We investigated geographic disparity in numbers of hantavirus pulmonary syndrome (HPS) cases in the United States. The 12-year incidences of HPS (cases/100,000 for total and rural residents) by state did not parallel the number of cases per state. The state with the greatest overall incidence was New Mexico, with Montana ranking second. When rural incidence based on rural human population sizes were compared, New Mexico also had the highest incidence, but Utah, Nevada, Montana, Arizona, and Colorado, in that order, also had high incidences. From these evaluations, it is clear that, in order to allow a precise risk assessment of acquiring HPS, we must first understand the host-virus cycle and we must have data regarding more exact conditions of human behaviors and exposure to the etiologic agent. Vector-Borne Zoonotic Dis. 5, 189–192.
