DISEASES DUE TO ANIMAL PARASITES 193 



DISEASES CAUSED BY CESTODES 

 TAPEWORMS 



Tapeworms have two states the larval state, which 

 is found in one species of animal, and the adult state, 

 occurring in another species. 



Tsenia Solium, or Pork Tapeworm. This is composed 

 of a small head armed with suckers and a double row of 

 booklets, whereby it attaches itself to the intestines, a 

 slender neck, and numerous segments which compose 

 the body. Each segment contains male and female 

 elements. At maturity the segments contain thousands 

 of ripe ova. The segments are continually discharged 

 with the bowel movements. Each ovum contains an 

 embryo with six booklets. To develop further, the 

 ovum must be taken into the stomach of the pig or man. 

 There the shell is digested, and the embryo set free, 

 passes through the stomach wall and becomes encysted 

 in various organs, as the muscles, brain, liver, or eye, 

 where they develop into larvae or cysticerci. When the 

 flesh containing the cysticerci is eaten by man or cer- 

 tain other animals the cyst is dissolved, the parasite 

 fastens itself to the mucous membrane of the intestine, 

 and develops into the adult worm, with segments and 

 ova as before. While either the larval or the adult 

 stage of this tapeworm may occur in man, it is usually 

 the adult type to whom man is host. 



Morbid Anatomy. No anatomic changes occur. 



Morbid Physiology. Practically the only disturbance 



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