The Cholera Epidemics Were They Caused by Bacteria Living in the Soil or Water

In the rapidly growing European cities of the 19th century, cholera epidemics claimed many thousands of lives. In the time before 1860, nobody had a realistic idea about the cause of these epidemics. It was not until 1883, when Robert Koch discovered the bacteria which caused the illness (Brown 1935) that physicians were able to look for the natural reason of these bacteria. Two different hypotheses characterized the dispute of the following 10 years. Max von Pettenkofer and his followers were convinced that the cholera bacteria lived and grew in the soil and that the infections were caused by contact with soil and dust particles (von Pettenkofer 1882). Robert Koch and his followers supported the opinion that infection by cholera bacteria resulted from surface waters which were often used as sources of drinking water without any processing (Brown 1935).

In 1892, cholera appeared in Hamburg. All the victims of this disease had been supplied with drinking water which came directly from the river Elbe without sand filtration. The central prison and the Attendorfer lunatic asylum with its own groundwater supplies remained completely unaffected by cholera (Kluge and Schramm 1986). In the neighboring town of Altona, the morbidity was significantly lower, although water from the Elbe was used there as well. Was the rate of infection so much lower because the water was sand-filtered in the Altona waterworks? After some months, the number of illnesses was about 18000 and the number of deaths 7600. But up to this point, the cholera bacillus was only found in the bodies and excrement of those taken ill. But just one year later, the cholera bacillus was also detected in the water of the river Elbe and most notably also in the pumps. After the source of the cholera infection had been identified, an effective solution to the problem had been found: sand filtration in waterworks and wastewater discharge into the river as before (Fl├╝gge 1893) or groundwater withdrawal as shore filtrate and wastewater treatment by irrigation fields (Virchow 1868; Hobrecht 1884). Both methods were employed, the first in Hamburg, the second in Berlin. The idea that a river can be loaded with untreated wastewater and then be cleaned by "self-purification" was upheld for the next 80 years. Only in the 1960s did we realize that wastewater must be treated in plants before being discharged into surface waters!

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