Predicting myxomatosis distribution in Iberian hares (Lepus granatensis) through active surveillance

Spatial epidemiology is key to follow the distribution and evolution of emerging pathogens. During outbreak investigations, information is initially obtained via passive surveillance and later complemented with data from active surveillance for a comprehensive picture of disease distribution. In 2018, a recombinant myxoma virus (ha-MYXV) emerged in Iberian hares (Lepus granatensis), significantly impacting their populations. Here, we use information generated by active surveillance, validating it with passive surveillance results (454 municipalities with confirmed cases), to predict the current distribution of myxomatosis in Iberian hares. Using a mixed-effects model, we modelled serological results from 647 hares sampled via active surveillance between 2018 and 2024, incorporating individual traits, bioclimatic variables and information on land uses as predictors. The model's predictions (risk of exposure) were projected at the municipality level within the Iberian hares' distribution range. Results revealed that high-risk areas were concentrated in southern Iberia, largely aligning with municipalities with documented outbreaks. The identified risk of exposure to myxomatosis hotspots broadly coincides with areas that have high hare densities and vector activity, driving direct and indirect ha-MYXV transmissions. Notably, the model identified high-risk municipalities without prior outbreak notifications, highlighting the value of active surveillance as a complementary tool to reports of clinical disease. Our findings underscore the need for comprehensive long-term surveillance strategies targeting the virus, vectors, and host populations. In addition, by improving the understanding of myxomatosis epidemiology in Iberian hares, this study can guide management efforts for this threatened lagomorph.