JOHN SNOW: BIOGRAPHY, DISCOVERIES AND CONTRIBUTIONS - MEDICINE - 2025

John Snow was one of the leading physicians in early 19th century England. Born in York in 1813, his studies on epidemiology helped reduce the mortality caused by outbreaks of diseases such as cholera. He was also one of the first to study how to apply anesthesia more safely and reliably.

Part of his fame, accompanied by the title of sir, was obtained after anesthetizing Queen Victoria in the delivery of her eighth child. Snow's studies of cholera led to a shift in scientific thinking at the time. Until then, miasms were blamed for the appearance of massive cases of this disease.

The doctor drew up a map that related the water deposits contaminated by fecal matter with the places where the outbreaks arose. His method, called epidemiological, has been very important throughout history in order to combat contagious diseases.

Biography

John Snow was born into a family of humble workers on March 15, 1813. During his childhood he lived in one of the poorest neighborhoods in his city of birth, York, England.

He was the eldest of nine siblings and his father worked in the local coal yards. Due to family circumstances, Snow had to start looking for a job at a young age.

Apprenticeship training

Young Snow did his primary studies in York until he was 14 years old. At that age he began as an apprentice to a famous surgeon in Newcastle-upon-Tyne, William Hardcastle. Thanks to this work, Snow was able to change his life.

For this he received the help of his uncle, who was a close friend of Hardcastle. In turn, he was the personal physician of George Stephenson, the inventor of steam engines. These relationships made it much easier for him to continue his training far from York.

London

During that early period, Snow also came to work as a surgeon. In 1833 he became a practicing assistant for the first time, and until 1836 he carried out this work in several different localities.

Finally, in late 1836, he traveled to London to enter the Hunterian School of Medicine. Only a year later he found work at Westminster Hospital. The following year, on May 2, 1838, Snow was admitted to the Royal College of Surgeons of England.

It would still be a few years until he could graduate from the University of London, since he did not obtain the title until 1844. In 1950 he joined the Royal College of Physicians, an independent institution from the College of Surgeons.

Death

John Snow always tried to lead a very healthy life. He was a vegetarian, a teetotaler and always drank water after filtering it. On the subject of food he wrote a not very well known treatise entitled On the adulteration of bread as a cause of rickets.

However, death surprised him very soon. He suffered a stroke while working at home when he was just 45 years old, on June 10, 1858. Six days later he passed away and was buried in Brompton Cemetery.

In addition to being named a sir by Queen Victoria, Snow received multiple accolades. The last of these was having been voted in 2003 by British doctors as the most important of all time.

Discoveries and contributions

Anesthesia

Despite the fact that anesthesia was already known before, John Snow's studies represented a great advance in its use, especially in its safety.

In this way, he was the first to offer a method for calculating the amount of ether and chloroform that was necessary for surgical use.

Thanks to his research, the annoying and painful side effects that the use of these substances sometimes brought about were eliminated.

Snow captured his discoveries in a work published in 1847 entitled On Inhalation of Ether Vapors and in another posthumously published book called Chloroform and Other Anesthetics.

The doctor got part of his fame thanks to this topic. Queen Victoria enlisted his services at the birth of two of her children, and Snow administered the anesthesia personally.

epidemiology

Even before he became famous during the cholera epidemic, Snow was already very critical of the scientific explanations that were given to explain the spread of certain diseases.

The dominant theory at that time was that conditions such as cholera or plague were transmitted by miasma, a kind of noxious air.

There were still a few years until the germ theory appeared, so no one could suspect their responsibility in the contagion.

Although Snow was also unaware of germs, he did not believe that diseases spread by breathing air polluted with miasmas.

In 1849 he dared to publish an essay blaming contaminated water as the culprit for cholera outbreaks, but it was not widely accepted. The second treatise on the subject was written after her outstanding participation during the epidemic in London.

Epidemic

At that time London was the most populated city in the world. In 1854 it had more than 2.5 million inhabitants and dirt was omnipresent. There was no efficient garbage system and the sewers were working very badly.

It was in August of that year that a virulent cholera epidemic broke out in the center of the city. Mortality rates reached 12.8% in some areas.

The most affected was the Soho neighborhood, which did not even have a sewage system. The chronicles affirm that about a thousand residents of the neighborhood died in a very short time.

John Snow's office was very close to Soho, and even the doctor knew several of the victims. Living in the area, he was well aware of the problems with the water that was drunk there, which was drawn from a public fountain on Broad Street.

Snow, convinced of the theory he had published, set out to prove that the source was responsible for the outbreak.

Cholera map

The first thing he did was buy a map showing the street map of the entire affected area. Then he began to visit the houses of each deceased, linking the places with a black line.

Once the tour was completed, the resulting map perfectly showed the areas in which the most cases had occurred, and could establish a pattern. The result was that most of the deaths had occurred near the Broad Street fountain.

To complete his study, Snow interviewed the relatives of some of the deceased who resided far from the aforementioned source. The explanation confirmed their suspicions: everyone used to pass by Broad Street and they often drank from it.

With all that data, John Snow managed to get the authorities to close the source, which prevented the disease from continuing to spread. Somewhat later it was discovered that the cause of the epidemic had been a diaper from a sick baby, which had contaminated the entire source.

In 1855, a year after the epidemic, Snow submitted a full report to the official committee investigating the outbreak. According to their study, more than 70% of the deaths had occurred within the area where the source was.

Paradigm shift

Scientifically, the studies presented by John Snow were the origin of modern epidemiology; that is, the analysis of the evolution of a disease in a human community to discover how it spreads.

Despite this, the medical community did not accept Snow's conclusions willingly and it was not until years later, already in the late 1960s, that he achieved recognition.

References

1. Biographies. John Snow. Obtained from biografias.es
2. Moncayo Medina, Alvaro. Reflection Article: Bicentennial of the Birth of John Snow (1813 - 2013). Obtained from encolombia.com
3. EcuRed. John Snow. Obtained from ecured.cu
4. The John Snow Society. About John Snow. Retrieved from johnsnowsociety.org
5. Tuthill, Kathleen. John Snow and the Broad Street Pump. Retrieved from ph.ucla.edu
6. Kukaswadia, Atif. John Snow - The First Epidemiologist. Retrieved from blogs.plos.org
7. Rogers, Simon. John Snow's data journalism: the cholera map that changed the world. Retrieved from theguardian.com
8. Zielinski, Sarah. Cholera, John Snow and the Grand Experiment. Retrieved from smithsonianmag.com