1854 Broad Street cholera outbreak

The Broad Street cholera outbreak (or Golden Square outbreak) was a severe outbreak of cholera that occurred in 1854 near Broad Street (now Broadwick Street) in the Soho district of the City of Westminster, London, England, and occurred during the 1846–1860 cholera pandemic happening worldwide. This outbreak, which killed 616 people, is best known for the physician John Snow's study of its causes and his hypothesis that germ-contaminated water was the source of cholera, rather than particles in the air (referred to as "miasmata").[1][2] This discovery came to influence public health and the construction of improved sanitation facilities beginning in the mid-19th century. Later, the term "focus of infection" started to be used to describe sites, such as the Broad Street pump, in which conditions are good for transmission of an infection. Snow's endeavor to find the cause of the transmission of cholera caused him to unknowingly create a double-blind experiment.

John Snow memorial and pub
Broadwick Street showing the John Snow memorial and public house. The memorial pump was removed due to new construction in March 2016. A plaque affixed to the public house reads: The Red Granite kerbstone mark is the site of the historic Broad Street pump associated with Dr John Snow's discovery in 1854 that cholera is conveyed by water.


Punch-A Court for King Cholera
A Court for King Cholera. Illustration from Punch (1852).

In the mid-19th century, the Soho district of London had a serious problem with filth due to the large influx of people and a lack of proper sanitary services: the London sewer system had not reached Soho. Cowsheds, slaughter houses, and grease-boiling dens lined the streets and contributed animal droppings, rotting fluids and other contaminants to the primitive Soho sewer system.[3] Many cellars had cesspools underneath their floorboards, which formed from the sewers and filth seeping in from the outside.[3] Since the cesspools were overrunning, the London government decided to dump the waste into the River Thames, contaminating the water supply.[4] London had already suffered from a "series of debilitating cholera outbreaks".[5] These included outbreaks in 1832 and 1849 which killed a total of 14,137 people.[5]

Competing theories of cholera

Preceding the 1854 Broad Street cholera outbreak, physicians and scientists held two competing theories on the causes of cholera in the human body: miasma theory and germ theory.[6] The London medical community debated between these causes for the persistent cholera outbreaks in the city. The cholera-causing bacterium Vibrio cholerae was isolated in 1854, but the finding did not become well-known and accepted until decades later.[7]

Miasma theory

Miasma theorists concluded that cholera was caused by particles in the air, or "miasmata", which arose from decomposing matter or other dirty organic sources. "Miasma" particles were thought to travel through the air and infect individuals, and thus cause cholera.[6] Dr. William Farr, the commissioner for the 1851 London census and a member of the General Register's Office, believed that miasma arose from the soil surrounding the River Thames. It contained decaying organic matter which contained miasmatic particles and was released into the London air. Miasma theorists believed in "cleansing and scouring, rather than through the purer scientific approach of microbiology".[6] Farr later agreed with Snow's germ theory following Snow's publications.[8]

Germ theory

In contrast, the germ theory held that the principal cause of cholera was a germ cell that had not yet been identified. Snow theorized that this unknown germ was transmitted from person to person by individuals ingesting water. John Simon, a pathologist and the lead medical officer for London labeled Snow's germ theory as "peculiar".[6]

Excerpt from John Simon:

"This doctrine is, that cholera propagates itself by a 'morbid matter' which, passing from one patient in his evacuations, is accidentally swallowed by other persons as a pollution of food or water; that an increase of the swallowed germ of the disease takes place in the interior of the stomach and bowels, giving rise to the essential actions of cholera, as at first a local derangement; and that 'the morbid matter of cholera having the property of reproducing its own kind must necessarily have some sort of structure, most likely that of a cell."[6]

Even though Simon understood Snow's theory, he questioned its relation to the cause of cholera.

Investigation by John Snow

Original map by John Snow showing the clusters of cholera cases (indicated by stacked rectangles) in the London epidemic of 1854. The contaminated pump is located at the intersection of Broad Street and Cambridge Street (now Lexington Street), running into Little Windmill Street.

