Pinworms
Enterobius vermicularis, also known as pinworms, is the most common worm infection in the world. It is most often found in children. It spreads very easily between children, especially among groups (e.g. daycares). Pinworms of animals are not spread to people. Pinworms are tiny, white, thread-like worms that live in the intestines of people. The worms crawl out of the anus at night and lay their eggs on the nearby skin. Symptoms of this infection include intense scratching in the anal area (especially at night), irritability and trouble sleeping. Severe scratching may also cause a skin infection. When an infected person scratches an itchy area, the eggs get stuck on the fingers and under the fingernails. The eggs can then be passed to other people on the hands or on objects touched. The eggs can live for several weeks outside the body. It is easy to treat pinworms–talk to your doctor or pharmacist for advice.
Roundworms
Ascaris lumbricoides is a large intestinal worm found in humans. This is a disease of particular risk to children between 3 and 8 years. The eggs are microscopic and can survive for several weeks in fecally contaminated soil. Children pick up the eggs on their fingers when they are playing. The eggs can then be transferred to the mouth by the child’s hand and are eventually swallowed. The eggs hatch into worms that migrate through the body into the lungs where they may cause symptoms such as wheezing, coughing, fever and pulmonary infiltration. The eggs can also be ingested by eating raw produce that has been contaminated with feces. This worm is not passed by person-to-person contact, only through ingestion of the infective eggs.
Hookworms
Hookworms are found in humans, dogs and cats. It is more common in rural and tropical areas where sewage disposal practices might allow feces to contaminate the soil. The eggs will survive in loose, moist soil and hatch to the larval stage. The larvae then penetrate the skin, usually of the foot, producing dermatitis (“ground itch”). The larvae migrate through the bloodstream to the lungs, up the esophagus and are then swallowed into the intestine. The larvae may also be swallowed directly. Larvae become mature worms and lay thousands of eggs per day in the intestine. The infection is not passed from person to person. Tropical beach-goers are at greatest risk of acquiring this infection because their bare feet are exposed to soil. Children are also at risk of swallowing the larvae on unwashed hands that have been in contact with contaminated ground.
Adapted from Pinworms, Hookworms and Roundworms Fact Sheet, Feb 2000, Canadian Institute of Public Health Inspectors, by the CD Program, Hastings Prince Edward Public Health, March 2013.
