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Clinical Characteristics

Infection with Trichuris is usually an incidental finding in the evaluation of a patient, often for other parasites. The majority of cases are asymptomatic and may be difficult to diagnose if only a few worms are present. The whipworm is frequently seen in combination with Ascaris, hookworm, or Entamoeba histolytica because they have a similar geographical distribution, and in such cases Trichuris is usually of lesser importance in causing symptoms.

A heavy infection with Trichuris, especially in poorly nourished children, can cause severe chronic diarrhea or dysentery which may last from 6 months to 3 years, with blood and excess mucus in the stools, tenesmus, abdominal pain, rectal prolapse (Fig. 17.7), weakness, pallor, anorexia, dehydration, and weight loss. Other symptoms include nervousness, irritability, headache, insomnia, decreased cognitive ability, vomiting and abdominal distention. The pain in the abdomen may be generalized, but is often localized to the right lower quadrant. Trichuris has been associated with appendicitis in the tropics, possibly due to superimposed infection with pyogenic bacteria or as a result of irritation of the sympathetic nervous plexus. In one series from Colombia, Trichuris was found in 16 of 20 patients with true appendicitis.

Allergic manifestations such as urticaria, rhinitis and eosinophilia are frequently seen. Because of these hypersensitivity phenomena, Siffert, in his review of 250 patients, proposed that the diarrhea and hypermotility of the large bowel were caused by the presence of a toxin produced by the whipworm. This was said to interfere with the digestion of food by inhibiting the action of amylase. This theory is purely speculative, however, since other investigators have found no evidence of such a toxin. Another theory for the mechanism by which Trichuris affects the human host relates to the damage produced at the site of the worm's attachment to the cecal or colonic mucosa.

Hartz suggested that the diarrhea and abdominal pain of trichuriasis may be caused by irritation of the nervous elements of the colonic mucosa by the adjacent worms, resulting in increased peristalsis. This also may be of significance in causing rectal prolapse, which may be present in up to 70% of children with severe infections. In such cases there are usually numerous small bleeding ulcers with adult worms threaded to the prolapsed rectal mucosa (Fig. 17.7). Occasional deaths from profuse hemorrhage have been reported from Singapore, Panama, and other tropical countries. Intussusception caused by a bolus of trichurids has been reported as a rare cause of death, with the worm-laden cecum acting as the intussusceptum into the ascending colon (Fig. 17.8). There are seldom significant residual changes in the colon after treatment.

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Fig.17.7 A Rectal prolapse in a child with massive trichuriasis. B Close-up of the prolapsed rectum of another child showing numerous male and female trichurids clinging to the rectal mucosa (B. courtesy of Dr. Herman Zaiman).

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Fig. 17.8. Colonic intussusception secondary to massive trichuriasis. (A) Autopsy specimen from a San Salvador patient whose death was directly attributable to intussusception of the cecum, containing a large bolus of whipworms, into the ascending colon. (B) The intussusceptum has been pulled out of the way to reveal innumerable whipworms clinging to the mucosa of the ascending colon. AFIP 67-8462-3& 2 (Courtesy of Dr. Julio Astacio, previously from San Salvador, now in McAllen Texas).

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