The Broad Street outbreak was an effect rather than a cause of the epidemic. Snow's conclusions were not predominantly based on the Broad Street outbreak, as he noted that he hesitated to come to a conclusion based on a population that had predominantly fled the neighborhood and redistributed itself. He feared throwing off results of the study.[9]

Snow was skeptical of the prevailing miasma theory, which held 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 established at this point (Louis Pasteur did not propose it until 1861). Snow did not understand the mechanism by which disease was transmitted, but the evidence led him to believe that it was not due to breathing foul air. Based on the pattern of illness among residents, Snow hypothesized that cholera was spread by an agent in contaminated water.[10] He first published his theory in 1849, in an essay titled "On the Mode of Communication of Cholera".[11] In 1855 he published a second edition, including a more elaborate investigation of the effect of the water supply in the 1854 Soho outbreak.[12]

The cholera epidemic of 1849-1854 was also related to the water supplied by companies in London at the time. The main players were the Southwark and Vauxhall Company, and the Lambeth Water Company. Both companies provided water to their customers that was drawn from the Thames River, which was highly contaminated with visible and invisible products and bacteria. Dr Hassall examined the filtered water and found it contained animal hair, among other foul substances. He made the remark that:

It will be observed, that the water of the companies of the Surrey Side of London, viz., the Southwark, Vauxhall, and Lambeth, is by far the worst of all those who take their supply from the Thames[13]

Other companies, such as the New River Company and Chelsea Company, were observed to have better filtered water; few deaths occurred in the neighborhoods which they supplied. Snow concluded that the companies were not to blame for the spread of the epidemic. These two companies not only obtained their water from cleaner sources than the Thames, but they filtered the water and treated it until there were no obvious contaminants.[13]

As mentioned above, Snow is known for his influence on public health, which arose after his studies of the cholera epidemic. In attempting to figure out who was receiving impure water in each neighborhood, what is now known as a double-blind experiment fell right into his lap. He describes the conditions of the situation in his essays:

In many cases a single house has a supply different from that on either side. Each company supplies both rich and poor, both large houses and small; there is no difference in the condition or occupation of the persons receiving the water of the different companies...As there is no difference whatever either in the houses or the people receiving the supply of the two Water Companies, or in any of the physical conditions with which they are surrounded, it is obvious that no experiment could have been devised which would more thoroughly test the effect of water supply on the progress of Cholera than this, which circumstances placed ready made before the observer. The experiment too, was on the grandest scale. No fewer than three hundred thousand people of both sexes, of every age and occupation, and of every rank and station, from gentlefolks down to the very poor, were divided into two groups without their choice, and, in most cases, without their knowledge; one group being supplied water containing the sewage of London, and amongst it, whatever might have come from the cholera patients, the other group having water quite free from such impurity.[13]

Snow went on to study the water contents from each home through a test performed on each sample. In this way, it could be deduced from which supplier the home was receiving their water. He concluded that it was indeed impure water on behalf of the big companies that allowed the spread of cholera to progress rapidly. He went on to prove his theory through the observation of prisons in London, finding that cholera ceased in these places only a few days after switching to cleaner water sources. [13]

Broad Street outbreak

On 31 August 1854, after several other outbreaks had occurred elsewhere in the city, a major outbreak of cholera occurred in Soho. Snow, the physician who eventually linked the outbreak to contaminated water, later called it "the most terrible outbreak of cholera which ever occurred in this kingdom."[14]

Over the next three days, 127 people on or near Broad Street died. During the next week, three quarters of the residents had fled the area. By 10 September, 500 people had died and the mortality rate was 12.8 percent in some parts of the city. By the end of the outbreak, 616 people had died.

Many of the victims were taken to the Middlesex Hospital, where their treatment was superintended by Florence Nightingale, who briefly joined the hospital in early September in order to help with the outbreak. According to a letter from Elizabeth Gaskell, "She herself [Nightingale] was up night and day from Friday afternoon (Sept. 1) to Sunday afternoon, receiving the poor creatures (chiefly fallen women of that neighbourhood - they had it the worst) who were being constantly brought in - - undressing them - putting on turpentine stupes, etc, doing it herself to as many as she could manage".[15]

By talking to local residents (with the help of Reverend Henry Whitehead), Snow identified the source of the outbreak as the public water pump on Broad Street (now Broadwick Street) at Cambridge Street.[16] Although Snow's chemical and microscope examination of a sample of the water from this Broad Street pump water did not conclusively prove its danger, his facts about the patterns of illness and death among residents in Soho persuaded the St James parish authorities to disable the well pump by removing its handle.

