I/O IV MILK BECOMES TYPHOID INFECTED 313 



bility which in part explains the large number of very mild, and often 

 unrecognised, cases of the disease. Unquestionably such cases, as 

 in most other infectious diseases, are potent of mischief in the 

 spread of the complaint. Variability in bacillus {e.g. paratyphoid 

 bacilli) may be the explanation also of conditions simulating typhoid 

 fever, a species of anomalous typhoid, which appears occasionally. 



How milk becomes typhoid infected. — On examination of 

 those milk-borne epidemics of typhoid fever which may be looked 

 upon as fully proved to be thus conveyed, we shall find the modes 

 of infection of the milk to be various. Amongst the most common 

 is watered milk. It is now an axiom that typhoid pollution is most 

 frequently conveyed by water. Water is readily contaminated 

 with typhoid matter. The ways in which infected water finds its 

 way into milk are numerous. It may be added to milk, deliber- 

 ately, in adulteration ; or it may gain access accidentally, as in a 

 case which actually occurred, where some typhoid infected water 

 had been left in the bottom of the churn, and the milk was added 

 without previously emptying the churn. Milk-churns, milk- 

 measures, and other dairying utensils have on more than one 

 occasion been " cleaned " with water to which typhoid excreta had 

 obtained access. Again and again, repeated ad iiauseani, the 

 primary infection has arisen through such unclean dairying. In 

 the remarkable epidemic at Springfield, Massachusetts, it is re- 

 ported that the contents of a privy in which the stools of a patient 

 were deposited were spread over a field in which certain farm 

 labourers were working. Their boots became clogged with this 

 manure, which was thus conveyed to some boards covering the sur- 

 face of a well, and so into the well-water beneath. The milk from 

 the farm was cooled by submerging it in this well. The cans used in 

 this submergence were stoppered by wooden plugs. Around these 

 wooden plugs, it was aftervvards found, in four cans out of nine there 

 was leakage, and in this way the water from the well entered the cans. 



Another frequent mode of infection is that the patient or the 

 nurse of the patient has continued to assist in the dairy work 

 whilst able to convey infection ; or infected clothing is washed 

 at the implicated farm ; ^ or the udders of the cows are washed 



' The interesting researches of Firth and Horrocks into the dissemination 

 of enteric infection by means of fabrics show that the typhoid bacillus may be 

 recovered from khaki drill fabrics 74 days after contamination, from khaki serge 

 after 87 days, and from ordinary blue serge after 78 days. The whole of this 

 research is full of suggestion and throws an important light upon tj'phoid 

 infection generally. See Brit. Med. Jour. ^ 1902, vol. ii., pp. 936-941. 



