Causes of a human tapeworm infection include ingestion of tapeworm eggs, eating infected meats, reinfecting oneself and insect to human transmission, according to Medical News Today. A tapeworm infection mainly occurs from beef tapeworm, pork tapeworm, fish tapeworm and dwarf tapeworm.
A person can ingest tapeworm eggs through drinking water or eating food contaminated with feces from an animal with a tapeworm, states Mayo Clinic. For example, a pig infected with a tapeworm passes tapeworm eggs in its feces, which later drops onto the soil. This soil contaminates food or water sources, infecting the person who drinks or eat from the contaminated source.
A person can ingest tapeworm larvae through eating undercooked or raw meat from an infected animal, explains Mayo Clinic. The larvae in the intestines then develop into adult tapeworms. These tapeworms attach themselves to intestinal walls, causing irritation. Tapeworms can be as 50 feet long and can live in the human body for as long as 30 years.
Humans can also re-infect themselves during treatment. It is important to wash hands properly after using the toilet to avoid reinfection, as human stools may contain tapeworm eggs. Beetles, such as fleas, may also pick up tapeworm eggs through eating droppings from infected rats, infecting humans, notes Medical News Today.