DISEASES CAUSED BY INFECTED MILK 121 



infected with diphtheria bacilli from eruptive diseases of 

 the udder. It is quite possible that open wounds upon cows 

 may become infected with the diphtheria micro-organism 

 and thus contaminate the milk. 



Dean and Todd isolated the diphtheria bacillus from 

 ulcers of the teats and udders of a cow which presumably 

 became infected from the throat of the milker, who was 

 shown to have diphtheria. Such instances are rare. When 

 diphtheria is found in milk it is practically always of hu- 

 man origin. 



The diphtheria bacillus has actually been isolated from 

 market milk by Bowhill, Eyre, Klein, and Dean and Todd. 



Bacillus-carrying is exceedingly common in diphtheria. 

 About one per cent of the population at large have micro- 

 organisms resembling the diphtheria bacillus in their 

 throats. Convalescents from diphtheria frequently con- 

 tinue to carry the diphtheria bacillus in the secretions 

 of the nose and throat for months after the attack of the dis- 

 ease. Persons who come in contact with diphtheria pa- 

 tients are very apt to become bacillus carriers without 

 actually having the disease. Further, many cases of diph- 

 theria are exceedingly mild and resemble a transient sore 

 throat, so that they escape detection unless a careful bac- 

 teriological examination is made. It is these mild cases 

 and the bacillus carriers that have been responsible for the 

 great majority of instances in which milk has spread diph- 

 theria. Bacillus-cariying in diphtheria is, then, even more 

 common and quite as insidious as it is in typhoid fever. 

 Even certified milk has on one occasion become contam- 

 inated in this way. 



Trask collected twenty-three epidemics of diphtheria 

 reported as spread by milk between the years 1895 and 

 1909. Fifteen of these occurred in the United States and 

 eight in Great Britain. In eighteen of these epidemics, 

 cases of the disease were traced to the dairy farm or the 

 distributing dairy or milkshop. In four of the epidemics dis- 



