486 PATHOGENIC BACTERIA IN MILK 



question, as our knowledge of small epidemics due to this micro- 

 organism is still too fragmentary. 



Cholera Spirilla. Three small epidemics of Asiatic cholera, appar- 

 ently traceable to contamination of a milk supply, have been reported 

 by Gaffky, Simpson, and Kniippel; the spirillum of Asiatic cholera 

 itself has never, however, been found in milk. 



Dysentery Bacilli. Dysentery bacilli of the Shiga, Flexner, Kruse, or 

 Strong type, which have been isolated in cases of human dysentery in 

 adults and children, have never been found in milk; but since epidemics 

 have been traced to water, the possibility of the occasional presence 

 of these bacilli in milk cannot absolutely be denied. 



Bacillus Diphtherias . The Bacillus diphtherise has been occasionally 

 found in milk, and a number of small epidemics of diphtheritis 

 have been traced to the milk supply. Dean and Todd found a case 

 of particular interest in which 4 persons were infected by the milk of 

 a certain cow suffering from teat ulcerations which contained diph- 

 theria bacilli. The ulcerations, however, were not due to the diphtheria 

 bacilli which were present in the open sores only as an accidental 

 contamination. Trask, in analyzing the literature, found 23 diph- 

 theria epidemics due to milk, 15 in the United States and 8 in Great 

 Britain. Such milk epidemics usually show a sudden, almost explosive 

 onset, because the infected milk imparts the disease simultaneously 

 to a number of persons. Milk is a favorable culture medium for the 

 Bacillus diphtheriae, which is introduced into it through coughing, 

 sneezing, or otherwise, by persons engaged in collecting and handling 

 milk, who have more or less recently passed through a severe, light, 

 or entirely masked and undiagnosticated attack of the disease, and 

 who still harbor the bacilli in the pharynx. Several milkborne diph- 

 theria outbreaks in California have been reported by Ward. 



Scarlet Fever. Scarlet fever outbreaks, according to Trask, have 

 been traced to milk 51 times. As the cause of scarlet fever is still 

 unknown the statements as to milkborne epidemics are not very 

 trustworthy, and it must be remembered that the virus may be spread 

 by those who deliver the milk and in whom the affection may be so 

 mild as not to be recognized as scarlet fever. Typical cases in children, 

 for instance, not infrequently lead to sore throats in adults, and the 

 latter, in whom the infection is not recognized, may spread the 

 typical disease to others. The author has encountered such a case of 

 masked scarlatina in a nurse who spread the disease to several persons. 

 The true state of affairs, so far as the nurse herself was concerned, 

 was only accidentally discovered by a complement deviation test. 1 

 Scarlet fever is, of course, not a disease of cattle, and McFadyean's 

 experiments to produce the affection experimentally in calves were all 

 negative. 



1 For complement fixation test see Chapter VII. This is the test used to discover latent 

 syphilis in persons (Wassermann test), and it is sometimes also positive in scarlet fever. 



