542 Typhus Fever 



and others who cared for patients suffering from the disease, as 

 contrasted with its persistent spread to new patients at the foci of 

 infection. They also had the recently gained knowledge of the part 

 played by insects and arthropods in the transmission of malaria, 

 relapsing fever, African lethargy, etc., the whole matter being of 

 such nature as to make the conclusion that the infection was trans- 

 mitted by an insect host, a justifiable one. 



The first to work upon this problem were Nicolle, Couer and 

 Conseil,* the selected insects being pediculi. They permitted lice 

 to feed upon the blood of an infected monkey, and then upon a 

 healthy monkey. The healthy monkey contracted typhus fever. 

 In the same year, and working independently, Goldberger and 

 Andersonf made two attempts to infect healthy monkeys by per- 

 mitting lice fed upon cases of typhus fever in men, to bite them. 

 They had partial success — the monkeys became diseased but no 

 immunity tests were made for confirmation of the nature of the 

 disease. 



Ricketts and Wilder J working in Mexico succeeded in transmitting 

 typhus fever from man to monkeys by means of lice — Pediculus 

 vestimenti. They also succeeded in transmitting the disease to a 

 monkey by scarifying its skin and applying the abdominal contents 

 of some infected lice, so that it was proved by them that the cause 

 of infection was in the lice. Later Nicolle and Conseil§ also suc- 

 ceeded in infecting a monkey by the bites of infected lice. 



Wilder 1 1 further found that the infectious agent passes from the 

 infected lice to a second generation of insects, as does the spiro- 

 chaeta of relapsing fever to subsequent generations of ornithodorus 

 ticks. Wilder failed in experiments directed toward infecting 

 monkeys by fleas or bed-bugs. 



In the experiments recorded by Wilder, the transmission of typhus 

 fever to monkeys, by lice, was successful in 7 out of 10 attempts. 

 It required 1 7 lice to infect a monkey. In one case a monkey 

 seemed to be immunized by being bitten by very young lice. 



Goldberger and Anderson** also experimented with the head 

 louse Pediculus capitus and succeeded in showing that it too takes 

 up the typhus fever virus and may pass it on from human being to 

 monkey, and hence probably from man to man. 



A description of the lice will be found in the chapter upon "Re- 

 lapsing Fever." 



*"Compt.-rendu de I'Acad. des Sciences de Paris," 1909, cxLix, 486. 

 t "Public Health Reports," 1910,'xxv. 

 j "Jour. Amer. Med. Asso.," 19 10, Ltv, 1304. 



§ "Compt.-rendu. de I'Acad. des Sciences de Paris," 1911, CLin, 1522- 

 I] "Journal of Infectious Diseases," 1911, ixi. 

 ** "Public Health Reports," 1912, xxvii. 



