252 BACTERIOLOGY FOR NURSES 



sion and in all probability the head louse too, a fact which justifies 

 its classification as a filth disease. Typhus fever still occurs in 

 certain parts of Europe and in North and South America. In 

 Mexico it appears epidemically under the name of Tarbardillo. 

 An infection known as Brill's disease and thought by Brill to be a 

 new malady has recently been shown to be a mild form of typhus 

 fever. 



For a long time the disease has been attributed to a filtrable 

 virus, and some observers still hold the opinion. Many extensive 

 investigations have been made as to its etiology, and various 

 organisms have been described as the probable causal agent, 

 but until quite recently all attempts to obtain cultures failed. 

 In 1914 Plotz obtained from the blood of cases of Brill's disease 

 an organism which he succeeded in cultivating anaerobically. 

 In a great many subsequent cases Plotz and his co-workers have 

 found the same organism and have demonstrated the presence of 

 agglutinins and complement-fixing antibodies in the blood of 

 convalescents. Much of the evidence so far obtained is in favor 

 of the bacillus as the causal agent of typhus fever. 



