Itaru KIKUYAMA
Yoshihide ASATO
Megumi SHIMABUKURO
Naoya SHIMABUKURO
Department of Pediatrics, Okinawa Prefectural Nanbu Hospital, Itoman, Okinawa 901-03, Japan.

Isao SHIMABUKURO
Department of Parasitology, Faculty of Medicine, University of the Ryukyus, Nishihara, Okinawa 903-01, Japan.

Hideo Hasegawa
Yoshiya SATO
Department of Parasitology and Research Center of comprehensive Medicine, Faculty of Medicine, University of the Ryukyus, Nishihara, Okinawa 903-01, Japan.

Abstract
Diphyllobothrium yonagoense infection was observed in a 13-year-old female residing on Okinawa Island, Japan. A complete worm, 407 cm long and composed of ca. 2,700 proglottids, was successfully expelled by Gastrografin administration. The worm was relaxed in tap water with chloroform at 4C overnight and then fixed with 5% formalin solution for morphological observation. The mature proglottids and eggs were identical with those previously reported for d. yonagoense. Meanwhile, the scolex was quite different from those in the former descriptions because it was cordate in lateral view and its bothrial rims were not folded. These discrepancies were considered to have been caused by the difference in fixation methods. It is presumed that an adequately relaxed D. yonagoense has a cordate scolex with non-folded bothrial rims. Careful attention should be paid to the morphological changes due to fixation methods on identification of diphyllobothriids expelled from humans.