Cholera is one of history's most deadly human diseases and has spread across the entire world creating a pandemic. It is an acute diarrhoeal illness of an infection of the intestine with the bacterium Vibrio cholerae and is spread by ingesting water and food contaminated by the faeces of a cholera victim. Even casual contact with a contaminated toilet can be all that is needed to contract the disease. Symptoms are severe diarrhoea and vomiting and if left untreated, the patient will become dehydrated and it will be too late to save them. It only takes a few days for a patient to contract the infection, develop the symptoms and become dehydrated, so it is critical that treatment should be administered quickly.

The first cholera pandemic of 1817-1823 broke out in Calcutta and spread from India to Southeast Asia, Central Asia, the Middle East and Russia, killing hundreds of thousands of people; since that time it is estimated that millions have died. The most recent cholera epidemic, which was part of the seventh and current pandemic, was in Pohnpei, Indonesia, beginning in 1961 and lasting for ten years. This was a new strain of cholera called the El-tor strain and although it is now under control, thanks to the development of modern medicine, many died. In 1991 cholera appeared in South America and still remains throughout parts of Latin America, Africa and Asia.

Two specific trends in the biological and social sciences led to the current knowledge of bacterial and viral diseases such as cholera, tuberculosis and AIDS. The development of the microscope led to a microbiological view of living things and the development of social statistics allowed us to see and quantify many types of social patterns.

Anton van Leeuwenhoek made the first effective microscopes in the 1660s, enabling us to view the microscopic biological world of cells, bacteria and viruses. (See article on Leeuwenhoek). Up until the mid-1800s the western medical establishment believed that vapours in the air caused illnesses. That changed during the Golden Age of Microbiology from 1850-1920, when scientists such as John Snow, Louis Pasteur, Joseph Lister and Robert Koch appeared. (See articles on Pasteur, Lister and Koch)

The spread of Cholera

In 1817 when the first outbreak of cholera occurred in Calcutta, people from all over India gathered for a Kumbh Festival at Hardwar. The visitors all shared the water from the Ganges and so carried cholera back to their homes in other parts of India. After this, it followed the trade routes into Iran, Baku and Russia, spreading from port to port along the trade routes and by 1827 became the most feared disease of the century. The Industrial Revolution encouraged the cholera pandemic with the growth of cities and slums and the poor management of sewer and water treatment, thus giving the cholera bacteria plenty of places in which to fester and infect people.

It first hit England in 1831 in Sunderland and the government established forty-day quarantine in an effort to curb the high incidence of cholera. The infection spread to America through immigrants from Northern and Western Europe, many died on the ships before they reached America and the huge numbers of deaths led to the declaration of a cholera epidemic in New York.

The Broad Street Pump Outbreak

By the middle of the 19th century, Soho had become an insanitary place of cowsheds, animal droppings, slaughterhouses, grease-boiling dens and decaying sewers. Underneath the floorboards of the overcrowded cellars were old cesspits, many of which had never been drained. It was only a matter of time before disease reared its head and cholera arrived suddenly in the summer of 1854.

When the Asiatic cholera first arrived in England in 1831, it was thought to be spread by 'a miasma in the atmosphere' and at the time of the Soho outbreak, twenty-three years later, medical knowledge about the disease had hardly changed. One man, Dr. John Snow, a surgeon, anaesthesiologist, and pioneer of the science of epidemiology had recently published a report suggesting that cholera was spread by contaminated water, but neither the authorities nor the rest of the medical profession considered that this could be such a possibility.

