It is a severe life-threatening illness cause by a hantavirus now named Sin Nombre virus. It causes acute respiratory disease, and is carried in wild rodents such as deer mice. This virus was first recognized and identified in 1993 when a cluster of cases was reported in the four corners area of the southwestern U.S. Investigations completed since the virus was first identified in 1993 indicate the presence of Sin Nombre virus throughout most of the continental U.S. and the presence of the virus has now been documented as far back as 1959.
Rodents are the natural hosts for all hantaviruses.
Humans are thought to be infected from exposure to rodent droppings, urine, saliva, either through aerosols or direct inoculation. Rodents may be chronically infected with hantavirus and shed the virus for months. There are no documented cases of hantavirus being transmitted from infected patients to health care workers. The first symptoms of HPS associated with Sin Nombre virus in the U.S. usually occur 2-3 weeks after exposure and are flulike in nature. Within 3-4 days, rapid onset of severe respiratory failure may follow.