Trichuris trichiura commonly known as whipworm causing trichuriasis or whipworm infectionis the third most common helminth, and it is found primarily in warm climates where poor sanitation practices, such as defecating directly into the soil or using human feces as fertilizer, are common. The warm, humid South of the United States, particularly in rural areas, has been known to harbor whipworm. Children and people in psychiatric facilities are especially vulnerable to whipworm infections.
Trichuris and Ascaris infections are both known to occur. This is most likely due to the fact that the human port of entry, which serves as the mode of organism transmission for both parasites, is identical.
Morphology of Trichuris trichiura
Egg of Trichuris trichiura
The typical barrel-shaped (also considered by some to be football-shaped) Trichuris trichiura eggs are 50 to 55 m by 25 m in size. The undeveloped unicellular embryo is encased in a smooth shell that has a yellow-brown color from contact with host bile. At each end, a prominent hyaline polar plug can be seen.
Adults Trichuris trichiura worm
The average adult whipworm is 2.5 to 5 cm long. The adult’s anterior end is colorless and has a slender esophagus. The intestine and reproductive systems are pinkish-gray in color on the back end. Adult males are typically smaller than adult females. Aside from a digestive system, intestinal tract, and reproductive organs, the male has a distinct curled tail. The adult T. trichiura has a large posterior end that resembles a whip handle. The front end is much smaller and resembles the whip itself. The name whipworm is derived from these two morphologic characteristics.
Life Cycle of Trichuris trichiura
Human infection begins with the ingestion of infective T. trichiura eggs containing larvae. Larvae hatch from eggs in the small intestine. The larvae grow and develop as they migrate through the intestinal villi. The larvae return to the intestinal lumen and then to the cecum, where they finish maturing. The resulting adults settle in the colon, embedding themselves in the mucosa. Adult worms in untreated infections have a life span of 4 to 8 years. The adult female lays her undeveloped eggs after copulation. This is the stage of the egg that is passed into the environment via the feces. After about a month outside the human body, usually in the soil, the eggs embryonate, become infective, and are ready to begin a new cycle.
Clinical Symptoms
Asymptomatic
Patients with a mild whipworm infection are usually asymptomatic.
Trichuriasis: Whipworm Infection
Infections of 500 to 5000 worms cause a wide range of symptoms. The conditions that a whipworm infection can mimic differ depending on the host’s age. Children infected with T. trichiura typically exhibit symptoms similar to ulcerative colitis. A child can develop chronic dysentery, severe anemia, and possibly growth retardation from an infection of as few as 200 worms. It’s worth noting that in treated children, catch-up growth is common. Infected children also have increased rectal prolapse and peristalsis. Adults who are infected exhibit symptoms similar to those of inflammatory bowel disease. Infected people commonly experience abdominal tenderness and pain, weight loss, weakness, and mucoid or bloody diarrhea.
Laboratory Diagnosis of Trichuris trichiura
Stool is the preferred specimen for the recovery of T. trichiura eggs. These eggs are especially noticeable in infected samples treated with zinc sulfate flotation. Macroscopic examination of the intestinal mucosa may reveal adult worms. In severe infections, adults may be seen in areas of the intestinal tract up to and including the rectum. It is important to be aware that samples examined from whipworm infection patients may reveal distorted eggs in a variety of unusual shapes.
Treatment of Trichuriasis
Whipworm infections are best treated with mebendazole or albendazole.
Prevention and Control of Trichuriasis
The spread of T. trichiura infections can be slowed by following proper sanitation practices, particularly avoiding defecating directly into the soil, using feces as fertilizer, and putting potentially infective hands into the mouth, as well as treating infected people promptly and thoroughly when indicated. It is critical to educate children and assist institutionalized mentally handicapped people in personal hygiene and sanitation practices in order to completely eradicate whipworm infections.
Reference
Clinical Parasitology: A PRACTICAL APPROACH. Elizabeth A. Gockel-Blessing (formerly Zeibig) P.210-385
