Echinococcosis

Echinococcosis is a parasitic zoonosis caused by tapeworms of the genus Echinococcus. The two most important forms for human health are cystic echinococcosis (CE), caused primarily by Echinococcus granulosus, and alveolar echinococcosis (AE), caused by Echinococcus multilocularis. Humans are accidental, dead-end hosts.

Life cycle and transmission

Definitive hosts, mainly dogs and other canids, harbor adult tapeworms in their intestines and excrete eggs in feces. Intermediate hosts, such as sheep, cattle, and in some regions rodents, ingest eggs and develop hydatid cysts in organs, most often the liver or lungs. Humans become infected by ingesting eggs through contaminated food, water, or hands, or by contact with infected dogs. In CE, cysts grow slowly and may remain asymptomatic for years. In AE, indolent but invasive growth can resemble liver cancer and may spread to other organs.

Clinical features and diagnosis

Symptoms depend on the cysts’ size and location and can include abdominal pain, biliary or respiratory symptoms, or signs of organ compression. Rupture of cysts can cause anaphylaxis or secondary dissemination. Diagnosis uses imaging (ultrasound is primary; CT or MRI as needed) and serology to detect antibodies or antigens. Species identification is important for prognosis and treatment planning.

Treatment and prevention

CE management includes observation for inactive cysts, percutaneous methods (PAIR), or surgery, often combined with antiparasitic drugs such as albendazole or mebendazole. AE requires long-term antiparasitic therapy, with surgery or liver transplantation in selected cases. Prevention focuses on controlling infection in canids (regular praziquantel deworming), safe slaughter practices, proper meat inspection, hand hygiene, and ensuring clean food and water.

Epidemiology and impact

Echinococcosis is a global zoonosis with regional variation in prevalence. It represents a one-health challenge requiring veterinary and public health coordination to reduce transmission.