What Are the Different Types of Human Intestinal Parasites?

The thought of parasites is enough to make anyone's skin crawl. Parasites are tiny worms and other organisms that live their entire lives in or on a host creature. Although we would like to think that only animals have to deal with intestinal parasites the truth is that humans are just as likely to contract these little buggers by eating or drinking infected food or water or coming into contact with an already infected agent.

Pinworms

• About 200 million people worldwide are infected with pinworms (also known as seatworms or threadworms). Children are the most likely at risk with about 30 percent of children infected around the world. These small white worms are about half an inch in length and the females can lay about 15,000 eggs every day around the human rectum. A single dose of anti worm medication is usually enough to treat the infestation.

Hookworms

• Found mostly in tropical and subtropical regions, hookworm larvae live in the soil until a suitable host happens by. They then penetrate the skin and make their way to the small intestine via the bloodstream. Once comfortably settled in the small intestine, they latch onto the intestinal wall, feeding off the blood of the host. Most adult worms eventually pass in a year or two, which isn't fast enough for unsuspecting hosts.

Roundworms

• One of the most common parasites found in humans, roundworm infection begins with the accidental ingestion of the eggs. Once hatched, the larvae invade the intestines before traveling to the lungs. After maturing for about a week or two in the lungs, they travel to the throat and are swallowed, where they make their way back to the intestines to complete their development into adult worms. An adult female is capable of producing approximately 200,000 eggs per day.

Whipworms

• Over sixty species of whipworms exist but, luckily, very few of them can infect humans. Like just about all other parasitic worms, contamination starts with the ingestion of contaminated food or contact with soil containing the eggs. The eggs hatch in the small intestine where they stay until they mature, then they move to the colon. After about two months the adult females can shed anywhere from 3000 to 20,000 eggs per day.

Tapeworms

• Tapeworms are most common in cats and dogs who become infected when they swallow infected fleas. There are only two species of tapeworm that humans are the definitive hosts for: the 'beef tapeworm' and 'pork tapeworm', which are passed to humans via undercooked infected beef or pork. Once ingested the tapeworm eggs hatch, and the adult worms live in the intestine where they feed and breed for the rest of their lives.