Operationalizing the One Health Approach to Zoonotic Disease Surveillance in a COVID-19 Pandemic Context: The Added Value of a Joint, Multisectoral, Transdisciplinary and Systemic Investigation of a Rift Valley Fever Outbreak in Fatick, Senega

Abstract Located in central-western Senegal, Fatick is a pastoralist area with over 26 health facilities, including Ndiaye-Ndiaye Health Post. The latter notified a Rift Valley fever (RVF) case during the 41st epidemiological week (EW), while outbreaks were noted in northern Senegal and its border country. Thus to investigate this outbreak, despite the COVID-19 pandemic context, a cross-sectional study (respecting ethical considerations) was conducted in October 2020 using a systemic and One Health approach. Data were collected by a multisectoral and transdisciplinary team using observation, literature reviews, interviews and other specific tools (Biogents-Sentinel). Analysis used Excel 2010 ®, EpiInfo TM/7.2.4.0 ® and QGIS® software. Findings confirmed, according to Senegalese adapted WHO’s case definitions, the RVF outbreak in Fatick with already two human cases and one animal case. Further field investigation showed that among human 19.8% consulted at the 42nd EW, 89% complained of headaches versus 34% of asthenia. The most affected age group was 25–50 years old with women predominating including 38%, 32% and 8% of students, housewives and shopkeepers, respectively. Travel was most prevalent in Dakar and Touba (31%), while the most visited facilities were Ndiaye-Ndiaye (35%) and Peulga (20%), versus Emetteur (2%). Regarding animal health, 40 animals were sampled from five herds, including 35% under 1 year old, 67.5% females, 95% ovines and 32.5% local breeds. Finally, entomo-environmental surveys confirmed an ecology favourable to RVF and identified 33% of competent vector species, including Culex quinquefasciatus . Elsewhere, 139 ticks were collected from livestock and a moderate dissemination risk (risk-criticality: 36%) was assessed in Fatick and the surrounding area. Information © The Authors 2025