Human are infected chiefly by a species of whipworm called Trichuris trichiuris or Trichocephalus trichiuris which are round worm nematode that causes Trichuriasis ,one of the neglected tropical disease that infects human and animals large intestine. Because of the worm shapes (Look like a whip with wider handles at the posterior end), It is commonly known as Whipworm.
LIFE CYCLE TRICHURIA TRICHIURIS
Adult worm can live up to 5 years and the female worm can lay up to 20.000 eggs per day for an entire lifetime. Eggs are deposited from human feces to soil where, after 2 or 3 weeks becomes embryonated and enter the infective stage. Hence, the embryonated egg are the infective stage of T. trichiuris.
These infective eggs are ingested and hatch in human small intestine exploiting the intestinal micro flora as hatching stimulus. This is the location of growth, molting.Infective larvae penetrate the Villi and continue to develop in the small intestine.The yong worms love to the caecum and penetrate the mucosa, and there they complete development to adult worms in the large intestine.
The life cycle from the time of ingestion of eggs to development of mature worms takes approximately 3 months. During this time, there may be limited signs of infection in stools samples due to lack of egg production and shedding. The female worm begin to lay eggs after 3 months of maturity. Worms commonly live about 1 year, during which time females can lay up to 20.000 eggs per days as earlier stated.
MORPHOLOGY OF TRICHURIS TRICHIURA
THE ADULT WORM
Adult worm resembles a Whip. It has a narrow anterior esophageal end and shorter and thicker posterior end. The worm is pinkish-white in color and attaches to the host through their slender anterior end and feed on tissues secretions instead of blood.
It should be noted that female worm (35-50mm long) are larger than males ( 30-45 mm) and the females have a bluntly round posterior end while male have coiled posterior end.
The eggs have a mucogelatinous plug at each terminal end of the elongated egg that is bile-stained and barrel-shaped (bipolar protuberances). A smooth but thick shell covers the egg that is from 45 – 55µm in length and 20-23µm in width.
TRANSMISSION OF TRICHURIS TRICHIURA
Trichuriasis is usually spread when people eat contaminated food or drink water that contains eggs of the worms especially when contaminated vegetable are not fully cleaned or cooked.
The eggs are often found in the soil mostly in areas where people defecate outside and where untreated human feces are used as fertilizer. Therefore the best route of transmission is fecal-oral.
Children playing in such soil and putting their hands in their mouths can be easily infected.
Humans are the main but not the only reservoir for Trichuris trichiura.
SIGN AND SYMPTOMS
Minor infestations < 100 worms are frequently asymptomatic meanwhile heavier infestation >100 worms especially in children are symptomatic with gastrointestinal problems including abdominal pain and distension, bloody or mucus filled diarrhea and tenesmus (feeling of incomplete defecation)
Loss of appetite, growth retardation, weight loss, rectal prolapsed, nutritional deficiencies including anemia (Iron deficiency and blood loss)and vitamin A deficiency which may also occur and are characteristically sign and symptoms of Trichuriasis.
It does not commonly cause eosinophilia like other parasitic infections.
Trichuriasis can be diagnosed when Trichuris trichiura eggs are detected in stool examination. The egg are characterized with their elongated shape, smooth shell and are barrel-shaped, brown unembryonated and have bipolar plugs found in the terminal ends.
Apart from direct wet month, concentration techniques like The Kato-katz thick smear technique are used for identification of the eggs in stool sample
Adult worms are rarely seen in fecal samples but are useful in identifying an infection
PREVENTION OF TRICHURIS TRICHIURA
Proper sanitation especially hand washing and waste treatment or disposal and other means of maintaining a good sanitary environment will reduce the rate of contamination
TREATMENT OF TRICHURIS TRICHIURA
- Drug commonly used are obtain by combining mebendazole or albendazole with ivermectin which is very effective even with children.
- Another drug is Diferarsone
- People with diarrhea may also be treated with Ioperamide which increases the amount of drug contact with the parasites.
- District Laboratory practice in Tropical Countries (Monica CHEESBROUGH)