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John Snow (physician)

John Snow (physician)

Anaesthesia. locating source of a cholera outbreak, thus establishing the link between this infection and water as its vector.

John Snow (15 March 1813 – 16 June 1858) was an English physician and a leader in the adoption of anaesthesia and medical hygiene. He is considered one of the fathers of modern epidemiology. in part because of his work in tracing the source of a cholera outbreak in Soho, London, in 1854. His findings inspired fundamental changes in the water and waste systems of London, which led to similar changes in other cities, and a significant improvement in general public health around the world.

Early life and education

Snow was born 15 March 1813 in York. England. He was the first of nine children born to William and Frances Snow in their North Street home. His neighbourhood was one of the poorest in the city and was always in danger of flooding because of its proximity to the River Ouse. His father was a labourer [ 1 ] who may have worked at a local coal yard, by the Ouse, probably constantly replenished from the Yorkshire coalfield by barges, but later was a farmer in a small village to the north of York. [ 2 ] Snow was baptised at All Saints' Church, North Street, York

All Saints, North Street

Snow studied in York until the age of 14, when he was apprenticed to William Hardcastle, a surgeon in Newcastle upon Tyne. It was there, in 1831, that he first encountered cholera. which entered Newcastle via the seaport of Sunderland and devastated the town. [ 3 ] Between 1833 and 1836 Snow worked as an assistant to a colliery surgeon, first in Burnopfield. County Durham, and then in Pateley Bridge. West Riding of Yorkshire. In October 1836 he enrolled at the Hunterian school of medicine on Great Windmill Street. London. [ 4 ]


In 1837 Snow began working at the Westminster Hospital. Admitted as a member of the Royal College of Surgeons of England on 2 May 1838, he graduated from the University of London in December 1844 and was admitted to the Royal College of Physicians in 1850. In 1850 he was also one of the founding members of the Epidemiological Society of London. formed in response to the cholera outbreak of 1849. [ 5 ]

In 1857 Snow made an early and often overlooked [ 6 ] contribution to epidemiology in a pamphlet, On the adulteration of bread as a cause of rickets. [ 7 ]


John Snow was one of the first physicians to study and calculate dosages for the use of ether and chloroform as surgical anaesthetics. allowing patients to undergo surgical and obstetric procedures without the distress and pain they would otherwise experience. He designed the apparatus to safely administer ether to the patients and also designed a mask to administer chloroform. [ 8 ] He personally administered chloroform to Queen Victoria when she gave birth to the last two of her nine children, Leopold in 1853 and Beatrice in 1857, [ 9 ] leading to wider public acceptance of obstetric anaesthesia. Snow published an article on ether in 1847 entitled On the Inhalation of the Vapor of Ether. [ 10 ] A longer version entitled On Chloroform and Other Anaesthetics and Their Action and Administration was published posthumously in 1858. [ 11 ]


Map of a later cholera outbreak in London, in 1866

Legend for the map above

Snow was a skeptic of the then-dominant miasma theory that stated that diseases such as cholera and bubonic plague were caused by pollution or a noxious form of "bad air". The germ theory of disease had not yet been developed, so Snow did not understand the mechanism by which the disease was transmitted. His observation of the evidence led him to discount the theory of foul air. He first publicised his theory in an 1849 essay, On the Mode of Communication of Cholera. followed by a more detailed treatise in 1855 incorporating the results of his investigation of the role of the water supply in the Soho epidemic of 1854. [ 12 ]

By talking to local residents (with the help of Reverend Henry Whitehead ), he identified the source of the outbreak as the public water pump on Broad Street (now Broadwick Street ). Although Snow's chemical and microscope examination of a water sample from the Broad Street pump did not conclusively prove its danger, his studies of the pattern of the disease were convincing enough to persuade the local council to disable the well pump by removing its handle. This action has been commonly credited as ending the outbreak, but Snow observed that the epidemic may have already been in rapid decline:

There is no doubt that the mortality was much diminished, as I said before, by the flight of the population, which commenced soon after the outbreak; but the attacks had so far diminished before the use of the water was stopped, that it is impossible to decide whether the well still contained the cholera poison in an active state, or whether, from some cause, the water had become free from it.

