Hepatic echinococcosis: clinical and therapeutic aspects

Echinococcosis or hydatid disease (HD) is a zoonosis caused by the larval stages of taeniid cestodes belonging to the genus Echinococcus. Hepatic echinococcosisis a life-threatening disease, mainly differentiated into alveolar and cysticforms, associated with Echinoccus multilocularis (E. multilocularis) andEchinococcus granulosus (E. granulosus) infection, respectively. Cysticechinococcosis (CE) has a worldwide distribution, while hepatic alveolarechinococcosis (AE) is endemic in the Northern hemisphere, including NorthAmerica and several Asian and European countries, like France, Germany andAustria. E. granulosus young cysts are spherical, unilocular vesicles, consistingof an internal germinal layer and an outer acellular layer. Cyst expansion isassociated with a host immune reaction and the subsequent development of afibrous layer, called the pericyst; old cysts typically present internalseptations and daughter cysts. E. multilocularis has a tumor-like, infiltrativebehavior, which is responsible for tissue destruction and finally for liverfailure. The liver is the main site of HD involvement, for both alveolar andcystic hydatidosis. HD is usually asymptomatic for a long period of time, becausecyst growth is commonly slow; the most frequent symptoms are fatigue andabdominal pain. Patients may also present jaundice, hepatomegaly or anaphylaxis, due to cyst leakage or rupture. HD diagnosis is usually accomplished with thecombined use of ultrasonography and immunodiagnosis; furthermore, the improvementof surgical techniques, the introduction of minimally invasive treatments [suchas puncture, aspiration, injection, re-aspiration (PAIR)] and more effectivedrugs (such as benzoimidazoles) have deeply changed life expectancy and qualityof life of patients with HD. The aim of this article is to provide an up-to-date review of biological, diagnostic, clinical and therapeutic aspects of hepaticechinococcosis.