354 



WATER AND DISEASE 



Cholera. Water has been proved to be the causative agent in 

 the conveying of cholera in a number of instances. The two best 

 known cases are that of the Broad Street well, which has 

 already been considered, and the epidemic of 1892 in Hamburg. 

 This latter will ever remain classic on account of the clearness of 

 the circumstances and the fact that there is no missing link in 

 the chain of evidence, as the cholera vibrio was isolated from the 

 Elbe River water. 



The Hamburg epidemic occurred in 1892, and in a little over 

 two months there were 17,000 cases with 8605 deaths, whereas 

 Altona, which in reality forms with Hamburg one large city, was 

 practically free. The two cities are built on the same soil, pro- 

 vided with the same sewage system, and have the same climatic 

 conditions. They have the same social customs and were sepa- 

 rated only by a political boundary line. The boundary runs 

 through a street on one side of which is Altona and on the other 

 Hamburg. They have separate water supplies, but both derive 

 their water from the Elbe River which is a grossly polluted stream. 

 However, the water supply for the city of Altona was purified by 

 filtration, while that of Hamburg was not. The boundary of 

 the epidemic was just as clear as was that of the water system, or 

 in the words of Koch, "cholera in Hamburg went right up to the 

 boundary of Altona and there stopped. In one street, which for 

 a long way forms the boundary there was cholera on the Hamburg 

 side, whereas the Altona side was free from it." 



Typhoid. Contaminated water was the first recognized and 

 probably the most significant vehicle of typhoid infection. The 

 improvement in water supplies during recent years has been respon- 

 sible for the reduction in typhoid morbidity. The results compiled 

 by Kober clearly show the effect of improved water supplies on 

 typhoid mortality in American cities. 



EFFECT OF WATER PURIFICATION ON GENERAL AND TYPHOID 



DEATH-RATE. 



