TRICHURIS TRICHURIA Flashcards
What’s the common name for Trichuris trichuria?
Whip worm
What’s the habitat of T. trichuria?
T. trichiura lives in the large intestine
The adult worms attached to the wall of the caecum, less commonly to the appendix, colon and anal canal
Distribution of T. trichuria;
World wide but mostly in the tropics
about 800 million people infected!
frequently occurs with Ascaris.
Adult T. trichuria worm morphology;
- The male worm is 30–45 mm long,
- The female is slightly larger, about 40–50 mm.
- In shape, it resembles a whip;
- with the anterior three-fifth thin and thread-like
- the posterior two-fifth thick,
- appearing like the handle of a whip
- The attenuated anterior portion, which contains the capillary esophagus, is embedded in the mucosa.
- The posterior part contains the intestines and reproductive organs
- The posterior end of the male is coiled ventrally, while the hind end of the female is straight, blunt and rounded
- The worm has a lifespan of 5–10 years
T. trichuria Egg Morphology
- The egg has a characteristic appearance.
- It is brown in color being bile-stained.
- It has a triple shell, the outermost layer of which is stained brown.
- It is barrel-shaped and about 50 μm long and 25 μm wide in the middle, with a projecting mucus plug at each pole containing an unsegmented ovum
- The plugs are colorless.
- The egg floats in saturated salt solution.
- When freshly passed, the egg contains an unsegmented ovum.
- At this stage, the eggs are not infective to humans.
- The fertilized female lays about 3000 - 10,000 eggs per day.
Life cycle of T. trichuria
The unembryonated eggs are passed with the stool ①In the soil, the eggs develop into a 2-cell stage
②an advanced cleavage stage
③and then they embryonate
④eggs become infective in 15 to 30 days. After ingestion (soil-contaminated hands or food), the eggs hatch in the small intestine, and release larvae
⑤that mature and establish themselves as adults in the colon
⑥The adult worms (approximately 4 cm in length) live in the cecum and ascending colon. The adult worms are fixed in that location, with the anterior portions threaded into the mucosa. The females begin to oviposit 60 to 70 days after infection. Female worms in the cecum shed between 3,000 and 20,000 eggs per day. The life span of the adults is about 1 year
What are the hosts of T. trichuria?
Man. No intermediate host is required.
What are the infective and diagnostic forms of T. trichuria?
Infective form: Embryonated eggs containing rhabditiform larva.
DIAGNOSTIC FORM; unembryonated eggs
What arises from T. trichuria infection?
trichuriasis, whipworm
infection, or trichocephaliasis
Pathogenicity and Clinical features of trichuriaris;
is asymptomatic, except when the worm load is heavy.
- Disease may result either due to mechanical effects or allergic reaction; The worms lie threaded into the caecal mucosa and even though it is not a blood feeder, oozing of blood may occur at the sites of attachment.
- Mechanical blockage of the appendiceal lumen by masses of whipworms may cause acute appendicitis
- The blood loss is about 0.005 mL per worm per day. Over a period of time, this may lead to anaemia and
malnutrition. - In heavy infection, the worm may be abundant on the colonic mucosa, even up to the rectum.
- Mucus diarrhoea, chronic dysentery, abdominal pain,
weight loss and painful or frequent defecation. - Finger clubbing
- Some patients, particularly young children, may develop rectal prolapse.
Laboratory Diagnosis of Trichuriasis
Stool Examination
* The characteristic barrel-shaped eggs are found in
stools.
- The degree of infection can be assessed by egg counts.
- Less than 10 eggs per smear in direct stool preparation
is considered light infection and - More than 50 per smear as heavy infection
- Light infection is not considered to cause clinical
disease.
Sigmoidoscopy
* Sigmoidoscopy is useful as worms are found in the rectal
mucosa in whipworm diarrhea and dysentery.
Charcot- Leyden crystals are usually abundant in stools
of patients with whipworm dysentery.
- In heavy infection, sigmoidoscopy may show white
bodies of worm hanging from the inflamed mucosa, the
so called coconut cake rectum.
Blood Examination
* Differential leukocyte count (DLC) may show upto 25%
eosinophilia in the early stage of the disease
Treatment of Trichuriasis;
- Mebendazole (100 mg twice daily for 3 days) drug of
choice - Albendazole (single dose of 400 mg) are effective with
cure rates of 70–90% (may be used as an alternative
drug) - Ivermectin in combination with Albendazole – exhibit
better cure and egg reduction rate than Albendazole
alone - Iron supplements
Trichuriasis can be prevented by……………..
- Proper disposal of faeces.
- Avoiding consumption of unwashed fruits and vegetables.
- Treatment of infected persons.
- Mass treatment
- Health education
