[Occurrence of alveolar hydatid disease (multilocular echinococcosis) outside of Hokkaido and a proposal for its prevention].

Alveolar hydatid disease (AHD), had been endemic only in Rebun Island prior to 1945, it is now prevalent throughout the mainland Hokkaido. AHD cases have been reported also in 21 prefectures outside of Hokkaido, e.g. Aomori, Tokyo, Miyagi, etc. Case reports of AHD (n = 135) were reviewed and 76 cases were identified in 21 prefectures outside of Hokkaido in 1926-96. These cases were classified in 4 groups: 1) cases supposedly infected where they lived (n = 19), 2) cases that were infected in Hokkaido (n = 23), 3) cases that were infected in foreign countries (n = 30), 4) cases infected in unidentified places (n = 4). Prefectural distribution and sex ratios were characteristic according to the groups. The first group was supposedly infected were they lived, but it was suggested that this group had some relationship with the epidemics of AHD in Hokkaido. Cases of the 1st and 2nd group were estimated to have been infected prior to early 1970, and it was suggested that these 2 groups will increase the number hereafter in the prefectures outside of Hokkaido because the number of AHD cases has been increasing in the mainland Hokkaido since late 1980.