122 MILK BACTERIA AND HEALTH. 



Gastritis has been attributed to milk. One or two cases of 

 epizootic have been thus located, and at least one epidemic 

 of foot-and-mouth disease has been traced to milk of infected 

 cattle. All of these diseases are, moreover, quite rare and do 

 not, except under special circumstances, enter into the prob- 

 lems that arise in connection with the use of milk. Asiatic 

 cholera has also been shown to be capable of distribution by 

 this source. Instances are excessively rare, however, and 

 most cholera epidemics are traceable to the water supply. 



METHOD OF DETECTION OF MILK EPIDEMICS. 



With the exception of tuberculosis the other definite dis- 

 eases known to be associated with milk usually make their 

 appearance in the form of epidemics, and these epidemics, 

 by a careful investigation, can, in most cases, be followed 

 to their source. It is usually not difficult to trace a " milk 

 epidemic " of a contagious disease. The general character- 

 istics of an epidemic of typhoid, scarlet fever or diphtheria, 

 due to milk, are as follows: They are usually somewhat 

 violent and rapid, a number of cases appearing almost simul- 

 taneously or within a few days of each other. They are also 

 commonly quite fleeting, for, after a week or two, the cases 

 cease to develop and the subsequent history of the epidemic 

 is only one of recovery of the patients, with some cases of 

 secondary contagion. The violence of these epidemics varies 

 with conditions. Sometimes there may be only a small num- 

 ber of cases due to the milk supply, not over eight or ten, 

 and in other cases the number may run up to several hun- 

 dreds, all appearing within a very short time, many of which 

 are so far isolated from each other that no explanation of 

 direct contagion from case 'to case can be given. 



Since these epidemics are so violent and usually so defi- 

 nitely located, it is commonly not difficult to detect their cause. 

 If they are really due to milk it requires only a bit of careful 

 detective .work to trace them to their source. This, how- 



