Morphological studies on the Diphyllobothriid Tapeworm (Cestoda: Pseudophyllidea) found from a man in Kasuga city, Fukuoka prefecture, Japan *
A case of human diphyllobothriasis found in Fukuoka Prefecture, Japan is reported together with morphological examination of the strobila. The patient was a 33- year-old male, a sushi artisan, living in Kasuga City, Fukuoka who had spontaneously discharged fragmented strobilae in his feces at frequent intervals since around 1998. On June 6, 2000, the patient expelled a mature strobila with scolex about 340 cm in length and 8. 0 mm in maximum width after treatment with praziquantel. The morphological characteristics of the strobila and eggs were as follows : 1) The scolex was club-shaped in form, measuring 1. 72 mm long and 0. 55 mm in dorsoventral height. 2) The segments were much wider than long, measuring 1. 55 mm in length, 7. 7 mm in width and 0. 7 mm in thickness on average, with a length/width ratio of : 5 in the mature segments. 3) The genital pore was situated about 1/5 posterior from the anterior margin of the segment, and prominent papillae existed around the genital pore. 4) There were 5 to 6 uterine loops, which were not quite elongated laterally on each side. 5) The most anterior portion of uterine loops extended beyond the anterior margin of the cirrus-sac. 6) The testes were arranged in a single layer and there was a distinct boundary between neighboring segments. 7) The pyriform cirrus-sac, measuring 660 μm dorsoventrally and 360μm in diameter in a sagittal section was situated horizontally in the segment. 8) The eggs, measuring 60. 2 ,μm in length and 41.4 μm in width on average, were ellipsoidal with apical knobs, and the egg-shell was about 1.5μm thick without scattered pits on the surface. From these findings, the strobila in this case was identified to be Diphyllobothrium latum (Linnaeus, 1758) Luhe, 1910 by Rausch and Hilliard (1970). Although the source of infection in the present case was not well-defined, the patient, for occupational reasons, had customarily been eating raw marine fish of all kinds as well as shellfish. Recently, rainbow trout, Oncorhynchus mykiss (formerly Salmo gairdneri) which is well known as an intermediate host for D. latum, D. dendriticum and D. ditremum has been extensively imported into Japan from Chile and Norway. It is therefore possible that a considerable number of cases infected with D. latum and some other related species among human diphyllobothriasis cases still exist in Japan. (Accepted on September 26, 2001) Kawasaki Igakkaishi 27( 4 ): 263 -273, 2001
