TKICHTNIASIS — TRICHINOSIS. 



85 



this girl had some time previously eaten a quantity of raw ham. Virchow 

 and Leuckart returned to their investigations, and the life history of the 

 parasite soon became definitely known. 



Causation. Trichinosis is capable of attacking all mammifers with- 

 out exception, from a man to a mouse ; and most animals which can be 

 made the subjects of experiment contract the disease in varying degrees. 



The intestinal form is seen in birds, but the muscles do not become 

 infested by the embryos. 



Cold-blooded animals are proof against the disease. 



After the ingestion of meat containing cysts of the parasite, the 

 processes of gastric and intestinal digestion set the larvae at liberty. 

 These larvae become sexual at the end of four 

 to five days, and the females, which are usually 

 twice as numerous as the males, begin laj'^ing 

 eggs from the sixth day, continuing for a 

 month to six weeks. Each female lajs 

 approximately from 10,000 to 15,000 eggs. 

 The embryos perforate the intestinal walls, 

 pass into the circulation, and are hurried into 

 all parts of the system. This i^eriod of infes- 

 tation constitutes the first phase of the disease. 

 Askanaz3% in 1896, suggested that it was 

 not the embryos which perforated the intes- 

 tinal walls and thus reached the blood-vessels, 

 but the fertilised female trichinae themselves, 

 which entered the terminal chyle vessels and 

 laid their eggs directly within them. 



This observation is of great interest, for 

 it contradicts the view held by Leuckart and 

 proves that treatment is useless even in the 

 first phase. 



Fig. 46. — :Male trichina from 

 the intestine. (Colin.) 



The males are about -^^ inch in length, the females J inch to 



inch, 



and are ovoviviparous. 



Symptoms. The symptoms lack precise character, even when the 

 disease is known to be developing, and moreover they have only been 

 carefully observed in experimental cases. As soon as the laying period 

 begins, signs of intestinal disturbance may be observed, possibly due to 

 embryos perforating the intestinal walls (if we accept Leuckart's view), or^ 

 according to Askanazy, to adult females penetrating the chyle vessels and 

 disturbing intestinal absorption. 



These symptoms are only appreciable in cases of " massive " infesta- 

 tion. If slight, the disturbance passes unperceived. In severe cases 

 the symptoms consist of diarrhoea, loss of appetite, grinding of the teeth, 



