Trichuriasis

How to Cite This Chapter: Ledger M, Stefaniak J, Kłudkowska M. Trichuriasis. McMaster Textbook of Internal Medicine. Kraków: Medycyna Praktyczna. https://empendium.com/mcmtextbook/chapter/B31.II.18.84.1.2. Accessed October 23, 2024.
Last Updated: September 30, 2024
Last Reviewed: September 30, 2024
Chapter Information

Etiology and Pathogenesis

1. Etiologic agent: Trichuris trichiura (whipworm) is a nematode commonly classified as a soil-transmitted helminth (STH). Adult worms are 3 to 5 cm long and found in the large intestines. Eggs released in feces undergo embryonation in the soil and at ideal temperature and moisture become infective after ~3 weeks. Once ingested, they hatch in the small intestine and larvae penetrate the columnar epithelium, where they develop into immature adult worms over ~1 week. They then emerge and travel to the colon, where they develop into mature adult worms. In the colon the anterior end of the worm is embedded within the mucosal epithelium, with the posterior end in the lumen of the intestines. The worms cause a local inflammatory reaction in the intestine with blood loss from burrowing. The time from ingestion of infective eggs until maturation and detection of eggs in the stool (prepatent period) is 2 to 3 months. The typical lifespan of the adult worms is 1 year to 3 years.

2. Reservoir and transmission: Humans are the only host of T trichiura. Transmission is via the fecal-oral route. Infection occurs through ingestion of embryonated eggs from the soil. Humans may become infected through consumption of unwashed fruits and vegetables or soil-contaminated hands.

3. Risk factors: Consumption of unwashed fruits and vegetables or geophagy (ingestion of soil).

4. Incubation and contagious period: The period from infection until the parasites reach full maturity and eggs appear in stool is 2 to 3 months. The eggs are not infective at the time of excretion with stool. Eggs can survive for months in the soil and withstand freezing and high temperatures but are susceptible to desiccation.

Epidemiology

T trichiura has a worldwide distribution with an estimated 400 million people infected. The majority of infections occur in tropical and subtropical regions, particularly in sub-Saharan Africa, the Americas, and Asia. Infections are more often seen in regions with poor sanitation infrastructure. School-aged children typically harbor the highest burden of infection within communities. Locally acquired infections are rare in North America, most cases are imported from tropical and subtropical regions.

Clinical Features and Natural History

Symptoms are related to worm burden (the number of worms carried in the intestine or intensity of infection), with higher worm burdens causing more severe symptoms and complications.

Many infections with a low worm burden are asymptomatic or manifest with mild anemia, anorexia, abdominal pain, and diarrhea. High worm burden can result in colitis with significant anemia, weight loss, and diarrhea with blood. Eosinophil counts may not be elevated or can be mildly elevated. High worm burdens in children have been associated with growth impairment and malnutrition.

Diagnosis

Diagnostic Tests

Standard ova and parasite examination of stool for microscopic detection of T trichiura eggs in stool. For increased sensitivity ≥3 stool samples should be collected within ≤10 days (ideally every 48 h).

Differential Diagnosis

The differential diagnosis for abdominal symptoms is quite broad and includes other gastrointestinal helminths (eg, Ascaris, hookworms, tapeworms) and protozoa (eg, Entamoeba), bacterial causes of infectious diarrhea, as well as other causes of dyspepsia and abdominal pain.

Treatment

Antiparasitic Treatment

1. First-line treatment: Oral mebendazole 100 mg bid for 3 days.

2. Alternative treatment: Albendazole 400 mg once daily for 3 days, oral ivermectin 200 microg/kg/d for 3 days. If the response to treatment is poor, combined albendazole and ivermectin can be used.

The cure rates with antiparasitic agents are lower than for ascariasis. Repeat treatment may be necessary.

ComplicationsTop

Trichuris dysentery syndrome occurs in cases of high worm burdens, particularly in infants and young children, and is characterized by iron deficiency anemia, chronic bloody diarrhea, finger clubbing, and rectal prolapse.

Prevention

1. Washing hands before meals and after contact with soil.

2. Preventing geophagy in children.

3. Thorough washing of fruits and vegetables.

4. At the community level prevention involves access to sanitation facilities, access to clean drinking water, and avoiding the use of human feces to fertilize fruit or vegetable crops.

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