A 40-year old veterinarian presented with complaints of abdominal pain. On examination he was found to be icteric, the liver was palpable .Ultrasonography revealed the presence of cyst in the right lobe of liver. The definitive hosts of the agent causing this infection are -

Dogs are the definitive hosts of the tiny tapeworm Echinococcus granulosus. By handling a dog or drinking contaminated water,humans may ingest eggs. The embryo is liberated from ovum in the small intestine & gains access to the bloodstream & thus to the liver.In nearly 75% of patients with hydatid disease the right lobe of the liver is invaded.The resultant cysts grows causing Reference Harrison20th edition pg 1079