John Snow Facts & Worksheets

John Snow is widely regarded as the father of epidemiology or the study of population health. He is well recognized for his work tracking the spread of cholera during the 1854 London pandemic. It was widely assumed then that the disease was transmitted by poor air or miasmas. Snow’s book, published in 1848, proposed that the sickness was spread by a self-replicating agent in feces.

See the fact file below for more information on John Snow, or you can download our 25-page John Snow worksheet pack to utilize within the classroom or home environment.

Key Facts & Information

EARLY LIFE

• Snow was born on March 15, 1813, in York, England, as the first of nine children to William and Frances Snow in their North Street residence, and was baptized at All Saints’ Church, North Street, York. 
• His father was a laborer who worked at a local coal yard by the Ouse, which was constantly refilled by barges from the Yorkshire coalfield, but he subsequently became a farmer in a little settlement north of York.
• Filthy circumstances and contamination plagued Snow’s hometown as he grew up. Most streets were dirty, and the river was polluted by runoff water from marketplaces, cemeteries, and sewage.
• When he was 14, he began a medical apprenticeship with William Hardcastle in Newcastle-upon-Tyne. In 1832, while working as an apprentice surgeon-apothecary, he faced his first cholera pandemic in Killingworth, a coal-mining village.
• Snow vowed to abstain from alcohol, gambling, and marriage and became a vegetarian. He began medical studies at 23 and graduated from the University of London in 1844. 
• John Snow was Queen Victoria’s anesthetist and a founding member of the London Epidemiological Society. 
• Snow expanded his anesthetic practice in the cholera-affected zone in 1848 when he launched an independent inquiry into the disease.

SNOW AND CHOLERA

• By 1849, around 53,000 cholera deaths had been recorded in England and Wales. Snow was suspicious of the prevalent Miasma Theory and proposed that cholera was caused by contaminated water as the primary transmission mode.
• A cholera pandemic broke out in 1854, impacting the resident families of tailors and clerks from nearby Regent Street shops. The outbreak caused severe diarrhea and a high mortality rate, with 600 people dying in only one week in September 1854.
• According to the prevalent Miasma Theory, cholera was caused by the airborne transmission of deadly vapors from unpleasant odors induced by poor sanitation. Simultaneously, the opposing Germ Theory that had inspired Snow remained an unconfirmed minority opinion in medical circles.
• The terrible odors, colloquially known as “The Great Stink” at the time, from the Thames River flowing past the Houses of Parliament became so severe that MPs resolved to take action. 
• Finally, in 1864, Sir Joseph Bazalgette’s scheme saw the construction of two massive sewers along the Thames, sending sewage downstream and establishing sewage farms to handle the effluent. 
• The system is still in use but needs to be bigger to meet the demands imposed by the rising population and land development.
• When cholera struck London again, Snow set about testing his theory by comparing mortality rates in South London cohorts with varied water supplies. 
• Then, near his Soho house, a spectacular pandemic began, killing 550 people in two weeks.
• Snow conducted interviews with residents and gathered the addresses of those who had died, then plotted the instances on a map.
• This led him to believe the outbreak’s source was a water pump on Broad Street.
• Although Snow’s chemical and microscopic investigation of a water sample from the Broad Street pump could not definitively confirm its danger, his studies of the disease pattern persuaded the local council to disable the good pump by removing its handle.
• The cholera pandemic, which was already declining, vanished after the pumps were turned off. 
• As a result of this incident, Benjamin Disraeli and other Members of Parliament supported the Thames Authority’s proposal and passed laws requiring the repair of London’s water and sewage facilities, which, once completed, contributed to the absence of cholera.
• The highest rates of cholera occurred in sections of the city where two businesses with overlapping water mains served residences during the next London cholera outbreak, from September to October 1854.
• Snow later utilized a dot map to show the concentration of cholera cases near the pump. He also used statistics to demonstrate the relationship between water quality and cholera cases. 
• He demonstrated that residences served by the Southwark and Vauxhall Waterworks Company, which drew water from sewage-polluted areas of the Thames, had cholera rates fourteen times higher than those operated by the Lambeth Waterworks Company, which drew water from the cleaner Seething Wells upriver.
• This offered overwhelming epidemiologic evidence for his idea that the cause of the cholera epidemic was tainted Thames River water dispersed to residences across a vast area of south London.
• Snow’s pioneering epidemiologic work established the method of transmission of a waterborne disease that ravaged many parts of the world in the nineteenth century and continues to this day.

