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Laboratory Diagnosis

The laboratory diagnosis is made by identifying ova or proglottids in stool. Enzyme-linked immunosorbent assay (ELISA) techniques for antigen or antibody can reveal T. solium in the stools of tapeworm carriers even in the absence of proglottids. DNA probes can be useful in differentiating T. saginata and T. solium.

Clinical Characteristics

Most patients infected with the adult worm have few clinical symptoms: the worms are a chance finding on defecation. Abdominal discomfort, anorexia, malaise, weight loss, indigestion, diarrhea, and even constipation can occur. Patients may have up to 10% eosinophilia. Obstruction has been reported in some patients with multiple worms. Pruritus ani occurs in up to 25% of patients.

Radiological Diagnosis

Despite the ubiquitous presence of T. saginata throughout the world, it is seldom demonstrated radiologically on small bowel barium studies. Characteristically it appears in the lower jejunum or ileum as an unusually long and gradually widening radiolucent line within the barium column (Figs. 7.4, 7.5). It widens from 1-2 mm in diameter at its neck to 12 mm at its distal end. It may be folded on itself because of its great length, but it still appears as a continuous structure.


Fig. 7.4. (A)Adult T. saginata in the ileum of a 25-year-old Lebanese admitted to hospital with acute abdominal pain, which was intermittent and severe. Reflux of barium into the terminal ileum during a barium enema examination revealed a markedly elongated ribbon-like radiolucent shadow representing the adult tapeworm, which was coiled upon itself through part of its course. The patient was given a vermifuge and 210 cm of worm, including the scolex, was passed. (Courtesy of Dr. Lawrence E. Fetterman, Mobile) (B) Adult T. saginata showing the slender head and neck (center) and numerous proglottid segments.


Fig. 7.5. (A) Taeniasis saginata. Small bowel series reveals a solitary beef tapeworm of great length outlined by barium as a continuous radiolucent structure running through multiple loops of jejunum and ileum. Unlike Ascaris, a tapeworm has no alimentary canal and thus does not ingest barium. (B) Adult T. saginata recovered intact following its passage after a vermifuge was administered. Note the extraordinary length of this worm, which may at times reach 20-30 feet. The patient was a US. soldier seen at Tripler Army Medical Center in Honolulu, Hawaii with a history of extensive travel.

Unlike the roundworm Ascaris, tapeworms have no alimentary canal; each proglottid absorbs nutrients instead through its tegument. Ascaris may have a characteristic thread-like strand of barium within its alimentary tract and is much shorter.

Taenia solium has not been identified radiographically; presumably its appearance would resemble that of T. saginata, but it would be shorter.

Differential Diagnosis

Recognition of the adult T. saginata in the small bowel is not difficult, once seen: it is usually many feet in length and cannot be mistaken for the much shorter Ascaris or anything else. It must be emphasized, however, that it is uncommon for the worm, even when lengthy, to be demonstrated, and a normal upper gastrointestinal study and small bowel series do not exclude the possibility of a tapeworm.

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