Original map by John Snow showing the clusters of cholera cases in the London epidemic of 1854, drawn and lithographed by Charles Cheffins .

Snow later used a dot map to illustrate the cluster of cholera cases around the pump. He also used statistics to illustrate the connection between the quality of the water source and cholera cases. He showed that the Southwark and Vauxhall Waterworks Company was taking water from sewage-polluted sections of the Thames and delivering the water to homes, leading to an increased incidence of cholera. Snow's study was a major event in the history of public health and geography. It is regarded as the founding event of the science of epidemiology .

On proceeding to the spot, I found that nearly all the deaths had taken place within a short distance of the [Broad Street] pump. There were only ten deaths in houses situated decidedly nearer to another street-pump. In five of these cases the families of the deceased persons informed me that they always sent to the pump in Broad Street, as they preferred the water to that of the pumps which were nearer. In three other cases, the deceased were children who went to school near the pump in Broad Street.

With regard to the deaths occurring in the locality belonging to the pump, there were 61 instances in which I was informed that the deceased persons used to drink the pump water from Broad Street, either constantly or occasionally.

The result of the inquiry, then, is, that there has been no particular outbreak or prevalence of cholera in this part of London except among the persons who were in the habit of drinking the water of the above-mentioned pump well.

I had an interview with the Board of Guardians of St James's parish, on the evening of the 7th inst [7 September], and represented the above circumstances to them. In consequence of what I said, the handle of the pump was removed on the following day.

— John Snow, letter to the editor of the Medical Times and Gazette

John Snow memorial and public house on Broadwick Street. Soho

Researchers later discovered that this public well had been dug only 3 feet (0.9 m) from an old cesspit. which had begun to leak fecal bacteria. The nappies of a baby, who had contracted cholera from another source, had been washed into this cesspit. Its opening was originally under a nearby house, which had been rebuilt farther away after a fire. The city had widened the street and the cesspit was lost. It was common at the time to have a cesspit under most homes. Most families tried to have their raw sewage collected and dumped in the Thames to prevent their cesspit from filling faster than the sewage could decompose into the soil.

Thomas Shapter had conducted similar studies and used a point-based map for the study of cholera in Exeter. Devon years before John Snow, although this did not identify the water supply problem that was later held responsible. [ 13 ]

Political controversy

After the cholera epidemic had subsided, government officials replaced the Broad Street pump handle. They had responded only to the urgent threat posed to the population, and afterward they rejected Snow's theory. To accept his proposal would have meant indirectly accepting the oral-fecal method transmission of disease, which was too unpleasant for most of the public to contemplate. [ 14 ]

It wasn't until 1866 that William Farr. one of Snow's chief opponents, realized the validity of his diagnosis when investigating another outbreak of cholera at Bromley by Bow. as mapped here, and issued immediate orders that unboiled water was not to be drunk. [ 15 ]

Public health officials recognise the political struggles in which reformers have often become entangled. [ 16 ] During the Annual Pumphandle Lecture in England, members of the John Snow Society remove and replace a pump handle to symbolise the continuing challenges for advances in public health. [ 17 ]

Later life

In 1830 Snow became a member of the Temperance Movement. and lived for a decade or so as a vegetarian and teetotaler. In the mid-1840s his health deteriorated, and he returned to meat-eating and drinking wine. He continued drinking pure water (via boiling) throughout his adult life. He never married. [ 18 ]

Snow lived at 18 Sackville Street. London, from 1852 to his death in 1858. [ 19 ]

Snow suffered a stroke while working in his London office on 10 June 1858. He was 45 years old at the time. [ 20 ] He never recovered, dying on 16 June 1858. He was buried in Brompton Cemetery. [ 21 ]

Legacy and honours

Other articles

BBC - History - Historic Figures: John Snow (1813

John Snow (1813 - 1858)

John Snow © Snow was a British physician who is considered one of the founders of epidemiology for his work identifying the source of a cholera outbreak in 1854.

