Hantavirus Pulmonary Syndrome (HPS) is a potentially severe disease of the lungs which was first recognized in 1993 in the "Four Corners" area (where Utah, Colorado, Arizona, and New Mexico meet) of the southwestern United States. The disease is caused by a virus called Sin Nombre that is carried by wild mice and shed in their feces, urine, and saliva. HPS is a rare, but often fatal, disease.ā