TYPHOID 17 1 



the earlier investigators owing to the almost constant 

 presence in the waters of other organisms so closely resem- 

 bling the typhoid bacillus that their differentiation is a 

 matter of great difficulty. The organism which has given 

 rise to much confusion is the Bacillus coli coTnmunis. This 

 bacillus is a constant inhabitant of the intestinal tract and 

 the faeces of both man and animals, and therefore is almost 

 invariably found in all polluted waters. 



In order to ascertain whether the typhoid bacillus is 

 present in any given water, care must be taken that the -B. 

 coli coTnmunis is not mistaken for the former. This is a 

 very difficult matter, as the vitality of the B. coli communis 

 is much greater under all conditions than that of the 

 typhoid bacillus. The object is generally sought to be 

 attained by the addition of various chemical substances to 

 the nutrient media, which effectually inhibit or destroy the 

 growth of organisms other than the colon' and typhoid 

 baciUi. As pointed out by Frankland, such additions have 

 frequently destroyed the typhoid bacillus and left the B. 

 coli communis, owing to its greater power of resistance, 

 alone, master of the field. For the methods employed to 

 isolate the typhoid bacillus, see under The Examination of 

 Water. 



According to some authorities, notably Messrs. Koux 

 and Rodet, there is reason to believe that the B. coli 

 communis, under certain conditions, such as growth in 

 sewage, etc., assumes a pathogenic character, and gives rise 

 to a disease which is clinically undistinguishable from 

 enteric fever. This view is borne out to a great extent by 

 the apparent fact that water contaminated with faecal matter 

 may be instrumental in causing typhoid fever without the 

 recognition of the specific bacillus, as cases are on record 

 where water long known to be polluted has acquired the 

 property of conveying typhoid without the previous known 



