John Snow - Historical Giant in Epidemiology

British physician John Snow (1813-1858) is considered by many as the "father of modern epidemiology" for his seminal investigations of cholera in London, long before the bacterial agent and its deadly toxin were widely known. During the mid-1800s, the prevailing notion of the cause of cholera was being overcome by "bad air” (the miasma theory). Snow's epidemiological investigations, however, pointed to the disease being transmitted through contaminated water, likely by a biological agent of some ill-defined form (the germ theory), a conclusion that was widely debated until well after Snow's death at age 45. Unbeknownst to Snow, the Italian microbiologist Filippo Pacini (1812-1883) had already seen the causative agent of cholera in 1854 while Snow was conducting his famous field studies. The bacterium Vibrio cholerae was finally cultured and identified in January 1884 with great publicity by German physician and microbiologist Robert Koch who wrote widely of its distinctive comma shape, perhaps not aware of Pacini's earlier observations. While Koch hypothesized that the organism produced a toxin, another 75 years would pass before the cholera toxin and the exact method of pathogen transmission was clearly identified by Indian medical scientist Sambhu Nath De in 1959, a century after Snow's death.

One of Snow’s cholera investigations was in a neighborhood near his London home, termed the "Broad Street Pump outbreak," which led to authorities removing the handle from the pump, a lasting symbol of public health action to save lives in the face of uncertainty. Snow’s second major investigation was south of London’s River Thames, deemed the "Grand Experiment,” comparing cholera deaths in two sets of households, one receiving sewage-contaminated water from the nearby River Thames and the other receiving relatively clean water from an upriver location.

Innovative and personable, Snow was able with colleagues to support his epidemiological research, long before government funds or charitable organizations were there to assist. Instead he relied on: 1) data compiled from public listings provided by the Registrar General's Office, 2) amiable persuasion to assist with field work and 3) the earnings of his clinical practice as anesthesiologist. Snow's prominence as a master of anesthesia soared with his inventions, presentations and publications and when administering chloroform during the birth of two of Queen Victoria’s children. With his life of remarkable achievements in an era of biologic and anesthetic mystery, he remains a pioneering figure in the history of both epidemiology and anesthesiology.

TABLE OF CONTENTS

STREAM 1 - Introduction

a: Encyclopedia Entry and "Greatest Doctor"

b: Images and Medal of Snow

c: Father of Modern Epidemiology

d: John Snow's Publications

e: Memoir of his friend Benjamin Ward Richardson

STREAM 2 - Broad Street Pump Outbreak

a: Overview and Part 2 of Snow's 1855 Book, Map 1

b: Photo Tour of Snow's London Neighborhood

c: Photo Tour of Broad Street Pump Outbreak

d: Investigation of Broad Street Pump Outbreak

e: Handle Removal, Index Case and Rev Whitehead

f: Map, Myth and Error Making in BS Pump Outbreak

STREAM 3 - The "Grand Experiment"

a: Introduction and Part 3 Snow's Book, Map 2

b: Photo Tour of History of London's Water Supply

c: Photo Tour of Tidal River Thames

d: The "Grand Experiment"

e: Photo Tour of Southwark and Vauxhall Water Company

f: Photo Tour of Lambeth Water Company pre-1852

g: Photo Tour of Lambeth Water Company post-1852

STREAM 4 - John Snow's Life

a: John Snow's Early Years, Part 1

b: John Snow's Early Years, Part 2

c: John Snow's Professional Years

d: Anesthesia for Queen Victoria

e: John Snow's Death

f: Remembrances and New The Lancet Obituary

STREAM 5 - Additional Items

a: Overview of Snow's Significance

b: Part 1 of Snow's 1855 Book

c: Part 4 of Snow's 1855 book

d: Other Cholera Outbreaks

e: Writings on Snow for Young People

f: Cholera Theories and Conflicts

g: First Discoverer of Vibrio Cholerae

h: William Farr - Campaigning Statistician

i: Honoring John Snow in England and the USA

j: Conversation with "The Ghost Map" Author

k: The "Modern John Snow" - R. Piarroux, MD, PhD

l: Current Cholera Information and Implications of Snow

ACKNOWLEDGEMENT

The original John Snow website was created in 1999-2000 by then Professor and Chair Ralph R. Frerichs of the UCLA Department of Epidemiology to bring attention to John Snow as a historical icon in the field of epidemiology. The site grew and remained active until 2019 when accumulated changes in internet requirements resulted in a shut down. In late 2024, current Distinguished Professor and Department of Epidemiology Chair Zuo-Feng Zhang encouraged then retired Emeritus Professor Frerichs to once again upgrade the site, completed in the early fall of 2025. Both the Department of Epidemiology and the UCLA Fielding School of Public Health are currently serving as website hosts.