Antiplague antibodies against Yersinia pestis fraction-I antigen in serum from rodents either experimentally infected or captured in harbor areas of Japan, 1971--1977.

Antiplague indirect hemagglutination tests were investigated with Yersinia pestis fraction-I antigen and sera from experimentally infected rodents. The same tests with sera treated with acetone or acetone-2-mercaptoethanol were performed in parallel. Technical conditions were determined to insure the specificity and reproducibility of the reactions. Utilizing the methods studied, we carried out serological surveillance of plague with sera from wild rats (Rattus rattus and R. norvegicus) captured in the harbor areas of Japan during the period from 1971 to 1977. Four samples (all from R. norvegicus) out of 1,645 obtained in Kobe were positive. The public health significance of the data obtained is discussed.