672 



DISEASES OF SWINE 



spiralis. This is a quite common parasite in the hog in the United 

 States and also in Europe, and is of especial importance, in that 

 the parasites are transmissible to man by eating of the trichina- 

 infested pork. In man the parasite produces a very severe in- 

 flammation of the muscles and not infrequently produces death. 

 In the United States trichinosis in man is relatively uncommon on 

 account of the fact that we cook pork very thoroughly, and the 

 heat used in cooking the meat destroys the parasite. In European 

 countries, especially in Germany, Austria, and Russia, it is the 

 custom to eat pork in a raw or only partially cooked state, and, as 

 a result, the living parasite enters the 

 body of man, and it is not long in 

 producing severe results. 



Description. — The full-grown worm 

 is very minute in size and only about 

 3V inch in length. The larval form 

 of the trichina is only about 2^5 inch in 

 length. The parasite is divided into a 

 male and female sex. Eggs are gener- 

 ated in the body of the female and 

 hatch within her body. The newly 

 hatched larval parasite then passes 

 out into the tissues. This larva pene- 

 trates through the intestines of the 

 animal and works its way into the 

 muscles, where it buries itself and becomes surrounded by a 

 lemon-shaped cyst, which is to be made out on the cut surface of 

 the muscle as a small white speck scarcely visible to the unaided 

 eye. 



Mode of Infestation. — The most common mode of infestation 

 in the hog is by eating of rats. The rat becomes infested by eating 

 the meat of hogs and the offal around the slaughter houses and 

 around the farm at butchering time or during an outbreak of hog- 

 cholera. Hogs may also become infested through eating of dead 

 hog carcasses or offal from slaughter houses. 



When the body of the rat or the meat of an animal that is 

 infested with trichina is eaten by the hog, the cyst surrounding the 

 little larval parasites is digested from around them and they are set 



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Fig. 94. — Fresh muscle 

 trichinae (Mosler and 

 Peiper) . 



