354 



The Diseases of Animals 



not be used for food, nor placed where animals can eat 

 it, unless it has been thoroughly cooked to kill the 

 parasites. 



TRICHINA IN MEAT 



Trichinosis is a disease especially of pigs and man, 

 caused by the invasion of the tissues of the body by a 

 minute round -worm {Trichina spiralis), that bores its 

 way to the different parts of the body, and then be- 

 comes encysted. Fig. 54. Man usually contracts the 

 disease by eating infested pork that has not been thor- 

 lOughly cooked. Trichinae in pork are 

 invisible to the naked eye. When taken 

 into the stomach, the encysted worm is 

 liberated, develops into an adult, and 

 the females give birth to large numbers 

 (ten to fifteen thousand) of embryo 

 young. These young worms migrate, 

 boring their way, or carried by the blood 

 and lymph, to distant parts of the body, 

 there developing the cyst stage. When 

 these cysts are examined under a micro- 

 scope, each is found to contain the 

 small, cylindrical embryo worm, in a coiled or spiral 

 position, from which it takes its Latin name. 



When meat infested with trichinae is eaten, there 

 follows, in the human subject, considerable irritation of 

 the bowels, associated with diarrhea. This occurs in 

 three to ten days after the meat has been eaten. 

 During this period, the worms are multiplying in the 

 digestive tract of the patient. Following this, there is 



Fig. 54. 

 Trichina spiralis 

 encysted in lean 

 meat. Magnified. 



