162 



ROUNDWORMS— THE NEMATHELMINTHES 



carried over the body to invade the voluntary muscles where the little 

 worms wiggle around for a while and finally settle down and encyst. It 

 is this working around through the muscles that causes the serious symp- 

 toms of this infection. A single female may deposit approximately 1,500 

 larvae in the intestine and when we consider that a good mouthful of 

 heavily infected pork sausage may contain 25,000 encysted worms of 

 which about half are females, we can understand how about 18 million 

 larvae could be released in our bodies by the worms that we could ingest 

 in one bite. The movements of the worms through the muscles cause 



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Courtesy General Biological Supply House 



Fig. 11.6. Trichinella spiralis encysted in pork. If such pork is eaten without thor- 

 ough cooking, the worms become adults in the body and produce young that work their 

 way through the muscles causing a painful condition known as trichinosis. 



extreme pain and cramps which may result in death if the infection is 

 heavy enough. The females will die within two or three months so the 

 disease will play out if you can survive these pains, but you will always 

 carry the little encysted larvae in your muscles as a souvenir of your 

 experience. 



Since hogs do not have access to human flesh, we must still explain 

 how the larvae happened to be in the hog muscle to complete the story. 

 These larvae seem to be acquired primarily through an accidental can- 

 nibalism. When hogs are fed on garbage there may be some scraps of 

 uncooked pork that have been discarded during the preparation of the 



