Tapeworm
A tapeworm is a long, flat, intestinal worm found in humans and many other animals.
What Are Tapeworms?
Tapeworms are long, flat, intestinal worms called cestodes, found in humans and many other animals. Tapeworms do not have an intestinal tract, they absorb nutrients through their body surface. Human tapeworm infestations may be caused by eating meat or fish contaminated with tapeworm larvae but also by ingesting soil or water contaminated with human fecal matter containing the eggs. Meat contaminated with tapeworm larvae has larvae enclosed in cyst form within the meat. The larvae are worms at an intermediate stage of the life cycle between eggs and adulthood. They burrow into the animal tissue and form fluid-filled cysts, which are protective capsules. Like other intestinal parasites, these worms frequently cause infestations in areas with poor sanitation, where livestock animals are exposed to contaminated soil or fish to contaminated water, and have the parasites within their body tissues. Humans are either infested through ingestion of eggs or larvae. The tapeworms mature within the intestinal tract of the human and lay new eggs, which are released into the fecal matter and passed out of the body to begin the cycle again. Tapeworm infection may be prevented by thoroughly cooking meat until juices run clear and the centers are no longer pink or raw. Doing so ensures that any tapeworm cysts in the meat are destroyed.
What Are the Types of Tapeworm?
There are three common species of tapeworms: Taenia saginata (beef tapeworm), Taenia solium (pork tapeworm), and Diphyllobothrium latum (freshwater fish tapeworm). After ingesting contaminated tapeworm encysted meat or fish, the larvae travel to the intestines, where they latch onto the lining of the intestines and gradually grow into adults. Symptoms of a tapeworm infestation are often mild or nonexistent but can include abdominal pain, loss of appetite, diarrhea, tiredness, weight loss, and malnutrition. In individuals without symptoms tapeworm infestation is often not noted until pieces of worm are found in the stool or undergarments.
Beef, fish, and pork tapeworms:
Beef and fish tapeworms generally remain limited to the human gastrointestinal tract and usually only migrate to further tissues in animals. The pork tapeworm is unique because it is known for leaving the human gastrointestinal tract in larval form and migrating to other parts of the human body to create cysts of worm larvae in human body tissues. Whereas cysts may form in any body tissue, the most commonly affected part of the body is the central nervous system, including the brain. The condition of having a tapeworm cyst in body tissues is called cysticercosis. Having one in the brain is known as neurocysticercosis and may cause seizures*, blindness, or other nervous system abnormalities. Cysts may also form in the heart, eye, or other locations. If the encysted larvae die, the body may calcify (deposit calcium salts in) the region as part of the healing process. Calcified cysts may also cause health problems.
The fish tapeworm is often noted for causing vitamin B12 deficiencies. In the human body, vitamin B12 is absorbed in the end portion of the small intestines known as the ileum. The closer the fish tapeworm physically is to the ileum, the more severe the vitamin B12 deficiency in the person serving as its host. This vitamin is necessary for red blood cells to function. Vitamin B12 deficiency causes a type of anemia, or red blood cell deficiency, known as pernicious anemia. Because the body tissues are not getting enough oxygen, the individual with pernicious anemia feels tired and weak and may even have nerve damage if the anemia is bad enough. Pernicious anemia responds well to vitamin therapy.
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