PURDUE UNIVERSITY
Agricultural Experiment Station

Circular No. 60
LaFayette, Ind., March, 1917
TUBERCULOSIS
R. A. Craig	C. H. Clink
Tuberculosis is an infectious disease of man and domestic animals. The domestic animals commonly affected are cattle and hogs. Tuberculosis is the most widely distributed of germ diseases, and its great economic importance makes it very necessary for stockmen to have a better understanding of methods of controlling this disease.
Occurrence;.—The percentage of tuberculosis in cattle and hogs slaughtered in federal inspected abattoirs has steadily increased during the past few years. This condition shows that the disease is on the increase in the United States. Although no accurate data are available it is estimated that n per cent, of all dairy cattle in Indiana is affected with tuberculosis.
The organism causing the disease in cattle, birds and man shows slightly different characteristics that can be distinguished under laboratory methods. These distinguishing characteristics consist in differences in form as seen under the microscope and growth on cultural media. It has been shown, however, that the bovine type may infect man and that the human and avian types may be* used in producing immunity in cattle; hence many investigators contend that the tubercle bacillus changes its form and cultural characteristics when infecting different species.
Table I.—Animals Slaughtered at Federal Inspected Abattoirs
during 1915	_
Cattle	Calves	Swine	Sheep ■ Goats
Total number
inspected	6,964,402	1,735,902	36,247,958	12,909,089	165,533
Number carcasses wholly condemned	61,279	5,975	328,667	18,298	657
Number wholly condemned on account tuberculosis	32,644	440	66,023	6
Number carcasses
partly condemned 178,409	1,750	464,217	298	14
Number partly condemned on account tuberculosis	48,401__ 331	439,915 ________________