DISEASES COMMUNICABLE IN MILK 75 



If human streptococci are found in mastitis, they are most likely secondary 

 agents in an already existing inflammation due to bovine strains. The strepto- 

 cocci in different epidemics differ culturally and those similar culturally differ in 

 their immunity reactions. Cultural similarity of strains from man and cattle 

 is insufficient to prove their identity; cultural identity in every detail or irnmuno- 

 logical identity is essential." 



In the course of the investigation the following practical points were 

 developed: (1) Few hemolytic types may be found even when the swabs 

 are directly inoculated upon blood agar; they may be lost on Loeffler 

 blood-serum smears submitted for examination. (2) On surface streaked 

 blood plates, typical hemolytic colonies may not be present, though 

 on longer incubation they may develop. (3) For the determination of 

 sugar fermentation, serum water is unsuited. All of the type strains 

 failed to ferment salicin, using this medium, although prompt fermenta- 

 tion took place using serum broth or serum water containing 1 per cent, 

 of peptone. 



Studies of Smillie. In forthcoming work, now in press, Dr. W. G. 

 Smillie develops the following points: 



1. His investigations of epidemics of septic sore throat confirm the 

 work of Smith and Brown. 



2. Though the Smith streptococci usually disappear from the throat 

 of the patient within 3 weeks after the passing of the clinical symptoms 

 they may persist for 4 months and possibly longer. 



In a small outbreak in a hospital he discovered the source to be a 

 nurse who 4 months before had contracted the disease in a milk-borne 

 epidemic and who as a carrier was conveying the disease to others by 

 contact infection. 



3. Out of 100 normal throats examined, 60 per cent, being those of 

 adults and 40 per cent, those of children,- but one yielded the Smith 

 streptococcus. 



He studied the throats of 25 persons who within 2 years had suffered 

 attacks of milk-borne septic sore throat and among them found but one 

 carrier, the nurse in the hospital. 



4. In a study of 25 cases of ordinary tonsillitis he found that about one- 

 half were due to the Smith streptococcus. Tonsillitis on the dairy farm, 

 therefore, should not be regarded lightly, for it may be the source of serious 

 milk infection. 



5. In a study of scarlet fever cases he found that most severe cases, 

 and some of the moderate and mild cases harbored the Smith streptococ- 

 cus in their throats. He believes that a case of scarlet fever may infect 

 the milk or the udder of the cow with Smith streptococcus. So there 

 may result from a scarlet fever case milk-borne cases of (a) scarlet fever, 

 or (6) septic sore throat or (c) a mixed infection of the two. 