John Snow was born into a labourer's family on 15 March 1813 in York and at 14 was apprenticed to a surgeon. In 1836, he moved to London to start his formal medical education. He became a member of the Royal College of Surgeons in 1838, graduated from the University of London in 1844 and was admitted to the Royal College of Physicians in 1850.

At the time, it was assumed that cholera was airborne. However, Snow did not accept this 'miasma' (bad air) theory, arguing that in fact entered the body through the mouth. He published his ideas in an essay 'On the Mode of Communication of Cholera' in 1849. A few years later, Snow was able to prove his theory in dramatic circumstances. In August 1854, a cholera outbreak occurred in Soho. After careful investigation, including plotting cases of cholera on a map of the area, Snow was able to identify a water pump in Broad (now Broadwick) Street as the source of the disease. He had the handle of the pump removed, and cases of cholera immediately began to diminish. However, Snow's 'germ' theory of disease was not widely accepted until the 1860s.

Snow was also a pioneer in the field of anaesthetics. By testing the effects of controlled doses of ether and chloroform on animals and on humans, he made those drugs safer and more effective. In April 1853, he was responsible for giving chloroform to Queen Victoria at the birth of her son Leopold, and performed the same task in April 1857 when her daughter Beatrice was born.

Snow died of a stroke on 16 June 1858.

FREE Cholera Essay

Topics in this paper Popular Topics

Cholera is caused by a comma-shaped bacterium, vibrio cholerae, which is ingested in contaminated water and food. The bacteria multiply enormously in the intestine, where epithelial cells allow fluid to leak into the intestine with intense diarrhea as a result. The word cholera comes from the Greek words meaning bile and flow and the disease has a 50 to 70% mortality rate during the 1800's. Today we now know that cholera can be simply and successfully treated by immediate replacement of the fluid and salts lost through diarrhea. Infected people can be treated with an oral re-hydration solution of sugar and salts mixed with water and drunk in large amounts. Today this same solution is used throughout the world to treat diarrhea. During an epidemic, 80-90% of diarrhea patients can be treated by oral re-hydration alone, but those who become severely dehydrated must be given intravenous fluids.

The conventional wisdom was that cholera was spread from person to person, primarily from people arriving in port cities on ships. In the 1800s, doctors didn't really know what caused it or how to cure it. It became a controversial health issue because many people felt it divided the have's from the have'nots, since cholera mainly infected the poor. In Britain citizens thought it was a way for medical professionals to take bodies for anatomical dissection. It was only in the mid-1800s that the world's first epidemiological study, conducted by British physician John Snow, discovered that many victims had been drinking from the same well. It proved the connection to contaminated water supplies.

The search for a cure was intense because the disease was terrifying. The first cholera outbreaks had been killing thousands and leaving untold others sick. V. cholerae, which hit the Western Hemisphere in the 1830s, disrupts the transport of sodium and potassium in cells, causing diarrhea so severe that a person can lose more than 50 p

This Essay is Approved by Our Editor Essays Related to Cholera

John Snow and His Influence on Public Health - Term Paper

John Snow and His Influence on Public Health

Proposal For:
John Snow and His Influence on Public Health
Monica Rodgers
PU120 Section 1
Professor Nicole Heim
Unit 2 Assignment

John Snow formulated a theory on the transmission of cholera, improved the mode of administration of anesthetics, and made advancements in resuscitation. He is considered a father of epidemiology, even though many of his concepts were not accepted until years after his death.
Among those who have left their mark on the development of public health is John Snow, a man who is considered a father of modern epidemiology. However, many of his concepts were not accepted until after his death. John Snow worked hard and published many great works. In this paper, I will briefly discuss John Snows background, his works, and the outcome of those works.
John Snow was the son of a humble laborer in York, England. Snow’s father eventually became a farmer and landlord after acquiring a sufficient amount of property. Snow on the other hand took a different path in society, becoming an apprentice to William Hardcastle. After obtaining an education from several schools, Snow became a licensed apothecary, surgeon, and physician.
John Snow first encountered cholera in 1831-32 in Newcastle. It was in the London epidemic of 1848-49 that Snow proposed that cholera entered the body through the mouth. In 1849, Snow wrote “On the mode of communication of cholera”. It was dismissed for lack of data.
In 1841, Snow published his first work, entitled “Asphyxia and the resuscitation of still-born children.” He made the premise that respiration was essential to life. He observed that lower temperatures enhanced survival. Snow’s experience showed him that one in twenty newborns died at birth. Snow created a modified device to get air into and out of a newborns lung.
In 1846, Snow heard about the use of anesthetics in America. Anesthetics.