Cholera had broken out four times between 1831 and 1854, and nothing had been done to stop its progression through the industrial cities where tens of thousands of victims had died. In 1853 there was an outbreak in Newcastle and Gateshead as well as London and a total of 10,675 died of the disease. In 1854 in London, the worst hit areas at first were Southwark and Lambeth, but Soho only had a few isolated cases in late August. Then, on the night of the 31st August, what Dr. Snow later called 'the most terrible outbreak of cholera which ever occurred in the kingdom' broke out.
It happened quite suddenly. During the next three days, twelve people living in or around Broad Street died. There were few families who did not lose at least one member and within one week, three-quarters of the residents had left their homes, leaving their shops shuttered, their houses locked and the streets deserted. Only people who could not afford to leave remained there and it was like a repetition of the Great Plague.

By 10th September the number of fatal cases had reached five hundred and the death rate of the St. Anne's, Berwick Street and Golden Square sub-divisions of the parish had risen to 12.8%, more than double for the rest of London. It was thanks to Dr. Snow that it did not rise even higher.

Dr. Snow lived in Frith Street, so his local contacts made him well placed to monitor the epidemic. In his previous researches he had noted that cholera 'always commences with disturbances of the functions of the alimentary canal' and was spread by a poison passed from victim to victim through sewage-tainted water. He had traced a recent outbreak in South London to contaminated water supplied by the Vauxhall Water Company, but it is not surprising that the authorities and the water company doubted his theory. With the outbreak in Soho he saw the opportunity to prove his theories by linking the outbreak to a single source of polluted water.

From the onset of the outbreak he visited families of the victims and his research led him to a pump on the corner of Broad Street and Cambridge Street which appeared to be at the epicentre of the epidemic. He found that nearly all the deaths had taken place within a short distance of the pump, and there had only been ten deaths in houses much nearer to another pump. Of these ten victims, five had always drunk the water from the Broad Street pump and three more, who were schoolchildren, were likely to have drunk from the pump on their way to school.

Dr. Snow took a sample of the water from the pump and after examining it under a microscope; he found that it contained 'white, flocculent particles'. By 7th September he was sure that these were the cause of the infection and he took his finding to the Board of Guardians of St. James's Parish, who were responsible for the pump. Although they doubted his theory, as an experiment, they finally agreed to remove the pump handle. By this time the new cases of cholera had already reduced, but once the pump handle was removed, the spread of cholera stopped dramatically.

By the end of September the outbreak was virtually over, but 616 residents of the Soho area had died. Dr. Snow still had to prove his theories, as there were several unexplained deaths from cholera that did not seem to be connected with the Broad Street pump. A widow living in West End, Hampstead, died of the disease on 2nd September and her niece, who lived in Islington, died of the same symptoms the following day. Neither of these women had been near Soho for some time, so Dr. Snow rode up to Hampstead to talk to the widow's son. From their conversation, he discovered that the widow had lived in Broad Street at one time and she liked the taste of the well water there so much that for some time she had been sending her servant to Soho each day to bring her back a large bottle. The last bottle of water she received, from which both she and her niece had drunk, had been on 31st August, at the very start of the Soho epidemic.

There were other factors leading Snow to believe that the Broad Street well was responsible for the outbreak of cholera in Soho. Of the 530 inmates of the Poland Street workhouse nearby, only five people had contracted cholera. The building had its own well, so it was not necessary for anyone living there to use the pump in Broad Street. Of the seventy workers in a Broad Street Brewery there were no fatalities, as they were given an allowance of free beer each day so they did not need to drink water at all. An Army Officer who lived in St. John's Wood had died after dining out in Wardour Street, where he had drunk a glass of water from the Broad Street well.

All these factors convinced Dr. Snow that the well was responsible for the outbreak, but still the authorities did not believe him. A few months later, a report by the Board of Health dismissed his 'suggestions' that 'the real cause of whatever was peculiar in the case lay in the general use of one particular well, situate (sic) at Broad Street i n the middle of the district, and having (it was imagined) its waters contaminated by the rice-water evacuations of cholera patients'. The report ended with the comment 'After careful inquiry, we see no reason to adopt this belief'.

