The Sin Nombre Hantavirus was first recognized in 1993 in the Four Corners region of the southwestern United States (Arizona, Colorado, New Mexico and Utah), but is now found primarily in the western United States. This virus is carried by the deer and white-footed mouse and the cotton and rice rat. Hantavirus includes a group of viruses that can sicken humans and cause kidney, blood or respiratory ailments, as well as fatality in some cases. While it is relatively rare, it is very serious and unpredictable.

People become infected with Hantavirus through several routes, but rodent infestation in and around the home remains the primary risk. The virus is mainly transmitted to people when fresh rodent urine, droppings, or nesting materials are stirred up, become airborne and are breathed in by people. It is carried by several rodent species, mainly deer mice In addition, if an infected rodent bites someone, the virus may be spread to that person. Researchers also suspect people can become sick if they eat food contaminated by urine, droppings, or saliva from an infected rodent.

Typically, symptoms of Hantavirus develop between one and five weeks after exposure to fresh urine, droppings, or saliva of infected rodents. Infection with Hantavirus can produce Hantavirus Pulmonary Syndrome, a severe respiratory disease which can be fatal. Early symptoms include fatigue, fever and muscle aches in the thighs, hips, back, and sometimes shoulders. The infected person may also experience headaches, dizziness, chills, and abdominal complaints, such as nausea, vomiting, diarrhea, and abdominal pain. Four to ten days after the initial phase of illness, the late symptoms of Hantavirus infection develop and HPS may appear. These include coughing and shortness of breath and progression to respiratory distress and failure. HPS has a mortality rate of 38 percent.

There is no specific treatment, cure or vaccine for Hantavirus infection, so rodent prevention and control both inside and outside the home are important. However, if an infection is recognized early and the patient receives acute medical care in an intensive care unit, they may do better. In these care settings, patients may receive mechanical ventilation for respiratory failure and be given oxygen therapy to help them through the period of severe respiratory distress.