Cholera Map of Dr

A Map Stops Cholera

By Matt Rosenberg. Geography Expert

Updated August 21, 2015.

In the mid-1850s, doctors and scientists knew there was a deadly disease called the "cholera poison" rampaging through London, but they weren't sure how it was being transmitted. Dr. John Snow used mapping and other techniques that would later be known as medical geography to confirm that the transmission of the disease occurred by swallowing contaminated water or food. Dr. Snow's mapping of the 1854 cholera epidemic has saved countless lives.

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The Mysterious Disease

While we now know that this "cholera poison" is spread by the bacterium Vibrio cholerae. scientists in the early 19th century thought it was spread by miasma ("bad air"). Without knowing how an epidemic spreads, there is no way to stop it.

When a cholera epidemic occurred, it was deadly. Since cholera is an infection of the small intestine, it results in extreme diarrhea. This often leads to massive dehydration, which can create sunken eyes and blue skin. Death can occur within hours.

If treatment is given quickly enough, the disease can be overcome by giving the victim a lot of fluids -- either by mouth or intravenously (directly into the blood stream).

However, in the 19th century, there were no cars or telephones and so getting quick treatment was often difficult. What London -- and the world -- really needed was someone to figure out how this deadly disease spread.

The 1849 London Outbreak

While Cholera has existed in Northern India for centuries -- and it is from this region that regular outbreaks are spread -- it was the London outbreaks that brought cholera to the attention of British physician Dr. John Snow.

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In a 1849 cholera outbreak in London, a large proportion of the victims received their water from two water companies. Both of these water companies had the source of their water on the Thames River, just downstream from a sewer outlet.

Despite this coincidence, the prevailing belief of the time was that it was "bad air" that was causing the deaths. Dr. Snow felt differently, believing that the disease was cause by something ingested. He wrote down his theory in the essay, "On the Mode of Communication of Cholera," but neither the public nor his peers were convinced.

The 1854 London Outbreak

When another cholera outbreak hit the Soho area of London in 1854, Dr. Snow found a way to test his ingestion theory.

Dr. Snow plotted the distribution of deaths in London on a map. He determined that an unusually high number of deaths were taking place near a water pump on Broad Street (now Broadwick Street). Snow's findings led him to petition the local authorities to remove the pump's handle. This was done and the number of cholera deaths was dramatically reduced.

The pump had been contaminated by a dirty baby diaper that had leaked the cholera bacteria into the water supply.

Cholera Is Still Deadly

Although we now know how cholera is spread and have found a way to treat patients who have it, cholera is still a very deadly disease. Striking quickly, many people with cholera don't realize how serious their situation is until it is too late.

Also, new inventions such as airplanes have aided the spread of cholera, letting it surface in parts of the world where cholera has otherwise been eradicated.

According to the World Health Organization. there are up to 4.3 million cases of cholera each year, with approximately 142,000 deaths.

Medical Geography

The work of Dr. Snow stands out as one of the most famous and earliest cases of medical geography. where geography and maps are utilized to understand the spread of a disease. Today, specially trained medical geographers and medical practitioners routinely use mapping and advanced technology to understand the diffusion and spread of diseases such as AIDS and cancer .

A map is not just an effective tool for finding the right place, it can also save a life.

John snow cholera essay

Mapping the 1854 London Cholera Outbreak

Dr. John Snow is regarded as one of the founding fathers of modern epidemiology. As London suffered a series of cholera outbreaks during the mid-19th century, Snow theorized that cholera reproduced in the human body and was spread through contaminated water. This contradicted the prevailing theory that diseasses were spread by "miasma" in the air.

