TABLE 3.

Anadromous species of Diphyllobothriuma

SpeciesDefinitive hostSecond intermediate hostSite of infectionDistributionReferences
D. alascense Rausch et Williamson, 1958bDog, occasionally humansBurbot, boreal smeltLumen of stomachNorth America (Alaska)2, 65, 133-135
D. nihonkaiense Yamane et al., 1986cBrown bear, humansPacific salmons, mainly cherry, pink, and chum salmon; Japanese huchenMusculature (free or encysted)Northern Pacific Ocean4, 10, 12, 72, 169, 172, 174, 181
D. ursi Rausch, 1954dBears (Ursidae), occasionally humansUnknownStomach (encysted on serous membrane)North America (Alaska)65, 131, 134
  • a Fish names are as follows: burbot, Lota lota; boreal smelt, Osmerus mordax; cherry salmon, Oncorhynchus masou; chum salmon, Oncorhynchus keta; Japanese huchen, Hucho perryi; red salmon, Oncorhynchus nerka; pink salmon, Oncorhynchus gorbuscha. Mammal names are as follows: brown bear, Ursus arctos; dog, Canis familiaris.

  • b Plerocercoids are small (0.7 to 1.5 mm long) and are located only in the gastric lumen of burbot; dogs are readily infected after consuming burbot.

  • c D. nihonkaiense Yamane, Kamo, Bylund et Wikgren, 1986. Kamo (73) proposed a reconsideration of the taxonomic status of tapeworms identified as being D. latum from patients in Japan. Yamane et al. (172) showed taxonomic differences between D. latum from Finland and that from Japan and proposed D. nihonkaiense as a new species. The validity of D. nihonkaiense was confirmed by biochemical (57, 59) and molecular (102, 169) differences from D. latum. Human cases had been limited to Japan, but the tapeworm has been recently reported from Canada (British Columbia) (169). Diphyllobothrium klebanovskii Kuratov et Posokhov, 1988, was isolated from the lower Amur River basin in the Russian Far East (72). Synonymy with D. nihonkaiense has been confirmed by molecular data (12).

  • d This species is a common parasite of bears but has also been found in humans. It is a large cestode (up to 11 m long) and differs from D. latum by a larger, more massive scolex. According to Rausch and Hilliard (134), D. ursi may be a junior synonym of D. gondo Yamaguti, 1942.