The question as to what caused the cholera outbreak still remained. The Reverend Henry Whitehead, Vicar of St. Luke's Church, Berwick Street, believed that it had been caused by 'divine intervention' and he prepared his own report on the epidemic to prove his point. His findings only confirmed Snow's claim and he subsequently helped Snow to isolate the probable cause of the whole infection. It appears that a child who lived at 40 Broad Street had been taken ill with cholera symptoms. Its nappies had been soaked in water, which was tipped into a leaking cesspool situated three feet from the Broad Street well.

Whitehead's conclusions were published in The Builder a year later, together with a report on the living conditions in Soho, undertaken by the magazine itself. They found that no improvements at all had been made since the outbreak.

'Even in Broad Street it would appear that little has since been done…In St. Anne's Place and St. Anne's Court, the open cesspools are still to be seen; in the court, so far as we could learn, no change has been made; so that here, in spite of the late numerous deaths, we have all the materials for a fresh epidemic…In some houses the water-butts were in deep cellars, close to the undrained cesspool…The overcrowding appears to increase.'

The Builder recommended 'the immediate abandonment and clearing away of all cesspools – not the disguise of them, but their complete removal'.

Snow's research and intervention in the Broad Street outbreak were only a small part of his broader investigations of cholera. His exhaustive books, articles, and presentations influenced the opinion of very few scientific or medical authorities of his day in England or in Europe. His work, when it was read, was largely rejected as "untenable" and inconclusive. Those who did value Snow's work thought that contaminated water might predispose persons to cholera, but unlike Snow, they did not believe that it was a sufficient single cause. His now famous 1855 edition of On the Communication of Cholera had sold only 56 copies by the time Snow died at the age of 45. Virtually all authorities continued to hold complex airborne miasma theories of cholera transmission for several more decades. Recognition and acceptance of Snow's work gradually increased over the next several decades, until the more foundational work of Koch and Pasteur cleared the way for contagion theory and documented the existence and disease-causing abilities of the "animalcules" (bacteria) hypothesised by Snow and others.

Snow himself was not widely known in epidemiology or medicine until more than 75 years after his death, when epidemiologist Wade Hampton Frost republished Snow's work in Snow on Cholera in 1936. It is sad to reflect that Snow worked unstintingly in public health for about ten years for no pay and in relative obscurity. When he died it was not recognised that he had come very close to understanding the nature of cholera and its transmission.

As to the Broad Street Pump, so few people of influence accepted Snow's waterborne theory of cholera that within several weeks after the outbreak, the pump was back in service. Records show that throughout London, shallow street pumps like that in Broad Street continued to be used for more than twenty years, but their existence was increasingly fought by medical and sanitary reformers who warned of the danger they posed. Even when cholera was present, the pumps often remained in service. An Editorial from the Times of London, dated 28th July 1866, written by two physicians during the peak of the next major cholera epidemic, complained bitterly that the Broad Street pump and others like it should be closed. Apparently, by then, the waterborne theory was gaining some credibility in the medical community, but the St. James Vestry and others with authority over the pumps remained unconvinced.

Three days later, a medical officer wrote to the vestry, pleading,

'I dare not take the responsibility of remaining quiet while these pumps are open, and, at the risk of offending you by my pertinacity, I implore you to order the pumps to be shut.'

According to Chave (1958), this letter apparently had its desired effect, and there is no further reference anywhere to the Broad Street Pump, other than a statement from the 1880's that it had been covered.

Today the pump location is marked by a small red marker on the curb, and by a pub bearing the name of John Snow.

In the 20th Century, sanitary improvements largely eliminated cholera from industrialised countries, but as stated at the beginning of this article, it remains endemic in many areas of the world. After the Peruvian outbreak in 1991, Central and South America saw more than one million cases and eleven thousand deaths through 1995, and the disease also continues to produce significant morbidity and mortality in Africa and Asia.

Acknowledgements:
Broad Street Pump Outbreak
Biography of John Snow
History of Cholera
Dr. John Snow