IXFECTIOX BY MILK 71 



a. Tuberculosis. During recent years quite reliable 

 information has been obtained concerning the preva- 

 lence of tuberculosis in cattle, partly from the abattoirs 

 and partly from the use of the tuberculin test. 



The abattoir statistics of Denmark show differences 

 in the prevalence of this disease. In Copenhagen, 30 per 

 cent, of the mature cattle are affected ; the .same is true in 

 Odense, while Arrlius reports a greater percentage. 



In conse(|uence of the results obtained from the 

 tuberculin test, Bang regards it as probable that in Den- 

 mark half of the small herds of from 1 to 9 members are 

 free from tuberculosis, but only a fourth of the herds of 

 medium size of from 10 to 49 animals are free, and of 

 tlic large herds only a few are exempt. Concerning the 

 proportions in certain herds, the most of the animals 

 may be healtliy and tuberculosis limited to a few individ- 

 uals, but usually the disease is more widely distriljuted 

 and, in large lierds, often from 80 to 90 i)er cent., or even 

 a larger number are affected. 



The conditions in neighboring cduntries are about 

 the same. Tuberculosis of cattle, for example, is 

 scarcely less extended in Sweden, North (icrmany, 

 Belgium and England than in Denmark, while it is less 

 frequent in Norway and South Germany. [This disease 

 is also i)revalent in certain i)arts of America, especially 

 in the leading dairy sections of the Eastern United 

 States.] 



The localization of tuberculosis in the udder is of 

 especial interest in connection with milk control, since, 

 when this condition is present, milk is always contam- 

 inated with tubercle bacilli. But in certain other forms, 

 as uterine and intestinal tuberculosis, great quantities of 

 bacilli are eliminated with the discharges and the excre- 

 tions that soil the hind quarters, so these forms may 

 easilv lie the indirect cause of infection of the milk. This 



