Sadly, it was not enough for the professors who responded with such hostility that Semmelweiss was forced to leave. The American researcher and humanitarian Oliver Wendell Holmes had reached the same conclusions in 1843 and had been similarly vilified.1
© Mary Evans Picture Library
(4)Public Pump, England, 1855: John Snow’s careful detective work showed how water-borne cholera could be prevented and paved the way for public health legislation.
Another famous case is the conquest of cholera. Based on his theory that cholera is spread by contaminated water, John Snow, an early English anaesthetist, cut short an epidemic in the Soho district of London by removing the handle of the Broad Street pump.17 The outbreak had killed 500 people within ten days and Snow found that only households receiving water from the Broad Street pump were severely affected. Snow’s theory derived from epidemiological studies of the two London outbreaks of 1848-9 and 1853-4. By carefully charting the course of the disease among affected households, he deduced that the cholera agent enters the body via the mouth through contaminated food, water or the human hand: it is unhygienic conditions, he concluded, that create and perpetuate the chain of cholera victims. He then confirmed the role of contaminated water by showing that deaths were highest in households receiving the most contaminated water.
Snow’s epidemiological studies not only dispelled current theories of cholera based on animal experiments17 but also formed the basis of successful anticholera campaigns and led to legislation mandating all the London water companies to filter their water by 1857.10 This was still 26 years before Koch first isolated the guilty microbe from cholera patients.
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