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Tapeworms can come as an unpleasant surprise a few weeks later to anyone munching away on a bowl of cereal from an old box and noticing a few wriggling creepy-crawlies at the bottom of the bowl.

The Migrating Tapeworm Parasite

Often transmitted inside insect larvae living in dried fruit, dry cereal, and flour, tapeworms affect humans in every part of the globe.

In Europe and North America, tapeworms are also often transmitted in raw or lightly cooked meat, game, or fish. They have even been encapsulated and marketed as a "natural diet aid" by unscrupulous promoters, primarily in the American Southwest.

If you get an intestinal infection with a tapeworm, you are not the first host of your parasite. Typically the tapeworm releases its eggs into water, and the eggs are swallowed by a passing insect or animal. When you accidentally dine on a tapeworm-infected "bug" in your cereal or you intentionally dine on raw or undercooked tapeworm-infected meat, you become the new host for the parasite.

Once inside the human body, the adult tapeworm attaches itself to the wall of the intestine. Having no well-developed digestive tract of its own, the tapeworm feeds on digested human food and grows—sometimes as long as 40 feet (13 meters).

The tapeworm grows in segments. Each segment has its own digestive receptacle and reproductive organs. As the worm gets longer and longer, the segments can break off and pass out with bowel movement into sewer water, where they can release eggs for the next generation of tapeworms. The very last segment of the tapeworm is a strictly an egg-laying machine, making sure that the tapeworm reproduces as many times as possible.

After tapeworms hatch from their eggs, they enter a larval state. Usually humans do not accidentally consume larvae, but then they do, there can be serious consequences. Tapeworm larvae, unlike adult tapeworms, do not live just in the intestines. The larvae can migrate to many other parts of the body, even the brain.

Symptoms of Tapeworm Parasite Infection

Most of the time the tapeworm keeps a low profile in your colon. Not only does the worm not cause any symptoms, it even helps your immune system develop modifying factors that prevent autoimmune disease later in life. The tapeworm cannot develop many kinds of human food, but it can digest cellulose, releasing sugars from fiber that it shares with its human host.

People who are infected with tapeworm parasites usually find out when they notice tapeworm segments in their stools or they find tapeworms in their undergarments. There may be vague and intermittent abdominal pain, nausea, vomiting, and loss of appetite. Certain species of tapeworms, however, can cause more intense symptoms.

The species of tapeworm known as T. solium can increase appetite, and it may cause pain or a feeling of fullness around the belly button. The larval form of this species of tapeworm, however, can cause inflammation in the muscles and joints. The larvae of T. solium can migrate to the brain and calcify. This kind of tapeworm is found in Latin America, China, the Slavic countries, Southeast Asia, India, and China.

H. nana is the tapeworm found in the United States. Up to 20 per cent of American children can acquire it from their pets and from each other. It causes relatively mild symptoms. Spirometra is found in the Carolinas, Georgia, and Florida in the United States, and is most frequently transmitted by undercooked frog legs.

T. saginata is usually first noticed when segments appear in the stool. This kind of tapeworm can land in the appendix, causing appendicitis, and it can also block the ducts draining the pancreas and liver. This is the most common kind of tapeworm infection in South Asia and Africa.

Diphyllobothrium tapeworms cause mild stomach upset, but they consume so much vitamin B12 that they can induce a condition known as megaloblastic anemia. The resulting low red blood cell count can cause dizziness, memory loss, and dementia. This tapeworm is found over most of the northern Hemisphere from Russia to Canada and across Europe, northern China, and Japan. It is the tapeworm transmitted by improperly prepared sushi.

Hymenolepis can reproduce so rapidly it literally bursts the villi, or pockets, in the side of the intestines. The immediate result is painful colitis with bloody diarrhea. This is the tapeworm that spends part of its life in the beetles that can get into your breakfast cereal.

Diphyllobothrium caninum, the tapeworm you can catch from your pets, is recognized by causing itching.

Complications of tapeworm infection can occur as late as 20 years after the tapeworm is ingested. Most people with chronic tapeworm infections will develop just a single cyst, but people who get liver cysts tend to get cysts in the lungs as well.

Treating and Preventing Tapeworm Parasite Infections

A tapeworm infection is something you probably do not want to treat just with the traditional herbal remedies that use cassia bark and a high-fiber diet (although these work well when the problem is pinworms). Intestinal tapeworms are usually treated with the drugs praziquantel or niclosamide, which are effective up to 98 per cent of the time. The drugs kill the tapeworms quickly, although it may take up to a week for all the segments to pass out through the stool.

It usually takes 1 to 3 months to make sure that the tapeworms have been completely eradicated. When tapeworms have caused cysts elsewhere in the body, the cysts have to be carefully aspirated with a needle to remove pressure on adjacent tissues, and they may have to be surgically removed.

How You Can Prevent Infection with Tapeworm Parasites

With such severe consequences, tapeworms are a parasite everyone does well to avoid. The single most frequent offending food is, fortunately, relatively rare in the modern diet. Raw seal and whale meat frequently transmit tapeworms. Improperly prepared sushi is a problem, too.

In most of the world, however, the most common source of tapeworms is contact with infected pets. Be sure to clean your hands after cleaning out the cat's litter box or curbing your dog, and teach your children to wash their hands after playing with their pets and always before meals.

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