Also in 1994 a case occurred in a Lewis County resident who may have been exposed to rodents during travel outside the state. Six cases have been fatal. All cases lived in rural areas and only one had traveled out of state during the incubation period. All hantaviruses have rodent reservoirs. The deer mouse, Peromyscus maniculatus , is the primary reservoir of the Sin Nombre virus.
Rodents carry and excrete the virus without adverse health effects.
Transmission to humans occurs by inhalation of aerosolized virus and possibly by bites. Based on the available exposure information, most persons with HPS in the United States appear to have been exposed to infected rodents in or around rural homes. Several HPS cases in North America probably were caused by occupational exposures. Cases aIso occurred in a shepherd who slept in rarely used cabins and a farmhand who trapped deer mice daily. Exposure during recreational activities such as camping and hiking is also suspected in several HPS cases.