Department of Veterinary Anatomy and Pathology
University of Sydney
Reservoir: dogs or other canids
Intermediate Host:Sheep and Goats
Adult worms develop in dogs or other canid after ingesting a coenurus in the tissues of various intermediate hosts including sheep and goats. Coenuri are transmitted to humans through the consumpion of egg-containing feces-infected food or water.
Sheep or goats,the intermediate hosts for T. multiceps ingest the taenia egg. The egg hatches in the small intestine and the coernuri (the larval tapeworm) burrows through the intestinal wall and travels to the brain and spinal cord via the blood stream. The coenurus typically develops in the brain, reaching the infective stage in about 6 to 8 months. When dogs or other canids ingest infected sheep tissue, usually through the feeding of offal,the protoscoleces attach to the small intestinal wall and the worms begin to form proglottids (one of the segments of the tapeworm containing both the male and female reproductive organs). Proglottids containing eggs detach from the end of the worm and pass out in the feces. When humans ingest food or water contaminated by infected feces, the oncosphere hatches in the small intestine and makes its way into the blood vessels into the intestinal wall. The embryo is carried in the blood stream throughout the body but most frequently develops in the central nervous system. Protoscoleces bud from the inner surface of the cyst wall and attach to the target organ, and the cycle repeats.