Trichuris trichiura

Trichuris trichuria Known as the whipworm is also a soil-

transmitted helminth. Ascaris and Trichuris are frequently

observed as occuring together. Trichuris is also notable for its small size

compared with Ascaris lumbricoides. A holomyarian, based on the

arrangement of somatic muscles in cross section where cells are small, numerous and closely packed in a narrow zone.

Parasite biology

The male worm measures 30 to 45 mm, slightly shorter than the female.

The female worm is about 35 to 50 mm long.

The female has a bluntly rounded posterior end.

The male has a coiled posterior with a single spicule and retractile sheath.

Both worms have an attenuated anterior three-fifths traversed by a narrow esophagus resembling a string of beads.

And the robust posterior two-fifths contain the intestine and a single set of reproductive organs.

The female worm is about 35 to 50 mm

The male worm measures 30 to 45 mm

Posterior part of male Trichuris trichuria

Posterior part of female Trichuris trichuria

A female lays approximately 3000 to 10000 eggs per day.

The eggs approximately measures about 50 to 54 um. It is lemon shaped with plug like translucent polar prominence.

Fertilized eggs are unsegmented at oviposition and embryonic development takes place outside the host.

Compared to Ascaris eggs, Trichuris eggs in soil are more susceptible to desiccation.

Eggs

Eggs are lemon shaped with plug-like translucent polar prominences. 50~54um

Life cycle Trichuris worm inhabit the large intestine. After copulation, the female worm lays

eggs, which are passed out with feces and deposited in the soil.

Under favorable conditions, the eggs develop and become embryonated within two to three weeks.

If swallowed, the infective embryonated eggs go to small intestine and undergo four larval stages to become adult worm.

Unlike Ascaris, there is no heart lung migration.

Pathogenesis and Clinical Manifestation.

The anterior portion of the worm, which is embedded in the mucosa, cause petechial hemorrhages, which may predispose to amebic dysentery.

The mucosa is hyperemic and edematous; enterorrhagia is common and there may even be rectal prolapse.

The lumen may be filled with worms, and irritation and inflammation may lead to appendicitis or granulomas.

Infection with over 5,000 T. trichuria eggs per gram of feces are usually symptomatic.

Those with more than 20,000 eggs per gram feces often develop severe diarrhea or dysenteric syndrome.

Light infections, usually asymptomatic, and the presence of the parasite is discovered in stool examination.

In heavily parasitized individuals, the worm may be found throughout the colon and rectum.

Heavy chronic trichuriasis are often marked by:

Frequent blood-streaked diarrheal stools

Abdominal pain and tenderness Nausea Vomiting Anemia Weight loss

Diagnosis

Clinical diagnosis is possible only in heavy chronic Trichuris infection.

In light infection, where symptoms are absent, laboratory diagnosis is essential.

Direct fecal smear (DFS) with a drop of saline.

Kato thick smear method – highly recommended in diagnosis of trichuriases

Kato-Katz technique – used for egg counting to determine cure rate (CR), egg reduction rate (ERR), and intensity of infection.

Acid-ether Formalin-ether method Kato-cellophane – as well as Kato-Katz are

simpler and low-cost.

Treatment

Mebendazole – drug of choice for Trichuris.

Albendazole – may be used as an alternative drug.

Ivermectin in combination with albendazole – exhibit better cure and egg reduction rate than albendazole alone.

Egg reduction rate (ERR), cure rates (CR), re-infection rate and egg count should be determined pre and post-treatment.

Contraindication for albendazole is pregnancy.

Contraindication for mebendazole are hypersensitivity and early pregnancy.

Epidemiology Trichuris occurs in both temperate and

tropical countries, but is more widely distributed in warm, moist areas of t ranges he world.

Prevalence in temperate countries ranges from 20 to 30%.

In tropical countries, it ranges from 60 to 85%.

In the Philippines, the prevalence is from 80 to 84%.

In school surveys conducted in 2001, T. trichuria has been found to have higher infection rates than A. lumbricoides.

Factors affecting transmission are the same as that of Ascariasis namely:

Indiscriminate defecation of children around yards

Frequent contact between fingers and soil among children at play

Poor health education Poor personal and community hygiene Unhygienic behavior and eating habits.

Prevention and Control Mass treatment may be indicated id infection

rates are higher than 50% Infection in highly endemic areas may be

prevented by: Treatment of infected individuals Sanitary disposal of human feces by

construction of toilets Washing of hands with soap and water before

meal Health education on sanitation and personal

hygiene Washing and scalding of uncooked vegetables

especially if night soils is used as fertilizers