INFECTIOUS DISEASES OF CATTLE. 399 



Europe ami Russia, in Sicily and Iceland, and in Algiers it is said to 

 be quite rare. In most countries an effort is now being made to deter- 

 mine more accurately the prevalence of this disease. Some very valu- 

 able tables have been published by the German Government for the 

 year extending from October, 1888, to October, 1889. We learn from 

 this that of 1,270,004 animals killed for beef in public abattoirs 26,332, 

 or about 2 per cent, were tuberculous. 



In France, according to figures given by Arloing, there are, on the 

 average, 5 animals tuberculous in every 1,000, or about one-half per cent. 

 In the various cities of France the figures obtained by inspectors at the 

 abattoirs vary from 1.43 to 14.5 per 1,000, the observation extending 

 over a period of one to five years. In Belgium, according to Van Hert- 

 sen, the rate is 4 per cent. In Holland it varies from 4 to 19.6 per 

 1,000. In England, according to Cope, it varies from 1 to 26 per cent, 

 according to the locality. At Copenhagen, according to Bang, during 

 1888, the rate was 6 per cent; for cows alone it rose to 16 per cent. In 

 the Argentine Republic, according to Even, tuberculosis seems to attack 

 the recently imported improved stock (10 to 15 per cent), while it is 

 comparatively rare among natives (one-half per cent). 



In our own country cattle (mostly milch cows) slaughtered at Balti- 

 more under the auspices of this Bureau several years ago were found 

 tuberculous to the extent of 24 to 3 per cent. Among 2,273,547 head 

 of cattle, chiefly steers, slaughtered for beef in the various meat in- 

 spection districts of the United States from May 15, 1891, to March 1, 

 1892, only 492 or .02 per cent were found tuberculous. For the year 

 ending December 31, 1889, there were found in the same districts among 

 54,158 cows 669 cases of tuberculosis, or 1.23 per cent. 



It is not far from the truth to assume from these statistics that one 

 of every fifty head of cattle in the more densely populated areas of 

 Europe and America is tuberculous. When we consider the age and 

 sex of the affected animals some striking differences are observed. 

 According to the German report the statistics of a large number of 

 abattoirs showed that 0.9 per cent of the cows, 3.6 per cent of the oxen, 

 2.6 per cent of the bulls, and not quite 1 per cent of the calves and 

 yearlings were tuberculous. It has also been observed that tuberculosis 

 increases in frequency with the age of the animals. If we take the 

 number of cases of animals of a year and under affected with tubercu- 

 losis as the unit of comparison, animals from one to three years old 

 furnish ten times, those three to six years old thirty times, and those 

 over six years forty times the number of cases. 



The cause of this disease may be considered as twofold, the tubercle 

 bacillus first and foremost, without which this disease could never 

 develop, and en-tain predisposing causes which prepare the way for it. 

 First, as to the way sin which tubercle bacilli find their way into the body. 

 These in the order of their importance may be considered under four 

 heads: (1) By inhalation into the lungs; (2) into the digestive tract in 



