Alveolar echinococcosis

Alveolar echinococcosis (AE) is a rare but serious parasitic disease caused by the larval stage of the tapeworm Echinococcus multilocularis. It is also known as alveolar hydatid disease or multilocular echinococcosis. Humans become infected accidentally by ingesting eggs of the parasite, typically through contact with infected foxes, dogs, or other definitive hosts, or by consuming contaminated food such as wild berries or vegetables. The disease is not inherited but acquired through environmental exposure. The parasite primarily affects the liver, where it forms tumor-like, infiltrative parasitic masses that grow slowly over years, often mimicking hepatic malignancy. The larval tissue proliferates by external budding, invading surrounding structures in a manner similar to a malignant tumor. If untreated, the disease can metastasize to distant organs including the lungs, brain, and bones. Key symptoms include upper abdominal pain, hepatomegaly, jaundice, weight loss, and fatigue. Because of its slow growth, the disease often has an asymptomatic incubation period of 5 to 15 years before clinical manifestation, and diagnosis is frequently made at an advanced stage. Treatment of alveolar echinococcosis requires a multidisciplinary approach. Radical surgical resection of the parasitic lesion, when feasible, remains the treatment of choice and offers the best chance of cure. Long-term antiparasitic therapy with benzimidazoles (primarily albendazole) is essential, both as adjunctive treatment following surgery and as the primary treatment for inoperable cases. Continuous albendazole therapy may be required for years or even lifelong in patients with non-resectable disease. Without treatment, the mortality rate is very high, exceeding 90% within 10 to 15 years of diagnosis. Early detection through screening programs in endemic areas and advances in imaging and serological diagnostics have improved outcomes. Liver transplantation may be considered in select cases with extensive hepatic involvement.

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