122 PRINCIPLES AND PRACTICE OF MILK HYGIENE 



become chronic bacilli carriers. The bacilli may also be 

 carried by flies and be blown about in dust. 



The typhoid bacillus multiplies rapidly in milk and 

 the number may be greatly increased in a short time. The 

 milk is not changed in appearance. The organism grows 

 in slightly sour milk; it is checked or destroyed by a high 

 degree of acidity, but it survives the degree of acidity 

 existing in cream ripe for churning. It may live in milk 

 several days and may be present in fresh butter and new 

 cheese. Bruck found virulent bacilli in butter after 

 twenty-seven days. Typhoid bacilli in milk are destroyed 

 when exposed to a temperature of 60 C. (140 F.) for 

 two minutes (Rosenau). 



When an outbreak of typhoid fever occurs which has 

 the characteristics of a milk-borne epidemic, the sus- 

 pected milk supply should be stopped, or pasteurized 

 under supervision, and an investigation made with the 

 object of discovering and abolishing the source of the 

 infection of the milk. Immediate medical attention to 

 cases of illness affecting the dairyman, his employees, or 

 members of their households, proper supervision of cases 

 of typhoid fever by health authorities, the sterilization of 

 milk bottles before refilling, and a pure water supply will 

 greatly reduce the liability of the occurrence of such epi- 

 demics. There is no method known which is entirely 

 satisfactory in preventing the direct infection of milk by 

 walking typhoid cases or by chronic bacilli carriers. 

 Recently, some local health authorities have required that 

 blood samples be taken from dairy employees and sub- 

 mitted to the Widal test as a safeguard against chronic 

 bacilli carriers ; a few high-class dairies have been follow- 

 ing this plan for some time. Several states have laws 

 requiring dairymen to report to the local health author- 



