Echinococcosis

Echinococcosis is a parasitic disease caused by tapeworms of the genus Echinococcus, classified under ICD-10 code B67 and ICD-11 code 1F88. The disease occurs in four recognized forms, with cystic echinococcosis (hydatidosis) caused by Echinococcus granulosus and alveolar echinococcosis caused by E. multilocularis representing the two most clinically significant forms globally. Two additional neotropical forms—polycystic echinococcosis caused by E. vogeli and unicystic echinococcosis caused by E. oligarthrus—have been identified primarily in Central and South American regions. The disease is transmitted through ingestion of parasite eggs shed in the feces of infected carnivore definitive hosts, with humans serving as accidental intermediate hosts in the parasite's lifecycle.

Echinococcosis is characterized by prolonged asymptomatic incubation periods that can persist for many years before clinical manifestations appear, creating significant challenges for early diagnosis and intervention. In cystic echinococcosis, the larval stages develop as fluid-filled cysts most commonly located in the liver (approximately 75% of cases) and lungs (5-15% of cases), with less frequent involvement of bones, kidneys, spleen, muscles, central nervous system, and eyes. Clinical presentation varies according to cyst location and size, with hepatic involvement typically presenting as abdominal pain, nausea, and vomiting, while pulmonary disease manifests as chronic cough, chest pain, and shortness of breath. Alveolar echinococcosis exhibits an incubation period of 5-15 years and develops as an infiltrative, tumor-like lesion primarily in the liver that progressively invades surrounding tissues and may metastasize to distant organs including the lungs and brain. Without treatment, alveolar echinococcosis follows a progressive and fatal course, typically resulting in hepatic failure.

Cystic echinococcosis demonstrates a global distribution present on every continent except Antarctica, with the highest prevalence observed in pastoral communities where close human-animal contact facilitates transmission. In endemic regions, human incidence rates can exceed 50 per 100,000 person-years, with prevalence levels reaching 5-10% in specific areas of Argentina, Peru, East Africa, Central Asia, and China. Alveolar echinococcosis remains confined to the northern hemisphere, with particular concentration in regions of China, the Russian Federation, continental Europe, and North America. Among livestock in hyperendemic areas of South America, slaughterhouse surveys have documented cystic echinococcosis prevalence ranging from 20% to 95% of examined animals, reflecting substantial environmental contamination and ongoing transmission pressure.

Echinococcosis is a zoonotic disease maintained in nature through a lifecycle involving carnivore definitive hosts and herbivorous or omnivorous intermediate hosts. Dogs, foxes, wolves, and other carnivores harbor adult tapeworms in their intestinal tract and shed parasite eggs in their feces, contaminating the environment. Intermediate hosts become infected through ingestion of eggs in contaminated food or water, after which the parasite develops into larval stages in visceral organs. Humans acquire infection through accidental ingestion of eggs, typically through close contact with infected dogs or contaminated environments, and serve as dead-end intermediate hosts that do not transmit infection back to definitive hosts. Definitive hosts become infected through consumption of viscera from infected intermediate hosts containing viable parasite larvae.

Populations at elevated risk for echinococcosis include pastoral and agricultural communities with close contact with dogs and livestock, particularly in regions where traditional animal husbandry practices facilitate parasite transmission. Individuals engaged in activities involving potential environmental contamination with carnivore feces, including farmers, shepherds, hunters, and veterinarians, face increased exposure risk. Children may be at particular risk due to behavioral factors and closer contact with dogs. In endemic areas, the general population experiences elevated background exposure, with community-wide prevalence reaching significant levels in hyperendemic regions.

Prevention strategies focus on interrupting the parasite lifecycle through coordinated animal and human health interventions. Key measures include regular deworming of domestic dogs, preventing dogs from feeding on uncooked offal or carcasses of infected livestock, improved slaughter practices to prevent dogs from accessing infected organs, and public education regarding hygiene and handwashing after handling dogs or working in environments potentially contaminated with feces. In endemic areas, comprehensive control programs combining veterinary surveillance, animal treatment, and community engagement have demonstrated effectiveness in reducing transmission pressure and human disease incidence.

Echinococcosis surveillance presents particular challenges due to the disease's prolonged asymptomatic phase, variable clinical presentation, and the need for specialized diagnostic capabilities. Ultrasonography serves as the primary imaging modality for case detection, typically supplemented by computed tomography and magnetic resonance imaging for characterization and staging. Serological testing for specific antibodies provides supportive diagnostic evidence, though sensitivity varies according to cyst location and parasite species. Given the long incubation period, surveillance systems should consider retrospective exposure assessment and maintain awareness that current cases may reflect environmental exposures occurring years or decades previously. Integration of human and veterinary surveillance data is essential for understanding transmission dynamics and targeting control interventions in endemic areas.

1. 1 WHO Health Topics. Echinococcosis.
2. 2 WHO Fact Sheet. Echinococcosis.
3. 3 WHO Q&A. Echinococcosis.
4. 4 Wikidata. echinococcosis.
5. 5 Wikipedia. Echinococcosis - Wikipedia.

ICD-10

B67

ICD-11

1F88

Total cases

71K

Total deaths

30

Peak month

2017-03

Coverage

3 reporting countries · 2000-01-01 → 2026-05-02