Etiology. Auatoniical Symptoms. 157 



Most commonly aflVctcMl are ruminants and hogs; a few cysts 

 are sometimes fonnd in the hmgs of horses. (For more details 

 on the frequency of echinococcosis, see the chapter on echino- 

 coccosis of the liver.) 



Etiology. Echinococci are the cysticerci of the dog par- 

 asite Taenia echinococcns, the oncospheres of which are prob- 

 ably carried by the blood current from the intestines into the 

 lungs; they change into cysts in the pulmonary tissues; these 

 cysts grow very slowly in size. Infection occurs by swallow- 

 ing the ova of Taenia echinococcns with food or water (on the 

 developmental history and the various forms of echinococcns, 

 see echinococcosis of the liver). 



Anatomical Changes. In some cases, the lungs contain 

 only a few echinococcns cysts, in others these occur in so great 

 numbers that they cannot be counted, so that the weight of the 

 organ may have become increased considerably^ (in a case re- 

 ported byFindeisen, the lungs of a steer weighed seventy-eight 

 pounds). The surface of the lungs then becomes uneven, nodu- 

 lar, and the palpating hand feels the cysticerci in their interior, 

 surrounded by a connective tissue capsule and containing a 

 clear serous fluid. These cysts may be felt as firm, tense, 

 globular nodules, up to the size of a fist. If the cysts are cut 

 into they discharge a serous fluid, and the elastic membrane 

 forming the interior surface can then be peeled off easily from 

 the external capsule. The cysts are sometimes provided with 

 scolices, or they maj^ frequently be sterile, or exceptionally 

 also contain daughter cysts. Small, dry, caseous nodules or 

 mortarlike masses are also often present in foci, Avhich look 

 similar to caseous tubercles, but in which the microscope shows 

 sometimes folded parts of the chitinous membrane, occasionally 

 also booklets. The pulmonary tissue in the immediate neigh- 

 borhood of the cysts appears compressed, flaccid, either entirely 

 void of air, or containing very little of it. Echinococcns 

 multilocularis has once been found in the lung of a steer. Other 

 cysticerci are usually found in the other organs, particularly 

 in the liver. 



Symptoms. Only if the invasion is considerable, does the 

 disease manifest itself by difficult respiration, which develops 

 very insidiously, and which, therefore, remains unnoticed for a 

 long time and very rarely takes on a threatening character. 

 With such difficulties of respiration, a cough appears ; it is fre- 

 quently heard after short intervals, usually weak, dull, some- 

 times even hardly audible. Difficulties of respiration and 

 cough may suddenly increase without any apparent cause (rup- 

 ture of a cyst into a bronchus or into the pleural cavity). 

 Sometimes exhaustion and overheating bring about an aggra- 

 vation of the condition. In case of rupture of a cyst, a watery 

 fluid is sometimes discharged through the nose, in which shreds 



