Résumé
Rift Valley fever (RVF) is a mosquito-borne viral zoonosis caused by RVF virus (RVFV), a member of the Phlebovirus genus (family Phenuiviridae). Although the cycle of RVFV infection in savannah regions is well documented in Africa, its distribution in tropical rainforest areas has been poorly investigated. In the context of a PhD with the support of the EBO-SURSY project, we conducted a study in the Northeast of Gabon (province of Ogooué-Ivindo) mainly composed of primary forest to evaluate the circulation of RVFV among hunted wildlife animals, displayed roadside and sold for consumption. Among a total of 163 animal samples collected, four animals from Cephalophus species were detected positive to RVFV by PCR (polymerase chain reaction). Phylogenetic analysis revealed a close proximity of the four sequences of RVFV from Gabon with the nucleotide sequence of Namibia 2004 and the Egyptian clade A. A cross-sectional survey in populations of sheep and goats living in villages within the same area was also conducted to determine the prevalence of immunoglobulin G (IgG) specific to RVFV in small ruminants. From a total of 306 animals (214 goats and 92 sheep), an overall RVFV specific antibody prevalence of 15.4% was found by ELISA. Unexpectedly, our study showed that the prevalence of anti-RVFV antibodies was higher in goats compared to sheep (20.1% versus 3.3%), suggesting a greater sensitivity or exposure of goats to RVFV. Age, sex, and season were not significant risk factors. Our findings highlight the risk of RVF for domestic ruminants bred in this region and for the human rural population living in contact with these animals. In addition, they emphasize the need to develop adequate control measures to limit this public health threat, such as awareness campaigns for villagers on the risk of RVFV infection through the manipulation of contaminated animals.