Retrospective diagnosis of hantavirus pulmonary syndrome, 1978-1993: Implications for emerging infectious diseases

Objective. - To investigate the occurrence of unrecognized cases of hantavirus pulmonary syndrome preceding the detection of the 1993 outbreak in the southwestern United States and the initial description of the syndrome. Design. - Retrospective clinicopathologic and immunohistologic study. Patients. - Eighty-two patients who died prior to April 1993 with histologically unexplained noncardiogenic pulmonary edema. Methods. - Clinicopathologic review and immunohistochemical evaluation of autopsy tissues for evidence of hantaviral infection. Results. - Twelve retrospective fatal cases of hantavirus pulmonary syndrome were identified through clinicopathologic review and immunohistochemical testing of tissues. Patients' ages ranged from 16 to 49 years. The earliest identified case occurred in 1978, 15 years prior to the outbreak of hantavirus pulmonary syndrome in the southwestern United States. Immunohistochemical testing showed widespread deposition of hantaviral antigens, primarily within endothelial cells, similar to the pattern observed with current hantavirus pulmonary syndrome cases. Conclusions. - Although hantavirus pulmonary syndrome was first recognized in 1993, the findings from this study document the earlier existence of this disease. These findings underscore the need for systematic archiving and analysis of clinical information and specimens from patients with diseases of unknown etiology to facilitate the study of new clinical entities and their associated etiologic agents.