Images in Clinical Medicine. Taenia saginata Infestation.

A 38-year-old man presented with worsening abdominal pain, vomiting, anorexia, generalized weakness, and weight loss that had begun 3 days earlier. He had a history of eating raw beef. Examination of stool showed an embryonated egg containing an oncosphere.

[Morphological observation on the adult worms of Taenia saginata in western China].

OBJECTIVE: To investigate the morphological characteristics of the adult worms of Taenia saginata from four areas of Western China. METHODS: 42, 41, 7 and 18 integral worms of Taenia saginata were collected from Duyun and Congjiang of Guizhou Province, Wushi of Xinjiang, and Lhasa of Tibet respectively. The length of worms was measured and the segments were counted. The specimens of scolex, mature and gravid proglottids of the worms were stained, measured and photographed. RESULTS: The mean length of the worms from Duyun, Congjiang, Wushi and Lasa was (1.81+/-0.69) m, (3.84+/-1.32) m, (2.76+/-0.86) m and (3.72+/-1.12) m, and with (574.64+/-189.33), (913.84+/-317.41), (971.29+/-168.30) and (940.38+/-368.26) proglottids, respectively. The mean ratio of the distance between two lateral excretory vessels and the length of vitellarium of the mature proglottids was (1.71+/-0.13), (2.23+/-0.06), (2.03+/-0.21), (2.31+/-0.15) respectively. All the 3 parameters of the worms from Duyun were significantly less than those from other 3 areas (P<0.05). Rudimentary rostellum was found obviously in 3 of 10 scolices of the worms from Duyun. CONCLUSION: The morphological characteristics of the adult worms from Duyun are similar to that of Taenia saginata asiatica, while those of the worms from Congjiang, Wushi and Lhasa are alike to those of Taenia saginata saginata.

Jejunal perforation caused by morphologically abnormal Taenia saginata saginata infection.

We report a case of jejunal perforation caused by infection with taeniid tapeworm possessing unusual morphology that has not been previously described. Among five cestodes recovered during operation, one exhibited a bifurcation at the posterior end and the other harbored a lateral branching of immature segments from the main strobila. By sequence analysis of the mitochondrial cytochrome c oxidase I gene and the 28S rRNA gene has confirmed them to be Taenia saginata saginata.

Portrait of human tapeworms.

The tapeworms of the genus Taenia that infect human beings are T. solium, T. saginata and T. saginata asiatica. Taenia solium and T. saginata exhibit unequivocal features that characterize them; in contrast, only recent DNA studies, morphological characteristics, and epidemiological and sanitary aspects indicate that T. saginata asiatica is a subspecies of T. saginata. These 3 tapeworms occur in humans in their adult stage, and the intermediate hosts are pigs for T. solium and T. saginata asiatica and cows for T. saginata. Their identification is crucial considering the migratory increase from Asia to the Western Hemisphere and the fact that these tapeworms coexist in the same environment in Asia; furthermore, it is estimated that movement in both directions across the United States-Mexico border exceeds 200 million persons per yr, and thus, opportunities for acquiring and transporting T. solium infections are multiplied. It is not easy to distinguish among these tapeworms; therefore, a comparative diagram of the 3 parasites is shown in this article, which will facilitate their identification. All morphological features, some of which allow for identification, are clear and can be easily distinguished among the 3 tapeworms.