Originally published in The Ottawa Citizen May 29, 2004
Original Title: Bugs down the gullet

They have exotic names but they are less than endearing. Intestinal parasites come in all shapes and sizes. Each has its own way of taking advantage of the body’s metabolism and anatomy.

Although there’s a wide variety of parasites, let’s look at the most common vermin to hitchhike the intestinal highway (sorry, if you are eating breakfast).

Pinworm or Enterobius vermicularis is a worldwide infection affecting about 200 million adults and approximately 30 per cent of children.

These small roundworms or nematodes measure eight to 13 millimetres for females and two to five millimetres for males. Transmission of the parasite’s eggs occurs via the fecal-oral route. Poor hand washing and hygiene can transfer them from person to person.

Once the eggs are swallowed, they hatch in the initial portion of the small intestine called the duodenum. From there they migrate to the large intestine and settle in the cecum located in the right lower quadrant of your abdomen. The female will take a nightly crawl from the cecum to the outside edge of the rectum where she will lay up to 15,000 eggs.

This infestation causes few symptoms, is self-limiting and lasts about six weeks (if the host person remains isolated from any new infected contacts).

Rectal, vaginal and perineal (the skin between the rectum and vagina or scrotum) irritation and itch are the most common symptoms. Indeed, children who complain of rectal itch and are unable to sleep may have pinworm. Weight loss, bladder infections and appendicitis are very rare complications.

Applying cellophane tape to the rectal area will pick up the eggs. They can be seen under the microscope.

One dose of mebendazole (Vermix) taken two weeks apart will kill the pinworms. Prevention includes treating household contacts and cleaning the bedrooms and beds.

Giardia lamblia often invades individuals who hike in the wilderness, hence its nickname “beaver fever.” Poor sanitation and contaminated waterways contribute to this protozoan’s worldwide presence. Like pinworm, it follows a fecal-oral route of transmission but lives in water.

Indeed this infection, known as zoonosis, can survive in chlorinated city water and cold mountain streams. It infects many species including beavers, dogs, rodents, cattle and bighorn sheep, thus ensuring a rich reservoir.

Giardia will incubate for about two weeks before symptoms occur. It may cause an upset stomach, nausea, fatigue, gas, cramps, fatty stools, weight loss and diarrhea. Some may have itching and rashes. The infection persists two to four weeks. Malaise, fatigue and depression may wax and wane over many months if the condition is not treated.

A stool examination for ova (eggs) and parasites will uncover giardia. Treatment with the antibiotic metronidazole will eradicate the infection in adults.

The infection can be prevented by employing proper sewage treatment and disposal. Travellers to at-risk areas should drink only bottled water. Water treatment options include boiling for one minute, using iodine water-purifying tablets eight hours prior to drinking, and proper handwashing technique.

Entameba histolytica is another protozoal infection spread by the fecal-oral route. Poor hygienic food preparation techniques and food grown in soil fertilized with human waste are common worldwide problems. Ten per cent of the world’s population carries the infection. Although 90 per cent of infected people do not have symptoms, the remaining 10 per cent or 50 million people will experience intestinal bleeding, fatigue, weight loss, severe abdominal cramps and pain, copious bloody diarrhea and fever — worldwide, 100,000 die each year from it.

It can escape from the intestine, causing abscesses in the liver and the tissues lining the lung (pleura) and heart (pericardium).

Metronidazole is a common antibiotic choice for uncomplicated infestation. Avoid eating unpeeled fruits and vegetables when travelling to endemic areas. Stick to bottled water and use iodine tablets for any non-bottled water source.

Consult your doctor should you experience diarrhea and malaise after travel.

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© Dr. Barry Dworkin 2004