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Common Intestinal Worms

Intestinal worms are a common occurrence, especially in the tropics. Most affected in Indonesia are children, but adults can also be the host of these parasites, which feed on nutritious bowel content as well as the blood of its host. Worms come in various size and shape, and are classified three main categories:

  • Roundworms (nematodes)
  • Tapeworms (cestodes)
  • Flukeworms (trematodes)

Because of its common occurrence and asymptomatic character, many practitioners recommend regular de-worming therapy for children living in tropical countries. Unless there are known contraindications for this, there is certainly no harm in following that advice. The drugs used for this are effective against the most common types of worms.
If a person detects worms in his stool, it is best to try and collect a specimen of the parasite, and to see a practitioner for investigations and treatment.

Intestinal roundworms (nematodes)

Round worms are the most frequent parasites infecting human and are very frequent in Indonesia. Intestinal round worms have adult stages infecting the intestinal tract of human and eggs and/ or larval stages can be found in the stools. For some roundworms larval stages can be found in organs outside the intestinal tract, like cardiovascular system, lungs and muscles.

The most common species affecting humans are mainly:

  • Pinworms (Enterobius vermicularis) are very small roundworms who in some areas can infect up to 40% of children.
  • Ascaris lumbricoides, which is the largest roundworm found in humans and is usually much more symptomatic than the pinworm.
Other species include whipworms (trichuris trichiura), hookworms (necator americanus and ancylostoma duodenale), threadworms (strongyloides stercoralis and trichostrongylus) and thichinosis (trichinella spiralis)

Human are infected by ingesting eggs through consumption of contaminated food or drinks, but another route of infection is through walking on fecal-contaminated soils (hookworms and threadworms).

Most of the persons infected by roundworms are asymptomatic, and therefore not aware that they are carrying worms and excreting eggs. When people are suffering symptoms, these are mainly non-specific intestinal symptoms with cramps, colic, diarrhea, itching around the anus (esp. for pin worms). Rarely does it come to surgical complications through migration of the worm into the appendix (appendicitis) or gallbladder (cholecystitis). Some roundworms migrate through the lungs (hookworms, ascaris and threadworms) which can cause respiratory symptoms accompanied by fever and coughing. Uncommon but possible is the migration of roundworms to other organs and parts of the body, where it may then cause symptoms.

It is not uncommon for patients to detect living worms in the stool, which then triggers a visit to the doctor and treatment. However, if worms are suspected based of a patient's complaint or clinical signs, the diagnose can be made by stool sampling, where the worm is identified by the characteristics of the larva and/or eggs. The cellophane–tape impression is used for the diagnostic of pinworms, thereby a strip of cellophane is attached to the skin around the anus, and then analysed for eggs that may stick to the tape. This is best done in the early morning, since eggs are placed there overnight by the adult worm. A blood test can help to make the diagnosis by identifying a specific type of immune response (eosinophilia for the roundworms with tissue migration).

Egg of ascaris in the stools

Once a roundworm has been identified, the patient requires erradication treatment, some specific drugs used are mebendazole, albendazole or pyrantel. Usually the stool needs to be checked again two weeks after treatment, and if remaining parasites are identified a second course of treatment prescribed. The drugs usually don’t kill the worms, but paralyze them. Therefore it is normal for a patient to pass living worms in the stool after the medicine was taken.

The best treatment is prevention, good sanitation and hygiene can break the fecal-oral contamination cycle. It is important to remember that eggs can be transmitted through soil on vegetables, contaminated water, hand towels in bathrooms as well as through direct hand-to-mouth contact.

Intestinal flatworms/tapeworms (cestodes)

Tapeworms are segmented flatworms, three species are common:

  • Beef (taenia saginata) and pork (taenia solium) tapeworms which are long flatworms. The photo above shows a 12-feet long beef tapeworm.
  • Hymenelopis nana, which is a small tapeworm.

Infection occurs when people eat raw or under-cooked beef and pork. The vector for hymenolopis nana is the same as for roundworms: by fecal contaminated food and water.

Like roundworms, most of the infections by tapeworms are asymptomatic. When symptomatic, the symptoms are abdominal pain, change in appetite, weight loss, itchy skin, and rarely for the pork tapeworm some larval migration (cysticercosis) with neurologic and muscular symptoms.

The diagnosis like for roundworms is based on the stool examination which can reveals eggs or (flat) fragment of worms. These are not usually visible by the patient himself. Some blood testing for antibodies is also available.

Fragment of beef tapeworm in the stools

The treatment of tapeworms is similar for all the flat worms. Medication is given as a single dose. The treatment of migrating larva is more complex, and may even involve surgical treatment. After treatment, the stools need to be checked at 1 month and 3 month time.

Similar as with all intestinal infection, prevention is the best treatment. Apart from avoiding uncooked meat or beef, veterinary control of cattle and domesticated pigs is an effective measure.

Intestinal flukeworms (trematodes)

Flukeworms are categorized according to the body part they tend to affect. The liver, blood, lungs and intestines are most commonly involved. Adult intestinal flukeworms are 2-8 cm long and infected persons are commonly asymptomatic. Only with heavy worm infestation do symptoms such as abdominal pain, diarrhea and occasional malabsorbtion and weight loss can occur. Like with other intestinal worms, the eggs are excreted through feces and go through a life cycle outside the body to develop into the cyst form, which is then ingested by humans through contaminated vegetables or water.

Once the diagnose is made through stool examination and treatment started, the prognosis is excellent.

If you have medical-related questions about living in Indonesia to ask of medical professionals, see Ask the Experts.

We trust this information will assist you in making correct choices regarding your health and welfare. However, it is not intended to be a substitute for personalized advice from your medical adviser.

Our appreciation to Dr. Uwe Stocker of International SOS, an AEA Company who contributed this article in response to a health threat faced by expatriates in Indonesia.