This disease first appeared in a small epidemic among New Mexico Navaho Indians in mid1993 as a fatal respiratory infection with resemblance to influenza or mycoplasma disease. It subsequently affected some Europeans and Hispanics. Symptoms began as an upper respiratory infection with fever and myalgias, after which acute respiratory failure developed. Thrombocytopenia was present in about 70% of cases, and leukocytosis with mild neutrophil immaturity was frequent. The reservoir of infection was identified as the deer mouse.

Diagnosis is possible using serologic tests for hantavirus antibody. Nucleic acid probe with PCR amplification can be attempted on peripheral blood leukocytes, although lung biopsy tissue yields twice as many positive results.