Cestodes

This 1973 image depicts two Taenia solium cysticerci, which represent the larval, or intermediate, immature developmental stages of this pork tapeworm.Life cycle of Taenia saginata and T. solium (See PHIL 3420 for a illustrative diagram depicting the following life cycle):Taeniasis is the infection of humans with the adult tapeworm of T. saginata or T. solium. Humans are the only definitive hosts for T. saginata and T. solium. Eggs or gravid proglottids are passed with feces; the eggs can survive for days to months in the environment. Cattle (T. saginata) and pigs (T. solium) become infected by ingesting vegetation contaminated with eggs or gravid proglottids. In the animal's intestine, the oncospheres hatch, invade the intestinal wall, and migrate to the striated muscles, where they develop into cysticerci. A cysticercus can survive for several years in the animal.Created: 1973

This photograph depicted the strobilocercus, or larval stage of an unidentified tapeworm of the order Cyclophyllidea. Families that are members of this order include Dipylidiidae, i.e., cucumber tapeworm and double-pore tapeworm, Hymenolepidadae, Taeniidae, i.e., livestock parasites, and Anoplocephalidae, i.e., horse and ruminant tapeworms.Created: 1973

This is an illustration of the life cycle of Hymenolepis diminuta, the causal agent of Hymenolepiasis.Created: 2002

This is an illustration of the life cycle of Dipylidium caninum, which mainly infects dogs and cats, seldom in humans.Created: 2002

This photomicrograph revealed some of the ultrastructural morphology exhibited by an adult cestode, Echinococcus granulosus, which had been found in a dog. E. granulosus causes what is known as cystic echinococcosis. As dogs and other canids are the only definitive hosts for Echinococcus, adults are not expected to be found in the human host. Adults range from 3mm - 6mm in length and usually consist of a scolex, and three proglottids. The third (terminal) proglottid is gravid, and is longer than wide, as can be seen in this instance. The scolex contains four suckers and a rostellum with 25 - 50 hooks.Created: 1975

This is an illustration of the life cycle of Diphyllobothrium spp., the causal agents of Diphyllobothriasis.Created: 2002