560 FILTERABLE VIRUSES 



mortality varies greatly; in the eastern part of the United States the 

 disease is mild in character, 1 so mild in fact that the malady was spoken 

 of as Brill's disease in honor of Brill who described the clinical features 

 of it in great detail. The mortality in Europe, where the disease is 

 very prevalent in certain areas, especially the more southern lands, is 

 usually high. 



The first definite communication relating to the mechanism of 

 infection was that of Nicolle 2 and of Nicolle, Comte and Conseil. 3 

 They succeeded in infecting an anthropoid ape with the blood of a 

 typhus patient, and very shortly afterward, and independently, 

 Anderson and Goldberger 4 infected two monkeys, a Macacus rhesus 

 and a capuchin, in the same manner. These results have been con- 

 firmed by Ricketts and Wilder, 5 and others. Anderson 6 states that 

 guinea-pigs may also be infected with the blood of typhus patients. 



It has been shown by animal experimentation that one attack 

 of typhus confers immunity, and this method has been taken advantage 

 of to show that typhus, Brill's disease and tabardillo mutually 

 confer immunity on monkeys; that is, an animal recovered from 

 either of the three clinical types is immune to infection with the other 

 two. 



The filterability of the virus of typhus has been a subject of discus- 

 sion; the concensus of opinion appears to be that blood serum filtered 

 through stone filters has not been definitely shown to be infective 

 for monkeys, although Nicolle, Anderson and Goldberger, and Rick- 

 etts and Wilder have noticed that the injection of filtered serum appears 

 to render monkeys refractory to subsequent inoculation with the 

 virus. 



Recently Plotz 7 has isolated a small, anaerobic, Gram-positive 

 bacillus from the blood of a series of cases of Brill's disease and of 

 typhus which when used as an antigen caused fixation of comple- 

 ment with the sera of these cases. The bacillus measures from 0.2 

 to 0.6 micron in diameter and from 0.9 to 2 microns in length. 8 It 

 is non-acid-fast, possesses no capsule, and exhibits bipolar staining. 

 In the latter respect it suggests the organism seen but not cultivated 



1 Brill, Am. Jour. Med. Sc., April, 1910, 484; August, 1911, 196. 



2 Compt. rend. Acad. sci., 1909, cxlix, 157. 



3 Ibid., p. 486. 



4 Public Health Rep., 1909, 1861; ibid., p. 1941; 1910, 177. 



5 Jour. Am. Med. Assn., 1910, liv, 463; ibid., 1304, 1373. 

 Public Health Rep., 1915, xxx, 1303. 



7 Jour. Am. Med. Assn., 1914, Ixii, 1556. 



8 Plotz, Jour. Am. Med. Assn., 1914, Ixii, 1556. 



