Retrospective and prospective studies of hemorrhagic fever with renal syndrome in rural China.

Residents of two villages in Zhejiang Province, China, were interviewed and serum samples were collected to assess prevalence of hantavirus infection. Antibody prevalence was 12% (219/1811), with a ratio of illness to infection of 1.0:5.4. Seroprevalence increased with age, but no association was found with sex. There was also no evidence of vertical transmission. One year later, 2.3% (30/1325) of seronegative subjects had seroconverted including 2 who had hemorrhagic fever with renal syndrome. Peak incidence of infection occurred in those 15-39 years old. Hantaan was the dominant serotype; Seoul serotype was less common (5:1). Host reservoirs were Apodemus agrarius in agricultural fields and Rattus norvegicus in houses. Risk factors for infection were traces of rat-contaminated food, travel to other areas for farm work, direct rodent contact, camping in grain fields, living in a house on the periphery of a village, stacking straw stacks outside houses, and keeping cats. All may provide exposure to infectious rodent reservoirs.