What John Snow and cholera tell us about the COVID pandemic


It’s hard to imagine that someone could die from diarrhea. If you live in America today, you’ve likely never heard of anyone with cholera, and certainly never of anyone dying from diarrhea. Yet, in the middle of the nineteenth century, it was fairly commonplace. Medicine just wasn’t advanced at the time. Amputating limbs of fully-conscious human beings was only recently falling out of favor with the discovery of ether as an anesthetic in 1847. Louis Pasteur had yet to publish his germ theory that would revolutionize the understanding of infectious diseases.

In between these two landmark discoveries, at the West End of London in a town called Soho, was the cholera epidemic of 1854. Dozens of Londoners were dying from unrelenting diarrhea, profound dehydration, and electrolyte disturbances. Most people of the era pointed to the miasmatic theory of disease as the cause, meaning that bad smells caused the disease. It may sound silly now, but think about explaining germ theory to someone who has never heard it. Would you go with invisible creatures or tiny, tiny bugs as the cause of disease?

Ultimately the hero that would help put an end to the outbreak was John Snow – and before you ask – no, not the “winter is coming” Jon Snow. He had his doubts about the miasmatic theory and set out to find the true cause of the epidemic, mapping every person infected and searching for the common denominator. His results were striking. Nearly every death was clustered around a single water pump – the Broad Street pump. When he explored the outliers from this common denominator, he found that almost all persons not living directly near the Broad Street pump were still getting their water there due to preference.

So John Snow set out to prove his point with a plea to public officials, armed with his theory of water contamination and a map of cases clustered around the Broad Street pump that would go down in history as a revolutionary epidemiologic discovery. He was largely met with doubt and skepticism. Though, due to his persistence, officials would reluctantly order that the pump handle be removed from the Broad Street pump. Simple as that, the cholera outbreak in Soho came to a trickle.

Fast-forwarding to today’s pandemic, the rules still apply. Social intervention is, by far, the most powerful tool in mitigating the spread of infectious disease outbreaks. Cholera expedited medical advances, such as the invention of oral rehydration therapy and intravenous fluids. But these advancements were of greater benefit to posterity than the epidemic at hand. Today, rapid advancements in telemedicine, vaccination programs, and oxygenation therapies in acute respiratory distress syndrome will be tremendously helpful to our posterity. However, they will not stop, or even slow, a pandemic. This fact is largely because good science takes time, and social interventions do not.

After the epidemic in Soho came to a halt and John Snow essentially proved his theory correct, you can imagine what happened next. The people of Soho hosted a large parade in his honor, hoisted a statue to commemorate his revolutionary advancement in epidemiology, and gave him thousands of dollars as a thank you. Except they did none of those things. In fact, after the epidemic slowed, John Snow was met with nearly more doubt than before. Most people clenched tightly to their miasmatic theory. Even an appointed Committee of Scientific Inquiry who looked into the epidemic would attribute it to miasma. After only a brief period, public officials even replaced the Broad Street pump handle, and it would remain there, distributing water contaminated by a nearby cesspool for years.

In epidemiology, it’s difficult to prove your point, especially if the conclusion would incite change or overturn conventional theories. Either the intervention doesn’t work, the disease continues to spread, and people doubt you; or the intervention works, the disease stops, and people doubt you. The latter is often rationalized that the initial fears were overblown, and the intervention wasn’t necessary in the first place.

Similar viewpoints are being brought up in the COVID pandemic. Many states are seeing infection rates vastly below initial predictions, making the illogical conclusion that social interventions weren’t necessary in the first place. In fact, many are calling for an abrupt halt to social distancing and protesting for such changes. Instead of clutching to bad smells this time, it’s conspiracy theories and hidden agendas. It will likely be the case that, just like John Snow, epidemiologists and public policy will likely go woefully under-appreciated during this time period. Judging from the cholera outbreak, it will only take a century or two for people to come around.

Brian Elliott is an internal medicine resident.

Image credit: Shutterstock.com


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