Snow, John

John Snow

British physician John Snow (1813–1858) is called the "father of epidemiology" (the prevention and control of disease) because of his innovative investigative methods. Living in England's Victorian era, he gained prominence as one of the first physicians to use anesthesia. During a cholera epidemic of 1854, he revealed that the disease was caused by water–borne microorganisms.

John Snow was born in York, England on March 15, 1813, the oldest of nine children. His father, William Snow, was an unskilled laborer, and his family lived in one of the poorest sections of York, which was an industrial shipping area located on the River Ouse. Until he was 14, Snow was educated at a common day school for poor families. In 1827, he traveled to Newcastle–upon–Tyne, 80 miles from his home, where he began serving a six–year apprenticeship in medicine under surgeon William Hardcastle. From Hardcastle, Snow learned the daily realities of running a medical practice. The apprenticeship included attending lectures at the Newcastle Infirmary. During this apprenticeship, which lasted until 1833, Snow became a vegetarian as well as a total abstainer of alcohol.

Advanced Medical Education

While in Newcastle, Snow was employed as one of three surgeon apothecaries at the Lying–In Hospital. He also worked as a secretary. In addition, he held an appointment as mining doctor at the Killingworth Colliery. Through this appointment, he came to know George and Robert Stephenson, the father and son team of locomotive engine designers who hailed from the area. In 1827, they were listed as patients in Snow's practice.

During the cholera epidemic that lasted from 1831 to 1832 that hit a coal mining region near Newcastle, Snow worked as a colliery surgeon and unqualified assistant, treating victims. Cholera caused diarrhea and vomiting and, at the time, was fatal in about fifty percent of all cases. Victims usually died within two or three days, from dehydration. From the 1830s through the 1850s, Snow would come in close contact with the devastation the disease caused, and later in his career he would become keenly interested in preventing its outbreak.

Between 1833 and 1836 he was an assistant in practices in Burnopfield, Durham, and in Pateley Bridge, North Yorkshire. In addition, he often returned to his home town of York, where he was involved in the temperance movement, which sought to restrict the consumption of alcohol. Also in York, Snow joined the practice of Joseph Warburton.

In 1836, Snow decided to advance his medical education. In October, he moved to London, where he began advanced studies at the Hunterian School of Medicine at Great Windmill Street. Snow made the journey on foot, following a path that took him through Liverpool, Wales, and Bath. His initial research involved the toxicity of arsenic. The following year, he attended the medical practice at the Westminster Hospital and, in May 1838, he was admitted as a member of the Royal College of Surgeons of England. In October of that year he became a licentiate of the Society of Apothecaries and then set up his own practice at 54 Frith Street, in the Soho district of London. Still, he continued his medical education, regularly attending the meetings of the Westminster Medical Society (which would later become known as the Medical Society of London), where he would present results of his own research on various scientific issues.

Published Articles

Snow also wrote up his research as articles that were published in medical journals in the late 1830s and early 1840s. In this way, his name became well known in English medical circles. His topics of interest included toxicology and respiratory physiology. Specific subjects included the danger of candles incorporating arsenic, postscarlatinal anasarca, and haemorrhagic smallpox. His first published paper, "Arsenic as a Preservative of Dead Bodies," appeared in the prestigious British medical journal The Lancet in 1838. But his best–known paper, "On Asphyxia, and on the Resuscitation of Still–born Children," was published in 1842. His research in this area would later lead to his interest in anesthesia.

In November 1843, he earned a bachelor of medicine degree from the University of London and, on December 20, 1844, he graduated with a doctorate of medicine from the institution. However, all of Snow's hard work took a toll, and he experienced a physical breakdown. In 1844, he suffered health problems, including an attack of tuberculosis and kidney disease. Health problems would trouble him all through his life after this.

In 1845, he was appointed lecturer on forensic medicine at the Aldergate Street School of Medicine. He held the position until 1849, when the school closed down. In June 1850, he became a Licentiate of the Royal College of Physicians of London.

Became Interested in Anesthesia

In the late–1840s, Snow became interested in anesthesia, particularly ether, which was starting to be used as an anesthetic in America. In England, the use of anesthesia was first demonstrated by dentist James Robinson in 1846. Snow investigated the medical efficacy of ether as an anesthetic, and then he made improvements on how the drug was administered by designing his own inhaler. He was granted permission to demonstrate the results of his research in the dental out–patient room at St. George's Hospital. In 1847, after he published a textbook on the administration and effects of anesthetic vapors, Snow became a recognized leader in anesthesiology in London, and he investigated the use of other anaesthetizing agents, including chloroform. On April 7, 1853, Snow made news in England when he administered chloroform to Queen Victoria when she gave birth to Prince Leopold. He used the agent on the Queen once again during the birth of Princess Beatrice on April 14, 1857.

As a physician, Snow treated patients from a range of social backgrounds, and he frequently practiced medicine in the poorest sections of London, providing good medical care to those who could least afford it. In 1852, the Medical Society of London (previously the Westminster Medical Society), chose Snow to be its orator for the coming year. In 1853, he moved his home and practice to 18 Sackville Street. On March 10, 1855, he was inducted as the Medical Society's president. Snow also was a member of the Royal Medical Chirurgical Society and the Pathological Society. In 1854, he served as president of the Physiological Society. In 1857, he was president of the Epidemiological Society.

