Tapeworm infection is caused by eating the raw or undercooked meat of infected animals. Cattle usually carry Taenia saginata (T. saginata). Pigs carry Taenia solium (T. solium).

In the human intestine, the young form of the tapeworm from the infected meat (larva) develops into the adult tapeworm. A tapeworm can grow to longer than 12 feet and can live for years.

Tapeworms have many segments. Each segment is able to produce eggs. Eggs are spread alone or in groups, and can pass out with the stool or through the anus.

Adults and children with pork tapeworm can infect themselves if they have poor hygiene. They can ingest tapeworm eggs they pick up on their hands while wiping or scratching their anus or the skin around it.

Those who are infected can expose other people to T. solium eggs, usually through food handling.
Symptoms

Tapeworm infection usually does not cause any symptoms. However, some people may have abdominal discomfort.

People often realize they are infected when they pass segments of the worm in their stool, especially if the segments

How do tapeworms get into the heart?

Here is simple tapeworm migration scheme: intestine - a liver - the right heart - a lung - a trachea - a throat - then leave human body. More info in http://www.youtube.com/watch?v=DxL2qHBetvI

Actually tapeworm larva follow instinct, aspire to be distributed in regular intervals in an organism and take root into human bodies while migration. It can lead to very serious changes: a hepatitis, a cirrhosis of a liver, regeneration of cells of a liver, changes in a cardiac muscle (myocardium), bronchitis, pneumonia, tonsillitis, antritises, otitises and many other things to diseases.

So larva not only settle in those organs of an organism on which pass, but also get into them and migrate on different channels, hurt vital body organs.