November 13, 1914] 



SCIENCE 



719 



infections in the human are relatively com- 

 mon; consequently, in an investigation of 

 large numbers of cows and of milk handlers, 

 as it is usually necessary to do in studying 

 these epidemics, one is very apt to find in- 

 stances of one or the other and hence drav? 

 conclusions accordingly. On the other hand, 

 the real source of streptococci may be over- 

 looked on account of some hidden focus of in- 

 fection in the throat or tonsils of a milker 

 which could not be detected in an ordinary 

 throat examination. Or a cow might be suf- 

 fering with inflammation of the udder and 

 discharging millions of streptococci in the 

 milk and still, as the writer has shown experi- 

 mentally, the udder may show no physical 

 signs of disease and might thereby escape de- 

 tection on inspection. For these reasons it is 

 readily seen how one might be misled in his 

 conclusions when looking for the ultimate 

 source of streptococci causing an epidemic. 

 In the Boston epidemic the source of the 

 streptococci was not clear, Winslow stating 

 that it was probably a carrier. In the Chi- 

 cago epidemic, certain facts suggest that the 

 origin was bovine, but absolute proof was lack- 

 ing. Stokes and Hatchell from their investi- 

 gations of the Baltimore outbreak " feel rea- 

 sonably sure the infection was caused by 

 streptococci of the epidemicus type from 

 cases of mastitis among the herds supplying 

 the dairy." * In the report of the Concord, 

 N. H., epidemic, made by Mann^ no mention 

 is made of a possible bovine source. There 

 was evidently sufficient opportunity for con- 

 tamination of the milk by human carriers on 

 the farms supplying the milk. In the Wake- 

 field and Stoneham (N. T.) epidemic re- 

 ported by Morse,^ a very definite connection 

 seemed to exist between the epidemic and a 

 throat abscess in one of the milkers. In the 

 report of the Cortland and Homer epidemic 

 made by North, White and Avery, the state- 

 ment is made that " two cows having inflamed 

 udders in the herd of Dairy X were undoubt- 

 edly responsible for the epidemic of septic sore 



* Public Health Reports, 1912, Vol. 27, p. 1923. 

 5 Jour, of Inf. Vis., 1913, 12, 481. 

 ^Am. Jour. Pub. Health, 1914, 4, 506. 



throat." ^ At Jacksonville, HI., the epidemic, 

 studied by Dr. J. A. Capps and the writer, was 

 caused by hemolytic streptococci and from 

 two cows supplying milk to Dairy X the same 

 type of organisms were isolated. No sus- 

 picious human carriers could be found on the 

 farms or among the milk handlers. 



From the above it is seen that bovine and 

 human sources are suspicious, and perhaps 

 each or both at times may be responsible. It 

 is known that human streptococci may be 

 highly virulent for cows^ and the reverse may 

 also very probably be true. In an analysis of 

 milk organisms, therefore, the fact that hemo- 

 lytic streptococci have been the cause in prob- 

 ably all the sore throat epidemics centers our 

 attention at once upon this type of strepto- 

 coccus. As yet there is no evidence that other 

 types have any sanitary significance whatever 

 so far as sore throat or any other human dis- 

 ease is concerned. I therefore call attention 

 to the fact that in any investigation of milk 

 streptococci, whether from the standpoint of 

 pure or applied bacteriology, the relation of 

 the streptococci to hemolysis of blood should 

 be carefully noted. It is well known, of 

 course, that hemolysis may not be an abso- 

 lutely stable property in any given strain. A 

 strain may occasionally alter its power in this 

 respect just as it may change its fermentative 

 properties under certain conditions. For 

 practical purposes, however, it is of very great 

 value, as I believe every one who has occasion 

 to work with pathogenic streptococci will ad- 

 mit. Furthermore, the fact that the hemo- 

 lytic property can not be correlated with other 

 properties such as those of fermentation does 

 not detract from its value as a differentiating 

 feature, but rather adds to it. 



The question of pasteurization is an inter- 

 esting one in relation to these infections. In 

 the case of at least four of the epidemics in 

 this country the infected milk had been pas- 

 teurized by the " flash " method and the evi- 

 dence in all indicated quite clearly that the 

 milk was contaminated before pasteurization. 

 Nothing further need be said, therefore, con- 



T Jour. Inf. Disease, 1914, 14, p. 132. 

 8 Davis, Jour. Inf. Bis., 1914, 15, 135. . 



