It refers to the human infection by the immature form of tapeworm, Echinococcus. One of three forms of the Echinococcus spp., E. granulosus, lives on dogs and livestock, and infects humans through contact with these animals. Allergic reactions and damage to various organs from cyst formation are the most common forms of disease in humans. Treatment depends on the size and location of cysts, as well as the symptoms they are producing. Surgical removal of cysts and/or surrounding tissue is the accepted method of treatment. Recent studies using medication alongside aspiration and drainage of cysts instead of surgery are very encouraging. Albendazole can be taken before or after surgery but its effectiveness as a single treatment is not known still. Response to treatment is best monitored by serial CT scans or similar x-ray studies. In primary echinococcosis, metacestodes develop from oncospheres, In secondary echinococcosis, larval tissue proliferates after being spread from the primary site of the metacestode. In each anatomic site, cysts are surrounded by the periparasitic host tissue (pericyst), which encompasses the endocyst of larval origin. The central cavities of cysts filled with clear fluid, numerous brood capsules. The spectrum of symptoms depends on involved organs, complications caused by rupture of cysts. Annual incidence rates of diagnosed human cases per 100,000 inhabitants vary widely, from less than 1 case per 100,000 to high levels. Cystic echinococcosis is rarely fatal. Occasionally, deaths occur because of anaphylactic shock or cardiac tamponade in heart echinococcosis. Individuals of all ages are affected. In some endemic countries, children have higher infection rates because they are most likely to play with dogs.