A tapeworm infection of the liver common in sheep rearing areas such as Greece, Australasia and Wales.
In man hydatid disease is caused by one of two tape-worms Echinococcus granulosus and Echinococcus multilocularis. Echin. granulosus infections occur following ingestion of food contaminated with infected dog faeces. Echin. multilocularis is carried by foxes and small rodents. Sheep and cattle perpetuate the life cycle. In humans the embryos hatch in the duodenum and enter the liver via the portal system. Once in the liver the embryos form a hydatid cyst and may be disseminated to the lung, kidney or brain.
The disease may be symptomless but chronic right upper quadrant pain with enlargement of the liver is the common presentation. The cyst may rupture into the biliary tree or peritoneal cavity and may cause an acute anaphylactic reaction.
Eosinophilia is common and serological tests are available. Small, calcified cysts may be seen on plain abdominal X-ray. Ultrasound or CT scanning can demonstrate cysts.
Mebendazole or albendazole is commenced prior to any intervention. Percutaneous ultrasound guided fine needle aspiration with injection of scolicidal agents and reaspiration may be used. Large symptomatic cysts may be surgically excised intact taking great care to avoid contamination of the peritoneal cavity.