London's water supply system consisted of shallow public wells where people could pump their own water to carry home, and about a dozen water utilities that drew water from the Thames to supply a jumble of water lines to more upscale houses. London's sewage system was even more ad hoc: privies emptied into cesspools or cellars more often than directly into sewer pipes. So the pervasive stench of animal and human feces combined with rotting garbage made the miasma theory of disease seem very plausible. Disease was more prevalent in lower-class neighborhoods because they stank more, and because the supposed moral depravity of poor people weakened their constitutions and made them more vulnerable to disease.

The September 1854 cholera outbreak was centered in the Soho district, close to Snow's house. Snow mapped the 13 public wells and all the known cholera deaths around Soho, and noted the spatial clustering of cases around one particular water pump on the southwest corner of the intersection of Broad (now Broadwick) Street and Cambridge (now Lexington) Street. He examined water samples from various wells under a microscope, and confirmed the presence of an unknown bacterium in the Broad Street samples. Despite strong scepticism from the local authorities, he had the pump handle removed from the Broad Street pump and the outbreak quickly subsided.

Snow subsequently published a map of the epidemic to support his theory. A detail fom this map is shown below. The complete map shows the locations of the 13 public wells in the area, and the 578 cholera deaths mapped by home address, marked as black bars stacked perpendicular to the streets.

Some anomalies are worth noting. Although the large workhouse just north of Broad Street housed over 500 paupers, it suffered very few cholera deaths because it had its own well (not shown on the map). Likewise, The workers at the brewery one block east of the Broad Street pump could drink all the beer they wanted; the fermentation killed the cholera bacteria, and none of the brewery workers contracted cholera. Many of the deaths further away from the Broad Street pump were people who walked to work or market on the Broad Street and drank from that well. The water from the Broad Street well reportedly tasted better than water from most of the neighboring wells, particularly the smelly water from the Carnaby Street/Little Marlborough Street well a few blocks to the northeast.

Steven Johnson's 2006 book The Ghost Map: the Story of London's Most Terrifying Epidemic, and How it Changed Science, Cities and the Modern World (available in paperback) is a highly entertaining account of the epidemic and Snow's analysis of it.

Cholera- Biological Weapons

Weapons of Mass Destruction (WMD) Cholera

Cholera is a disease caused by the bacteria Vibrio cholera. The disease first emerged in the 1800s from Calcutta, India where it had caused disease for centuries. Since then, 7 cholera pandemics have swept through the world. 16 strains of Vibrio cholera have been discovered with the deadliest being the 01 and 0139 strains of the bacteria. The bacterium secretes chloride to block the small intestine's ability to absorb sodium, which produces thin, grayish brown, mucoid diarrhea in the victims. Victims lose 10-12 liters of fluids a day.

The First Asiatic Cholera Pandemic, suspected to have begun at the Kumbh festival on the upper Ganges River, lasted from 1817 to 1823. 10,000 British troops and countless Indians died during this pandemic. By 1820, the pandemic had spread to Thailand and Indonesia, and then spread throughout Asia to Russia and Turkey leaving destruction in its path. The severe winter of 1823-4 stopped the pandemic at the doorsteps of Europe in the Caspian Sea area.

The Second Pandemic lasted from 1826 to 1837. It spread from the Indian subcontinent to Afghanistan and Russia by 1827, and Poland, Hungary, Germany, and the British Isles by 1831. Immigrants brought the deadly pandemic to Canada and the United States in 1832, and cholera spread down to Mexico and Cuba. The pandemic reached Portugal and Spain by 1833 and then spread across to France and Italy between 1834 and 1836. Through other branches of the pandemic, cholera was spread to Syria, Palestine, Mecca, and Cairo. The disease spread along the trade routes, from port to port, aided by the urbanization of the industrial revolution.

