Taeniasis is the parasitic disease caused by the adult tapeworm installed within the human intestine. Cysticercosis occurs when humans ingest eggs or pregnant proglottids of taenias, for example, through badly washed food or self infection. In cysticercosis humans assume the role of intermediate hosts of the parasite and the cysticerci develop within human organs like muscles, brain, eyes and subcutaneous tissue. The brain infestation by cysticerci, a condition known as neurocysticercosis, is extremely severe and may lead to death.
In the normal life cycle of taenias the humans are the definitive hosts and develop taeniasis, a less serious disease, and not cysticercosis.