Question: What is the name of the physician who studied the cause of the 1854 Broad Street cholera outbreak in London, England?

Passages:
s of 24 September 2012 , a cholera outbreak in Sierra Leone has caused the deaths of 392 people.  It is the country's largest outbreak of cholera since first reported in 1970 and the deadliest since the 1994–1995 cholera outbreak.  The outbreak has also affected Guinea, which shares a reservoir near the coast.  This is the largest cholera outbreak in Africa in 2012. 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 London, England.  This outbreak, which killed 616 people, is best known for the physician John Snow's study of its causes and his hypothesis that contaminated water, not air, was the source of cholera.  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" would be used to describe sites, such as the Broad Street pump, in which conditions are good for transmission of an infection.  John Snow's endeavor to find the cause of the transmission of cholera caused him to unknowingly create a double-blind experiment. <P3-S0> Cholera Hospital was established on June 24, 1854, at Franklin Street in New York City. <P3-S1>  The institution was built to treat cholera patients who were denied admittance to City Hospital in Manhattan during an onset of the disease in the summer of 1854. <P3-S2>  The Mayor of New York, Jacob Westervelt, and the New York City Commissioners, took control of the building at 105 Franklin Street in anticipation of an eminent cholera epidemic. <P3-S3>  A few weeks afterward a second hospital for cholera sufferers was opened at a schoolhouse on Mott Street (Manhattan). <P3-S4>  A book published by a New York physician in 1835 shows that a hospital called the Duane-Street Cholera Hospital existed in New York as early as 1835, but the relationship between the Duane-Street hospital and the Cholera Hospital at Franklin Street is unclear. The 1853 Copenhagen cholera outbreak was a severe outbreak of cholera which occurred in Copenhagen, Denmark in 1853 as part of the third cholera pandemic.  It killed about 4,800 people. The Papua New Guinea cholera outbreak is an outbreak of cholera along the Northern Coast of Papua New Guinea.  It is the country's first outbreak of cholera in 50 years, and is currently spreading across the country, raising fears of an epidemic. The fifth cholera pandemic (1881–96) was the fifth major international outbreak of cholera in the 19th century starting in India.  It spread throughout Asia and Africa, and reached parts of France, Germany, Russia, and South America.  The 1892 outbreak in Hamburg, Germany was the only major European outbreak; about 8,600 people died in that city.  Although many residents held the city government responsible for the virulence of the epidemic, it continued with practices largely unchanged.  This was the last serious European cholera outbreak of the century. In October 2016, an outbreak of cholera began in Yemen.  The outbreak is "unprecedented scale," according to the World Health Organization (WHO) and is ongoing as of 30 September 2017.  The Cholera outbreak is a result of the ongoing war led by Saudi led coalition and Houthis in Yemen since March 2015.  As stated by in the statement of the UNICEF and WHO esecutive directors: "This deadly cholera outbreak is the direct consequence of two years of heavy conflict.  Collapsing health, water and sanitation systems have cut off 14.5 million people from regular access to clean water and sanitation, increasing the ability of the disease to spread.  Rising rates of malnutrition have weakened children’s health and made them more vulnerable to disease.  An estimated 30,000 dedicated local health workers who play the largest role in ending this outbreak have not been paid their salaries for nearly 10 months" <P0-S0> 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. <P0-S1>  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. <P0-S2>  Dr. John Snow was a revered anesthetist who carried out epidemiological work in Soho, London. <P0-S3>  Around the mid-1850s Snow figured out the source of cholera contamination to be the drinking water from the Broad Street pump. The 2008 Zimbabwean cholera outbreak was an epidemic of cholera affecting much of Zimbabwe from August 2008 until June 2009.  The outbreak began in Chitungwiza in Mashonaland East Province in August 2008, then spread throughout the country so that by December 2008, cases were being reported in all 10 provinces.  In December 2008, The Zimbabwean government declared the outbreak a national emergency and requested international aid.  The outbreak peaked in January 2009 with 8,500 cases reported per week.  Cholera cases from this outbreak were also reported in neighboring countries South Africa, Malawi, Botswana, Mozambique, and Zambia.  With the help of international agencies, the outbreak was controlled, and by July 2009, after no cases had been reported for several weeks, the Zimbabwe Ministry of Health and Child Welfare declared the outbreak over.  In total, 98,596 cases of cholera and 4,369 deaths were reported, making this the largest outbreak of cholera ever recorded in Zimbabwe.  The large scale and severity of the outbreak has been attributed to poor sanitation, limited access to healthcare, and insufficient healthcare infrastructure throughout Zimbabwe. 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.

Supporting sentences:
 This outbreak, which killed 616 people, is best known for the physician John Snow's study of its causes and his hypothesis that contaminated water, not air, was the source of cholera. John Snow (15 March 1813 – 16 June 1858) was an English physician and a leader in the adoption of anaesthesia and medical hygiene.