All tapeworms have three sections. The scolex, or head, attaches to the lining of the intestines; the neck is the second section, and leads to the third section, or the body of the tapeworm. The body is made up of segments, called proglottids, which have both sex organs and produce the eggs. Whenever tapeworms infect humans, they get their nutrients from the small intestines, and can cause a variety of health conditions.
Taeniasis Saginata
Taeniasis saginata is a disease people may develop from a beef tapeworm, called Taenia saginata, if there are larvae of the tapeworm in any undercooked or raw beef that they eat. Americans are at a very low risk for getting this infection from American cattle because of federal inspections, according to The Merck Manuals Online Medical Library. People with taeniasis saginata may not have any symptoms, or may have mild cramps and some discomfort.
Diphyllobothriasis
The fish tapeworm Diphyllobothrium latum causes this disorder. The infection develops when people eat undercooked or raw fish that has the worm larvae. The larvae become worms in the small intestines, but they do not cause a lot of harm there. Some people will become anemic, because the worms absorb vitamin B12, as explained by the "Review of Medical Microbiology and Immunology." Normally, the small intestines absorb vitamin B12. A vitamin B12 deficiency can lead to a megalocytic anemia where the red blood cells are larger than normal. People with diphyllobothriasis may not have any other symptoms, or may have diarrhea.
Taeniasis Solium
If pigs eat meat contaminated with the eggs of the Taenia solium pork tapeworm, the eggs travel to their muscles and develop into larvae. If people then eat the contaminated pork and do not thoroughly cook it, the live larvae develop into tapeworms in their intestines. They may not have any symptoms, or might have diarrhea. If someone eats the eggs, they develop into larvae in the intestines, go through the intestinal wall and enter the bloodstream. Traveling through the bloodstream, they can reach the muscles, liver, brain, lungs, heart and eyes. This is called cysticercosis because the larvae of Taenia solium and Taenia saginata are also called cysticerci. The Merck Manuals Online Medical Library warns that severe symptoms will develop if the cysticerci reach the brain, including seizures, confusion and decreased alertness.
Hymenolepis Nana Infection
In "Review of Medical Microbiology and Immunology," Dr. Levinson writes that the Hymenolepis nana is the most common tapeworm in America. It is called the dwarf tapeworm because it is so small, only measuring approximately 3 to 5 cm long. If people eat the eggs, they will hatch in the small intestines and mature into adult worms. Physicians usually find many adult worms in the intestines--sometimes hundreds of worms. And yet, this tapeworm does not cause much harm and most infected people do not have any symptoms.
References
- "Review of Medical Microbiology and Immunology," Warren Levinson, M.D., Ph.D.; 2008
- The Merck Manuals Online Medical Library: Taeniasis saginata
- The Merck Manuals Online Medical Library: Taeniasis solium and Cysticercosis
