74 CITY MILK SUPPLY 



relation to similar ones isolated from the five cows. Most strains could 

 be excluded because of fermentative and other reactions. Very few had 

 characteristics of the bovine strains and nearly all came from the non- 

 exposed on farms R and C; consequently the non-hemolyzing strains 

 were excluded from consideration as the caustive organism. 



The hemolyzing types obtained from the throats of the cases, from 

 the throats of persons at the Oceanside dairy and the culture from a 

 complicating case of peritonitis, had the same cultural characteristics 

 and were similar to the hemolyzing strain from cow 2 1 . But one hemolyz- 

 ing strain was isolated from the non-exposed, to wit, from Mrs. E. R. on 

 farm R, but this strain, though it gave the same sugar fermentations, was 

 different from the other hemolyzers in other cultural reactions, its mor- 

 phology and other characteristics. 



The isolation of a distinct race of streptococci from the throats of 

 the cases, from a complicating peritonitis and also from the throats of 

 persons and from a cow on one dairy farm, together with the absence of 

 this streptococcus in the throats of persons on other farms, when consid- 

 ered in connection with the epidemiological data, viz., the presence of 

 sore throat on the one farm before the general outbreak, makes it 

 practically certain that the following sequence of events occurred. Miss 

 W., was infected on April 16 and by contact infection gave sore throat 

 to Mrs. W. on May 9. From one of the two the driver became infected 

 on May 11 and either he or Mrs. W., probably the latter, infected the 

 cow. Multiplication of the organism in the milk ducts and in the milk 

 itself with contamination of the mixed milk occurred, culminating in 

 the outbreak. 



"Therefore it is concluded that the facts give strong added evidence to the 

 view that infection in milk-borne septic sore throat is of human and not of bovine 

 origin. The fact that the cow infected with 'human' streptococci had no phys- 

 ical evidence of mastitis whereas another cow having mastitis yielded another 

 unrelated 'bovine' variety of streptococcus is also of value as evidence in this 

 connection. Previous investigations have shown that some types of 'human' 

 streptococci can multiply for a shorter or longer period in the udder without 

 producing evidence of mastitis." 



Krumwiede and Valentine conclude that: 



"Streptococci, similar culturally and identical in their agglutination, were 

 isolated from cases of septic sore throat and from the udder of one cow which 

 showed no evidence of mastitis, except the peculiar character of the milk from 

 one-quarter. Both the bacteriological and epidemiological facts show that the 

 infection was primarily of human origin. The streptococci in the various epi- 

 demics, including this Rockville Center epidemic, have all been the same cultur- 

 ally with one exception, namely ' outbreak A ' of Smith and Brown. In tracing 

 the source of such an epidemic, the effort should be toward finding cases of sore 

 throat among those engaged in producing milk, not mastitis in the cow alone. 