Although this action has been popularly reported as ending the outbreak, the epidemic may have already been in rapid decline, as explained by Snow:

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.[17]

Snow later used a dot map to illustrate how cases of cholera occurred around this pump.[18] Snow's efforts to connect the incidence of cholera with potential geographic sources was based on creating what is now known as a Voronoi diagram. He mapped the locations of individual water pumps and generated cells which represented all the points on his map which were closest to each pump. The section of Snow's map representing areas in the city where the closest available source of water was the Broad Street pump included the highest incidence of cholera cases. He also used statistics to compare fatalities among the customers of London's different water suppliers, and to illustrate the connection between the quality of the source of water and the number of cholera cases.[19]

Regarding the decline in cases related to the Broad Street pump, Snow said:

It will be observed that the deaths either very much diminished, or ceased altogether, at every point where it becomes decidedly nearer to send to another pump than to the one in Broad street. It may also be noticed that the deaths are most numerous near to the pump where the water could be more readily obtained. [13]

There was one significant anomaly—none of the workers in the nearby Broad Street brewery contracted cholera. As they were given a daily allowance of beer, they did not consume water from the nearby well.[20] During the brewing process, the wort (or un-fermented beer) is boiled in part so that hops can be added. This step killed the cholera bacteria in the water they had used to brew with, making it safe to drink. Snow showed that the Southwark and Vauxhall Waterworks Company were taking water from sewage-polluted sections of the Thames and delivering it to homes, resulting in an increased incidence of cholera among its customers. Snow's study is part of the history of public health and health geography. It is regarded as the founding event of epidemiology.

In Snow's own words:

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 was, that there had 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 Thursday, the 7th 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.[21]

It was discovered later that this public well had been dug 3 feet (0.9 m) from an old cesspit that had begun to leak faecal bacteria. Waste water from washing nappies, used by a baby who had contracted cholera from another source, drained into this cesspit. Its opening was under a nearby house that had been rebuilt further away after a fire and a street widening. At the time there were cesspits 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.

At the same time, an investigation of cholera transmission was being conducted in Deptford. Around 90 people died within a few days in that town, where the water was known to be clean, and there had been no previous outbreaks of cholera. Snow was informed that the water had recently turned impure. Residents were forced to let the water run for a while before using it, in order to let the sudsy, sewer-like water run until it was clear. Snow, finding that the water the residents were using was not different from the usual water from their pump, determined that the outbreak must be caused by a leak in the pipes that allowed surrounding sewage and its contaminants to seep in to the water supply. This scenario was similar to that of the Broad Street outbreak. The incoming water was being contaminated by the increasing levels of sewage, coupled with the lack of proper and safe plumbing.[12]

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 afterwards they rejected Snow's theory. To accept his proposal would have meant indirectly accepting the oral-faecal method of transmission of disease, which was too unpleasant for most of the public to contemplate.[22]

Snow's post-outbreak evaluation

Snow's analysis of cholera and cholera outbreaks extended past the closure of the Broad Street pump. He concluded that cholera was transmitted through and affected the alimentary canal within the human body. Cholera did not affect either the circulatory or the nervous system and there was no "poison in the blood...in the consecutive fever...the blood became poisoned from urea getting into the circulation".[23] According to Snow, this "urea" entered the blood through kidney failure. (Acute renal failure is a complication of cholera.)[24]

Therefore, the fever was caused by kidney failure, not by a poison already present in the subject's bloodstream. Popular medical practices, such as bloodletting, could not be effective in such a case. Snow also argued that cholera was not a product of Miasma. "There was nothing in the air to account for the spread of cholera".[23] According to Snow, cholera was spread by persons ingesting a substance, not through atmospheric transmittal. Snow cited a case of two sailors, one with cholera and one without. Eventually the second became sick as well from accidentally ingesting bodily fluids of the first.

Involvement of Henry Whitehead

Whitehead henry1884
Rev. Henry Whitehead

The Reverend Henry Whitehead was an assistant curate at St. Luke's church in Soho during the 1854 cholera outbreak.

