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Tapeworm
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.
Cysticercosis
Imaging Diagnosis
The calcified cysticercus produces single (rarely) or multiple
(often several hundred) calcifications in the soft tissues, which
are linear or oval in shape and usually measure 4-10 mm or more in
length and 2-5 mm in width. Cysts as large as 23 mm have been
reported. The calcified cysts will have their long axes in the plane
of the surrounding muscle bundle (Figs. 7.11-7.14).
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Fig. 7.11 A-C.
Cysticercosis in three patients showing typical rice grain
calcifications in the soft tissues and muscles of the lower
extremities. Note that the oval and linear cysticerci are aligned
with their long axes in the plane of the muscle bundles of the legs.
Note also the variation in size and shape of the cysticerci,
although the majority are approximately 10 mm in length by 4 mm in
width.
 ..
Fig. 7.12 A, B.
Cysticercosis of the muscles of the back, abdomen, buttocks, and
lower extremity of another patient. Note the alignment of the
calcified cysticerci in the axes of the muscle fibers and their
variation in shape from elongate and linear to more plump oval or
elliptical configurations. Many of the calcifications have a small
lucent center and, when viewed from the side, may resemble ring
calcifications.
 ....
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Fig. 7.13 A-D.
Extensive cysticercosis of the soft tissues, muscles, diaphragm, and
lungs in a 13-year-old Colombian woman. Note in B-D that the
rice grain calcifications overlying the abdomen are actually in soft
tissues and muscles of the buttocks, flanks, anterior abdominal
wall, and back. In C and D calcified larvae can be
seen in the diaphragm as well as in the muscles of the chest and
abdominal wall, axillae, and neck. (Courtesy of Dr. William Thomas,
McLean).
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Fig. 7.14
A,B. Cysticercosis involving the muscles of the neck, axillae,
and chest wall (A) and the back, buttocks, abdominal wall,
and thighs (B) of another patient.
In some series,
calcified larvae have been demonstrated in up to 97% of patients
examined 5 or more years after infection; such a high rate of
detection is not to be expected routinely. Some patients with
cerebral cysticercosis will have no evidence of calcified cysts in
the muscles and are unaware of their infection.
Partially calcified
cysts and even noncalcified cysts have been demonstrated by soft
tissue radiography. The technique is useful when there is a
localized (clinical) swelling, but as a method of "search" it is
unreliable and unjustified.
Cysticerci may be seen
in the lungs, where they are about 3-6 mm in diameter. The outer
shell is calcified, with a somewhat lighter and softer center. In
the lungs, the cysts remain more nearly round compared with the oval
or elongate calcified cysts in muscle.
In the liver, the
cysticercus is larger and has been described as the size of a cherry
(1 cm in diameter). If a cyst is seen in the liver and there are
other calcified cysts in the muscles or lungs, the diagnosis is
reasonably reliable; but if cysts are seen in either the lung or
liver solely (a rarity), they cannot be differentiated from other
causes of small calcified nodules.
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