Tapeworms or cestodes are flattened, ribbon-shaped worms composed of numerous segments or division. Tapeworms vary in size from very small to several inches in length. The head or anterior end is much smaller than the rest of the body. Since tapeworms may be very small, careful examination often is necessary to find them. A portion of the intestine may be opened and placed in water to assist in finding the tapeworms.
The pathology or damage tapeworms produce in poultry is controversial. In young birds, heavy infections result in reduced efficiency and slower growth. Young birds are more severely affected than older birds.
All poultry tapeworms apparently spend part of their lives in intermediate hosts, and birds become infected by eating the intermediate hosts. These hosts include snails, slugs, beetles, ants, grasshoppers, earthworms, houseflies and others. The intermediate host becomes infected by eating the eggs of tapeworms that are passed in the bird feces.
Although several drugs are used to remove tapeworms from poultry, most are of doubtful efficacy. In general, tapeworms are most readily controlled by preventing the birds from eating the infected intermediate host. Tapeworm infections can be controlled by regular treatment of the bird with fenbendazole or leviamisole.