A former believer in the miasma theory of disease, Whitehead worked to disprove false theories. He was influenced by Snow's idea that cholera spreads by consumption of water contaminated by human waste. Snow's work, particularly his maps of the Soho area cholera victims, convinced Whitehead that the Broad Street pump was the source of the local infections. Whitehead joined Snow in tracking the contamination to a faulty cesspool and the outbreak's index case (the baby with cholera).[25]

Whitehead's work with Snow combined demographic study with scientific observation, setting an important precedent for epidemiology.[26]

Board of Health

The Board of Health in London had several committees, of which the Committee for Scientific Inquiries was placed in charge of investigating the cholera outbreak. They were to study the atmospheric environment in London; however, they were also to examine samples of water from several water companies in London. The committee found that the most contaminated water supply came from the South London water companies, Southwark and Vauxhall.[2]

As part of the Committee for Scientific Inquiries, Richard Dundas Thomson and Arthur Hill Hassall examined what Thomson referred to as "vibriones". Thomson examined the occurrence of vibriones in air samples from various cholera wards and Hassall observed vibriones in water samples. Neither identified vibriones as the cause of cholera.[2]

As part of their investigation of the cholera epidemic, the Board of Health sent physicians to examine in detail the conditions of the Golden Square neighbourhood and its inhabitants. The Board of Health ultimately attributed the 1854 epidemic to miasma.[2]

Dr Edwin Lankester's evaluation

Dr Edwin Lankester was a physician on the local research conglomerate that studied the 1854 Broad Street Cholera Epidemic. In 1866, Lankester wrote about Snow's conclusion that the pump itself was the cause of the cholera outbreak. He agreed with Snow at the time; however, his opinion, like Snow's, was not publicly supported. Lankester subsequently closed the pump due to Snow's theory and data on the pattern of infection, and infection rates dropped significantly. Lankester eventually was named the first medical officer of health for the St. James District in London, the same area where the pump was located.[23]

Broadwick Street Pump in the 21st century

A replica pump was installed in 1992 at the site of the 1854 pump. Every year the John Snow Society holds "Pumphandle Lectures" on subjects of public health. Until August 2015, when the pump was removed due to redevelopment, they also held a ceremony here in which they removed and reattached the pump handle to pay tribute to Snow's historic discovery. The original location of the historic pump is marked by a red granite paver. In addition, plaques on the John Snow pub at the corner describe the significance of Snow's findings at this site.[27]

See also


  1. ^ Eyeler, William (July 2001). "The changing assessments of John Snow's and William Farr's Cholera Studies". Sozial- und Präventivmedizin. 46 (4): 225–32. doi:10.1007/BF01593177. PMID 11582849.
  2. ^ a b c d Paneth, N; Vinten-Johansen, P; Brody, H; Rip, M (1998-10-01). "A rivalry of foulness: official and unofficial investigations of the London cholera epidemic of 1854". American Journal of Public Health. 88 (10): 1545–1553. doi:10.2105/ajph.88.10.1545. ISSN 0090-0036. PMC 1508470. PMID 9772861.
  3. ^ a b Frerichs, Ralph R. "Broad Street Pump Outbreak". www.ph.ucla.edu. Retrieved 2017-02-24.
  4. ^ Paneth, Nigel; Vinten-Johansen, Peter (October 1998). "A Rivalry of Foulness: Official and Unofficial Investigations of the London Cholera Epidemic of 1854". American Journal of Public Health. 88 (10): 1545–1553. doi:10.2105/ajph.88.10.1545. PMC 1508470. PMID 9772861.
  5. ^ a b "Broad Street Cholera Pump". Atlas Obscura. Retrieved 2017-02-24.
  6. ^ a b c d e Frerichs, Ralph R. "Competing Theories of Cholera". www.ph.ucla.edu. Retrieved 2017-03-05.
  7. ^ "John Snow | British physician". Encyclopedia Britannica. Retrieved 2017-07-28.
  8. ^ "John Snow | British physician". Encyclopedia Britannica. Retrieved 2017-07-28.
  9. ^ Snow, John (1855). On the Mode of Communication of Cholera. London: John Churchill.
  10. ^ "John Snow | British physician". Encyclopedia Britannica. Retrieved 2017-02-24.
  11. ^ Snow, John (1849). On the Mode of Communication of Cholera (PDF). London: John Churchill.
  12. ^ a b Snow 1855.
  13. ^ a b c d e Snow 1855, pp. [1].
  14. ^ Robert Friis. Epidemiology 101. Jones & Bartlett. p. 13.
  15. ^ O'Malley, Ida (1931). Florence Nightingae, 1820-1856, A Study of Her Life Down to the End of the Crimean War. London: Thornton Butterworth. p. 208.
  16. ^ 51°30′48″N 0°8′12″W / 51.51333°N 0.13667°WCoordinates: 51°30′48″N 0°8′12″W / 51.51333°N 0.13667°W
  17. ^ Snow 1855, p. 38.
  18. ^ Snow 1855, p. 45.
  19. ^ Johnson, Steven (2006). The Ghost Map: The Story of London's Most Terrifying Epidemic – and How it Changed Science, Cities and the Modern World. Riverhead Books. pp. 195–196. ISBN 978-1-59448-925-9.
  20. ^ Snow 1855, p. 42.
  21. ^ Snow 1855, pp. 39-40.
  22. ^ Frank Chapelle, Wellsprings, New Brunswick, New Jersey: Rutgers University Press, 2005, p. 82
  23. ^ a b c Frerichs, Ralph R. "John Snow and the removal of the Broad Street pump handle". www.ph.ucla.edu. Retrieved 2017-03-05. Dr. Edwin Lankester wrote: 'The Board of Guardians met to consult as to what ought to be done. Of that meeting, the late Dr. Snow demanded an audience. He was admitted and gave it as his opinion that the pump in Broad Street, and that pump alone, was the cause of all the pestilence. He was not believed -- not a member of his own profession, not an individual in the parish believed that Snow was right. But the pump was closed nevertheless and the plague was stayed.'
  24. ^ Knobel, B.; Rudman, M.; Smetana, S. (1995-12-15). "[Acute renal failure as a complication of cholera]". Harefuah. 129 (12): 552–555, 615. ISSN 0017-7768. PMID 8682355.
  25. ^ Johnson, Steven (2006). The Ghost Map: The Story of London's Most Terrifying Epidemic – and How it Changed Science, Cities and the Modern World. Riverhead Books. p. 206. ISBN 978-1-59448-925-9.
  26. ^ Frerichs, Ralph R (11 October 2006). "Reverend Henry Whitehead". Archived from the original on 16 December 2007. Retrieved 2007-12-10.
  27. ^ "Broad Street Cholera Pump". Atlas Obscura. Retrieved 2017-03-05.


