74 CONFERENCE ON MILK PROBLEMS 



milk is a commoner carrier of infection than clean milk, be- 

 cause the conditions that enable other foreign substances to 

 find their way into milk also expose it more seriously to the in- 

 troduction of specific infectious materials ; but, on the other 

 hand, the otherwise cleanest and best milk may be infected with 

 specific agents of disease, and infected milk of the otherwise 

 most satisfactory character is more dangerous than nonin- 

 fected milk that contains an objectionable amount of dirt and 

 bacteria. 



The introduction of infectious materials into milk from 

 the bodies of diseased cows is a danger that can be checked to 

 a great extent by careful inspection, including the application 

 of the tuberculin test to eliminate tuberculosis. But, if in- 

 spection and tuberculin test are really sufficient, I am strongly 

 inclined to believe that this is due more to the fact that rela- 

 tively few diseases of cattle are transmissible to man than to a 

 thoroughly effective exclusion from milk of the specific agents 

 that cause disease among cattle. In animals and human beings 

 alike, we must remember that diagnosis, the recognition of 

 the dangerous character of a disease, more commonly follows 

 than precedes the period at which the dissemination of in- 

 fectious materials begins. 



When we come to the infection of milk, by human beings, 

 with germs to which the human body is certainly susceptible, 

 we have really reached the most complex question with which 

 the fight for pure milk must deal. The protection of milk 

 against infection through those persons who are visibly af- 

 fected with communicable diseases presents no insurmount- 

 able difficulty, as they are usually quarantined under the su- 

 pervision of health officers whose duty it is to protect the 

 public health. But what about chronic disseminators of dis- 

 ease germs? How about persons whose natural resistance to 

 infection does not reach actual immunity, but is great enough 

 to enable them to pass through disease without showing suf- 

 ficiently marked symptoms to make a diagnosis possible; that 

 is, persons actually afflicted with communicable disease but who 

 are looked upon as being merely a little indisposed? How 

 about persons who continue to work during the early stages 

 of an infectious disease before a diagnosis has been made; or 

 persons who, aftr** exposure to such infected persons among 



