TRICHINOSIS 



271 



The neck burrows into the mucosa, and much importance has been attributed 

 by the French to the possibility of this paving a way for the entrance of pathogenic 

 bacteria. They do not seem to produce serious symptoms. 



Trichinella spiralis (Trichina spiralis). -The cause of trichinosis is 

 usually termed Trichina spiralis in medical works. 



The adults live in the duodenum and jejunum; the males are about 1/16 of an 

 inch (1.5 mm.) long with two tongue-like caudal appendages and without a spicule. 

 These two lateral projections enable the male to hold the female in copulation 

 the cloaca being evaginated to act as a penis. 



The females are about 1/7 of an inch (0.3 to 0.4 mm.) long. The female gives 

 off embryos from the vulva which is near the mouth end (viviparous). 



These parasites can be seen with an ordinary magnifying glass. With higher 



FIG. 74. Trichina spiralis (Ziegler). 



powers the oesophagus has the appearance of a serrated line instead of an cesophageal 

 bulb. The male is about 40^ broad and has a prominent testicular enlargement 

 filling the posterior extremity. The female is about 6o/x broad and has a rounded 

 posterior extremity with a prominent slit-like cloaca. It is in this posterior extremity 

 that the female increases in size as she becomes filled with eggs. The vulva is in the 

 anterior third. After fertilization of the females the males die, and the females 

 bore into the intestinal mucosa and begin to produce embryos to the number of 

 more than 1000 each. These gain access to the lymph channels and are distributed 

 by the blood stream to the striated muscles. Embryos reaching other tissues fail to 

 develop. 



It is about ten days before they reach the muscle. In the muscle they become 

 encysted as the oval lemon-shaped areas containing coiled-up embryos that every- 

 one is familiar with. These oval areas are about 450X250;* and have a chitinous 

 capsule. 



The encysted trichinae are found chiefly in the muscle fibers of the tongue and 



