138 ANNUAL REPORT OF THE Off. Doc. 



It is unnecessary to quote further statistics on this point. The 

 extent of intestinal tuberculosis varies in diiferent countries and in 

 different paris of the same country — a fact which of itself indicates 

 a local factor, such as the greater or less prevalence of tuberculosis 

 in cattle. One cannot study such statistics as those given without 

 being fully convinced that a very important proportloii of the children 

 who die of tuberculosis are infected through their food, and that 

 the report made to the council of the British Medical Association 

 was justified, namely, that "the mortality- from tuberculosis in early 

 childhood is not decreasing as it is at other ages in the United King- 

 dom; and the opinion that this great prevalence of the disease in 

 childhood is due to infection through the alimentary canal by milk 

 from tuberculous cows appears to be well founded." 



Extent of Tuheradosis in Cattle. — It is well known and so univer- 

 sally acknowledged that tuberculosis is a wide-spread scourge in 

 cattle that it would be superfluous to give an array of figures show- 

 ing the extent of its ravages in various countries. Those interested 

 in this phase of the subject will find the latest statistics given by Dr. 

 Leonard Pearson, m Bulletin No. 75, issued by the Commonwealth 

 of Pennsylvania, Department of Agriculture. In studying such sta- 

 tistics it must be borne in mind that it is in the milch cow, and es- 

 pecially the cow on the dairy farms near large cities, that is most 

 apt to fall a victim to tuberculosis. In Pennsylvania, Dr. Pearson 

 has found that of the tubercular herds tested about 13 per cent, of 

 the animals had tuberculosis. Some herds show a very high pro- 

 portion of diseased animals. Thus, for example: 



Among 174 cattle 166 were tubercular. 



73 cattle 59 were tubercular. 



22 cattle, 17 were tubercular. 



14. cattle, 14 were tubercular. 



20 cattle 20 were tubercular. 



59 cattle 53 were tubercular. 



In other parts of the State tuberculosis is very rare or even un- 

 known. These places are found in the interior counties, where the 

 stock is "native" for the most part, or were stocked at a time when 

 bovine tuberculosis was very little known in the United States. 



There has been and is considerable discussion as to the stage of 

 the disease at which a tuberculous cow becomes dangerous through 

 the passage of tubercle bacilli into her milk. Some authorities hold 

 that there must be actual disease of the udder for this to occur, while 

 others believe that this is not necessary. As early as 1893 Dr. Theo- 

 bald Smith showed that the tubercle bacillus may be found in the 

 milk of tuberculous cows when the udder, so far as the naked eye 

 could tell, was free from disease. In a series of experiments at the 

 laboratory of the State Live Stock Sanitary Board of Pennsylvania 



