Biology of the Echinococcus

Abstract

Hydatid disease, also known as echinococcosis, is a parasitic infestation that has a worldwide distribution. The term ``hydatid'' is from the Greek word meaning a drop of water or ``watery vesicle''. The word ``echinococcus'' means ``hedgehog berry''. Hydatid disease was alluded to by Hippocrates around 400 BC. Its parasitic nature was hypothesized by Pallas in 1766. The history of hydatid disease and human infections with other helminths was reviewed in the 1990s and the basic life cycle of the hydatid parasite (colloquially known as a tapeworm) was finally elucidated by Groove (1990). Human cystic echinococcosis is caused by the larval stage of Echinococcus granulosus or E. multilocularis. Humans are only the accidental intermediate hosts in the life cycle of the Echinococcus. The infection is acquired by humans and other intermediate hosts after the ingestion of vegetables, fruits, and drinking water contaminated by eggs excreted by infected carnivores along with the feces, or by the handling of infected pet dogs (Milicevic 2005).