ECHINOCOCCUS DISEASE OF THE LIVER 149 



ing stables and pastures where they are taken up by herbiv- 

 orous animals. The embryos which hatch from the eggs 

 in the stomach and intestines of the new host wander into 

 the bile ducts and portal circulation of the liver in which 

 organ they form cysts, some of which contain scoleces. The 

 cysts vary in size from a pea to a human head. In turn if a 

 liver containing the cysts' is eaten by a dog there develops 

 in the intestine of the dog the parent tapeworm, the Taenia 

 echinococcus. 



Two varieties of Taenia echinococcus have been deter- 

 mined: (1) The Echinococcus unilocularis, which is the most 

 common form, is usually found in sheep. This cyst forms either 

 a simple cyst or there may be adherent to a principal cyst 

 secondary or tertiary cysts. (2) The Echinococcus multi- 

 locularis. This cyst is comparatively rare and is found in 

 cattle. It has no capsule but forms in the liver a prolifer- 

 ating tumor containing many lacunae and macroscopically 

 resembles somewhat a carcinoma. 



Besides the liver the echinococcus may invade the lung, 

 heart, muscle, brain, and peritoneum, or even occasionally 

 bone or cartilage (the sternum). 



Symptoms. — The symptoms produced by the presence of 

 this parasite in the liver are usually very vague. In cattle 

 notwithstanding a great development of cysts in the liver the 

 animals usually appear perfectly healthy. In general the 

 symptoms are those of a chronic digestive disturbance and 

 emaciation. Sometimes the animals show sensitiveness over 

 the region of the liver and on percussion an increase in the 

 area of hepatic dulness. On rectal examination sometimes 

 the enlarged nodular liver may be felt. In individual cases 

 chronic bloating may result, as in mediastinal tuberculosis, 

 causing compression of the gullet. In swine ascites is an 

 occasional symptom. In very rare instances the rupture of 

 superficial cysts causes fatal peritonitis. Recent application 

 of the complement-fixation test, using the fluid contained 

 in the cysts as the antigen, has demonstrated that it is 

 valuable in diagnosis. 



Treatment. — No satisfactory treatment for the disease is 

 known. Of great importance is the prevention which consists 



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