On The Trail of a Killer Disease: The Unlikely Source of Cholera

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On the Trail of a Killer Disease: The Unlikely Source of Cholera

On September 4, 1854, the narrow courts and streets of London’s usually bustling district of Soho were strangely deserted. Yellow flags hung at each street corner, and milky-white puddles of lime chloride lay everywhere. There was a ghostly calm.

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In the preceding few days hundreds of people in Soho had died from the ravages of cholera, one of the most devastating and least understood diseases of the age. The yellow flags were a traditional plague warning, the lime chloride a desperate attempt at disinfection. Having made an effort to arrest the disease, most of Soho’s terrified inhabitants had fled. Local hospitals were over flowing with the dying. At the height of the epidemic, 143 deaths were recorded in a single day. Corpses were so numerous; they were unceremoniously piled on carts and taken away for burial.

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The Mystery Disease

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At that time opinion in the medical profession was divided as to the cause of cholera. Most doctors favored the theory that it was spread by foul air in the overcrowded quarters of the poor. Others suggested that height above sea level was significant: the higher the altitude, the purer the air. One authority solemnly concluded that people with dark hair were more vulnerable than blonds or redheads. But the grim fact was that no one knew how to prevent or cure the disease.

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Snow’s reasoning was simple enough. Cholera, he pointed out, first manifests itself as a stomach disorder; therefore, it was reasonable to conclude that what he called the cholera “poison” had to be swallowed. The major symptoms were vomiting and diarrhea, followed by spasms and cramps in the limbs. People tended not to wash before eating, and anyone in contact with a victim could easily take in leaking privies and overflowing cesspools such as Soho, there was every chance the disease passed directly into the local supply of drinking water.

But why had cholera broken out in such epidemic proportions in Soho?

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Snow noticed that the Soho outbreak was confined to a small area. In the center, at Broad Street, stood an old water pump that supplied drinking water to the community.

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Ironically the Broad Street pump, which was served by a well, had an excellent reputation for the purity of its water.  Despite the availability of a supply from water mains, many people still preferred to use the local pump. And many families depended on the pump on weekends, when the water mains were shut off. Concluding that the pump must be responsible for the cholera out break, Snow persuaded the local authorities to take it out of service by removing the handle. They reluctantly did so on September 7.

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Death’s Dispensary: Until the theory of a London doctor was finally accepted by the medical profession in 1866, the carrier of cholera – contaminated water – remained unknown. Unfortunately, many people died after drinking from communal water pumps in the 1854 cholera epidemic that swept London.

Detective Work

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By September 11 the epidemic was almost over, having claimed more than 500 lives. At this point the authorities decided to launch an investigation into the causes. Their most dedicated investigator was the local curate, the Reverend Henry Whitehead. Wholly unconvinced by Snow’s theory, Whitehead was determined to prove Snow wrong.

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Snow had noticed that the cholera reached only so far down certain streets: “The deaths…diminished, or ceased altogether, at every point where it becomes decidedly nearer to send to another pump than to the one in Broad Street.” Snow drew attention to the local brewery, where no one had fallen ill. It had its own well, and most of the workers quenched their thirst with free beer. The nearby workhouse, which had its own pump as well as water from mains, also remained unaffected. Residents in the single house visited by death in an otherwise unaffected street had been the only ones to use water from the Broad Street pimp.

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But at a factory in Broad Street itself, 18 workers had died – and so had the widow of its founder, who lived a few miles away. Partial to the pump water, she had a bottle a day sent to her home.

The Final Proof

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It was Whitehead, Snow’s opponent, who provided the final statistics. Of 137 people who lived in Broad Street and used the pump, 80 had died. Of the 297 who did not take water from the pump, only 20 had contracted cholera. Faced with this evidence, the honest curate abandoned his opposition and sided entirely with Snow.

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Despite the evidence, the medical establishment remained unconvinced that the area’s privies were the root of the problem. It was Snow’s new convert, Whitehead, who uncovered the final proof. He noticed that a day before the epidemic had struck the neighborhood; a baby girl had died of the disease at No. 40 Broad Street. Her mother had washed diapers in the house privy. Whitehead discovered that the privy leaked into the well that fed the Broad Street pump.

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It was not until 1866, when another cholera epidemic threatened Britain, that the medical profession finally accepted Snow’s theory. By that time Snow was dead. Then in 1884 the German microbiologist Robert Koch discovered the direct cause of cholera: Spirillum cholera, a germ with a behavior that matched the hypothetical cholera “poison” described by Snow. The way was open to begin to attempt control of the disease.