Hantavirus is a disease spread by rodents that is similar to the flu.

Hantavirus has probably caused people to get sick for years in the United States, but it was not recognized until recently.

In 1993 there was an outbreak of fatal respiratory illness on an Indian reservation at the border of Utah, Colorado, New Mexico, and Arizona. Researchers discovered that hantavirus caused the epidemic. Since that discovery, hantavirus disease has been reported in every western state, and in many eastern states.

Hantavirus is carried by rodents, especially deer mice. The virus is in their urine and feces, but it does not make the carrier animal sick. Humans are thought to become infected when they are exposed to contaminated dust from mice nests or droppings.

The disease is not passed between humans. People may encounter contaminated dust when cleaning long-empty homes, sheds, or other enclosed areas.

The U.S. Centers for Disease Control and Prevention (CDC) reported that rodents carrying hantavirus have been found in at least twenty national parks. The CDC says it is possible that the virus is in all of the parks.

The CDC suspects that 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.

So far, 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.