TYPHUS FEVER. 727 



may pass through an attack of typhus so mild 

 that it can not be recognized clinically. Vaccina- 

 tion results." 



Nicolle succeeded in transmitting the typhus Transmission. 

 fever of Tunis from chimpanzees to monkeys by 

 means of the common body louse. Anderson and 

 Goldberger and Bicketts and Wilder succeeded in 

 producing tabardillo in the monkey through the 

 bite of the louse. The lice were allowed to feed 

 on the blood of patients with tabardillo and sub- 

 sequently permitted to bite the monkeys. Eicketts 

 and Wilder also demonstrated that infected lice 

 transmitted the infection to their eggs, which gave 

 rise to lice capable of infecting monkeys. Their 

 observations of the spread of the disease render it 

 reasonably certain that lice are the ordinary means 

 of transmission. Studies on the bed bug and flea 

 indicate that they play no part in the spread of 

 this infection. 



The virus of typhus fever is not filterable. Microbic 

 Various organisms have been described in the 

 blood. Eicketts and Wilder describe a small bac- 

 illus in stained blood preparations. The organism 

 resembles the plague bacillus and those organisms 

 described in spotted fever. The organism was 

 also found in the intestinal tract of infected lice. 

 Cultivation was unsuccessful. Further studies 

 are necessary to establish the etiologic relation- 

 ship to typhus. 



The production of immunity through a light immunity. 

 attack of typhus in the monkey has already been 

 mentioned. The serum of convalescents is said to 

 be curative in a moderate degree (Legrain). 