CHOLERA

• The V. cholera organism was first cultured in 1854, but it was only published in local Italian medical journals and was not recognized internationally. 
• In 1883, the prominent German bacteriologist Robert Koch received international recognition for the definite identification and culture of the bacterium during his examination of a cholera epidemic in Egypt.
• The Broad Street pump incident revealed that cholera was waterborne; hence, the techniques to prevent it had been established about 30 years earlier. 
• Snow also helped to create the core approach of modern public health for infectious illness inquiry and added to the validity of the Germ Theory, which was still highly disputed at the time.
• One of the most significant breakthroughs in public health has been the disinfection of drinking water through filtration and chlorination methods. 
• Clean water was responsible for about half of the total mortality decrease in big cities, three-quarters of the reduction in infant mortality, and nearly two-thirds of the decline in child mortality.

CURRENT RELEVANCE OF JOHN SNOW’S STUDY

• Cholera outbreaks can also develop in natural disaster zones, particularly where sanitation services fail. A recent example of such an occurrence can be seen in Haiti, where an earthquake in 2010 killed over 200,000 people and displaced over one million others.
• Waterborne sickness is now given less attention because water and sewage treatment standards are considered a part of modern life. 
• However, waterborne enteric disease remains one of the leading causes of death in many parts of the world, particularly among youngsters.

John Snow Worksheets

This fantastic bundle includes everything you need to know about John Snow across 25 in-depth pages. These ready-to-use worksheets are perfect for teaching kids about John Snow. John Snow is widely regarded as the father of epidemiology or the study of population health. He is well recognized for his work tracking the spread of cholera during the 1854 London pandemic.

Complete List of Included Worksheets

Below is a list of all the worksheets included in this document.

1. John Snow Facts
2. Get to Know Snow
3. Vocabulary
4. Timeline
5. Picture Analysis
6. Make it Make Sense
7. Humanity
8. Investigation Time
9. Mapping
10. Words of Snow
11. Trace It

Frequently Asked Questions

Who was John Snow?

John Snow (1813-1858) was an English physician and a pioneer in the field of epidemiology. He is best known for his work in identifying the source of a cholera outbreak in 1854 in London’s Soho district.

What did John Snow discover about cholera?

John Snow discovered that cholera was spread through contaminated water, not through “bad air” or miasma as was commonly believed at the time. By mapping the cases of cholera and pinpointing the source of the outbreak to a contaminated water pump on Broad Street, Snow was able to provide evidence supporting his theory.

How did John Snow’s discovery impact public health?

John Snow’s discovery had a significant impact on public health. By identifying the source of the cholera outbreak, he helped establish the link between contaminated water and the spread of diseases. His findings paved the way for improvements in sanitation and the development of water treatment systems, leading to a reduction in the incidence of cholera and other waterborne diseases.

What is John Snow’s famous map?

John Snow’s famous map, known as the “Ghost Map,” was a visual representation of the cholera cases he investigated during the 1854 outbreak. By marking the locations of cholera deaths on a map of Soho, Snow was able to identify a cluster of cases around the Broad Street pump, which ultimately led him to conclude that the pump was the source of the contamination.

How did John Snow’s work influence modern epidemiology?

John Snow’s work laid the foundation for modern epidemiology, the study of patterns, causes, and effects of diseases in populations. His emphasis on collecting and analyzing data, mapping disease outbreaks, and identifying the source of infection has become a fundamental approach in epidemiological investigations. Snow’s contributions have shaped public health practices and continue to influence the field to this day.

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