BACTERIA OF WATER AND SEWAGE 297 



developed in a population of 780. This epidemic was very 

 definitely traced to the water supply connected with an under- 

 ground stream which became contaminated with the dis- 

 charges of typhoid fever patients. In 1885, the Plymouth 

 epidemic occurred which has become a classical example of a 

 water-borne typhoid epidemic. In that year, more than one 

 thousand cases developed in a very short period of time out of a 

 population of 8000 (Fig. 60). It was conclusively shown that 

 the disease was caused by the discharges of a typhoid patient 

 living and nursed on the banks of the stream from which the 

 water supply of the city was taken. Many other epidemics 

 have been definitely traced to an infected water supply, and the 

 time must soon come when no city will think of taking water 

 for drinking purposes which comes from a source that is not 

 properly protected from sewage contamination. The dangers 

 that come to cities taking their water supply from an infected 

 source is well illustrated in those cities situated on the Mohawk 

 and Hudson river valleys. 



Asiatic cholera is also a water-borne disease. Fortunately, 

 Asiatic cholera has been kept out of American and European 

 countries for many years, and it is hoped that it will never re- 

 turn in epidemic form. If it does, however, it will travel, 

 as it has in the past, largely through water. That it is a water- 

 borne disease is very strikingly shown by the facts developed 

 in Germany in 1893. Hamburg and Altona are two con- 

 tiguous cities. Hamburg took its water supply from the 

 River Elbe. Because it had its intake situated somewhat 



