MILK-BORNE INFECTIONS 457 



six months' test, annual tests should thereafter be made. All 

 reacting animals should at once be separated from the new herd 

 and the stables which they have occupied thoroughly disin- 

 fected. 



"4. The milk from reacting animals may be pasteurized and 

 used. 



"5. Any reacting animal which develops clinical symptoms of 

 tuberculosis should be promptly slaughtered. 



"6. An animal that has once reacted to tuberculin should under 

 no circumstances be placed in the sound herd. 



"7. As soon as the herd has become well established, infected 

 animals should be slaughtered under proper inspection. 



"Group 3. — Herds where a large number (15 to 50 per cent.) 

 of the animals are diseased. The procedure is as follows: 



"Herds that come within this group should be dealt with either 

 as in Group 2, where the herd is separated, or as in Group 1, 

 where all of the animals are considered as suspicious and an 

 entirely new herd developed from the offspring." 



When a stable has been occupied by tuberculous animals it should 

 be disinfected before a sound herd is admitted. Gaseous disinfect- 

 ants are not suitable, since it is difficult to seal a barn tightly 

 enough to prevent leakage of the gas. Milk of lime or, better, milk 

 of lime with 1 pound of chlorid of lime for each 3 gallons, crude 

 carbolic acid, and liquor cresolis compositus, U. S. P., are recom- 

 mended for disinfection. Milk of Ume with chlorid of lime is 

 probably the best all-round disinfectant for a stable, as phenol 

 compounds have a strong odor which may be imparted to the 

 milk. Before disinfection the walls, ceiling, floor, and all fix- 

 tures should be washed. The disinfectant is then sprinkled on 

 all surfaces. Mangers can be washed with a strong solution of 

 copperas. Bedding and other loose material should be burned. 

 The grass in pastures where tuberculous cattle have grazed 

 should be plowed under or burned. 



Immunizing cattle against tuberculosis was first tried out by 

 Koch, while an antitoxin was prepared by Maragliano. Several 

 investigators have followed similar lines of work, with the result 

 that a temporary immunity was established, but none of sufficient 

 duration and intensity to be of practical value. Injection of 

 human bacilli into cattle also produces a limited degree of im- 

 munity. Von Behring's "bovovaccine," an attenuated culture of 

 living tubercle bacilli of the human type, has been tested rather 

 extensively. Experiments with bovovaccine have been carried 

 out by Russell and Hoffmann. The authors conclude that in 

 view of the expense connected with the process, and since only 

 young cattle can be treated, the practical usefulness of the treat- 



