Adult form of Echinococcus is found in:
The adult forms of Echinococcus Granulosus (3 to 6 mm long) resides in the small bowel of the definitive hosts (dog or other canids). Humans are accidental hosts and human echinococcosis (hydatid disease) is caused by the larval stages of Cestodes (tapeworms) of the genus Echinococcus. Adult form of Echinococcus (Adult worm/Mature Cestode) : Lives in the small intestine of the definitive host. Definitive host: Dogs/foxes/other canines.(Dog is the principle definitive host) Embryonated eggs are passed in the feces of Definitive host. Eggs ingested by intermediate host (sheep, cattle, Goat, swine). Intermediate hosts for the parasite, enable the worms to develop, but not to pass infectious eggs. Eggs ingested by Accidental host (humans). Accidental intermediate hosts also enable the worms to develop, but not to pass infectious eggs. They fuher usually represent dead end for the parasite. Egg shell disintegrates (Egg hatches) and each egg released &;an embryo&; called "Oncosphere" Oncosphere penetrates intestinal wall and enters blood strain where it is distributed to various tissues (Liver/Lung/Brain) Once the Oncosphere arrive in their end organs they gradually develop into fluid filled cysts called Hydatid cysts. Hydatid cysts represent parasitic larval stages in their viscera. The innermost layer of the Hydatid cyst contains germinal membrane from which offsprings will bud. The offsprings are called protoscolices because they contain the hooklets and suckers found in the scolex of adult however, the protoscolices are folded in upon themselves.("invaginated") No fuher development happens in the intermediate hosts. Completion of the life cycle depends upon consumption of invaginated protoscolioces by canines when they feed upon cysts in raw organ meat ("offal") Consumption of INFECTED RAW organ meat("offal") Ref: Medical parasitology by Arora and Arora 4th edition pgno: 145
Dog
Humans
Sheep
Felines
parasitology