External links

1846–1860 cholera pandemic

The third cholera pandemic (1846–60) was the third major outbreak of cholera originating in India in the nineteenth century that reached far beyond its borders, which researchers at UCLA believe may have started as early as 1837 and lasted until 1863. In Russia, more than one million people died of cholera. In 1853–54, the epidemic in London claimed over 10,000 lives, and there were 23,000 deaths for all of Great Britain. This pandemic was considered to have the highest fatalities of the 19th-century epidemics.Like the earlier pandemics, cholera spread from the Ganges delta of India. It had high fatalities among populations in Asia, Europe, Africa and North America. In 1854, which was considered the worst year, 23,000 people died in Great Britain.

That year, the British physician John Snow, who was working in a poor area of London, identified contaminated water as the means of transmission of the disease. After the 1854 Broad Street cholera outbreak he had mapped the cases of cholera in the Soho area in London, and noted a cluster of cases near a water pump in one neighborhood. To test his theory, he convinced officials to remove the pump handle, and the number of cholera cases in the area immediately declined. His breakthrough helped eventually bring the epidemic under control. He was a founding member of the Epidemiological Society of London, formed in response to a cholera outbreak in 1849, and he is considered one of the fathers of epidemiology.

Cholera outbreaks and pandemics

Seven cholera pandemics have occurred in the past 200 years, with the seventh pandemic originating in Indonesia in 1961. Additionally, there have been many documented cholera outbreaks, such as a 1991-1994 outbreak in South America and, more recently, the 2016–18 Yemen cholera outbreak.

Although much is known about the mechanisms behind the spread of cholera, this has not led to a full understanding of what makes cholera outbreaks happen in some places and not others. Lack of treatment of human feces and lack of treatment of drinking water greatly facilitate its spread. Bodies of water have been found to serve as a reservoir, and seafood shipped long distances can spread the disease.

