THE MILK SITUATION IN THE DISTRICT OF COLUMBIA. 55 



Y. THE TUBERCULIN TEST. 



EXTENT OF TUBERCULOSIS AMONG HUMANS. 



Tuberculosis is responsible, in one form or another, for an astound- 

 ing percentage of the deaths occurring annually throughout the United 

 States. Statistics show that 14 out of every 100 persons who die 

 in this country are affected to a greater or less degree with tubercu- 

 losis, and that throughout the entire country over 11 per cent of all 

 deaths primarily result from this disease. 1 It may be assumed that 

 probably many other deaths are additionally due to tuberculosis, 

 though erroneously assigned to other causes. We may reliably esti- 

 mate, therefore, that at least one-seventh of the aggregate number of 

 persons dying in the United States are infected with tuberculosis. 

 It is safe to assume, moreover, that in a very considerable number of 

 these instances tubercular lesions exist without possible detection by 

 means of clinical examination. 



It is noteworthy in this connection that autopsies indicate that few 

 human beings entirely escape tubercular infection, though this infec- 

 tion is, in a majority of cases, so relatively unimportant that many 

 persons are not conscious during their lives of being so infected. 

 Post-mortem examinations by three European investigators of 1,452 

 and of 500 and 100 bodies, respectively, of persons who died from 

 various causes, showed among this total of 2,052 bodies that not less 

 than 91 per cent contained lesions of tuberculosis. 



Since, furthermore, tuberculosis is obviously responsible for the 

 death of cattle in large numbers, being beyond all measure the most 

 destructive malady affecting beast and man, every known safeguard 

 should be interposed to arrest the progress of this dread disease and 

 to finally accomplish its extermination. 



A compilation of statistics of investigators embracing 1,734 sam- 

 ples of milk examined in recent years deduces the fact that 11.3 per 

 cent of the samples examined were found to contain tubercle bacilli. 



It has been asserted by Dr. E. C. Schroeder, superintendent of the 

 Bethesda Station of the Bureau of Animal Industry, and one of the 

 foremost authorities in the world on the subject of bovine tubercu- 

 losis, that fully 1 sample among every 12 of milk sold throughout the 

 country by dairies contains living, virulent tubercle bacilli, which 

 conclusion is based on four of the most recent and reliable investiga- 

 tions on the subject. 



In his summary of our information on the subject he adverts to 

 the fact that tuberculosis is the commonest disease of human beings 

 and dairy cows; that tuberculous cows expel tubercle bacilli long 

 before they show signs of their diseased condition; that milk is so 

 often infected with virulent bacilli that, unless we know it to be 

 derived from cows that are certainly free from tuberculosis, it is not 

 safe to use it in the raw state ; that tubercle bacilli in milk are trans- 

 ferred to cream, butter, and cheese made from it, and may occur in 

 these products in greater concentration than in the milk from which 

 they were derived ; that the available evidence regarding the differ- 

 ent types of tubercle bacilli shows that bacilli of bovine types have 

 been found in human lesions and human types in bovine lesions, and 



i Census report for 1900. 



