90 PRINCIPLES AND PRACTICE OF MILK HYGIENE 



the disease. Findel, Reichenbach and Alexander 19 found 

 that at least 400,000,000 tubercle bacilli are necessary 

 to produce infection when only a single dose is fed to 

 guinea pigs and that 800,000 tubercle bacilli given fifty 

 times by the mouth are not certain to produce infection. 

 Ostermann 20 reports that milk containing 1000 bacilli 

 per c.c. may be repeatedly ingested without effect. 

 Fliigge and his co-workers also found that while a very 

 few tubercle bacilli are sufficient to produce a severe 

 tuberculosis when injected into a guinea pig, 200 are 

 necessary when the bacilli are inhaled and 140,000,000 

 when they are ingested. 



4. How can Contamination of Market Milk with 

 Tubercle Bacilli be Prevented? The information at 

 hand shows that cows with tuberculosis of the udder are 

 by far the greatest factors in infecting market milk with 

 tubercle bacilli and that next in -order are those with ap- 

 parently healthy udders but showing clinical symptoms 

 of the disease in other organs. Compared with these 

 two classes, cows which present no evidence of tubercu- 

 losis except a reaction to the tuberculin test are a rather 

 insignificant source of contamination. 



The contamination of milk with tubercle bacilli can 

 be most thoroughly and most certainly prevented by re- 

 moving from the herds concerned in a milk supply the 

 cows belonging to all three classes. This could only be 

 accomplished by making a tuberculin test and physical 

 examination and repeating them at certain intervals. A 



19 Cited by Ostertag, Zeitschr. fur Fleisch u. Milchhy., p. 

 27, No. 2, vol. xxiii. 



20 Cited by Klimmer, Osterreich. Wochenschr. fiir tierheilk. 

 u. Tierzucht, No. 45, 1912. 