The first cholera pandemic occurred in the Bengal region of India, near Calcutta starting in 1817 through 1824. The disease dispersed from India to Southeast Asia, the Middle East, Europe, and Eastern Africa through trade routes. The second pandemic lasted from 1826 to 1837 and particularly affected North America and Europe due to the result of advancements in transportation and global trade, and increased human migration, including soldiers. The third pandemic erupted in 1846, persisted until 1860, extended to North Africa, and reached South America, for the first time specifically affecting Brazil. The fourth pandemic lasted from 1863 to 1875 spread from India to Naples and Spain. The fifth pandemic was from 1881–1896 and started in India and spread to Europe, Asia, and South America. The sixth pandemic started in India and was from 1899–1923. These epidemics were less fatal due to a greater understanding of the cholera bacteria. Egypt, the Arabian peninsula, Persia, India, and the Philippines were hit hardest during these epidemics, while other areas, like Germany in 1892 and Naples from 1910–1911, also experienced severe outbreaks. The seventh pandemic originated in 1961 in Indonesia and is marked by the emergence of a new strain, nicknamed El Tor, which still persists (as of 2019) in developing countries.Cholera did not occur in the Americas for most of the 20th century after the early 1900s in New York City. It reappeared in the Caribbean toward the end of that century and seems likely to persist.Deaths in India between 1817 and 1860, in the first three pandemics of the nineteenth century, are estimated to have exceeded 15 million people. Another 23 million died between 1865 and 1917, during the next three pandemics. Cholera deaths in the Russian Empire during a similar time period exceeded 2 million.

Dot distribution map

A dot distribution map, or dot density map, is a map type that uses a dot symbol to show the presence of a feature or a phenomenon. Dot maps rely on a visual scatter to show spatial pattern.

Elijah Williams (chess player)

Elijah Williams (7 October 1809 – 8 September 1854) was an eminent British chess player of the mid-19th century. He was the first president of the Clifton Chess Club, and publisher of a book of games from the Divan Club. His most notable result was at the 1851 London tournament, in which he defeated the celebrated British player Howard Staunton in the play-off for third place.

He was accused by Staunton of taking an average of 2½ hours per move during some matches, a strategy thought to cause opponents to lose their focus on the match. According to Staunton, following a particularly dilatory performance by Williams in the London 1851 tournament, a 20-minute per turn time limit was adopted for standard play the next year. However other sources contradict this viewpoint and indeed it was not uncommon for Staunton to attribute his losses to the intolerable dilatory play of his opponents. Staunton is quoted as remarking while playing against Williams, "... Elijah, you're not just supposed to sit there – you're supposed to sit there and think!"

In The Complete Chess Addict by Mike Fox and Richard James he was dubbed "the Bristol Sloth" due to his alleged extreme slowness. This sobriquet inspired a musical tune "The Bristol Sloth" by guitarist Leo Kottke (who also applied the term 'sitzkrieg' in describing Williams' playing style).

Williams died in London, a victim of the 1854 Broad Street cholera outbreak.

Hand pump

Hand pumps are manually operated pumps; they use human power and mechanical advantage to move fluids or air from one place to another. They are widely used in every country in the world for a variety of industrial, marine, irrigation and leisure activities. There are many different types of hand pump available, mainly operating on a piston, diaphragm or rotary vane principle with a check valve on the entry and exit ports to the chamber operating in opposing directions. Most hand pumps are either piston pumps or plunger pumps, and are positive displacement.Hand pumps are commonly used in developing countries for both community supply and self-supply of water and can be installed on boreholes or hand-dug wells.

History of water filters

The history of water filters can be traced to the earliest civilisations with written records. Water filters have been used throughout history to improve the safety and aesthetics of water intended to be used for drinking or bathing. In modern times, they are also widely used in industry and commerce. The history of water filtration is closely linked with the broader history of improvements in public health.

Human geography

Human geography is the branch of geography that deals with the study of people and their communities,

cultures, economies, and interactions with the environment by studying their relations with and across space and place. Human geography attends to human patterns of social interaction, as well as spatial level interdependencies, and how they influence or affect the earth's environment. As an intellectual discipline, geography is divided into the sub-fields of physical geography and human geography, the latter concentrating upon the study of human activities, by the application of qualitative and quantitative research methods.

Jacob's Island

Jacob's Island was a notorious slum in Bermondsey, London, in the 19th century. It was located on the south bank of the River Thames, approximately delineated by the modern streets of Mill Street, Bermondsey Wall West, George Row and Wolseley Street. Jacob's Island developed a reputation as one of the worst slums in London, and was popularised by the Charles Dickens novel Oliver Twist, published shortly before the area was cleared in the 1860s.

List of epidemics

This article is a list of epidemics of infectious disease. Widespread and chronic complaints such as heart disease and allergy are not included if they are not thought to be infectious.

