Seroprevalence of Peste des Petits Ruminants (PPR) and associated risk factors in selected sub-counties of Lyantonde district, South Western Uganda.

Abstract

BACKGROUND: Lyantonde District, Uganda, is a recognized hotspot for Peste des Petits Ruminants (PPR) outbreaks. However, the magnitude and risk factors of PPR in this area remain poorly characterized. This study aimed to determine the prevalence of PPR antibodies in goats and sheep and to identify associated risk factors in selected sub-counties of Lyantonde District. METHODS: A cross-sectional serosurvey was conducted in July 2024 in three purposively selected sub-counties (Lyantonde, Lyakajula, and Kinuuka), chosen for their large small ruminant populations, high livestock trade activity, and active animal movement. Farms without a history of PPR vaccination were randomly selected, and simple random sampling was used to select study animals. Whole blood samples were collected from the jugular vein and analyzed using the ID ScreenPPR competitive ELISA kit to detect virus-specific IgG antibodies. Multivariate analysis was performed using Modified Poisson regression to identify risk factors associated with PPR seroprevalence. Adjusted prevalence ratios (aPRs), 95% confidence intervals (CIs), and p-values were reported. RESULTS: A total of 351 goats and sheep were sampled, with an overall apparent seroprevalence of 42.17% (n&#x2009;=&#x2009;148). The Rogan-Gladen estimator gave a true prevalence of 44.27%, with goats showing a significantly (p&#x2009;=&#x2009;0.046) higher prevalence (46.27%) compared to sheep (33.62%). Age was significantly associated with seropositivity. Animals aged&#x2009;>&#x2009;1-3 years (aPR&#x2009;=&#x2009;1.86; 95% CI: 1.16-2.97, p&#x2009;=&#x2009;0.009), and >&#x2009;3-5 years (aPR&#x2009;=&#x2009;2.56; 95% CI: 1.54-4.24, p&#x2009;<&#x2009;0.0001) had higher prevalence ratios compared to those&#x2009;<&#x2009;1 year. Goats also had higher prevalence ratios than sheep (aPR&#x2009;=&#x2009;1.59; 95% CI: 1.01-2.53, p&#x2009;=&#x2009;0.046). Farms reporting wildlife interactions had a 43% higher prevalence ratio (aPR&#x2009;=&#x2009;1.43; 95% CI: 1.07-1.91, p&#x2009;=&#x2009;0.015), and acquisition of new animals from other farmers was similarly associated with higher prevalence ratios (aPR&#x2009;=&#x2009;1.32; 95% CI: 1.02-1.71, p&#x2009;=&#x2009;0.029). CONCLUSION: This study shows the high burden of PPR among small ruminants in Lyantonde district, with higher prevalence in goats than sheep and identification of risk factors associated with seropositivity. The study provides baseline evidence of PPR exposure and documents differences by species, age group, animal acquisition practices, and reported wildlife interactions. These findings contribute to improved characterization of PPR epidemiology in Lyantonde district and may inform the design of future surveillance and control activities aimed at reducing PPR burden.