Parasite
Echinococcus granulosus
Hydatid cyst tapeworm of dogs and sheep
eh-kye-noh-KOK-us gran-yoo-LOH-sus
High-yield clue
Dog is the definitive host and sheep the intermediate host; humans ingest eggs and develop slow-growing hydatid cysts, often in the liver.
Overview
A tiny dog tapeworm whose larval stage forms large fluid-filled hydatid cysts in intermediate hosts, the classic study model for cystic echinococcosis.
Classification
- Cestode (tapeworm)
- Tiny adult in canine definitive host
- Sheep/livestock intermediate host
- Larval hydatid cyst in humans
Lab & identification clues
- Hydatid cyst with daughter cysts on imaging vocabulary
- Protoscoleces / 'hydatid sand' concept
- Serology for cyst antigens
Associations
- Dog-sheep cycle, egg ingestion from canine feces
- Liver and lung hydatid cysts
- Risk of anaphylaxis if a cyst ruptures (teaching point)
- Sheep-raising region epidemiology
Commonly confused with
- Taenia species
- Diphyllobothrium latum
Frequently asked questions
What is Echinococcus granulosus?
A tiny dog tapeworm whose larval stage forms large fluid-filled hydatid cysts in intermediate hosts, the classic study model for cystic echinococcosis.
What are the lab clues for Echinococcus granulosus?
Lab clues for Echinococcus granulosus include Hydatid cyst with daughter cysts on imaging vocabulary, Protoscoleces / 'hydatid sand' concept, and Serology for cyst antigens.
What is Echinococcus granulosus commonly confused with?
Echinococcus granulosus is commonly confused with Taenia species and Diphyllobothrium latum.
Original student-study summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment, dosing, or specimen-handling guidance.