The Third Pandemic began in India and spanned from 1846 to 1863. It was the most deadly of the cholera pandemics. The pandemic began in the lower Bengal region and spread to Afghanistan in 1839. The bacteria was transported by British troops to China in 1840 and spread through the Philippines and Burma by 1844. In 1845, the pandemic reappeared in India and devastated the Middle East. After a brief pause, it spread up the Caspian coast to penetrate Russia, and by 1848, it had unleashed its fury on Europe. In 1854, 23,000 victims died in Britain alone. Cholera entered the United States through New York and New Orleans. The pandemic also spread throughout the Americas and Africa, repeatedly being renewed from its Indian source.

John Snow and the Broad Street Pump

Besides being dubbed the "Father of Epidemiology" for solving the mystery of cholera, John Snow was also a renowned anesthesiologist and credited as the first to use chloroform. Unlike most during the 19th century, Snow believed that the cholera contagion entered the victim through the mouth rather than being brought by "miasma" or a cloud of bad vapor in the air that descended on victim after victim. In 1849, Snow published an essay titled "On the Mode of Communication of Cholera" arguing that "cholera poison" spread through contaminated food or water.

During the 1853-4 outbreak of cholera in London (Third Cholera Pandemic), John Snow was able to test his theory. In late August 1854, a heavy outbreak occurred in the area of Golden Square and Soho Square south of London's Oxford Street. Snow carefully reviewed records of all fatal cases of cholera in the area at the General Register's office and conducted interviews of family members of the victims. Though his detective work, Snow constructed a spatial tally of all deaths in the area. There were thirteen water pumps in the area. Snow discovered that the heaviest casualties were clustered around the Broad Street water pump.

According to Snow's records, most public houses and coffee shops in the area mixed pump water with spirits. At a local coffee shop, a popular place frequented by mechanics, water was had with dinner. The shop reported 9 dead among its customers. A local brewery that had its own water supply and allocated to its employees a free allowance of beer suffered no cholera deaths among its 70 workmen. A lady who moved away from the Soho area to Hampstead, where there was no epidemic, but still drank from the Broad Street pump because she enjoyed the taste of its water, also contracted cholera and died. A gentleman who came to see his dying brother arrived too late. He stayed only 20 minutes, but drank water from the Broad Street pump, and was attacked with cholera the next day and died. In his famous spatial analysis, Snow charted 616 deaths around the Broad Street pump.

Snow recommended to the local authorities that the handle be removed from the Broad Street pump, which was done in 8 September 1854. The removal of the pump handle correlated with a decline in cholera cases, but this decline may have been due to the natural shape of the epidemic and the fact that possible human hosts had deserted the area rather than the removal of the pump handle. It was disclosed that the Broad Street pump reached 28 feet into the ground within yards of a sewer at 22 feet. Authorities remained skeptical; Snow had not produced direct evidence of the "cholera poison" he claimed had caused the disease. Snow further attempted to dispel their skepticism through what he called "The Grand Experiment."

Two water companies serviced the London area: the Lambeth Water Company and the Southwark and Vauxhall Water Company. While the former took its water from the Thames about 20 miles upstream from the London city sewers, the later took its water downstream. Snow examined records of the households serviced by the two water companies. Those serviced by Lambeth Water Company saw 37 deaths every 10,000 households and those serviced by Southwark and Vauxhall Water Company saw 315 deaths every 10,000 households. Snow's results showed a strong correlation between the consumption of polluted London waters and cholera deaths.

Fighting Cholera

The Fourth Pandemic began in 1865 in the Lower Bengal region of India. It was suspected that Indian Muslim pilgrims visiting Mecca spread the disease to the Middle East. Mecca was dubbed the relay point of cholera from east to west. It was reported that at least 30,000 of the 90,000 pilgrims were victims of the disease. The pandemic spread into Europe by 1865, and killed 90,000 in Russia in 1866. The disease returned to Russia from 1868 to 1869 and ravaged the Black Sea ports in 1871. Africa and the United States were heavily affected.

