322 PRINCIPLES OF VETERINARY SCIENCE 



CESTODES 



Tape worms (Taenia) are the most common representatives 

 of the cestodes. Cattle in America are infested with three 

 larval and two adult tapeworms. Our sheep harbor four of each. 

 Tape worms never occur in hogs and are rare in horses. These 

 worms have flat, ribbon-shaped bodies that are segmented. 

 They are provided with sucker-like disks by which they attach 

 themselves to the lining of the intestines. Instead of a digestive 

 tract they are provided with minute openings on their bodies 

 through which nourishment is absorbed. Each segment is 

 complete in itself and capable of self-fertilization,- for it is a 

 true hermaphrodite, possessing both male and female genital 

 organs. 



Man acts as the host for two tape worms that pass their larval 

 stage in food-producing animals. The disease is contracted 

 by man through eating raw or rare meat containing the larvae. 

 Animals in turn become infested as a result of consuming the 

 eggs of the tape worm with food or water contaminated by the 

 feces of man. The term measles is applied to infested meat 

 on account of the small cysts containing the parasites which 

 may be seen on close inspection to stud the meat. 



The beef measle parasite (Cysticercus bovis) is the inter- 

 mediate stage of Taenia saginata, a human tape worm. The 

 cysts are from Y± inch to % inch in diameter and are found in 

 the muscles of the heart, tongue, jaws, and diaphragm of cattle. 

 Since the parasite dies if the beef carcass is allowed to hang for 

 thirty days in the cooler, the federal meat inspection laws make 

 this requirement instead of condemning infested meat as unfit 

 for food. Raw measly beef is to be viewed as injurious to man. 



The hog measle parasite (Cysticercus cellulose) is the larval 

 stage of Taenia solium, a human tape worm. Heat is required 

 to kill pork measles, so affected carcasses are rendered into 

 lard, unless the infestation is excessive, in which case the carcass 

 is condemned. 



NEMATODES 



Round worms of various kinds are classified under this head. 

 They are characterized by having round bodies and a complete 

 digestive apparatus. A number of different species are found 



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