Outbreaks of disease compatible with certain types of hantavirus infection have been described in Europe and Asia since the 1930s. However, in the United States, there were no reports of acute disease associated with hantavirus prior to 1993. In the spring of that year, an outbreak of severe respiratory disease caused by a newly recognized strain of hantavirus occurred in the southwestern U.S. It is now apparent that illnesses due to this strain occurred before the 1993 outbreak, but were not recognized.
Hantavirus Pulmonary Syndrome (HPS) fact sheet, P-42053A
Hantavirus Hemorrhagic Fever with Renal Syndrome (HFRS) fact sheet, P-42053