Trichuris Trichiura (Whipworm) Infection (Trichuriasis)

Updated: Apr 15, 2016
  • Author: Kwame Donkor, MD; Chief Editor: Jeter (Jay) Pritchard Taylor, III, MD  more...
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Overview

Background

Trichuriasis, which is infection with the parasite Trichuris trichiura, or whipworm, is a very common intestinal helminthic infection worldwide. About one quarter of the world's population is thought to carry the parasite. Principally a problem in tropical Asia and, to a lesser degree, in Africa and South America, a lack of a tissue migration phase and a relative lack of symptoms characterize whipworm infection. Trichuris is also notable for its small size compared with Ascaris lumbricoides. Only individuals with heavy parasite burden become symptomatic. Vitamin A deficiency has been seen in patients with trichuriasis.

Poor hygiene is associated with T trichiura transmission, and children are especially vulnerable because of their high exposure risk. This is especially true in developing countries, where poor sanitary conditions correlate with heavy disease burden and infections. One study in Nigeria was undertaken to determine helminth infection status and hygienic conditions in primary schools. Prevalence of helminth infection was higher in the schools where hygiene conditions (ie, tapwater, handwashing soap) were lacking. The study results recommended that the school health programs include deworming, health education, and improvement of hygiene conditions. [1]

The whipworm derives its name from its characteristic whiplike shape; the adult (male, 30-45 mm; female, 35-50 mm) buries its thin, threadlike anterior half into the intestinal mucosa and feeds on tissue secretions, not blood. This relative tissue invasion causes occasional peripheral eosinophilia. The cecum and colon are the most commonly infected sites, although in heavily infected individuals, infection can be present in more distal segments of the GI tract, such as the descending colon and rectum. See the image below.

Adult Trichuris trichiura males are 30-45 mm long, Adult Trichuris trichiura males are 30-45 mm long, with a coiled posterior end. Adult females are 35-50 mm with a straight posterior end. Both sexes have a long, whip-like anterior end. Adults reside in the large intestine, cecum, and appendix of the host. Image shows the posterior end of an adult T trichiura, taken during a colonoscopy. Image courtesy of Duke University Medical Center and Centers for Disease Control and Prevention.

Note that T trichiura is usually found in association with other helminths that flourish under similar conditions, a common pathogen being A lumbricoides.

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Pathophysiology

Trichuris, as with Ascaris lumbricoides, is spread via fecal-oral transmission. Eggs are deposited in soil through human feces. After 10-14 days in soil, eggs become infective. In contrast to other parasites, such as A lumbricoides, no tissue migratory phase occurs with Trichuris organisms, confining infection to the GI tract. Larvae hatch in the small intestine, where they grow and molt, finally taking up residence in the large intestine. The time from ingestion of eggs to development of mature worms is approximately 3 months. During this time, there may be no shedding of eggs and only limited evidence of infection in stool samples. Worms may live from 1-5 years, and adult female worms lay eggs for up to 5 years, shedding up to 20,000 eggs per day.

See the image below.

This is an illustration of the life cycle of Trich This is an illustration of the life cycle of Trichuris trichiura, the causal agent of trichuriasis. Image courtesy of Centers for Disease Control and Prevention, Alexander J. da Silva, PhD, and Melanie Moser.

Immunologically, cytokines such as interleukin 25 (IL-25) mediate type 2 immunity and are required for the regulation of inflammation in the gastrointestinal tract.

Recent linkage analyses of a genome-wide scan revealed that two quantitative trait loci on chromosomes 9 and 18 may be responsible for the susceptibility to trichuriasis in some genetically predisposed individuals. [2]

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Epidemiology

Frequency

United States

Whipworm infection is rare overall but is more common in the rural Southeast, where 2.2 million people are thought to be infected.

International

Whipworm infection is more common in less-developed countries. T trichiura is carried by nearly one quarter of the world population.

Mortality/Morbidity

Whipworm infection is rarely fatal and is usually asymptomatic, but symptoms may be present in heavily infected individuals. Loose stools may be present with minimal blood with the development of chronic anemia if bleeding is chronic. Nocturnal stooling is quite common. Finger nail clubbing may also be present. In children, vitamin deficiencies (vitamin A) may contribute to developmental delay and growth retardation. Rectal prolapse may occur in heavily infected hosts.

Race

Trichuriasis has no racial predilection.

Sex

Boys are more likely to be infected with T trichiura because they are thought to eat more dirt than girls.

Age

Children are more commonly infected than adults due to poor hygiene and increased consumption of soil. Children are also more heavily infected. Furthermore, it is widely believed that partial protective immunity develops with age and children are not protected initially.

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