278 TUBERCULOSIS. 



Inasmuch as flesh is rarely the seat of the tubercular infection, and 

 accidental contamination with the butcher's knife will be on its 

 surface, cooking will almost always render it harmless, unless the 

 infection is deep-seated. For these reasons the flesh of animals 

 slightly infected with this disease need not be condemned as food. 

 It is universally admitted that the actual danger from this source is 

 very small and perhaps does not exist at all. 



Milk. The problem of the use of milk from tuberculous 

 animals is a more difficult one to settle. The milk of tuberculous 

 cattle does not always contain the bacilli and it is an unsettled question 

 whether it will ever contain them unless the disease be located in the 

 udder. At all events, cows having tuberculous udders (some- 

 where about i per cent.) will produce milk infected with tubercu- 

 losis bacilli. That these bacilli are active and vigorous is proved 

 by thousands of experiments which have shown that such milk 

 is capable of producing tuberculosis in guinea-pigs. It is true 

 that the bacilli do not multiply in milk, but milk from one cow 

 can, by being mixed with other milk, infect a large amount. It 

 is possible that such milk may be a danger to the public health. 

 It has been abundantly shown that market milk frequently contains 

 tubercle bacilli in sufficient quantity to produce an infection in 

 guinea-pigs, and the same is true of market butter. All of these 

 facts certainly indicate a possible danger to the public from this 

 source. 



In regard to the extent of this danger there has been a wide 

 difference of opinion. It has certainly been magnified by some. 

 The danger is, beyond question, frequently overdrawn. It is 

 sometimes doubted that mankind can ever acquire tuberculosis 

 from this source. Experiment has shown that large numbers of 

 the bacilli must be swallowed at once to produce infection even in 

 susceptible animals. The number of bacilli which a person will 

 swallow with a drink of milk will commonly be rather small, and 

 the human individual has a considerable power of resistance 

 against the disease. It is a further fact that, although bovine 

 tuberculosis has been increasing, human tuberculosis has been con- 

 stantly declining in recent years, and the decline has been equally 



