940 DISEASES CAUSED BY FILTRABLE VIRUS 







is followed by a rapid rise of temperature after an incubation time 

 of five days or more, and the fever remains high for three to five 

 days, after which it comes down by lysis. Occasional recrudescences 

 have been noticed in monkeys. Goldberger and Anderson have had 

 a mortality of 2 per cent in their monkeys. The disease may be 

 transmitted from monkey to monkey with the blood, which is in- 

 fectious during the febrile period and may be so for as long as 

 thirty-two hours after the temperature returns to normal. 



The first successful transmission of the disease to guinea-pigs 

 was accomplished by Ricketts and Wilder. In these animals the 

 only symptoms are fever, a matter which has made experimentation 

 with these animals relatively difficult. According to Nicolle, guinea- 

 pig inoculation may occasionally result in no symptoms at all, and 

 yet blood of such animals may produce the fever reaction in others 

 inoculated with it. There seems to be a considerable difference in 

 the degree of susceptibility in guinea-pigs. Anderson found about 

 44 per cent of his guinea-pigs resistant in the first generation of 

 transmission from the typhus patient. Da Rocha-Lima believes that 

 about 80 to 90 per cent of young guinea-pigs weighing not anore 

 than 300 grams, will usually be found susceptible. The typical reac- 

 tion to guinea-pigs is a rise of two or three degrees of temperature 

 on the sixth, seventh or eighth days. 



Although ordinary observation shows only the fever reaction 

 in guinea-pigs, it has been lately claimed by Lowy 12 that careful 

 inspection of the inner surface of the skin of guinea-pigs may reveal 

 small hemorrhagic spots, not unlike the typhus eruptions in human 

 beings. 



Etiology. The disease was at first suspected to be caused by 

 a filtrable virus, an opinion which is still held by some observers. 

 Most workers agree to-day, especially because of the work of Ander- 

 son and Goldberger, that filtered blood will not convey the disease, 

 and, although Nicolle, Conor and Conseil, Ricketts and Wilder, and 

 others have reported that occasionally inoculation with filtered blood 

 renders monkeys refractory to later inoculation, it is generally 

 believed at present that the disease is caused by some agent too 

 large to pass through the Berkefeld or Chamberland filters. 



Work on the etiology of typhus has been very extensive and 

 many microorganisms have been described. 



Lowy, Wien. klin. Woch., 18, 1916. 



