Present status of trichinellosis in Japan

Abstract

There have been three mass outbreaks of human trichinellosis in Japan. The first was in 1974 in Iwasaki, Aomori Prefecture, involving a group of hunters who ate raw meat of a black bear they had shot. Of the 20 people who ate the bear meat raw, 15 showed clinical symptoms of trichinellosis. The second outbreak was experienced in Sapporo, Hokkaido, in 1980. The patients had eaten the raw meat of a brown bear served in a local restaurant. Twelve people were diagnosed positive on the basis of clinical symptoms and the results of serological tests. The third outbreak was reported in 1982. Of the 434 people who had eaten raw black bear meat at a local restaurant in Yokkaichi, Mie Prefecture in December 1981, 60 were diagnosed as positive for trichinellosis. The first finding of Trichinella spiralis in Japan was in 1957, when the parasite was detected in a formalin-preserved specimen of an indigenous dog in Sapporo, Hokkaido. Since then T. spiralis infection has been reported in imported animals, such as mink (1957), polar bears (1960, 1969, 1986), tiger (1986), and black leopard (1986). To date, spontaneous infection of T. spiralis in wildlife in Japan has been reported in sables (in Hokkaido, 1963), Japanese black bear (in Aomori, 1974, 1975), brown bear (in Hokkaido, 1980) and raccoon dog (in Yamagata, 1984).