532 THE ANIMAL PARASITES OF MAN 



ation be performed immediately after the exploratory puncture ; indeed, it is a 

 question whether aspiration should be performed at all. 



Echinococcus disease is not always easy to diagnosticate. Frequently at 

 the autopsy, in the liver or other organs, cysts the size of a child's head and 

 even larger are found which had not produced the slightest symptoms during 

 the life of the patient. The gravity of the disease depends upon the location 

 of the cyst, the size, the effect upon neighboring organs, and, possibly, the 

 purulent character of the contents of the cyst. Should it suppurate, small 

 echinococcus cysts in the brain and spinal cord may cause severe symptoms; 

 on the contrary, occasionally, large sacs which have no deleterious effect upon 

 the surrounding area exist for a long time without giving rise to serious symp- 

 toms. In general, the symptomatology may be described as follows : 



SYMPTOMS 



The embryo which has entered the body causes a reaction of the tissue 

 which leads to the formation of the wall of a cyst. "With continued growth 

 the effect of pressure upon the neighboring tissue becomes apparent, and 

 decided disturbances in circulation, secretion and excretion are manifest. 

 Particularly dangerous is the development of the echinococcus in cavities 

 where the growing tumor cannot fail to cause serious disturbance, as for in- 

 stance in the pelvis, by compression of the organs situated in this region. 

 When the development of the echinococci occurs ia the respiratory tract, the 

 symptoms there are also severe. The symptoms, however, become especially 

 threatening if suppuration supervene, or the contents of the cyst should per- 

 forate its walls. If the contents of the cyst be emptied into the abdominal or 

 thoracic cavities, fatal disease usually follows. When there is adhesion among 

 neighboring organs, after penetrating the wall of the cyst the parasite enters 

 these, and permeates them in the same way as the organs primarily affected. 

 Thus the parasite traverses remarkably great distances. The course is most 

 favorable when perforation occurs through the skin. Discharge into the 

 stomach and intestine and into the pelvis of the kidney, into the bladder or 

 into the vagina is relatively favorable. A cyst of this kind may very readily 

 become the starting point of a fatal pyemia. Perforation into the trachea, 

 into the bronchi, and particularly into the circulatory system is always most 

 serious. Echinococcus of the superficial organs runs a less dangerous course. 



The general condition of the patient is usually most affected when the 

 echinococcus exerts an influence upon the neighboring organs by its size, or 

 when suppuration occurs. Only after attention has been thus called to the 

 affection does the patient seek professional aid. A number of conspicuous 

 phenomena, such as the slow, steady, painless growth of the tumor, the absence 

 of cachexia, the uniform roundness of the tumor, the smooth surface, the 

 absence of fever, the elasticity, the presence of fluctuation, and the possible 

 demonstration of a hydatid thrill, in general favor the existence of an echino- 

 coccus sac. By a hydatid thrill we mean that sensation which the tumor con- 

 veys to the percussing flnger or to the palpating hand, a sensation similar to 

 that obtained by pressing upon a cushion with springs. The cause of the hyda- 



