MILK-BORNE INFECTIONS 479 



among artificially fed than among breast-fed infants, the facts 

 would seem to justify a serious indictment against milk. Still 

 there are other known causes and perhaps unrecognized ones which 

 may contribute to the high death-rate of bottle-fed babies. 



The absence of hydrochloric acid from the stomach of infants 

 permits the passage of bacteria into the digestive tube. The 

 membrane of the alimentary tract of infants is delicate, and it is 

 conceivable that large numbers of bacteria, including varieties 

 usually considered harmless, may cause disturbances. So far no 

 specific organism has been identified as the cause of cholera in- 

 fantum. Schereschewsky (quoting Pietschel, Leifmann and 

 Lindemann, and others) has stated "that the influence of cow's 

 milk in causing summer infant mortality has been overestimated." 

 However, it is important in our present state of knowledge that a 

 good grade of milk, preferably certified milk, be used for infant 

 feeding, and that relative security from infection be assured by 

 the use of boiled or pasteurized milk. A discussion of the relation 

 of milk to gastro-intestinal troubles of infants will be found in a 

 separate chapter. 



There is a distinct relation between infant mortahty and the 

 season of the year. During the colder months — from October to 

 March — the infantile death-rate is relatively low, while with the 

 commencement of spring the number of deaths increases rapidly 

 and reaches the highest point in August. The curve of infantile 

 mortality follows closely the curve of temperature, the curve of 

 bacterial content of milk, and the increase in the number of flies. 



Schereschewsky, who has studied the relation of infant mor- 

 tality to the three factors mentioned, has shown that the mor- 

 tality curve rises within a short time after a period, or even after 

 a single day, of hot weather. He believes that cholera infantum 

 occurs as a seasonal disease rather than in the form of an epidemic, 

 as would be expected were food alone to blame. 



Hot weather is weakening to the system and, therefore, causes 

 a predisposition to infection. Abt agrees that debility is caused 

 by heat, and that the influence of heat is emphasized when it is 

 accompanied by excessive moisture in the atmosphere. Flies 

 become more numerpus in hot weather and may have some con- 

 nection with high infant mortahty. What this connection may 

 be is not understood, but an observation by Armstrong is sug- 

 gestive. He selected two districts in New York City which were 

 similarly located; had approximately the same population, with 

 similar hving conditions; and had about the same number of 

 infants. One of these districts was supplied with screens for doors 

 and windows and the inhabitants were instructed in methods of 

 excluding flies. The other district was left unprotected. It was 



