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Introduction of Trichuris trichiura

Trichuris trichiura is one of the intestinal parasites, structure looks like a whip, so it is called whipworm, the common name having a size of 5.0 cm, present in the site of the host large intestine with the portal of entry mouth ingestion. The infective stage is embryonated egg and organism present in contaminated food and water. It causes the disease trichuriasis (a type of helminthiasis which is one of the neglected tropical diseases).

Scientific Classification

• Kingdom: Animalia
• Phylum: Nematoda
• Class: Enoplea
• Order: Trichocephalida
• Family: Trichuridae
• Genus: Trichuris
• Species: T. trichiura
• Binomial name: Trichuris trichiura

Geographical Distribution: Common in warm moist regions

Habitat: The adult worm lives in the large intestine of man, particularly in the caecum, also in the vermiform appendix.

Morphology of Trichuris trichiura

Morphology of adult worm
The worm is oviparous.
Male:
It measures 3-4 cm in length.
Its caudal extremity is coiled ventrally.
Female :
It measures 4—6 cm in length.
The caudal extremity is either shaped like a “comma” or an arc.

Morphology of egg

Size about 50μm in length by 25μm in a breath.
color, brown (bile–stained ), has a double shell, the outer one is bile-stained. Barrel-shaped with a mucous plug at each pole.
contains an unsegmented ovum when the egg leaves the human host.
Floats in a saturated solution of common salt. The eggs when freshly passed are not infective to man.

Life cycle of Trichuris trichiura

Larva liberated from the egg in man intestine and each larva develops into an adult male or female

Adult worms life span is 10 years

Eggs escaping in stools

Development of eggs in the soil

Rhabditiform larva infective (3 to 4 weeks)

Ingestion of rhabditiform larva and again cycle repeats.

Pathogenicity and clinical features

Infection with T. Trichiura is known as trichuriasis.

Mode of infection
portal of entry: Mouth, ingestion
Infective agent: Embryonated egg
Usually, the worm does not produce any pathogenic effect. The worm inhibiting the vermiform appendix may give rise to symptoms of acute appendicitis.
In heavy infections, the patient often complains of abdominal pain, mucous diarrhea often with blood-streaked stool, and loss of weight. Prolapse of the rectum has occasionally been observed in massive trichuriasis.

Laboratory Diagnosis of Trichuris trichiura

It is established by the finding of characteristics of eggs by direct microscopical examination of a saline emulsion of the stool. Adult worms may occasionally be present in the stool. The degree of infection can be determined by egg count. Proctoscopy examination show a worm on the rectal mucosa in diarrhea caused by a parasite.

Direct Method

Laboratory diagnosis can be made by demonstration of characteristic eggs in the feces by microscopy and concentration method. Microscopy: Smear preparation and eggs are observed under the microscope.

Concentration method

Flotation method: Using brine solution (saturated sodium chloride solution) or zinc sulfate solution. Formal Ether sedimentation method: Using formalin and ether. Eggs count: Fecal egg count may be indicated in assessing the severity(worm burden ) in certain cases.

Note:- 10 eggs/ smear indicate light infection: No clinical disease

50 eggs per smear indicate a heavy infection: Clinical disease

Indirect method
Blood examination: Eosinophilia

Presence of Charcot-Leyden crystals in stool

Treatment of trichuriasis

The drugs at present available for the treatment of trichuriasis are thiabendazole and mebendazole (100 mg twice daily for 3 days )
Albendazole (400 mg daily for 3 days) is also effective.
Ivermectin (200μgm/kg ) is also used in combination with albendazole (400 mg).

Prophylaxis

1.  Proper disposal of the night-soil.
2. Prevention of the consumption of uncooked vegetables and fruits grown in native gardens.
3. Sanitary disposal of feces.

References

1. Atlas of Medical Helminthology and protozoology -4th edn  -P.L.  Chiodini, A.H. Moody, D.W. Manser
2. Merkell and Voge’s medical parasitology
   9th edition.
3. Parasitology: 12th edition
   By K. D. Chatterjee
4. District laboratory practice in Tropical countries –Part-I.
   By Monica Chesbrough.
5. Isenberg clinical microbiology procedures Handbook
   2nd edition. Vol. 2
6. Medical Parasitology by Abhay R. Satoskar, Gary L. Simon, Peter J. Hotez and Moriya Tsuji
7. Atlas of Human Parasitology, Lawrence R Ash, Thomas C. Orihel, 3 rd ed, Publisher ASCP Press, Chicago.
8. Molecular Medical Parasitology. Editors: J. Joseph Marr, Timothy W. Nilsen, and Richard W. Komuniecki, Publisher Academic Press, an imprint of Elsevier Science.
9. Topley & Wilson’s Principle of parasitology. Editors: M.T. Parker & amp; L.H. Collier, 8 th ed 1990, Publisher Edward Arnold publication, London.