Studies on the Helminth Fauna of Alaska. XLIX. The Occurrence of \u3ci\u3eDiphyllobothrium latum\u3c/i\u3e (Linnaeus, 1758) (Cestoda: Diphyllobothriidae) in Alaska, with Notes on Other Species

Cestodes representing six species of the genus Diphyllobothrium Cobbold, 1858, were collected from naturally infected terrestrial mammals in Alaska during the period 1949-1970. Additional specimens were reared in experimentally infected animals. Of the species identified, viz., D. latum (Linnaeus, 1758), D. dendriticum (Nitzsch, 1824), D. lanceolatum (Krabbe, 1865), D. ursi Rausch, 1954, D. dalliae Rausch, 1956, and D. alascense Rausch and Williamson, 1958, all but D. alascense were obtained from man after treatment with quinacrine. D. latum occurred most commonly in humans; D. ursi is reported for the first time from this host, and D. lanceolatum in humans was represented by a single plerocercoid. D. lanceolatum, a characteristic parasite of phocids, was found also in dogs; D. alascense was obtained only from dogs. In humans, rate of infection by Diphyllobothrium spp. were highest in the delta region of the Kuskokwim and Yukon Rivers, western Alaska. Included is a description of D. latum and a discussion of morphologic variation, based upon specimens from Alaska, with a consideration of differential characters of the other species reported. Some biological characteristics of these cestodes are briefly discussed