Associations of Deforestation and Predator Species Richness with the Spillover Risk of Hendra Virus in Australia

Abstract

Hendra virus (HeV) is a highly pathogenic virus causing fatalities in humans and horses for which the natural reservoir is pteropid bats (also called flying foxes). Anthropogenic stressors, such as land-use change and biodiversity loss, may increase the risk of cross-species transmission from the reservoir to horses by increasing the activity of the reservoir and subsequently its contact with horses. However, only a few studies have investigated the effect of environmental changes on spillover events. This study aims to investigate the impacts of deforestation and predator species richness on HeV spillover in Australia. Historical records of HeV outbreaks on horse farms in Australia were collated as an outcome variable. The study area was divided into 0.5° × 0.5° grids and categorized based on reported HeV occurrences. Open-source data for wildlife occurrences and estimated deforestation level were used as the major explanatory variables, representing predator species richness and deforestation, respectively. Logistic regression models were employed to estimate the associations. The results showed that higher Carnivora species richness was associated with lower odds of HeV spillover (odds ratio = 0.01; 95% confidence interval = 0.00 to 0.17). However, the degree of deforestation did not significantly affect HeV occurrence. Altogether, these findings demonstrate potential effects of predator species richness on suppressing cross-species spillover. Follow-up studies are highly recommended to elaborate on these associations.