BACILLI OF THE COLON-TYPHOID-DYSENTERY GROUP 677 



the organisms disappear with relative speed, no rule can be set up. 

 Klein 106 claims to have found typhoid bacilli alive in natural waters 

 for as long as thirty-six days. 



Since the organisms can remain in the soil for limited periods of time, 

 unwashed vegetables, salads, etc., are dangerous, and, as we shall see, 

 oysters grown near sewage outlets, may also be sources of infection. 



CHANNELS OF TRANSMISSION. Suspicion of typhoid infection by 

 means of water supplies dates back to the early writing of the English 

 physician, Budd, in 1856, who not only believed that sewage contam- 

 inated water conveyed the disease, but suggested that the origin of this 

 pollution lay in human feces. Since that time, of course, bacteriological 

 investigation and sanitary water purification on a large scale has indis- 

 putably proven the danger of water supplies in this respect. In a few 

 cases, direct proof of typhoid bacilli in the water supply has been 

 brought, but, as a rule, indirect proof has had to be adduced, since 

 the rapid dilution, the usual lateness of water investigation after the 

 occurrence of cases, and the many agencies which lead to the destruc- 

 tion of typhoid bacilli in water supplies, has made it extremely difficult 

 to find the organisms in the water. Indirect evidence, however, has 

 been sufficiently convincing in that colon bacillus tests have revealed 

 massive human feces contamination of water to which typhoid infection 

 could be epidemiologically traced. Also, in many localities the direct 

 diminution of typhoid fever in a community after purification of the 

 water supply has left little room for doubt. Thus, in Schuder's 107 inves- 

 tigations of 640 epidemics, 72 per cent were directly traceable to water. 

 Water was unquestionably in former years the most important means 

 of the conveyance of typhoid fever when it occurred in definite epi- 

 demics, and whenever typhoid cases occur in any considerable number 

 in cities and towns, the water supply must first be excluded as a source 

 of infection. It must also always be taken into consideration when 

 typhoid fever occurs in country districts where small well supplies 

 are the chief sources of drinking water. In Schiider's statistics, 110 of 

 his 640 epidemics could be indirectly traced to milk. Gay 76 states 

 that in the rural communities typhoid fever has remained more or less 

 stationary during the last ten years, while, in the cities, owing probably 

 to water-supply supervision, it has been diminishing progressively. 

 The methods of examining water under such circumstances will be 

 detailed in the section on water, where emphasis will also be placed 



lofi Klein, Medical Officers Report, Local Govern. Board. 

 107 Schiider, Zeit. f. Hyg. u. Infec., 38, 1901, 343. 



