Intestinal Helminths: Trichuriasis

Intestinal helminths are common worldwide, but the most important and common soil transmitted helminthic infections are by Ascaris lumbricoides, Trichuris trichiura, and the two hookworm species Ancylostoma duodenale and Necator americanus.

Trichuris trichiura is commonly known as the “whipworm” because of its morphology. Its life cycle is simpler than that of the other helminths ( Fig. 117.1 ). Trichuris eggs are ingested in contaminated food and water (see Fig. 123.1 ). They mature in the distal small bowel and then pass into the colon. Adult worms migrate to the cecum and the appendix, where they live, copulate, and deposit eggs. The eggs pass through the feces to complete the life cycle.

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Trichuriasis: Life Cycle of Trichuris Nematode Helminth (Whipworm).

Trichuriasis currently affects an estimated 1 billion persons worldwide, with most infections concentrated in the tropics or the semitropics. Trichuris trichiura most often infects humans, who are the only host of the species. It is identified in approximately 1% of stool specimens in the United States, most often in young children. Most humans harbor only a few worms, but the infection can be extremely heavy in some patients. The life span of the worm can range from 1 to 8 years, and each female may produce as many as 3000 to 20,000 eggs. The eggs may penetrate or attach to the mucosa and cause a significant pathologic response.