Cestodes (tapeworms)

Adult tapeworms maintain anchorage to the host small-gut mucosa by means the scolex, a holdfast structure. The rest of the body forms the strobila and consists of a chain of flattened proglottids, which proliferate just behind the scolex. The life cycle then includes larval stages in one or more intermediate hosts. Many species of tapeworm, all zoonoses, infect humans as adult worms or larval stages. Serious disease can result when larval stages occur accidentally in humans, whereas infections by the adult stages often cause little harm. Two groups of cestode infect humans: the Cyclophyllidea and the Pseudophyllidea. The former have a terrestrial life cycle and cystic larvae; the latter have an aquatic cycle and worm-like larvae.