Estimating the spatiotemporal drivers of Hendra virus spillover in Australian flying foxes

Hendra virus (HeV) is a highly lethal bat-borne paramyxovirus, which emerged in Australia in 1994 and has caused over 100 cases in horses. Spillover cases and virus shedding from bats peak in winter, but a high variability between years and roosts have been observed. Mechanisms and seasonal drivers responsible for inter-annual and geographic differences in pathogen shedding this are still debated, and may include temperature, food availability or loss of habitat. With the present work we aim to gain further insight into viral dynamics in bat populations and explore seasonal drivers responsible for spatiotemporal variations in pathogen shedding. We built a set of compartmental models simulating HeV spread into a wild bat population, and fitted them to longitudinal data of bat urine and serum samples collected between July 2017 and September 2020 at two study roosts. Our model provides new evidence supporting the hypothesis that bats can be persistently infected with HeV and undergo seasonal cycles of reactivation with active shedding. In addition, we quantify variations in key epidemiological parameters between years and between sites. This work lays the ground for improved ability to predict zoonotic spillover risk, providing a template for other bat-borne viruses.