The beef tapeworm Taenea saginata can be up to 12 feet in length (see picture on the right) once it reaches adult stage. Here’s how this works: A cow or pig eats vegetation infected with the egg or proglottids (a piece of the tapeworm). One of the immature stages of the tapeworm embeds and migrates through the tissues of the animal. A human comes along and eats the undercooked or raw meat and the immature parasite matures in the intestinal tract of the human.
Taenia pisiformis: Can infect dogs, cats, foxes, bobcats, coyotes, and wolves, and are passed to the cat from eating dog or cat fleas and rodents.
Tapeworms are flat like a ribbon, and made up of segments called proglottids. The proglottids contain between 50 to 60,000 eggs. As the tapeworm grows, the proglottids eventually break off and exit via the anus. Tapeworms live in the small intestine and they anchor into the intestinal wall by means of a scolex.
Tapeworm—Sparganosis comes from water infected with Cyclops protozoa. The plants growing in this water (like watercress) get infected with the stage of development passed on to humans when they eat the plant.
Hymenolepis nana and H. diminuta are passed to humans if a human eats flour infested with beetles that have eaten rat poop. In addition to normal tapeworm symptoms, nervous system disturbances such as increased restlessness and convulsions can occur.