Taenia Saginata - Life Cycle

Life Cycle

The life cycle is indirect and complicated, and is completed in humans as the definitive host and cattle as the intermediate host. The adult worm inhabits the small intestine of humans. Fertilized eggs are released through the faeces along with the gravid proglottid which gets detached from the strobila. Cattle ingest the infective embryo while grazing. The digestive enzymes will break the thick shell of the egg and allow formation of the zygotes called "oncospheres". These zygotes then penetrate the mucous layer of the digestive tract and enter the circulation of the host. This is where the young larval stages form a pea-sized, fluid filled cyst, also known as “Cysticercus bovis” and these cysts seem to form in the muscular fibers and are sometimes seen in specific organs like the lungs and liver. Humans acquire the infective larvae from eating undercooked meat i.e.,measley beef. The digestive enzymes break down the cysticercus and the larval cyst is released and the inverted scolex is able to come out and attach to the host’s intestine. Adult tapeworm take about 2 months to develop, and within three months it can reach 5 m long.