196 PATHOLOGY 



TRICHINA SPIRALIS 



Trichina occurs in both the larval and adult form in 

 man and the lower animals. Infection occurs from eat- 

 ing improperly cooked pork. The larvae are set free, 

 develop into adults in the intestines, where they dis- 

 charge embryos. Some of the embryos die or escape 

 by the feces, while others penetrate the intestinal wall, 

 and are either carried by the blood or lymph-stream or 

 by their own migrations to the muscles, where they be- 

 come encysted. When the migration begins, symptoms 

 of intestinal irritation, with fever, vomiting, and perhaps 

 collapse occur, followed by excruciating pain in the 

 muscles resembling rheumatism, the gravity of the 

 disturbance depending upon the number of the parasites 

 developed. 



ANKYLOSTOMA DUODENALE (HOOK-WORM) 



This worm is so called from the head being armed 

 with six sharp hook-like teeth, whereby it fastens 

 itself to the wall of the small intestine. The parasite 

 causes intense anemia and debility. It is thought 

 that a poison is secreted by the worm, which causes 

 the profound blood changes. 



FILARIA SANGUINIS HOMINIS 



This is a small worm about the thickness of the diam- 

 eter of a red blood-corpuscle. Infection occurs through 

 the bite of a mosquito, in whose body occurs one cycle 



