THE MILK SITUATION IN THE DISTRICT OF COLUMBIA. 61 



were tested, of which 162 gave indications of tuberculosis and 39 were 

 held as suspicious, a percentage of 18.27 of all animals inspected 

 being shown thereby to be affected to a greater or less degree with 

 tuberculosis. 



During the same period the application of the test to 289 head of 

 cattle in Maryland resulted in 48 reactions and 6 suspects, with a 

 consequent percentage of 15.74. 



It is conspicuously noteworthy that during the same interval there 

 were retested in Virginia 966 animals, of which 923 passed examina- 

 tion, only 39 reacted, and 4 were held for further examination, mak- 

 ing a percentage on the retest of 4.45, which result contrasts strongly 

 with the percentage of 18.27 reactors and suspects among cattle sub- 

 jected in the first instance to the test. 



A similarly remarkable improvement in the conditions of the herds, 

 so far as infection with tuberculosis is concerned, was evidenced in 

 Maryland, when on retest 301 animals successfully withstood the test, 

 while only 5 reacted and 3 cases were suspicious, making a percentage, 

 including those reacting and suspected, of 2.58, a marked reduction 

 from the percentage of 15.74 shown in the original test. 



A retest of cattle in the District, embracing 455 individuals, showed 

 423 to be free from tuberculosis, 31 reacting, and 1 suspect, evidencing 

 a very gratifying reduction in the percentage to 7.03. 



These examinations have demonstrated beyond question the feasi- 

 bility of eliminating tuberculosis from existing herds at the con- 

 clusion of not more than three or four tests. Frequently a herd has 

 been found to be clear of tuberculous infection on a second test. 



Aside from the efficacy of the test in eliminating diseased cattle 

 from the herds, the same examination gave convincing evidence of 

 the remarkable accuracy and reliability of the application of tuber- 

 culin in indicating infection with tubercle bacilli. In the tests made 

 in the District of Columbia tuberculosis was demonstrated in cattle 

 which reacted in something over 98 per cent of the cases, and in 

 examinations of 126 cattle in and near the city of Washington tuber- 

 cular lesions were found in 99.21 per cent of the cases which reacted, 

 showing an error of but seventy-nine hundredths of 1 per cent. 



RESULTS OF TESTS THROUGHOUT THE UNITED STATES. 



By consulting a statement prepared by the Bureau of Animal 

 Industry, giving the results of the tuberculin testing of cattle by 

 State and Federal officers, we find that between 1893 and 1908 there 

 were tested 400,008 cattle in all parts of the United States. Of this 

 vast number 37,000 head reacted to the test, yielding a percentage 

 of 9.25 of all cattle tested. Of the number reacting, 24,784 were 

 slaughtered under inspection, and upon post-mortem examination 

 24,387, or 98.39 per cent, of these were shown to be infected with 

 bovine tubercle bacilli. 



At the Bethesda Experiment Station of the Department of Agri- 

 culture a number of District herds, apparently in the best of health 

 so far as evidenced by physical examination, were subjected to the 

 tuberculin test, and 40 per cent of these animals reacted. The react- 

 ing animals were shown to be intermittently expelling tubercle 

 bacilli, and, since the commonest mode of expulsion of the bacilli 

 from the body of the cow is with her feces, the very general contami- 



