97 



which elapsed between biting the infected and biting the healthy 

 mice were a few seconds, 18 hours, 7 days, 15 days and 71 days. The 

 exact parts played by bites and by faeces in the ten transmissions 

 are impossible of determination. White mice readily eat living and 

 dead bugs. White mice that eat infected bugs usually contract 

 tularaemia. Of 20 white mice that each ate one infected bug, 14 

 died from acute tularaemia. The average length of time from the 

 date of infection of the 14 bugs until they were eaten was 65 days. 

 Three white mice which each ate a bug infected 100 days previously 

 died 5, 4 and 5 days later from tularaemia. Guinea-pigs apparently 

 do not eat bugs intentionally. Those bitten by infected bugs failed 

 to contract tularaemia, with one exception ; in that instance the 

 guinea-pig probably ate one infected bug unintentionally and thereby 

 contracted the infection. The fresh faeces of bed-bugs, which were 

 infected with Bacterium tularense by sucking the blood of infected 

 white mice and which were fed every ten days thereafter on the blood 

 of healthy white mice, contained virulent organisms of this infection 

 at all times, and did so up to 120 days after the date of infection of 

 the bugs. Faeces of infected bed-bugs deposited on filter papers at 

 least 46 days after the dates of infection of the bugs and subsequently 

 dried for 20 days, contained virulent organisms of Bactermm tularense 

 at the end of that time. In spite of these facts, the fresh faeces of 

 infected bed-bugs have always failed to infect white mice or guinea-pigs 

 which ate those faeces. Bacterium tularense suffered no apparent 

 diminution of virulence by reason of long residence in bed-bugs. 



Francis (E.) & Lake (G. C). Tularaemia Francis 1921. V. Trans- 

 mission of Tularaemia by the Mouse Louse, Polyplax serratus 

 (Burm.). — Puh. Health Repts., Washington, xxxvii, no. 3, 20th 

 January 1922, pp. 96-101. 



The authors' summary of experiments with Polyplax serratus in 

 the transmission of tularaemia is as follows : — 



The transmission of tularaemia was effected in 12 out of 17 attempts 

 through the agency of the mouse louse, Polyplax serratus, by the 

 transfer of lice from white mice dead of tularaemia to healthy white 

 mice, the intervals elapsing between infestation of the healthy mice 

 and their death varying from 5 to 12 days, the average being 7^ days. 

 The number of lice transferred in the 12 successful attempts varied 

 from 12 to 43, the average being 25. The intervals which elapsed 

 between the deaths of infected mice and the transfer of their hce to 

 healthy mice varied from a few minutes to 18 hours. Transmission 

 of tularaemia by lice was thus effected to two series of mice, the first 

 series being infected by lice removed from inoculated mice, and the 

 second series being infected by lice removed from the louse-infected 

 mice of the first series. When inoculated mice were dropped into a 

 jar in contact with lousy healthy mice, the infection killed oft" all the 

 healthy mice in 25 days. Transmission in this case was probably due 

 to the lice. Blood-sucking mites, Liponyssus isahellinus, removed from 

 an infected white mouse, were crushed and injected subcutaneously 

 into another white mouse, causing its death from tularaemia. The 

 urine of infected white mice was infective to guinea-pigs when in- 

 jected subcutaneously into the latter. Similar urine failed to infect 

 white mice when fed to them on maize meal. 



