Hydatidosis or cyst hydatic disease is a cosmopolitan larval cestodosis caused principally by the <i>Echinococcus granulosus</i> tapeworm, the adult form of which parasitises the intestine of dogs. Hydatidosis generally affects large domestic herbivores; humans are dead-end hosts, infected through contact with herding dogs or through ingestion of food contaminated with canine excrement.

Failure of the immune system to protect the body adequately from infection, due to the absence or insufficiency of some component process or substance.