There are more than 3,000 known species of tapeworm, all of which can infect man. Giant tapeworms with total lengths of 10 to 30 feet may be found in the small intestines of humans. There are three major species of tapeworms and all are transmitted by eating raw, undercooked or smoked infected meat or fish. Taenia saginata larvae are found in beef, Taenia solium in pork, and Diphyllobothrium latum in fish. In most tapeworm infections, the animal (or fish) host ingests eggs which develop into larvae and invade the animal's muscles and other organs. A person then acquires the infection by eating the infected animal.
Taeniasis, if not detected and treated quickly, and depending on the type, can cause grave and permanent damage to the internal organs of the body. Tapeworm larvae which hatch from its eggs, penetrate the capillaries and spread throughout the body, particularly into the brain, and within a few months develop into cysticerci of about 5 to 20 mm in diameter containing a tapeworm head in a bladder filled with fluid. Cysticercosis can provoke convulsions, cerebral hypertension and psychiatric disorders. If not treated, it may be fatal.