Echinococcus Cyst of the Liver

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ECHINOCOCCUS disease is a parasitic disorder seldom encountered in the United States. The condition is also known as echinococcus cyst, hydatid cyst, echinococcosis, and hydatidosis. It is characterized by cystic lesions in the liver and lungs resulting from the infestation of Taenia echinococcus, and by lesions which are not truly cystic in some other organs, such as the bone and the brain. For this reason, many writers prefer the name echino-coccosis or hydatidosis.

The etiologic agent is Taenia echinococcus, or the dog tapeworm.1 It is a cestode morphologically similar to other tapeworms, having a head with suckers and hooklets and segments of its body called proglottids (usually three, sometimes four or five). The terminal proglottid contains the ova. The eggs, which resemble those of T. saginata, the beef tapeworm, are emptied into the bowel lumen of the definitive host by the adult taenia which is present in the small bowel. The definitive host for this parasite is usually a dog but may be a wolf, cat, or some other carnivorous animal. The ova are deposited with the feces of the host. The fecal material containing the ova contaminates grass, vegetables, or water, and by ingesting such substances, the intermediate host is infested. The intermediate host is usually a sheep or other mammal, such as man. Human beings are believed to become infested principally by contact with dogs.

Upon ingestion the parasite ovum proceeds down the digestive tract of the intermediate host and loses its membrane in the alkaline medium of. . .



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