Natural experiment

A natural experiment is an empirical study in which individuals (or clusters of individuals) are exposed to the experimental and control conditions that are determined by nature or by other factors outside the control of the investigators. The process governing the exposures arguably resembles random assignment. Thus, natural experiments are observational studies and are not controlled in the traditional sense of a randomized experiment. Natural experiments are most useful when there has been a clearly defined exposure involving a well defined subpopulation (and the absence of exposure in a similar subpopulation) such that changes in outcomes may be plausibly attributed to the exposure. In this sense, the difference between a natural experiment and a non-experimental observational study is that the former includes a comparison of conditions that pave the way for causal inference, but the latter does not.

Natural experiments are employed as study designs when controlled experimentation is extremely difficult to implement or unethical, such as in several research areas addressed by epidemiology (like evaluating the health impact of varying degrees of exposure to ionizing radiation in people living near Hiroshima at the time of the atomic blast) and economics (like estimating the economic return on amount of schooling in US adults).

Pikuach nefesh

Pikuach nefesh (Hebrew: פיקוח נפש, IPA: [piˈkuaχ ˈnefeʃ], "saving a life") describes the principle in Jewish law that the preservation of human life overrides virtually any other religious consideration. When the life of a specific person is in danger, almost any mitzvah lo ta'aseh (command to not do an action) of the Torah becomes inapplicable.

Slow sand filter

Slow sand filters are used in water purification for treating raw water to produce a potable product. They are typically 1 to 2 metres deep, can be rectangular or cylindrical in cross section and are used primarily to treat surface water. The length and breadth of the tanks are determined by the flow rate desired by the filters, which typically have a loading rate of 200 to 400 litres per hour per square metre (or 0.2 to 0.4 cubic metres per square metre per hour).

Slow sand filters differ from all other filters used to treat drinking water in that they work by using a complex biological film that grows naturally on the surface of the sand. The sand itself does not perform any filtration function but simply acts as a substrate, unlike its counterparts for UV and pressurized treatments. Although they are often preferred technology in many developing countries because of their low energy requirements and robust performance, they are also used to treat water in some developed countries, such as the UK, where they are used to treat water supplied to London. Slow sand filters now are also being tested for pathogen control of nutrient solutions in hydroponic systems.

Steven Johnson (author)

Steven Berlin Johnson (born June 6, 1968) is an American popular science author and media theorist.

The Ghost Map

The Ghost Map: The Story of London's Most Terrifying Epidemic – and How it Changed Science, Cities and the Modern World is a book by Steven Berlin Johnson in which he describes the most intense outbreak of cholera in Victorian London (See 1854 Broad Street cholera outbreak) The book incorporated the idea of gemeinschaft, dealing with the effects of an epidemic in a city of common values, language, and traditions. The two central protagonists are Dr. John Snow, who created a map of the cholera cases, and the Reverend Henry Whitehead, whose extensive knowledge of the local community helped determine the initial cause of the outbreak. Dr. John Snow was a revered anesthetist who carried out epidemiological work in Soho, London. Around the mid-1850s Snow figured out the source of cholera contamination to be the drinking water from the Broad Street pump.

The book was released on 19 October 2006.

The cholera outbreak from 1848-49 killed approximately 54,000-62,000 in London, and the outbreak from 1853-54 killed an estimated 31,000 in London.

Thematic map

A thematic map is a type of map specifically designed to show a particular theme connected with a specific geographic area.

Voronoi diagram

In mathematics, a Voronoi diagram is a partitioning of a plane into regions based on distance to points in a specific subset of the plane. That set of points (called seeds, sites, or generators) is specified beforehand, and for each seed there is a corresponding region consisting of all points closer to that seed than to any other. These regions are called Voronoi cells. The Voronoi diagram of a set of points is dual to its Delaunay triangulation.

It is named after Georgy Voronoi, and is also called a Voronoi tessellation, a Voronoi decomposition, a Voronoi partition, or a Dirichlet tessellation (after Peter Gustav Lejeune Dirichlet). Voronoi diagrams have practical and theoretical applications in a large number of fields, mainly in science and technology, but also in visual art.

They are also known as Thiessen polygons.

Wends of Texas

The Texas Wends or Wends of Texas are a group of people descended from a congregation of approximately 588 Sorbian/Wendish people under the leadership and pastoral care of John Kilian (Sorbian languages: Jan Kilian, German: Johann Killian) who emigrated from Lusatia (part of Germany) to Texas in 1854. The term also refers to the other emigrations (and all descendants) occurring before and after this group. However none came close to the size or importance of the Wendish culture in Texas.

William Farr

William Farr (30 November 1807 – 14 April 1883) was a British epidemiologist, regarded as one of the founders of medical statistics.

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