DIPHTHERIA. 



lamination is sure, but if the disease is located elsewhere the 

 question cannot be answered. An attempt has been made to 

 determine whether animals that react to tuberculin, but show 

 no visible signs of tuberculosis, are likely to produce milk 

 that contains tubercle bacilli. The results, though somewhat 

 in conflict, indicate that, in the majority of cases, the milk 

 of such animals contains no bacilli. But in some instances 

 the bacilli have been found, and hence, in order to protect 

 market milk absolutely from tuberculosis, it would be neces- 

 sary to exclude from the public dairy herd every animal that 

 reacts to tuberculin. This is quite impossible, and it follows 

 that there is no practical means of protecting market milk 

 absolutely from this contamination. Nevertheless if all 

 tuberculous animals that are suffering from visible udder 

 tuberculosis are excluded from the dairy herd, as well as all 

 cases of advanced, generalized tuberculosis, the danger of 

 contamination of the milk is vastly reduced, and would 

 probably be very slight. 



DIPHTHERIA. 



The cause of diphtheria is a well-known bacterium which 

 is capable of growing readily in milk (Fig. 22). That milk 

 has been a means of distributing this dis- 

 ease has been demonstrated by quite a 

 number of epidemics satisfactorily traced. 

 There have been, in the last twenty years, 

 about a dozen such diphtheria epidemics 

 traced, with more or less definiteness, to B. diphtheria. Sev- 

 milk as its source. The method by eral forms of the ^T 



tenum that causes diph- 



which the milk becomes contaminated 



with the bacilli is possibly twofold. 

 The most common means of contamination is one that 

 occurs subsequently to the milking. A person who is 

 suffering from a mild case of diphtheria, or is recover- 

 ing from such an attack, is allowed to work in the 



