Exploring community-based reporting of livestock abortions for Rift Valley Fever surveillance in Uganda: A pilot study

Abstract

Between March and June 2023, we carried out a pilot study to explore the feasibility of using self-reporting of livestock abortions as a method of syndromic surveillance for Rift Valley fever disease (RVF) in Isingiro District, Uganda. We established a call centre in the office of the District Veterinary Officer which was promoted through stakeholder meetings, media engagement and distribution of sensitization materials. We collected 200 sera and 269 vaginal swabs from cattle, sheep and goats that experienced an abortion within a target 14-day period. The apparent IgG seroprevalence of RVF was 38% [95% CI 29 – 47] in cattle, 33% [95% CI 14 – 61] in sheep and 20% [95% CI 12 – 31] in goats. For IgM, sheep showed the highest prevalence at 8% [95% CI 1 – 35], cattle at 2% [95% CI 1 – 6]. Host species was significantly associated with IgG positive status, with cattle having the highest risk of RVF seropositivity (OR = 3 [95%CI: 1 - 7], p = 0.014). Our results demonstrate the potential for a community led model for collecting abortion alerts through local call centres. If routinely implemented, such syndromic data collection could be used to develop early warning systems and prioritise case investigations. The IgG seroprevalence in our sample is comparable to the levels seen in endemically infected countries, suggesting historical circulation of RVF within the livestock population in this community. Our pilot study demonstrates a proof-of-principle that community-driven reporting of abortions could be used to build a surveillance system for RVF. However, the lack of confirmation of infection through PCR means we cannot draw a firm causal link between the reported abortions and RVF. To build a robust case of abortion surveillance, longitudinal studies are needed to measure seasonal variation in the distribution of abortion cases and incidence of active RVF infections.