Health

How Dangerous is Helminthiasis?

Dr Shamim Ahmed

Soil-transmitted helminthiasis (STH) or intestinal worm infestation is a group of parasitic infections of the intestine caused by parasitic worms and is the commonest parasitic infection worldwide. Soil-transmitted helminthiasis is the most prevalent of neglected tropical diseases and is responsible for significant morbidity and indirectly mortality.

The causal agents of soil-transmitted helminthiasis are roundworm (Ascaris lumbricoides), whipworm (Trichuris trichiura) and hookworm (Ancylostoma duodenale and Necator americanus).

According to the World Health Organization (WHO), some two billion people are thought to have active infections. Recent estimates suggest that roundworm infects over one billion people, whipworm 795 million and hookworms 740 million. The greatest numbers of STH infections occur in sub-Saharan Africa, South America, China, South and East Asia. The helminth infection is most prevalent in school-age children, the group most vulnerable to the long-term consequences of the infection.

Infection is caused by ingestion of eggs of the parasite from contaminated soil (roundworm and whipworm) or by active penetration of the skin by larvae in the soil (hookworms).

Survey shows that 79.8 percent children of Bangladesh are infected with helminthiasis.
Photo: Zahedul I Khan

People infected with soil-transmitted helminths have parasite eggs in their faeces. In areas with poor sanitation, the soil as well as the adjacent water sources becomes contaminated with faeces containing worm eggs. In the soil, the eggs mature -- a process that takes between two to four weeks, depending on the type of worm (about two weeks for roundworms and hookworms; about four weeks for whipworms)

The worms can then infect humans in the following ways:

The eggs are ingested from water sources which have become contaminated. Contaminated water is the source of different water borne diseases including helminthiasis and one should be careful while relishing fruit juices (sharbat), lassi, ice creams, fuchka and pickles (achar).

Many a times, young children who play on the ground and often put their hands in their mouths without washing them, ingest the eggs and become infected. Often, the eggs stick to vegetables grown in the area. If the vegetables are not carefully cooked, washed or peeled, the eggs are ingested and infect the person. Many vegetables and fruits sold at roadside vans, bus stations, launch terminals and railway stations are not cleaned properly such as cucumber, carrots, amra (Hog plum), starfruit (Carambola), pineapple and guava to name a few.

The hookworms' eggs hatch into larvae which rest in the soil. If a person walks on the contaminated soil, the larvae can penetrate the skin, usually between the toes.

There is no direct person-to-person transmission or infection from fresh faeces because eggs passed in faeces need about three weeks in the soil before they become infective.

The type and severity of symptoms is determined by the type of worm and the part of the body infected. Soil-transmitted helminths produce a wide range of symptoms including intestinal manifestations (diarrhoea, vomiting, abdominal pain, and distended abdomen), fever, general malaise, weakness, loss of appetite, malabsor-ption and weight loss. STH would lead to decreased physical development of children, decreased physical activities, decreased cognitive development, decreased performance in school and malnutrition. Hookworms cause chronic intestinal blood loss that result in anaemia. Rarely, worms may cause intestinal obstruction.

STH can be prevented by ensuring good personal hygiene like washing hands before eating and after using the toilet. Sanitary latrines keep away infected human faeces from the areas where people live. Clean and safe preparation of foodstuffs minimises infection. One must always use slippers or shoes and use proper toilet facilities. Over and above proper environmental sanitation should be ensured. One or more of the four anthelminthic drugs may be used for the treatment of helminthiasis (Albendazole/ Mebend-azole/ Levamisole/ Pyrantel).

Bangladesh is characterised by all the risk factors for intense STH transmission - poverty, poor hygiene, poor water and sanitation system and very high population density. A National Baseline Survey conducted in 2005 found some of the highest infection rates in the world. The overall results showed that 79.8 percent of the children were infected. Of them 43.6 percent had moderate-heavy Ascaris (roundworm) infections and 16.2 percent had moderate-heavy Trichuris (whipw-orm) infections. The plain-land area showed some of the highest infection rates in the region. Overall 96.8 percent of the children were infected.

The Government of Bangladesh is fully aware of the consequences of worm infections and its impact on the health of the population. Accordingly, about 17 million pre-school children (between the ages of 2-5 years) receive de-worming tablets (Albendazole) twice a year during National Immunisation Day (NID)/National Vitamin A Plus Campaign. The programme is implemented by the Institute of Public Health Nutrition (IPHN) under the Directorate General of Health Services. The entire amount of de-worming drugs is procured from government's own fund and is produced locally by the government-run Essential Drug Company Ltd (EDCL). Moreover, about 22 million school children (between 5 to12 years of age) receive de-worming drugs (Albendaz-ole/Mebendazole) during “De-worming Week”, held twice a year (during May and November) throughout one lakh sixty-two thousand primary schools across the country. A bulk of the requirement is funded through the Children Without Worms (CWW), a global initiative. The programme is implemented through the Communicable Disease Control (CDC) wing under the Directorate General of Health Services. The de-worming tablets are also available at the government district hospitals, upazilla health complexes and community clinics and are dispensed according to the complaints of the patients. It is expected that other target groups, particularly the adolescents should also receive due consideration.

Almost all the pharmaceutical companies in the country produce de-worming drugs and these are available at affordable price (Taka 5 per tablet only) at all pharmacies. The drug is absolutely safe and the side effects are minor and transient, that usually disappears spontaneously within 48 hours from onset, without need for hospitalisation. It can be taken at anytime of the day irrespective of meal consumed and at anytime of the year.