INFECTIVITY AND PATHOGENICITY OF YERSINIA-ENTEROCOLITICA SEROVAR-0 8 TO WILD RODENTS IN JAPAN/

Three species of wild rodents, Anderson's red-backed voles (Eothenomys andersoni), large Japanese field mice (Apodemus speciosus) and small Japanese field mice (Apodemus argenteus), mainly living in mountainous areas in Japan, were challenged orally with Yersinia enterocolitica s erovar 0:8 to determine infectivity and pathogenicity of this micro-or ganism with respect to wild rodents. Y. enterocolitica 0:8 was shown t o colonize the intestinal tract of these three types of wild rodents, and was occasionally fatal. The faecal excretion period of these mice was 10-14 days in E. andersoni and A. speciosus, and 35-49 days in A. argenteus. Wild rodents recovering from the infection showed resistanc e to a second challenge with the same infectious agent. These results suggest that these three species of wild rodents living in mountainous areas in Japan may play an important role in the ecology of Y. entero colitica 0:8.