Hantavirus is carried by rodents, especially deer mice. The virus is found in their urine and feces, but it does not make the animal sick.
It is believed that humans can get sick with this virus if they come in contact with contaminated dust from mice nests or droppings. You may come in contact with such dust when cleaning homes, sheds, or other enclosed areas that have been empty for a long time.
Hantavirus does not spread between humans.
Rodents carrying the hantavirus have been found in many U.S. national parks. As of November 1, 2012, the National Park Service (NPS) has announced a total of 10 confirmed cases of hantavirus infection in people who recently visited Yosemite National Parks. Campers and hikers may be more likely to catch the disease than most people. This is because they pitch tents on the forest floor and lay their sleeping bags down in musty cabins.
However, only a couple of cases have been directly linked to camping or hiking. Most people who are exposed to the virus have come in contact with rodent droppings in their own homes.