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Hydatid cyst of the liver caused by the Cysticerci of a Cestode. Hydatid cyst caused by the Echinococcus granulosus.
Hydatid disease in the liver, caused by cystic echinococcosis. Composite computer illustration showing Echinococcus granulosus hydatid cyst in the human liver and close-up view of larvae protoscolices inside hydatid cyst. E. granulosus is a parasitic tapeworm, also called dog tapeworm and hydatid worm, which causes cystic echinococcosis.
Humans are infected by ingestion of parasitic eggs excreted by feces of the definitive host (dogs and wild carnivores), the eggs hatch in the small intestine and release a six-hooked oncosphere, which in turn penetrate the intestinal wall, migrate through the circulatory system to other organs, mainly liver and lungs, and develop into a thick-walled hydatid cyst, which enlarges gradually, produces protoscolices and daughter cysts that fill the cyst interior. This cyst is slow-growing but can cause clinical symptoms and become life-threatening if untreated.
What is the Cause of Hydatid cyst in liver?
The main cause of the hydatid cyst of the liver is the cestode. Name as Echinococcus granulosus.
Man is neither a definitive host more intermediate host but infected accidentally. This cestode is about 3-6 mm long. It lives in the small bowel of its host (Dog or other canines).
The life cycle of Echinococcus granulosus (Hydatid cyst)
- It exists bowel of their host (Dog). Gravid proglottids release eggs. That passes into the feces.
- When intermedia hosts (Sheep, goat swine, cattle, horse, camel) ingest eggs. These eggs attach to their bowel and release an ONCHOSPHERE.
- These oncospheres penetrate their intestine and reach blood circulation and into various organs especially the liver and lungs.
- After reaching the lungs or liver, these oncospheres develop into CYST.
- This cyst enlarges gradually and produces PROTOSCOLICES and daughter cell which fill that cyst.
Note: Ingesting cyst containing organs of intermediate host infect the definitive host. After ingestion, protoscolices are turned inside out and attach to the intestinal mucosa and develop into adults in 30 to 80 days.
Humans are infected by ingesting eggs. This releases Onchoshere and attaches to the intestine and develops a cyst in various organs.
Cliical lab Diagnosis of Echinococcus granulosus hydatid cyst
- A cyst can be diagnosed by x.ray, CT scan, ultrasound.
- Casoni skin test is useful for hydatid cyst.
- Microscopic examination of cyst wall and aspirate fluid.
- Latex agglutination, indirect haemagglutination, and complement fixation are used for it.