Hydatid Cyst Disease (Echinococcosis)

Hydatid cyst disease or echinococcosis is a worldwide parasitic infection caused by the Echinococcus tapeworm larvae. Of the seven recognized species, Echinococcus granulosus and Echinococcus multilocularis, which cause cystic echinococcosis (CE) and alveolar echinococcosis (AE), respectively, pose clinically significant and potentially lethal public health risks. Human infection occurs after incidental ingestion of the parasite eggs from the stool of infected animals. Most of these cysts are solitary and occur in either the liver or the lungs. Although the cysts displace healthy tissue, the primary infection is typically asymptomatic unless rupture or mass effect occurs. Definitive diagnosis for most cases is by imaging with ultrasound or computed tomography (CT), although immunodiagnostic assays can be a useful adjunct in both primary diagnosis and follow-up. Surgery has the potential to remove the cysts and lead to complete cure; however, successful eradication requires the entire elimination of the parasite without intraoperative contamination or compromise of affected organ system(s). Alternatively, percutaneous aspiration, injection, and reaspiration (PAIR) has emerged as a less invasive treatment option in patients with CE who present high surgical risks because of underlying pathophysiology or who are remote from surgical care facilities.