The importance of a One Health approach in preventing human Rift Valley fever infections in Uganda

Abstract

Rift valley fever (RVF) is an endemic viral zoonosis in Uganda that causes sporadic outbreaks. In May 2021, a 19-year-old woman from Kasaana Village, Kiruhura District, Western Uganda was diagnosed with RVF. In addition, five case patients identified from the same village were immunoglobulin (Ig) M–seropositive for RVF virus (RVFV), all with a history of contact with livestock. We interviewed farmers in Kasaana Village to find out whether their livestock had recently experienced any sign of RVF (livestock abortions and neonatal mortality). We conducted a veterinary records review at the regional animal diagnostic laboratory and a case search for livestock that had a recent history of abortion or neonatal mortality. Among 162 livestock (94 cattle and 68 goats) from four farms reporting one or more abortions during March-June 2021, 57 (33 cattle and 24 goats) were randomly selected for testing for RVFV using enzyme linked immunosorbent assay. Verbal reports from farmers and veterinary records review revealed increases in livestock abortions and neonatal mortality during March-May 2021, before the human cases occurred. Serological testing indicated that eight (14%) livestock, including three (9%) cattle and five (21%) goats, were IgM-seropositive for RVFV. The presence of anti-RVFV IgM antibodies in sera suggested current infection in livestock, corroborating livestock abortions within the same period. Hence, human RVFV infections likely resulted from contact with infected animal products. The recurring pattern of livestock abortions observed before human RVFV infections in Uganda indicates a gap in the zoonotic disease surveillance system, through which reports on such events should trigger rapid response to detect disease, control spread among animals, and prevent spillover to humans. An expanded One Health approach on collaboration and information sharing on such events could facilitate RVF risk reduction in humans in Uganda.