The Ghost Map is a book about the 1854 London cholera outbreak. But it’s also about how hard it is to change our minds about ideas. A story about a pump, a man named John Snow, how disease theory changed, and how it set us to fail to react to covid.
We now know cholera spreads through contaminated water. In the 1850s, however, they only had two competing theories:
- Contagion: Direct person-to-person transmission.
- Miasmaists: Bad inner-city air makes people sick, often linked with poorer inner-city communities.
When cholera entered Britain in the 1830s, some started to suspect it wasn’t the air. From the Lancet: “We can only suppose the existence of a poison which progresses independently of the wind, of the soil, of all conditions of the air, and of the barrier of the sea.”
Yet it was a minor view. Miasma theory was dominant with influential people such as the sanitation commissioner, Edwin Chadwick, and the city demographer, William Farr. Many members of parliament also saw this as settled science. Serious people didn’t think otherwise.
People had a hard time believing bacteria were responsible for infection because Cholera was invisible to the human eye. From 1854 to 1856, researchers from Spain, Italy, and Portugal identified the bacteria in microscopes, but this didn’t spread in a useful way to take action.
In 1946, momentum grew to eradicate foul smells. Edwin Chadwick said, “All smell is, if it be intense, immediate acute disease; and eventually we may say that, by depressing the system and rendering it susceptible to the action of other causes, all smell is disease.”
He proposed large-scale solutions to eliminate the bad smells. By 1948, Britain’s early public health authority was established, centralizing water supplies and funneling waste into the rivers. Which led directly to increases in Cholera deaths.
A doctor, John Snow, had been studying cholera and the plague for several years and didn’t think miasmas caused disease, but this was only because he thought the vapors would disperse too much to have an effect. His general doubt still put him in a position to understand cholera.
As soon as the outbreak started in 1854, he began tracking the deaths and their location. He had a hunch that it was linked to the water supply. He found that homes supplied by water that came from downstream were 14x more likely to die of cholera. His original map:
This led him to the Broad Street pump and after analysis, he persuaded authorities to take the pump handle off. Here is his letter reporting on how he made this decision from 1854:
Despite making a correct decision that helped end the outbreak, he still did not have the correct explanation for why this specific outbreak happened. Contaminated drinking supplies were a problem, but this breakout was so bad because of its location relative to an early case.
The real cause was that a well from a nearby house was leaking into the water supply that fed the Broad Street pump. One of the first cases was in this house, and as multiple people in the house continued to get infected, their contaminated waste spread to the well.
Reverend Whitehead from the local church was confident Snow was wrong but changed his mind after his own research, “Slowly and I may add reluctantly,” the conclusion was reached “that the use of water (from the pump) was connected with the continuation of the outburst.”
He became a strong supporter of Snow’s theories. While one local health group accepted their ideas, most people still rejected it out of hand. Considering a fecal-oral route of transmission was something that was too taboo to consider communicating to the public.
John Snow would die in 1858 without any major governments or institutions accepting his waterborne theory of transmission. Although outbreaks like 1854 were avoided, Cholera remained a problem, albeit somewhat diminished because public health systems did improve.
It was not until 1966 during a cholera outbreak, likely aided by Whitehead’s strong support, that a major opponent of Snow, William Farr, finally issued an order that all water should be boiled.
It’s worth pausing to note that if not for Whitehead’s curiosity, a man with no formal medical training, the debates may have lasted even longer. Whitehead chose to be a devoted supporter of Snow’s theory after confirming the evidence on his own. From a book on Whitehead:
Side Note: An interesting fact from this book is the role of Tea. If not for tea, cholera outbreaks may have been worse throughout the 1800s. Boiling water and the tannic acid from tea served as a dual attack on bacteria.
But why was the miasma theory so durable and what does it have to do with Covid? Mostly because it served a purpose for many people. People like Florence Nightingale and Charles Dickens used it to support the poor, arguing that poor living conditions exacerbated miasmas.
Religious narratives saw the foul smells and resulting disease as god’s will. Here is Whitehead before he changed his mind: “the atmosphere, all over the world, is at this time favourable to the production of a most formidable plague.”
The miasma theory only started to crumble in the 1800s. In 1892, Hamburg Germany had a major cholera outbreak, and this helped to show the disease was waterborne. Yet even people like Nightingale did not ever abandon the miasma idea in her lifetime (she died in 1910).
In the 1910s, Germ Theory was starting to take off, led by people like Charles Chapin. This was a huge improvement, but the advance was paired with an aggressive push against ANY theories of airborne transmission.
In 2020 doctors were thus living with this legacy, terrified to say that diseases spread through the air. Wash your hands and “socially distance”. In 2021 aerosol spread is known, yet many still think that eating indoors behind a barrier magically stops disease spread.
Zeynep Tufekci has a great essay and quotes an epidemiologist from Australia: “If we started revisiting airflow, we would have to be prepared to change a lot of what we do…It will cause an enormous shudder through the infection control society.”
This might be good science but is not useful for decision-making during a pandemic. Many people seem to think that epidemiologists should be deciding public policy, but if it were up to them, they’d wait years for more data.
It took the WHO until July [2020] and the CDC in the US until October [2020] to confirm airborne transmission. Yet in April [2020] there was already acknowledgment that waiting would be costly.
“Is the coronavirus airborne? Experts can’t agree” “The World Health Organization says the evidence is not compelling, but scientists warn that gathering sufficient data could take years and cost lives” (Link to Nature article).
Here is the WHO in March 2020. It’s hard not to see the parallels of what John Snow dealt with back in the 1800s and wonder if this inability to update to new ideas is even harder in today’s world with so many embedded interests and stakes.
Quoting the WHO from March 28, 2020: (Link to WHO tweet).
John Snow was right not because he had firsthand evidence of cholera living in water. The organism had been identified, but it wasn’t shown as having a direct link until the 1890s. Instead, he used second-order reasoning, looking at deaths to come to his conclusion.
This was ignored for decades, and it took 50+ years to really shift to a new paradigm. Today, scientists similarly hide behind the need for more research and more science, but are they really motivated to improve thinking or simply to protect their own ideas?
So there we have it. John Snow and Reverend Whitehead were more or less right, but no one bothered to accept their wisdom for at least 12 years, and conventional wisdom never really shifted until the late 1800s, if not later.
What ideas are we desperate to hang on to today?
