In May 1993, the U.S. Centers for Disease Control and Prevention (CDC) responded to a Hantavirus outbreak in the southwestern U.S., which was transmitted via infected rodents. In Nov. 1993, the specific hantavirus that caused the Four Corners outbreak was isolated.

The Special Pathogens Branch at CDC used tissue from a deer mouse that had been trapped near the New Mexico home of a person who had gotten the disease and grew the virus from it in the lab. Shortly afterwards, the U.S. Army Medical Research Institute of Infectious Diseases grew the virus, from a person in New Mexico who had gotten the disease as well as from a mouse trapped in California. The new virus was called Muerto Canyon virus – later changed to Sin Nombre virus (SNV) –  and the new disease caused by the virus was named hantavirus pulmonary syndrome, or HPS.