130 TUBERCULOSIS 



hogs similarly inspected, 5,440 were sufficiently affected to 

 cause a condemnation of some part of the carcass. This is 

 equal to 0.023 per cent, or slightly more than one-fifth the 

 proportion found in beef cattle." 



" The slaughter house statistics of all countries show that 

 the percentage of affected hogs increases as the disease be- 

 comes more common in cattle, so that we must consider not 

 only the effect of the disease upon beef and milk producing 

 animals, but also upon swine. Tuberculosis is more acute 

 with hogs than with cattle, and there is a much greater ten- 

 dency to generalization, consequently the parts used for 

 human food are more likely to be affected, and if there is a 

 possibility to communicate the virus through the meat the 

 danger is increased by this peculiarity of the disease in swine." 



§ 108. Geographical distribution. Tuberculosis is an 

 exceedingly wide spread disease. In earlier times it was quite 

 prevalent among cattle in central Europe. It seems to have 

 existed in Western Asia and Northern Africa at an early date. 

 From these centers it has spread to nearly every cattle raising 

 country of the world. Its rapid spread during the last fifty 

 years is attributed to the increase in cattle exchange resulting 

 in the introduction of tuberculous animals into healthy herds. 

 It is stated that in many countries, and in large districts with- 

 in others, tuberculosis did not exist until it was introduced 

 within recent years by the importation of diseased animals. 



In countries where there has been little or no importation 

 of cattle, and in which the native breeds still exist unchanged, 

 as in many parts of Russia, Austria and Spain, in the north- 

 ern part of Sweden and Norway, and in parts of Africa, 

 tuberculosis is practically unknown. This is true of the cattle 

 on the island of Jersey where for more than a hundred years 

 foreign cattle have not been introduced. 



In the United States the disease is very widely distributed. 

 It is found to a considerable extent in certain localities where 

 the climatic conditions seem to be beneficial for tuberculous 

 people. The explanation for this seems to be that tuberculous 

 animals have been introduced into certain herds in these dis- 

 tricts. There are, however, large areas in which it is practi- 



