Tapeworm in the context of "Scolex"

Taenia solium, the pork tapeworm, belongs to the cyclophyllid cestode family Taeniidae. It is found throughout the world and is most common in countries where pork is eaten. It is a tapeworm that uses humans (Homo sapiens) as its definitive host and pigs and boars (family Suidae) as the intermediate or secondary hosts. It is transmitted to pigs through human feces that contain the parasite eggs and contaminate their fodder. Pigs ingest the eggs, which develop into larvae, then into oncospheres, and ultimately into infective tapeworm cysts, called cysticerci. Humans acquire the cysts through consumption of uncooked or under-cooked pork and the cysts grow into adult worms in the small intestine.

There are two forms of human infection. One is "primary hosting", called taeniasis, and is due to eating under-cooked pork that contains the cysts, resulting in adult worms in the intestines. This form generally is without symptoms; the infected person does not know they have tapeworms. This form is easily treated with anthelmintic medications which eliminate the tapeworm. The other form, "secondary hosting", called cysticercosis, is due to eating food, or drinking water, contaminated with faeces from someone infected by the adult worms, thus ingesting the tapeworm eggs, instead of the cysts. The eggs go on to develop cysts primarily in the muscles, and usually with no symptoms. However, some people have obvious symptoms, the most harmful and chronic form of which is when the cysts form in the brain. Treatment of this form is more difficult but possible.

Anthelmintics or antihelminthics are a group of antiparasitic drugs that expel parasitic worms (helminths) and other internal parasites from the body by either stunning or killing them without causing significant damage to the host. They may also be called vermifuges (those that stun) or vermicides (those that kill). Anthelmintics are used to treat people who are infected by helminths, a condition called helminthiasis. These drugs are also used to treat infected animals, particularly small ruminants such as goats and sheep.

Anthelmintic medication is also used in mass deworming campaigns of school-aged children in many developing countries. Anthelmintics are also used for mass deworming of livestock. The drugs of choice for soil-transmitted helminths are mebendazole and albendazole; for schistosomiasis and tapeworms it is praziquantel.

An oncosphere is the larval form of a tapeworm once it has been ingested by an intermediate host animal. The intermediate host must ingest the tapeworm's eggs either in food or water – once this has happened, the eggs hatch and develop into oncospheres which will then burrow through the gut wall of the intermediate host in order to access the organs or tissues of that host where they will continue the next stage of their development as cysticerci or bladderworms. The bladderworm is a cyst created by the oncosphere. In order to become an adult tapeworm, a cysticercus must then be consumed by its definitive host (in either raw or undercooked meat) and establish itself by anchoring in that host's digestive tract. From there, the worm will grow in length and eventually produce proglottids which will exit the intestinal tract with other waste material and then burst, releasing the worm's eggs and completing the cycle.