Robert Koch in 1876 isolated and cultivated the curved bacillus of cholera Vibrio cholera. a bacterium that continued to appear in a victim's feces long after symptoms subsided. Scientific evidence finally supported what John Snow hypothesized: cholera was spread from person to person through contaminated food and water. The deadly pandemics were helped along by open sewers, overflowing cesspools and latrines, and the absence of urban sanitation measures. In 1879, Louis Pasteur developed a cholera vaccine for fowl. Waldemar Haffkine, a student of Pasteur, developed a human vaccine for cholera and in 1892 tested the vaccine on himself, his first human subject. In a report to the Biological Society of Paris on 30 July 1892, Haffkine shared the success of his experiment: the side effects of the human vaccine were no more than slight fever, pain, and swelling. In 1893, Haffkine took the vaccine to India where he eventually inoculated over 20,000 subjects. Cholera fatality rate among the test subjects was 2% while they raged at 22-45% among the remaining population. Later, Haffkine also developed a vaccine for bubonic plague. In 1902, a public scandal transpired when a laboratory contamination of tetanus killed 19 cholera vaccine patients, but Haffkine was eventually exonerated of guilt. An inexperienced laboratory assistant had accidentally contaminated the vaccine. In 1925, the Plague Research Laboratory in Bombay was renamed the Haffkine Laboratory.

The Fifth Pandemic began in 1881 in the Bengal region and spread throughout India to Korea, Thailand, China and Japan. Robert Koch's discovery of Vibrio cholera allowed authorities to impose quarantine measures to fight the pandemic. Although cholera breached the strict quarantine measures and outbreaks occurred in France, Italy and Spain in 1884, this cholera pandemic was kept out of Britain and the United States thanks to quarantine measures. Despite these quarantine successes, the pandemic swept through Asia, South America, Africa, and parts of France and Germany.

The Sixth Pandemic from 1899 to 1923 also originated in northern India and caused more than 800,000 deaths in India in 1900, the highest recorded in India for a single year. India continued to suffer from cholera outbreaks during the first decades of the century. The pandemic moved up the Black Sea region into Mesopotamia, Persia, and then Russia by 1910. The Americas escaped from the pandemic except for the islands of Madeira in the Atlantic. Russian immigrants in 1910 brought the disease to Madeira. Incidents of cholera in Western Europe were rare, but central and southeastern Europe was affected. In 1910, gypsies brought the disease from Russia to Italy. During World War I, Austria and Hungary suffered from outbreaks, but German troops were vaccinated against cholera.

The Seventh Pandemic was named the El Tor pandemic caused by a strain of cholera, Vibrio comma. isolated by F. Gottslich in 1905 when he examined six dead Muslim pilgrims in El Tor quarantine station outside of Mecca. The Seventh Pandemic began in Sulawesi, Indonesia, and in 1961-62, spread among the Pacific islands of southwest Asia. In 1963, the pandemic arrived on the Asian mainland and traveled to India, Pakistan, the Middle East and the Soviet Union. In 1970, the pandemic arrived in Ethiopia and spread through the African continent. Cholera was still active in Africa in 1994 when the refugee camps set up after the Rwandan Genocide created ideal conditions for an outbreak. In 1991, a El Tor cholera outbreak occurred in Peru where cholera was last seen a century before. Epidemiologists hypothesized the disease was brought to Peru on ships from Asia, or that the marine environment acted as a holding space for cholera.

In the early 1990s, a new strain, cholera 0139, was discovered in Bangladesh and India. The 0139 strain is a more virulent, infectious, and robust strain on which traditional cholera vaccines has limited effect. Many scientists believed this to be the beginning of a new, eighth, global pandemic.

As of turn of the 21st century, epidemiologists are still uncertain about the origins of cholera pandemics, but all global pandemics originated on the Indian subcontinent. Scientists hypothesized that the disease flourishes on a seasonal, ecological cycle when the water is at the correct temperatures and salinity. Scientists also linked cholera bloom to phytoplankton blooms. Research by Dr. Colwell of the National Science Foundation connected cholera bacteria to copepods, crustaceans in the zooplankton family. Cholera bacteria ride on the backs of copepods and colonize in their intestines. Dr. Colwell also noted that cholera can enter a dormant, spore-like state that allows it to survive in adverse aqueous environments while remaining infectious.

