Trichuris trichiura ( WHIPWORM ) : PARASITOLOGY
The adult whipworm is 30 to 50 mm in length. The anterior two thirds is thin and thread-like, whereas the posterior end is bulbous, giving the worm the appearance of a tiny whip. The tail of the male is coiled; that of the female is straight. The female produces 3000 to 10,000 oval eggs each day. They are of the same size as pinworm eggs but have a distinc-tive thick brown shell with translucent knobs on both ends (Fig 55 – 2).
Trichuris trichiura has a life cycle that differs from that of the pinworm only in its exter-nal phase. The adults live attached to the colonic mucosa by their thin anterior end. While retaining its position in the cecum, the gravid female releases its eggs into the lumen of the gut. These pass out of the body with the feces and, in poorly sanitated areas of the world, are deposited on soil. The eggs are immature at the time of passage and must incu-bate for at least 10 days (longer if soil conditions, temperature, and moisture are subopti-mal) before they become fully embryonated and infectious. Once mature, they are picked up on the hands of children at play or of agricultural workers and passed to the mouth. In areas where human feces are used as fertilizer, raw fruits and vegetables may be contami-nated and later ingested. Following ingestion, the eggs hatch in the duodenum, and the re-leased larvae mature for approximately 1 month in the small bowel before migrating to their adult habitat in the cecum.