Intestinal Worms : how they affect health

The organisms that cause intestinal worms are called helminths. Helminths are a broad range of parasitic organisms (worms) which are able to infect humans or other animals and cause disease in them. There are numerous types of worms or helminths that can cause disease in human beings, but the worms that commonly and specifically affect the intestinal tract are Ascaris Lumbricoides (round worms), Trichuris Trichiura (whip worms), and Necator Americanus and Ancyclostoma Duodenele (hook worms).

Intestinal worm infestation or soil transmitted helminthiasis are among the most common infections worldwide and affects the poorest and most deprived communities especially. More than 1.5 billion people, or 24% of the world’s population, are infected with soil-transmitted helminth infections worldwide.

These infections are widely distributed in tropical and subtropical areas, with the greatest numbers occurring in sub-Saharan Africa, the Americas, China and East Asia. Over 267 million preschool-age children and over 568 million school-age children live in areas where these parasites are intensively transmitted, and are in need of treatment and preventive interventions.

How Intestinal Worms Affect the Body

Intestinal worm infestation can cause sickness and sometimes even death. The greater the number of worms, the greater the severity of the disease.

Severe round worm infestation which resulted in intestinal obstruction requiring surgery

When someone is infested with worms, there are a number of ways the intestinal worms can compromise the person’s health, especially in children. The ways include :

  1. Affecting the nutritional status of the child or adult. The worms feed on an infected persons tissues, including blood, leading to loss of proteins and iron leading to poor or delayed physical growth and development.
  2. The worms can increase malabsorbtion of micro nutrients in the intestine by competing for such nutrients like vitamin A and others, causing certain deficiencies.
  3. Some can cause loss of appetite which leads to reduced food intake, hence, low energy and physical fitness for carrying out normal activities.
  4. Hook worms can invade intestinal wall which causes chronic blood loss that results in anaemia.
  5. The worms can affect cognitive processes especially in preschool and school age children leading to poor learning and performances in class with difficulty to concentrate.
  6. Round worms can provoke intestinal obstruction and rectal prolapse which will require surgical intervention to correct.
  7. Worms can also induce tissue reactions such as granuloma.

Common Symptoms of Intestinal Worms

The symptoms of intestinal worm infestation is dependent on the number and type of helminth that is causing the disease. Generally, these symptoms may include :

  • Diarrhoea or constipation.
  • Abdominal pains.
  • General malaise (feeling of sickness).
  • Weakness.
  • Loss of appetite.
  • Gastrointestinal bleeding (causing anaemia symptoms).

How Intestinal Worms are Transmitted


Adult intestinal worms live in the intestines of infected individuals where they produce thousands of eggs each day. When these infected individuals excrete, the helminth eggs in their faeces then contaminates the soil or water in areas of improper sanitation like “defecating in the open.”

Other people can become infected with these eggs or larvae through any of these means :

  1. Drinking from contaminated water sources with these helminth eggs or larvae.
  2. Ingesting these helminth eggs or larvae in contaminated food like vegetables and fruits that are not carefully washed, peeled or cooked.
  3. Ingestion of the eggs or larvae directly from the contaminated soil especially among children who play with sand and do not properly wash their hands afterwards.
  4. Direct skin penetration by the eggs and larvae especially in those who walk barefooted on the ground.

There is no direct person-to-person transmission of these helminths and there is also no infection from fresh stools because the eggs passed in faeces need about 3 weeks in the soil before they become infective.

Treatment of Intestinal Worms

The WHO recommended medicines – albendazole (400 mg) and mebendazole (500 mg) – are effective, inexpensive and easy to administer by non-medical personnel (e.g. teachers). They have been through extensive safety testing and have been used in millions of people with few and minor side-effects.
Both albendazole and mebendazole are donated to national ministries of health through WHO in all endemic countries for the treatment of all children of school age.

Prevention and Control

WHO recommends periodic medicinal treatment (de-worming) without previous individual diagnosis to all at-risk people living in endemic areas. Treatment should be given once a year when the baseline prevalence of soil-transmitted helminth infections in the community is over 20%, and twice a year when the prevalence of soil-transmitted helminth infections in the community is over 50%. This intervention reduces morbidity by reducing the worm burden.

In addition, health and hygiene education reduces transmission and reinfection by encouraging healthy behaviours. This include advocacy for children and adults to cultivate handwashing practice and stoppage of defecation in the open, as well as using human faeces for manure.

provision of adequate sanitation is also important but not always possible in resource-poor settings.



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