Abstract

Hendra virus (HeV) is a recently emerged paramyxovirus in the genus Henipavirus. HeV came to our attention in 1994 and 1999 when three separate outbreaks caused the death of fifteen horses and two people. The fruit bat (genus Pteropus) has been identified as the natural wildlife reservoir of HeV. All four mainland species of Australian pteropid bats have antibodies to HeV but the seroprevalence differs significantly between species. In this study we use mathematic models to investigate the maintenance strategies of HeV in populations of Pteropus poliocephalus, P. scapulatus, P. conspicillatus, and P. alecto. We identify mechanisms that may lead to species differences in seroprevalence and explore how these differences could affect the comparative risk of spillover from pteropid species to domestic animals and humans. Our results indicate that HeV cannot be maintained in bat populations with simple SIRS-like dynamics. However, incorporating metapopulation dynamics, latency, or loss of resistance into the model led to maintenance of infection over time. Furthermore, our model indicated that Pteropus scapulatus is the species most likely to act as a reservoir for HeV in wild populations. We contrast the dynamics of HeV with that of sudden acute respiratory syndrome (SARS) in proposed wildlife hosts. The dynamics of this coronavirus are vastly different to that of HeV and we reflect on the different reservoir characteristics required to maintain these two viruses.