230 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



The total number of cattle in Virginia and Maryland tested during 

 the fiscal year was 6,174, which was an increase of 3,456 over the 

 nundior tested during the previous year. Of this total, 5,555 passed, 

 578 reacted, and 41 were regarded as suspicious, making a general 

 percentage of reactors and suspects of 10.02. 



Post-mortem examination of the carcasses of reactors that were 

 slaughtered under bureau supervision showed 80.16 per cent to be 

 alTected with localized tuberculosis, while 18.11 per cent showed gen- 

 eralized lesions, and lesions were not found in 1.73 per cent. 



ERADICATION OF BOVINE TUBERCULOSIS IN THE DISTRICT OF COLUMBIA. 



The work of eradicating tuberculosis from the District of Columbia, 

 which was undertaken in the fall of 1909 in cooperation with the 

 Commissioners of the District, was continued throughout the fiscal 

 year 1911 by the systematic retesting, at intervals of approximately 

 six months, of all cattle which had been upon premises found to have 

 been infected at the time of the first test, and the retesting of all other 

 cattle in the District after an interval of one year. These latter 

 retests are not yet completed. The tuberculin test was also applied 

 to all cattle entering the District of Columbia for purposes other than 

 immediate slaughter. A considerable number of persons who were 

 cattle owners at the time the order of the Commissioners became 

 elTective have since ceased to keep cattle, thus reducing the number 

 of premises, although the total number of cattle within the District 

 of Columbia has undergone but slight variation. 



Cattle w^ere found on 80 of the previously infected premises, and 

 the retesting disclosed infection on only 12 of these premises, thus 

 showing a reduction of 85 per cent in the number of infected premises 

 since the original tests. The number of cattle retested on previously 

 infected premises was 798, of which 764 passed, and 34 or 4.26 per 

 cent reacted. All of these reactors have been slaughtered, and in 

 every instance post-mortem examination show^ed lesions of tubercu- 

 losis. These lesions were found to be localized in 85.29 per cent of 

 the carcasses and generalized in 14.71 per cent. 



Annual retests were applied to 484 cattle upon 278 premises which 

 appeared to be free from infection at the time of the first test. Of 

 these 477 passed, and 7 reactors were found. Seven, or 2.52 per cent, 

 of newly infected premises were thus discovered by these retests, 

 representing 1.45 per cent of tuberculous cattle. The 7 reactors were 

 slaughtered, and in each instance showed localized lesions of tuber- 

 culosis of such a character that it was evident that the disease had 

 been contracted since the original testing of these animals. 



The combination of the results of the retests of cattle within the 

 District upon previously infected and u])on previously free premises 

 shows that 1,282 cattle were retested upon 358 premises. Of these 

 1,241 passed and 41 reacted, the percentage of reactors being 3.20, 

 with signs of infection showing upon 5.31 per cent of the premises. 

 Forty of the reactors have been slaughtered, and tuberculosis was 

 demonstrated upon post-mortem examination in each instance, 87.5 

 per cent of the carcasses showing localized lesions and 12.5 per cent 

 showing generalized lesions. 



An important feature for the control of tuberculosis w^ithin any 

 definite area is the prevention of the introduction of additional cases 



