Figure 3-5. Tapeworm (pork tapeworm).
a. Species of Medical Importance. There are a number of species of
tapeworm which are human parasites, but only these six attack man frequently:
Beef tapeworm (Taenia saginata)--common and found worldwide.
(2) Pork tapeworm (Taenia solium)--common and found worldwide, but no
longer transmitted in the US.
(3) Fish tapeworm (Diphyllobothium latum)--found in cold or temperate lake
regions worldwide, particularly in Europe, US, and Japan; also in the Middle East,
central and southern Africa, and in Chile.
Dwarf tapeworm (Hymenolepis nana)--found worldwide.
Dwarf tapeworm (Hymenolepis diminuta)--found worldwide.
Dog tapeworm (Dipylidium canim)--found in children in Europe and the
b. Beef Tapeworm. (Taenia saginata). The beef tapeworm is the most
common tapeworm in the United States. Tapeworm segments leave the host, and eggs
are expelled from the segments. The eggs hatch when they are ingested by cattle.
Embryos are released and lodge in the muscles of the cattle. When humans eat
undercooked beef from infected cattle, cysticerci, a larval form of tapeworm, have also
been eaten. In the human intestine, the cysticercus develops into an adult tapeworm.