Taenia hydatigena

Taenia hydatigena
Kingdom	Animalia
Phylum	Platyhelminthes
Class	Cestoda
Order	Cyclophyllidea
Family	Taeniidae
Genus	Taenia
Species	T. hydatigena

Also known as:

Taenia marginata Cysticercus tenuicollis

Hosts

Intermediate host: Sheep, horse, cattle, pig and deer.

Definitive host: Dog, fox, weales, polecat, and stoat.

Identification

T. marginata is a cestode, and large tapeworm around 5m in length. It has a large scolex, with two rows of hooks. The eggs are oval.

Life Cycle

The intermediate host is infected through the ingestion of tapeworm eggs. Sheep are the most frequent intermediate host, but the cysticerci can establish in other animals. The oncosphere hatches out of the egg in the small intestine of the sheep. Oncospheres travel to the hepatic portal system, where they transform to cysticerci. The grow rapidly while migrating through liver parenchyma, then to the peritoneal cavity. The cysticerci in the peritoneal cavity are approximately 8cm long; often found adhering to the omentum. Usually, liver damage heals, forming fibrotic tracts, which leads to condemnation at meat inspection. If a sheep swallows a whole proglottid, it leads to liver damage, and ultimately death (“cysticercosis hepatica”), but this is a rare event affecting a single animal in a flock.

The definitive host is then infected through ingestion of the infected intermediate host.

References

Taylor, M.A, Coop, R.L., Wall,R.L. (2007) Veterinary Parasitology Blackwell Publishing