of the country. Following this detection, a survey of humans, animals and ticks was launched to better characterize the ecology of this virus in this area. Human samples were tested by ELISA and RT-PCR. Serum and tick samples collected from cattle, sheep and goats were tested by ELISA and by RT-PCR, respectively. Antibodies against CCHFV were detected in 0.77 % of humans and 14.18 % of animal sera. The highest seroprevalence was observed in cattle (58.3 %), followed by goats (33.33 %) and sheep (8.33 %). The tick infestation rate was higher in cattle (8.2 %) than in sheep (1.2 %), while goats were not infested. Hyalomma rufipes was the first tick found infected in southeastern Senegal with a CCHF viral minimum field infection rate of 13.3 %. Thus, this study enabled us to better understand the mechanisms of CCHFV emergence in southeastern Senegal.