TRICHURIS TRICHIURIA (Whipworm)

GEOGRAPHICAL DISTRIBUTION

It is widely distributed in warm tropical climates such as South Asia, South East Asia and Africa.

MORPHOLOGY

Female worm is about 30-50 mm in length while the male is about 20-30 mm. The anterior 3/5^th of the body is thin while posterior 2/5^th is thick in both sexes. The posterior end of the male is curved.

LOCATION IN THE HOST

The worm inhabits the large intestine. The entire thin anterior end is threaded into the mucosa while the thick, short posterior end project into the lumen of the large intestine.

LIFE CYCLE

The female lays 2000-10000 eggs per day. The eggs have a characteristic ‘paddy seed’ shape, (50*20 µm) with ‘polar caps’. The eggs are passed in the faeces. They require a period of maturation in the soil. The optimal conditions are similar to those of Ascariasis. Because of this fact trichriasis often co-exist with Ascariasis. When infective eggs are ingested by humans the eggs hatch in the lower part of the small intestine and the larvae pass down into the large gut to mature into adults. The mode of transmission is similar to that of Ascariasis. But there is no pulmonary migration of larvae in trichuriasis.

PATHOGENESIS AND CLINICAL FEATURES

Light infections may be asymptomatic. Heavy infections lead to blood and mucous diarrhea. In children tenesmus and constant straining may lead to ractal prolapse. In some heavily infected children, the infection may result in ‘Trichuris Dysentry Syndrom-TDS’.There can be other clinical features as follows;

1. Trichuriasis and malnutrition; Both conditions can co-exist and it is difficult to determine a cause and effect. The infection shows a close correlation of the intensity of infection (worm load) and the severity of symptoms such as diarrhea, vomiting and rectal prolapse. TDS is generally seen with worm loads over 500 worms. The symptoms lead to lowering of food intake, which worsen the already existing malnutrition.

2. Trichuriasis and anemia; Anemia is a constant feature of heavy infection. It is hypochromic and microcytic. Anemia may be due to; blood loss from colonic mucosa: blood loss due to ingestion by worms. It is not certain whether Trichuris is a ‘blood sucker’. Few red cells are often seen in the intestine of the worm.

3. Growth retardation; This is a distinct association in trichuriasis. This is seen with even mild infections. This feature may be due to severe anorexia, nausea and vomiting associated with the infection.

4. Finger clubbing; this is another distinct association of the severe infection (TDS)

DIAGNOSIS

Diagnosis is by demonstrating the characteristic eggs in the faeces. A simple wet smear with saline/iodine is often sufficient. Concentration techniques such as formol-ether could be used. Foe quantitative studies Kato-Katz technique is good.

PREVENTION AND CONTROL

Vegetable that are usually eaten raw or undercooked should be washed thoroughly. Fruits fallen under trees should be washed before eating. Washing of hands after working with soil helps in the prevention.

Prevention of indiscriminate defaecation, provision of sanitary latrines, elimination of parasite reservoir by worm treatment and health education are important.

TREATMENT

Mebendazole (500 mg once) or albendazole (400 mg daily for 3 doses) is safe and effective for treatment.