Identifying leptospirosis hotspots in Fiji using a One Health model that incorporates watershed-scale pathogen transport

Leptospirosis is a water-related zoonotic disease with complex transmission pathways including direct transmission from infected animals and indirect transmission through contaminated soil and water. A research team developed an epidemiological model combining a Bayesian network with a hydrological pathogen transport model to predict leptospirosis in Fiji. The model identified key infection hotspots located adjacent to rivers and within degraded watersheds. Extensive data were used for model parameterization including expert elicitation, epidemiological surveys, and environmental data. Incorporating expert input on risk factors improved the model's predictive validity, with R² increasing from 0.71 to 0.91. This One Health modeling approach can support the design and evaluation of environment-based disease prevention strategies at the national scale.