The vaccine is also problematic because it causes people to test positive for a TB skin test, which is the mainstay for TB surveillance in this country. The new syndrome initially causes flu-like symptoms, and then causes its victims to gasp for air as their lungs fill with fluid. The disease kills about half the people it infects, usually within a week. A vaccine is being developed. It is carried by rodents and passed to people who inhale the aerosol particles emitted by the infected rodents' saliva, urine or feces.
People can become infected with hantavirus after being bitten by rodents.
Many people who have developed HPS live in mice-infested homes. One woman who developed the disorder, however, was exposed to rodents her pet cat dragged into her house. Another person succumbed to the disease after cleaning a rodent-infested barn. Hantaviruses are not passed directly from person to person. Experts suspect that rodents in the western United States have harbored the Muerto Canyon virus for quite some time, but unusual weather conditions led to an explosion of the deer mouse population in the early months of 1993.