A member of the Bunyaviridae family, the genus Hantavirus (first isolated in 1977) is responsible for Hantavirus pulmonary syndrome. Disease transmission is associated with exposure to infected rodents, the primary reservoir for this virus.

Data suggest that the deer mouse is the main source, but pinion mice, brush mice, and western chipmunks in proximity to humans in rural areas are also sources.

Infected rodents manifest no apparent illness but shed the virus in feces, urine, and saliva. Human infection may occur from inhalation, ingestion (of contaminated food or water, for example), contact with rodent excrement, or rodent bites. Transmission from person to person or by mosquitoes, fleas, or other arthropods has not been reported.

Hantavirus infections have been documented in people whose activities are associated with rodent contact, such as farming, hiking, or camping in rodent-infested areas, and occupying rodent-infested dwellings.

Noncardiogenic pulmonary edema distinguishes the syndrome. Common chief complaints include myalgia, fever, headache, nausea, vomiting, and cough. Respiratory distress typically follows the onset of a cough. Fever, hypoxia and, in some patients, serious hypotension typify the hospital course.

The first signs of illness appear within 1 to 5 weeks of exposure, especially fever and muscle aches. This is followed
by coughing and shortness of breath. At this point, the disease progresses rapidly, necessitating ventilation within 24 hours.