Isolation of Hantaan Virus, the Etiologic Agent of Korean Hemorrhagic Fever, from Wild Urban Rats

Urban rats captured in Seoul and four nearby Korean cities were found to have immunofluorescent antibodies reactive with Hantaan virus, the etiologic agent of Korean hemorrhagic fever (KHF). Serum antibodies were detected in 13% from 477 Rattus norvegicus and 11% of 47 Rattus rattus. Hantaan viral antigen was found in pulmonary tissues of 42 animals, and Hantaan virus was recovered from 23 rats, all but two of which were R. norvegicus. Wistar rats were qualitatively much more sensitive than Apodemus agrarius rodents for isolation of virus from tissues of wild rats. Wistar rats inoculated with one of these strains had virus in lung and spleen for at least 75 days. These results document the existence of an urban cycle for Hantaan virus, which had been suspected on the basis of the occurrence of sporadic urban cases in humans of KHF, and suggest that Rattus-borne Hantaan virus may be widely distributed in urban centers.