Investigated Cholera Epidemic

Along with anesthesiology, Snow's major interest included cholera. For a period of 20 years, London was ravaged by outbreaks of cholera epidemics. Snow became very interested in the cause and transmission of the disease in 1832, while he was still a medical apprentice and treated cholera victims.

In 1849, he published a pamphlet, "On the Mode of Communication of Cholera," which countered the conventional thinking regarding the disease. In the pamphlet, Snow remarked how the disease had a tendency to occur in the late summer, most often in the poorest sections of England, and in localized and isolated areas. He determined that cholera was a contagious disease caused by a poison that reproduces in the human body and is found in the vomitus and stools of cholera patients. Further, he suspected that cholera was spread through the microorganism contamination of food and water, but the foremost manner of transmission, he stated, was water contaminated with the poison. According to the prevailing theory, diseases such as cholera were transmitted by breathing in "miasmas," or contaminated vapors.

Despite contradicting the commonly held theory, Snow's pamphlet did not generate any great controversy, as many other theories about cholera were being advanced at the time. Still, he received a good deal of positive notoriety for his work, even though he had no way to prove his theory. However, another outbreak provided Snow the opportunity to prove that his ideas were indeed correct. In 1854, another severe cholera epidemic struck London, in a small area in Soho, where more than six hundred people died. Snow immediately began investigating water sources in the area. He was able to demonstrate—by thoroughly documenting, correlating, and comparing locations of cholera cases among the customer's of London's two water companies—that a higher concentration of incidents occurred among customers of one water company, the Southwark and Vauxhall. The company got its water from the downstream part of the Thames river, an area that was contaminated with London sewage. The other company got its water upstream from the main part of the city, where it was less likely to be contaminated. Snow's evidence was very strong, and it changed many minds.

One situation in particular underscored the soundness of Snow's theory. By mapping the location of cholera–related deaths, Snow found that in one area of the city, at the intersection of Cambridge Street and Broad Street, there was a higher concentration of cholera cases: more than 500 deaths occurred in only ten days. After investigating the situation, Snow determined the cause of so many deaths was due to a water pump on Broad Street. Before the outbreak, the pump had been reportedly discharging a foamy brown water that smelled like raw sewage. The cause of the odor soon became understandable. Further investigation revealed the that well of the pump was about 28 feet deep. At 22 feet, and only yards from the well, was a sewer. Snow was now certain that sewage had contaminated the water.

Snow strongly encouraged officials to remove the pump. The officials were doubtful but followed Snow's advice anyway. The epidemic was soon contained. Moreover, publicity from this part of this investigation drew a great deal of attention to the extremely poor sanitation conditions in London. Officials began a complete renovation of the city's water and sewage systems. As a result, there were no more outbreaks of cholera.

Snow's original 1849 pamphlet, "On the Mode of Communication of Cholera," was awarded a monetary prize from the Institute of France. A second edition of the pamphlet was published in 1855. This one contained a more detailed investigation into the effects of water supplies on certain districts of South London during the 1854 epidemic. Snow's insights and innovative methods led to widespread recognition.

Died Young

During his adult life, Snow suffered chronic health problems, including kidney disease, which led to his premature death on June 16, 1858. He was only 45 years old. At the time of his death, he had been engaged in ongoing research and was preparing a manuscript, "Chloroform and Other Anaesthetics." The work eventually was published posthumously by his friend and colleague Sir Benjamin Ward Richardson. Shortly before his death, he suffered a stroke that left him incapacitated. Although the stroke was given as the direct cause of death, an autopsy revealed that his overall health had been negatively affected by earlier attacks of tuberculosis. Snow, who never married, was buried in the Brompton cemetery, where a monument was erected in his memory.

Legacy

Because of his pioneering work on London's cholera epidemic, Snow became known as the "father of modern epidemiology." His methods forever changed the way illness, on a widespread scale, would be managed. The information he collected and the maps he created during the 1854 epidemic, which showed how the disease was distributed in relation to water sources, essentially became the first–ever epidemiological survey of an illness. Of course, through the years, medical researchers have built upon Snow's methodology, but he led the way. Modern disease prevention and control owes a great deal to Snow.

As a footnote to Snow's illustrious career, the handle from the infamous Broad Street pump still exists, and it is housed at the John Snow Pub, which is located near the former site of the pump. To honor the memory of the man who contributed so much to modern medicine, a John Snow Society was formed. The only requirement for membership is that one visits the John Snow Pub while in London.

Books

World of Health, Gale Group, 2000.

Online

"Biography of John Snow," UCLA Department of Epidemiology, http://www.ph.ucla.edu/epi/snow/snowbio.html (December 31, 2004).

"John Snow," BBC Online, www.bbc.co.uk/history/historic–figures/snow–john.shtml (December 31, 2004).

"John Snow," Center for Disease Control and Prevention, http://www.cdc.gov/ncidod/dbmd/snowinfo.htm (December 31, 2004).

"John Snow (1813–1858)," Royal College of Physicians, http://www.aim25.ac.uk/ (December 31, 2004).

"John Snow: The London Cholera Epidemic of 1854," Center for Spatially Integrated Social Science, http://www.csiss.org/classics/content/8 (December 31, 2004).