CDC Echinococcus Life Cycle

Life cycle of Echinococcosis, showing it's transmission to humans, courtesy CDC

Echinoccoccosis is a parasitic disease caused by the larvae of the echinococcus parasite. The larvae attach themselves to the lungs, liver or kidney and form cysts. The disease is often asymptomatic unless organ damage becomes severe or one of the cysts is accidentally ruptured. The latter event can lead to anaphylactic shock.

The adult parasite (a tapeworm) lives in the intestines of carnivorous animals, typically members of the canine family such as dogs, wolves and foxes. The adult lays eggs which are expelled in feces. The eggs are then eaten by herbivores, where they hatch into larvae, attach themselves to the organs of the affected animal, and lay in wait within the cysts until the intermediate host dies. The larvae are then eaten by carnivores along with the dead meat to start the life cycle again.

Humans are not a natural host of the parasite, as they are rarely scavenged animals. Most human cases are from accidental injection of the eggs from contaminated material or undercooked meat.

Because the disease is rare in humans, it is often mistaken for other conditions, such as Cirrhosis.

Alveolar hydatid disease at Wikipedia

Echinococcosis at Wikipedia

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