Rift Valley fever seroprevalence and risk factors among human populations in Uganda’s cattle corridor: a cross-sectional study

Introduction: Rift Valley fever (RVF) is an epidemic-prone zoonotic disease whose distribution of exposure is poorly described in endemic communities. We investigated the seroprevalence and risk factors for RVF among humans in Uganda’s cattle corridor.

Methods: This cross-sectional study used data and stored plasma specimens collected by the Uganda population-based HIV impact assessment (UPHIA) survey 2016/2017. Participants were sampled from 35 districts of the cattle corridor. Ethical and regulatory approvals were obtained to use the UPHIA data and to test the specimens for the presence of RVF anti-Gn glycoprotein immunoglobulin G (anti-Gn IgG) antibodies using an enzyme linked immunosorbent Assay (ELISA). RVF seroprevalence was calculated in Stata with household as the random intercept, and associations between potential determinants and RVF seropositivity were assessed using mixed effects logistic regression analysis.

Results: Overall, 267 households comprising 1319 individuals were included in the analysis. Over half (56.3%) of the participants were female, median age 22 (IQR 11–34) years. Most (84.2%) were rural and owned cattle (41.2%), sheep/goats (51.7%) and poultry (65%). The overall RVF seroprevalence was 10.24%, 95% CI 8.63% to 12.10%. RVF seropositivity was associated with advanced age (25–44 years adjusted OR 2.79 (95% CI 1.81 to 4.32); and 45–64 years (3.0 (95% CI 1.76 to 5.14)); ethnicity (Iteso 2.54 (95% CI 1.15 to 5.62), Langi 2.61 (95% CI 1.20 to 5.66) and Karamojong 3.70 (95% CI 1.61 to 8.47)); owning cattle (1.59 (95% CI 1.03 to 2.45)) and owning poultry (1.73 (95% CI 1.05 to 2.87)).

Conclusions: RVF seropositivity is common among humans in Uganda’s cattle corridor and the risk of exposure is mostly determined by increasing age, ethnicity, owning cattle and poultry. Future RVF seroprevalence and risk evaluation studies should include poultry as potential determinants of infection.