DISEASES WHOSE CAUSE HAS NOT BEEN ISOLATED 189 



Etiology. The specific cause has not been isolated. 

 It is extremely contagious and is usually transferred 

 directly from one individual to another. One attack 

 usually confers immunity. 



Morbid Anatomy. The disease has no special ana- 

 tomic changes, but enlargement of the tracheal and 

 bronchial tubes is commonly present. 



Morbid Physiology. There are no specific disturb- 

 ances. There is increased leukocytosis, and sugar and 

 albumin may appear in the urine. 



TYPHUS FEVER 



Definition. A contagious fever, characterized by high 

 temperature, great prostration, and a petechial eruption. 



Etiology. The specific germ is as yet unknown, but 

 the contagion is probably conveyed by the breath and 

 secretions of the skin. Recent investigations indicate 

 the presence of an insect carrier. Filth, squalor, over- 

 crowding, poor ventilation, and bad food are doubtless 

 predisposing causes. 



Morbid Anatomy. Changes characteristic of high 

 fever occur, as enlargement of the spleen and swelling 

 of the kidneys. The liver is enlarged and softened, and 

 granular degeneration of the muscles, especially of the 

 heart, is frequent. A petechial rash of the skin is 

 present. 



Morbid Physiology. The disturbances of function are 

 those of fever. 



