TRICHINOSIS. 



215 



about 1/6 of an inch. The female gives off embryos from the vulva 

 which is near the mouth end (viviparous). After fertilization of the 

 females the males die, and the females then begin to produce embryos 

 to the number of more than 1000 each. These pass out of the intestine 

 and wander about to the striated muscle; it being about 10 days be- 

 fore they reach the muscle. In the muscle they become encysted as 

 the oval areas containing coiled-up embryos that everyone is familiar 

 with. These oval areas are |about 450x250/4. The encysted larvae 

 may remain alive as long as 10 to 20 years; finally, however, the 

 cyst undergoes calcareous infiltration and the embryo dies. Among 



FIG. 67. Trichina spiralis (Zlegler). 



cannibals it would be easy to keep the cycle going by eating improperly 

 cooked or raw human meat, the parasite being thus transmitted. 



As this would not explain the transmission among civilized men, the 

 following is the life history: Man obtains his infection from eating 

 raw pork, the embryos encysted in the muscle of the hog being liberated 

 in the stomach, and the males and females developing in the intestine 

 as above described. The hog may gain his infection by eating the 

 meat of other hogs or rats. These rats eat scraps of pork at slaughter 

 houses and become infected. In man, while the adults are breeding in 

 the intestine, we have gastrointestinal symptoms. About 10 to 20 days 

 after infection the embryos begin to wander and we have the acute 



