TYPHOID FEVER 111 



accident is necessary to afford an indirect or direct 

 means of carrying typhoid bacilli into the water or milk. 



The typhoid bacillus can multiply rapidly in milk 

 and greatly increase in number in the course of a short 

 time, it resists the commencement of acid formation but 

 its growth is checked and, later, it is killed by great 

 acidity; yet it is not certainly killed by the degree of 

 scouring to which cream is subjected before churning. 

 Bolley and Field have found that typhoid bacilli will 

 live at least ten days in butter [and Brack has shown 

 that they were virulent after 27 days]. Hence, not only 

 milk and cream but also buttermilk (epidemic in Ham- 

 burg; Frankel and Koster), newly made butter and 

 fresh cheese may be bearers of virulent typhoid bacilli. 

 The typhoid bacillus is destroyed by pasteurization at 

 80 C. (176 F.) and heating for a few minutes at 70 

 to 75 C. (158 to 167 F.) will kill it. Care must be 

 taken to heat the whole volume of milk to this tem- 

 perature. (See "Pasteurization.") 



In pure culture, the typhoid bacillus does not change 

 the appearance of milk and alters its reaction but little. 

 It is very difficult to detect it in milk, as it is in drinking 

 water, for its colonies in gelatin are very similar to 

 those of the colon bacilli. To detect it, the milk must be 

 sown in the usual method in gelatin plates and then as 

 great a number as possible of suspicious colonies iso- 

 lated. These are then implanted in fermentation bulbs 

 in bouillon, some of which contain grape sugar and some 

 sugar of milk. Those forms which cause an acid reac- 

 tion in the milk sugar bouillon or those which ferment 

 the grape sugar with the formation of gas or which do 

 not change the reaction of the grape sugar bouillon are 

 to be rejected. Only those cultures which give a strong 

 acid reaction without producing gas in the grape sugar 

 bouillon, are really suspicious and these must be sub- 



