Etiology and epidemiology of the Four Corners hantavirus outbreak.

In May and June 1993, a handful of previously healthy residents of rural areas in the Four Corners region of the southwestern United States died of acute unexplained respiratory distress, later diagnosed as hantavirus pulmonary syndrome. Their illnesses were characterized most prominently by a prodrome of fever and myalgias, followed by thrombocytopenia, the presence of immature white blood cells on the peripheral smear, and catastrophic respiratory decline associated with the sudden onset of noncardiogenic pulmonary edema and hypotensive shock. Although the primary care doctors who treated these patients were spread over a relatively wide rural geographic area, this cluster was recognized in large part because these patients belonged to a defined cohort receiving medical care from a unified system of interconsulting physicians, the Indian Health Service. By just over 2 weeks after receiving laboratory diagnostic specimens, Public Health Service scientists had identified a newly recognized hantavirus as the cause of this disease cluster and Peromyscus maniculatus (the deer mouse) as the rodent reservoir for this zoonotic virus. The oral history of local American Indian healers describes clusters of similar deaths occurring over three cycles during the twentieth century in association with identifiable ecological markers. The abrupt introduction to Western medical practitioners of a disease long recognized by indigenous healers through illness occurring among a cohort of patients seeking care from medical officers of the U.S. Uniformed Services parallels the initial Western medical recognition of previous human illnesses associated with hantaviral infections through disease outbreaks among military troops. The remarkable speed with which the etiology of this disease was elucidated is attributable to both the power of modern genetic investigational techniques and the scientific groundwork laid by nearly half a century of systematic research on hantaviruses.