Infection and disease in reservoir and spillover hosts: determinants of pathogen emergence.

Infection and disease in reservoir and spillover hosts determine patterns of infectious agent availability and opportunities for infection, which then govern the process of transmission between susceptible species. In this chapter, using the zoonotic agents Hendra virus and Nipah virus as examples, the pathogenesis of infection in various species including the wildlife reservoirs and domestic spillover hosts is reviewed with an emphasis on the aspects of pathogenesis which contribute to the dissemination of infection. Through these discussions, the emergence of these zoonotic agents is explored.