The Ins and Outs of Intestinal Worms

Nothing creeps us out more then the thought of a worm gorging on our gut. Learn what you need to do to hedge an intestinal worm infestation.

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Could Parasites Be Making You Sick? Pt 1 (3:44)

Parasitic worms are enterprising creatures that force their way into the intestinal tracts of unsuspecting human hosts. Worm eggs can be transferred from a blade of grass to the tips of your children's fingers; or they can be swallowed at a four-star restaurant.

The human intestinal tract is the perfect accommodation for these freeloaders. Worms can gorge themselves in the human gut for months or years before they are detected, causing everything from a poor-night's sleep to life-threatening intestinal blockages and malnutrition.

There are hundreds of types of worms (helminths) that infect humans worldwide. They come in all shapes and sizes — flat, round, hooked and barbed.

Although intestinal worm infections are more common in countries where people endure poor sewage disposal, water treatment and food sanitation, adults and children living in the United States are very much at risk, particularly if they travel abroad.

Humans can become infected if they swallow eggs, larvae, cysts or adult worms living in food, drink, soil and feces.

Here are some of the parasites wiggling into the lives of people living in the US.

Ascariasis Roundworm

Ascariasis caused by Ascaris lumbricoides, a type of roundworm (nematode), is the most common parasitic worm infection worldwide. As soon as the eggs are swallowed, they begin to develop. The larvae penetrate the wall of the small intestines and wriggle into the bloodstream where they travel to the lungs. When they are more mature they crawl up from the lungs to the bronchial tubes and throat. The host coughs and swallows the worm-laden mucus. By the time the larvae reach the small intestines they are adult worms.

The full life-cycle takes two to three months. Each adult worm can live in the gut for up to two years and pass 200,000 eggs into feces every day. People acquire the infection when eggs in feces, soil, food and water are ingested.

Symptoms of Ascaris Roundworm:

  • Shortness of breath
  • Cough (sometimes containing worms)
  • Loss of appetite
  • Wheezing
  • Abdominal pain or distention
  • Intestinal obstruction
  • Eggs or worms in stool

Pinworms (Enterobiasis)

Parents who have young children in school know that children have potential for parasites — and  lice is not the only worrisome pest. More than 40 million children and adults have been infected with pinworms (aka seatworm or threadworm) caused by the roundworm Enterobius vermicularis. The eggs are swallowed and migrate down to the small intestines where they hatch into larvae. They continue on to the end of the large intestines where they feast on E. coli in stool and mature into adult worms. At night the worms crawl out of the anus to lay their eggs and in a few hours the eggs hatch.

Intense itching will wake infected hosts from sleep. The eggs that hitchhike under scratching fingernails can make their way back into the mouth of the original host or transferred to a new host when they are dropped onto toys, linens, towels or clothes.

Placing a piece of adhesive tape at the anal opening before bedtime can catch worms to confirm a diagnosis. Infection lasts from four to six weeks.

Symptoms of Pinworms:

  • Anal or vaginal itching
  • Sleep disturbances
  • Poor appetite and weight loss
  • Abdominal discomfort
  • Appendicitis

Tapeworm Infection (Taeniasis)

One of the most feared of all intestinal worms is the tapeworm. They are long, flat worms that have hooks that cling to the intestinal wall. They have no digestive system of their own but instead absorb predigested food in the human gut through their skin. They are self-mating machines that fertilize their own eggs; eventually, the eggs make their way to the end of their long bodies and pass through the host's feces in the hopes of infecting another.

Eggs deposited in soil where pigs and cattle graze can travel through the animal's bloodstream to eventually form walled-off cysts in the animal's muscle. Humans become infected when they eat raw or undercooked infected pork, beef and fish. When the cysts are ingested they break apart exposing the human gut to eggs. It takes about five weeks for the larva to mature into adult worms and some can grow up to 10 feet. They can survive in a human host for many years, sometime decades.

Symptoms of Tapeworms:

  • Loss of appetite
  • Diarrhea or constipation
  • Nausea
  • Abdominal discomfort

The best way to avoid parasitic infections is to practice scrupulous personal hygiene and smart food preparation. Diagnosis is made when worms are visualized or detected in stool. Infected individuals are de-wormed using anti-parasitic medications. 

Ways You Can Hedge Against Being a Host

  • Don't eat food that has come in contact or fertilized with human waste
  • Wear gloves if contacting soil that may be contaminated with human feces
  • Avoid eating or drinking food where safe and sanitary disposal of human waste is not practiced
  • Don't eat raw meat or fish of any kind
  • Wash, peel or cook all raw vegetables and fruits before eating, especially when traveling to endemic areas
  • Keep kids from putting things and fingers in their mouths
  • Wash hands thoroughly and frequently before and after using the bathroom or changing a diaper, and before eating
  • Keep your child's fingernails short and clean
  • Don't share washcloths and towels
  • Only drink bottled or purified water when traveling areas with poor sanitation
  • Do not defecate outdoors or near food sources
  • Dispose of diapers properly