Human hepatitis E virus (HEV) is a zoonotic infection that can be passed from swine and rodents to humans. A swine HEV-like virus has been shown to be endemic in swine herds in the Midwestern United States. Recently, the first human case of HEV infection acquired in the United States has been identified; the isolate demonstrated sequence homology closer to swine HEV than to known human HEV isolates. There is increasing public concern about the risks of waste products of intense hog farming operations. The long term goal of this project is a better understanding of the role of animal reservoirs in human infectious diseases, how humans are exposed to animal viruses, and the ability of animal viruses to be transmitted through the environment to humans. The specific goal of this project is to develop an epidemiologic model of environmental cross-species transmission of swine HEV infection.