This is the fourth chapter of the series of contents dedicated to the cholera map, created by Dr. John Snow during an epidemiological outbreak that killed hundreds of people within a week in 1854 in the Soho region of London. The previous chapter was Not everything is as it seems.
The administrative region was comprised of St. James Parish and community leaders requested action.
The commission formed to investigate the occurrences and propose solutions was organized by Mr. York, who requested Dr. John Snow and Reverend Whitehead to carry out an investigation and their findings were reported to Mr. Marshall, who produced the final document, consisting of:
- History of the outbreak
- Circumstances associated with the outbreak
- Main hypotheses
- Recommendations to the parish authorities
Population analyses accounted for the proportion of deaths per total inhabitants.
The local population comprised 14,000 people in an area of half a dozen blocks.
The intensity of the deaths is evident, northeast of Golden Square, in the Broad Street region.
The death rate per 10,000 inhabitants was 4% (440) in other areas of the city and reached 10% (1000) on Broad Street, as it moved away from Broad St. the proportion of deaths fell from 8 to 5%.
To give you an idea of the drama, in 21 families the death of the husband and wife followed by the children.
The population density was such that 33 deaths were counted in 4 houses, as different families crammed into a few rooms.
This situation led to an emptying of the region, which greatly hampered the investigative work.
The lines of investigation evaluated the percentage of deaths from walking on which the person lives, their age group, professional activity, temperature and humidity on the days with the most deaths, without finding correlations.
This already pointed out some disconnection with the miasma thesis, since wind speed was measured in order to relate it to a disease dispersion event.
It is striking to note how methodical the investigation had to be in order to demonstrate and rule out all transmission ratios attributable to the air.
You can see that they already knew the cause of the contamination and anticipated resistance to discovery.
Then comes an analysis of the primitive water supply and sewage drainage network.
The region was supplied by two companies, Grand Junction and New River, dismissing the thesis that the water was already contaminated, given the super location of the deaths and the large area served by the companies.
Therefore, the conclusion pointed to some source of local contamination in the so-called Cholera Area.
Concluding with Dr. Sutherland's observation:
It's hard to resist the statistical evidence presented that the people who consumed that water the most died.
This leads to John Snow's thesis that the well water was contaminated by a cesspool used by people with cholera.
Faced with irrefutable evidence and a map, the parish committee agreed to ban the Broad Street bomb.
This was done with the removal of its handle, under strong protests from locals who resented losing access to the water they so cherished.
As much as the ban may be considered a victory for the scientific method applied by Dr. Snow and Reverend Whitehead, their study was widely discredited by the medical community.
It was rehabilitated years later in another outbreak, at which time John Snow had already died.
We conclude the series in the next article, The awakening of life in cities.
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The full document may be found at this link.
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