EPIZOOTIOLOGICAL STUDY OF HANTAVIRUS INFECTION AMONG RATTUS-NORVEGICUS IN TOKYO BAY AREA, JAPAN

The prevalence of antibodies against hantavirus in 413 rats (Rattus no rvegicus) captured in eight regions of the Tokyo Bay area from 1983 to 1992 were examined by the indicrect fluorescent antibody test. Antibo dy-positive rats were found in Tokyo Port in 1983 (34.8%), 1984 (25.9% ), 1985 (22.0%) and 1986 (15.6%), in Kasai Seaside Park in 1989 (3.2%) and 1990 (4.2%) and in Chiba Port in 1990 (6.7%). In Tokyo Port, anti body-positive rats were found in any season in 1984 and 1985, and sero prevalences among two age groups, i. e., less than six months and six or more months of age were 18.1% and 28.4%, respectively. Three virus strains were isolated from rats captured on reclaimed land No. 13 in T okyo Port in 1985 and named TQR-23, TQR-48 and TQR-50. These strains w ere antigenically identical with other rat strains, e. g., strain SR-1 1 and TR-352 but were discriminated from 76-118 strain by the neutrali zation test. Until 1990, persistence of hantavirus among rats inhabiti ng the Tokyo Bay area was demonstrated and hantavirus may be continuou sly prevalent in rats in this area.