Dr Snow’s Battle Against King Cholera

This year a global pandemic that had devastated India, Russia and Europe met its match in London’s Soho.

The symptoms of cholera were at first mistakable for food poisoning, but then developed into profuse diarrhoea and vomiting leading to severe dehydration within hours. The conditions in Britain’s overcrowded cities, rich in animal droppings, cess pits, decaying sewers and slaughterhouses, provided the perfect insanitary environment for the disease to spread.

Dr John Snow set out to map the cases of cholera in his surroundings, believing that he might be able to stop its transmission even if he did not know its cause. Snow was a labourer’s son who had been born in 1813 in York. He was apprenticed to a surgeon-apothecary, and in that role first saw patients with cholera. He completed his apprenticeship, and after years of study moved to Frith Street, Soho, in 1838, where he set up in practice.

From long experience with cholera he deduced that it was caused by a waterborne infection. His 1849 essay On the Mode of Communication of Cholera observed that it was spread by unclean drinking water contaminated by the faeces of an infected person.

However, this work received little attention, so he set about trying to test his theory. A cholera outbreak began around Broad Street on 31 August 1854. Snow mapped the deaths from cholera in the locality, and proved that most of them had taken place in the vicinity of the Broad Street pump: no fewer than 38 houses out of the 44 where someone had died used water supplied by the Southwark and Vauxhall Water Company. Another company, whose supply was uncontaminated by London sewage, had far fewer deaths among its users. Snow presented this information to the civic authorities and they removed the pump’s handle, saving many lives.

This was the first time that a pattern of disease had been used in practical measures to combat disease, which makes Snow one of the fathers of epidemiology as well as a founder of public health medicine.

Sadly, he died in 1858 before the truth of his theory was independently proved.

‘Britain’s cities provided the perfect environment for the disease to spread’