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Trichuriasis is caused by infection of
the large intestine with Trichuris trichiura, the
whipworm. Whipworm infection is cosmopolitan, but it is far more
common in warm, moist climates, where the distribution of Trichuris and Ascaris overlap.1,2 Approximately
604 million people are infected worldwide. Infection is generally
acquired in childhood; whipworm ova often pollute the ground where
children play. Transmission of infection occurs by ingesting embryonated
eggs, which may contaminate hands or food, including fruits and
vegetables, that were fertilized using human feces.3 The
lifecycle is shown in eFig. 333.1.
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T trichiura is a distinctive nematode with a thin,
whiplike anterior and a broader posterior portion. Males are 3.0
to 4.5 cm long, with a coiled posterior end; females
are 3.5 to 5.0 cm long, with a blunt posterior end. The eggs are
barrel-shaped, 50 μm by 22 μm,
usually yellowish-brown with translucent polar plugs (Fig.
333-1). Adult worms live in the cecum with their anterior portions
anchored in the mucosa. The appendix and the lower ileum may also be
infected. The female lays 3000 to 10,000 eggs daily, which pass out
in feces. An infective-stage larva develops within the egg after 3
weeks in warm, shady, moist soil. After ingestion, the larvae hatch
in the duodenum and migrate to the cecum, where they develop into
mature, egg-laying adults within 1 to 3 months.
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The whipworm produces an inflammatory focus at the mucosal attachment
site and ingests whole blood. Heavy infections may be associated
with superficial mucosal erosions, colitis, and in young children,
rectal prolapse. Heavily infected persons may develop anemia of
chronic disease, primarily thought to be due to inflammation in
the large intestine. Hookworm infection often coexists with whipworm
infection and may contribute to anemia. Eosinophilia of up to 25% can
be found, but is rare.
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Clinical Manifestations,
Diagnosis, and Treatment
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Light infections are usually asymptomatic. Occasionally, there
may be anorexia or vague abdominal discomfort. In moderate infections, abdominal
pain (often in the right lower quadrant), low-grade fever, nausea,
vomiting, weight loss, and pruritus are the most frequent complaints.
Heavy infections may be accompanied by diarrhea, tenesmus, blood-streaked
stools, and rectal prolapse, often with worms visibly imbedded in
the rectal mucosa. Trichuriasis is difficult to differentiate clinically
from other intestinal nematode infections or from intestinal amebiasis. Chronic
infection can lead to impaired growth, physical fitness, and cognitive
function.
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Diagnosis is made by examining the stool for the characteristic
ova. Concentration techniques may increase the yield in light infections. Mebendazole
(Vermox) is commonly used for treating trichuriasis in both adults ...