DAIRY, SEED IMPROVEMENT, STOCK BREEDERS' MEETINGS. 201 



Second, when investigated they will always show a striking 

 peculiarity of distribution along certain milk routes confined 

 entirely to milk consumers. 



Third, that primary milk products which are made without 

 processes of heating to a high temperature, as cream, cheese, 

 butter, ice cream, etc., may transmit diseases in exactly the 

 same way as the milk from which they originally came. 



Fourth, another general characteristic of milk borne epidem- 

 ics is the fact that infection may come not infrequently from 

 the original milker to the home in which the milk is finally con- 

 sumed. 



(a) Typhoid. There are many clear cut illustrations of 

 transmission of typhoid by milk. Milk is particularly apt to be 

 infected with typhoid by chronic typhoid carriers engaging in 

 the milk business. Milk may swarm with typhoid fever germs 

 without being altered in the least in taste, odor or appearance. 

 In one instance, near Boston, 410 cases came from infection of 

 milk by one person. It is important to prove that milk is act- 

 ually, not simply apparently, the cause before definitely con- 

 demning the milk supply. Proof means recovering the germs 

 from the human carrier. We have done this twice in relatively 

 small epidemics in the past few months in the laboratory of 

 the State Health Department of Massachusetts. 



(b) Diphtheria. Like typhoid, the fact that diphtheria 

 germs could be transmitted through milk is of comparatively 

 recent recognition. Unlike typhoid, diphtheria bacteria do not 

 grow readily in ordinary milk and correspondingly the number 

 of milk borne diphtheria epidemics would seem to be very much 

 less than those of typhoid fever or even scarlet fever. Diph- 

 theria is a disease more acute than typhoid and better quaran- 

 tined. Widespread use of antitoxin tends to destroy the bacilli 

 in the earlier stages, and also from the fact that this disease 

 is spread by the mouth and nasal passages only, it is not so 

 apt to get on the hands from the mouth as are typhoid bacilli, 

 which are spread through the urine and fecal discharges. 



(c) Scarlet Fever. We do not yet know the exact cause of 

 scarlet fever but know that it is without question a disease 

 spread by a germ or a virus. In all probability the principal 

 channel of infection of scarlet fever is by germs thrown ofif 

 from nose or mouth cavity. It is now held to be rather doubt- 



