NEW YORK MILK COMMITTEE 75 



their friends or in their families, continue to come in contact 

 with milk? And how about convalescents and those who are 

 associated with convalescents, when we know that the reason 

 for terminating a quarantine is oftener a question of time than 

 a specific determination that the convalescent and his associ- 

 ates are safe persons to be at large? 



To ask these questions is not sounding an unnecessary 

 alarm because hundreds of epidemics have been traced directly 

 to infected milk, and because it is a noteworthy fact, a fact 

 that is constantly becoming more impressive wherever epidem- 

 ics are traced to their sources, that immediate personal con- 

 tact and the use of raw, infected milk are very conspicuous 

 among the causes about which definite statements can be made 

 and on w^hich the propagation of infectious diseases depends. 



The long continued, chronic dissemination of disease germs 

 by seemingly normal persons is a subject about which our 

 knowledge is very meagre. We have some reasons for be- 

 lieving that such persons are dangerous intermittently rather 

 than continuously, and if this is true, even a careful exami- 

 nation of all persons engaged in the dairy business will not 

 safeguard milk against periodic infection. If there is a cor- 

 rective measure that can be used against this danger, other 

 than its counteraction by pasteurization, I must confess that I 

 have not been able to see it. 



As to persons whose resistance to an infectious disease is 

 not sufficient to protect them wholly, though it is great enough 

 to prevent them from becoming more than slightly ill, we have, 

 so far as the infection of milk is concerned, a very similar prob- 

 lem to that presented by the chronic bearer of disease germs. 

 That such persons must be common no one can doubt who 

 has observed the enormous difference in the severity with which 

 different persons are attacked by the same disease during a 

 single epidemic. Every physician knows that the resistance of 

 individuals exposed to an epidemic ranges from absolute im- 

 munity to a fatally high degree of susceptibility. 



Between absolute immunity and a degree of susceptibility 

 which permits the development of only a barely diagnosable 

 affection, we no doubt have disease invaded individuals who 

 serve as dangerous disseminators of that infectious material 

 which enters human bodies from undiscoverable, mysterious 