Few cases of cholera occur in the developed world due to improvements in sanitation standards and urban building codes, but the developing world still suffer from the Seventh and the new 0139 Cholera Pandemic.

Cholera as a Biological Weapon

During World War II, the Japanese biological weapons program known as Unit 731 located in Pingfan Manchuria (24 kilometers south of Harbin) experimented with Vibrio cholera as a weapons agent. It was reported that the Japanese dropped cholera and typhus cultures into more than 1,000 Chinese wells and reportedly caused 10,000 cases in 1941. However, an estimated 1,700 of the deaths were Japanese soldiers, a testimony to the difficulty of protecting one's own troops from biological agents and controlling infections.

South Africa's biological weapons program, Project Coast (1981-1994), under the direction of Colonel Wouter Basson, developed cholera as a possible biological agent. It was reported that during South Africa's civil war, cholera, anthrax and other bacteria were released into water in rebel-held areas.

Iraq's biological weapons program reportedly began with the start of the Al-Hazen Institute in 1974 where cholera was one of the biological agents under study. North Korea reportedly also studied cholera as a possible biological weapons agent.

John snow cholera essay

(Click on thumbnails to enlarge image)

In its most severe forms, cholera is one of the most rapidly fatal illnesses known. It is closely identified with sanitation problems, particulary contamination of drinking water from sewage carrying the bacterium Vibrio cholerae.

Cholera likely has its origins in and is endemic to the Indian subcontinent. The disease spread by trade routes (land and sea) to Russia, then to Western Europe, and from Europe to North America. Cholera is now no longer considered a pressing health threat in Europe and North America due to filtering and chlorination of water supplies, but still heavily affects populations in developing countries.

The first major cholera pandemic lasted from 1816 to 1826. Previously restricted, the pandemic began in Bengal, and then spread across India and on into Russia, China and Indonesia. Seven major subsequent pandemics killed millions more and spread the disease through much of the world.

Prevention of cholera involves antibacterial treatment of sewage, sterilization of wastes from cholera victims, water purification.

- Drawn from Wikipedia, 2010

John Snow and the struggle to eradicate cholera

John Snow (15 March 1813 - 16 June 1858) was a British physician and a leader in the adoption of anaesthesia and medical hygiene. He is considered to be one of the fathers of epidemiology, because of his work in tracing the source of a cholera outbreak in Soho, England, in 1854.

Snow was a sceptic of the then dominant miasma theory that stated that diseases such as cholera or the Black Death were caused by pollution or a noxious form of "bad air". The germ theory was not widely accepted by this time, so he was unaware of the mechanism by which the disease was transmitted, but evidence led him to believe that it was not due to breathing foul air. He first publicized his theory in an essay On the Mode of Communication of Cholera in 1849. In 1855 a second edition was published, with a much more elaborate investigation of the effect of the water-supply in the Soho, London epidemic of 1854.

By talking to local residents (with the help of Reverend Henry Whitehead), he identified the source of the outbreak as the public water pump on Broad Street (now Broadwick Street). Although Snow's chemical and microscope examination of a sample of the Broad Street pump water was not able to conclusively prove its danger, his studies of the pattern of the disease were convincing enough to persuade the local council to disable the well pump by removing its handle.

- drawn from Wikipedia, 2010

Dr. John Snow (1813-1858).

Creative Commons image

Original map made by John Snow in 1854. Cholera cases are highlighted in black.

Map in Snow's book of 1855.

Snow, J. "On the Mode of Communication of Cholera," 1855. This is Map 2 in John Snow's book. It was used by Dr. Snow to describe the grand experiment of 1854 comparing cholera mortality among persons consuming contaminated water (Southwark and Vauxhall Company - blue, but faded to green on the map) versus cleaner water (Lambeth Company - red). The overlapping area (purple but faded to gray-red on the map) is where John Snow analyzed the results of a natural experiment.

There is a plaque commemorating Snow and his 1854 study in the place of the water pump on Broad Street (now Broadwick Street) with a water pump with its handle removed, near what is now "The John Snow" public house.