Submission ID 131059
| Issue/Objective | Rift Valley fever (RVF) is an emerging arboviral zoonosis with a significant impact on public health in Africa. In Senegal, sporadic human cases have been reported since 1987, and a large outbreak with human fatalities was declared in September 2025. Despite this, population-level data on human exposure to Rift Valley fever virus (RVFV), particularly in relation to livestock contact, remain limited, and the historical transmission dynamics of the virus are poorly characterized. This study aimed to estimate RVFV prevalence among different population groups, identify associated risk factors, and to reconstruct the historical epidemiology of the virus in Senegal. |
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| Methodology/Approach | A cross-sectional seroepidemiological study was conducted in three ecologically distinct sites in Senegal: Podor, Linguere, and Kedougou from 2022 and 2024. Healthy individuals with varying levels of animal exposure (daily, weekly, occasional, or none) were enrolled. Sera samples were tested for anti-RVFV IgM and IgG antibodies using ELISA, and positive samples were confirmed by plaque reduction neutralization tests (PRNT). Multivariable logistic regression was used to identify factors associated with RVFV IgG seropositivity. In Podor, serocatalytic modeling was applied to IgG-positive data to reconstruct historical transmission dynamics. |
| Results | Among 861 participants, RVFV IgG seroprevalence was 27.7% in Podor, 4.2% in Linguere, and 0.7% in Kedougou, resulting in an overall seroprevalence of 10.6%. Seroprevalence was higher among men than women, and increased with age in all sites except Kedougou. In Podor and Linguere, the prevalence of RVF is similar regardless of the level of exposure relative to livestock and exposure was more common during the rainy season. In multivariable analysis, age and locality remained the factors independently associated with RVFV IgG seropositivity. Serocatalytic modelling in Podor identified three distinct periods characterized by increased forces of infection. |
| Discussion/Conclusion | These findings indicate substantial and heterogeneous exposure to RVFV in Senegal, with evidence of long-standing virus circulation in certain areas. Strengthening integrated human-animal surveillance and targeted prevention strategies is essential to improve early detection and control of Rift Valley fever in endemic settings. |
| Presenters and Affiliations | Elisabeth Thérèse FAYE Institut Pasteur de Dakar Malick Fall Animal Biology Department, Faculty of Sciences and Techniques, Cheikh Anta Diop University, Dakar, Senegal, Etienne Simon-Lorière Institut Pasteur de Paris Samba Niang Sagne Institut Pasteur de Dakar Mareme Seye Thiam Institut Pasteur de Dakar Noe Ochida Institut Pasteur de Paris Ousseynou Sene Institut Pasteur de Dakar Sokhna Mayemouna Diop Institut Pasteur de Dakar Ndeye Sakha Bob Institut Pasteur de Dakar Moussa Dia Institut Pasteur de Dakar Moussa Moise Diagne Institut Pasteur de Dakar Oumar Faye Institut Pasteur de Dakar Ndongo Dia Institut Pasteur de Dakar Diawo Diallo Institut Pasteur de Dakar Anavaj Sakuntabhai Institut Pasteur de Paris Cheikh Talla Institut Pasteur de Dakar Simon Cauchemez Institut Pasteur de Paris Cheikh Loucoubar Institut Pasteur de Dakar Mamadou Aliou Barry Institut Pasteur de Dakar Gamou Fall Institut Pasteur de Dakar |
