Hantavirus infection in the United States: epizootiology and epidemiology.

Multiple species of murid and arvicolid (microtine) rodents serve as the reservoir hosts of hantaviruses, the etiologic agents of hemorrhagic fever with renal syndrome. Three antigenically distinct hantaviruses have been isolated from Rattus norvegicus, Mus musculus, and Microtus pennsylvanicus captured in the United States, and serologic evidence of a hantavirus enzootic has been found in several other indigenous rodent species. In residential districts of port cities such as Baltimore, nearly 50% of Norway rats are infected with viruses that are serologically indistinguishable from disease-causing Hantavirus strains isolated from rats in the Far East. Despite the widespread distribution of Hantavirus-infected rodents, confirmed cases of hemorrhagic fever with renal syndrome have not been recognized in the United States. Moreover, the overall risk of hantavirus infection in humans in the United States is low, even among individuals who have frequent exposure to commensal and wild rodents. Studies are needed to define the clinical spectrum of hantavirus infection in humans in the United States.