22 



ELEMENTS OF WATER BACTERIOLOGY 



EFFECT OF TEMPERATURE ON SURVIVAL OF TYPHOID 

 BACTERIA IN WATER 



(Houston, 191 i) 



Ruediger (191 1) has shown that colon bacilli are 

 far more abundant in the Red Lake River during the 

 winter when the river is covered with ice than in sum- 

 mer, although the volume of the river and the amount 

 of sewage pollution are about the same. Typhoid 

 bacilli in celloidin dialyzers floated down the river 

 showed only 2.5 and 3.5 per cent surviving in 2 days 

 and 0.51, 0.89, 2.2 and 3.2 per cent surviving in 3 days 

 when the river was not frozen, while dialyzers suspended 

 through the ice in colder weather showed 6.1, 10.5, 17.7, 

 46.8 and 62.9 per cent surviving in five different experi- 

 ments after 2 days, 31 per cent in 3 days, 19 per cent 

 in 7 days, and 2.5 per cent in 14 days. Ruediger 

 attributes this greater persistence at low temperatures 

 to the absence of poisonous waste products of other 

 organisms and to protection from the light; but there 

 can be little doubt that it is mainly a result of the general 

 preservative effect of cold. From an epidemiological 

 standpoint the conclusion that disease germs perish 

 quickly in warm waters is amply confirmed. Almost 

 without exception outbreaks of typhoid fever due to 

 polluted water occur in cold weather and this is, in 



