Transcript Epidemic Diseases of the 19th Century

Epidemic Diseases of the
th
19 Century
The Demographic Context
• 19th century experienced explosion of endemic
& epidemic diseases
• Related to:
–
–
–
–
Industrialization
Urbanization
Trade activities
Military activities
• Factors were similar to the Middle Ages
• Scale of these changes exponentially greater
• Britain first country to experience
industrialization
• Associated with:
– Significant population growth
– Significant migration to urban centres
• Explosive growth of cities outstripped their
infrastructures
– Water supply
– Sewage
– Housing
• Manchester is an example
Population Growth in Manchester
350,000
300,000
250,000
200,000
150,000
100,000
50,000
0
1717
1758
1773
1801
1821
1831
1841
1851
• Northern industrial cities such as Manchester &
Liverpool grew faster than London
• Result was horrific living conditions for the
working class
• Subject of many studies
– Chadwick: Report on the Sanitary Conditions . . .(1842)
– Engles: Condition of the Working Class . . .(1844)
– Mearns: Bitter Cry of Outcast London . . .(1883)
• Emergence of statistics helped Britons “see” the
impact of urbanization
• William Farr
– Prominent epidemiologist
– 2nd Registrar General of the Central Board of
Health
– Instituted systematic collection of vital statistics
– Developed many statistical methods still in use today
• Farr’s 1843 Report concluded that urban life
expectancy was lower than rural life expectancy
– Average national life expectancy: 41 years
• Rural Surrey: 46 years
• London: 36.7 years
• Liverpool: 25.7 years
– Highest mortality in children under age 5
• ½ of all children in Liverpool dead by 5th birthday
• In Surrey, ½ dead by age 50
• Several diseases emerged as significant threats to
health during this time
– Cholera
– TB
– Typhoid Fever
The Medical Context
• Most physicians & influential lay people believed
that epidemic diseases were caused by miasma
• Literally “pollution”
• By 19th century, understood as poisonous air
filled with particles from decomposed matter
• Night air was considered worse
• Idea originated in Hippocratic times
• By 19th century, a few diseases recognized as
contagious
– Smallpox
• Most were not
Contagion Theory
Miasma Theory
A material substance (animal
matter)
Required index case
Foul air
Mode of Transmission
Person to person
Contaminated water?
Local environmental conditions
Some localities more prone to
the problem
Seasonal variations
Signs & Symptoms
Specific to each disease?
Different symptoms could be
observed
Susceptibility
Attacked individual only once?
Attacked individuals repeatedly
Conditions Determining End Not well understood.
of Outbreak
Should be when everyone was
dead
Removal of source of miasma
Source
Disease generation could be
spontaneous
• Miasma theory supported by many prominent
19th century health reformers
– William Farr
– Florence Nightingale
• Made more sense given the knowledge of the
time
• Under girded the sanitary emphasis of the 1st era
of the public health movement
• Miasma theory also supported by business
community & politicians
• Would make quarantine unnecessary
• This kept international trade & military activity
going
Cholera
• An important example of a disease that
successfully moved out of its original
geographic location
• “concentrated people’s minds” (Porter)
• Cause: bacteria Vibrio cholerae
• Severe diarrheal disease spread through
contaminated water
• Death can occur within hours
• Victims were frightening to behold
– Complete loss of control of bodily functions
– Shock, circulatory collapse
– Bodies almost black
• Disease is endemic to India
• Often spread by religious pilgrimages
• Always burned out
• In 19th century, the difference was presence of
Europeans in India
• Spread to Europe, Asia & Africa along trade &
military routes
• 1st pandemic (1816-18)
– overland to Nepal, Afghan
– by sea to Asia, Africa
• 2nd pandemic (1826-1832)
–
–
–
–
to Russia 1831
Europe, winter of 1831-32
Canada, New York, 1832
Pacific coast, 1834
• Panic in Europe’s major cities
• No one knew what caused it
– Churches viewed it as a moral issue
– Others believed it was miasma
• Physicians emphasized protection of individual
constitutions
• 3rd pandemic (1852-60)
– Worst impact in Russia
• 4th pandemic (1863-75)
– Mostly Europe & Africa
• During 3rd pandemic, debate between advocates
of miasma & contagion crystallized
• Major figure of this era was John Snow (181358)
• Snow spent many years thinking about cholera
prior to 1854
• In 1831, as a medical student, cared for coal
miners sick with cholera near Newcastle
– Later speculated that it was spread by invisible
entities on their hands
• Living in London by 1848 when cholera struck
again
• Investigated origins of this outbreak
• Again proposed contagion as reason for spread
• Speculated that contaminated food or water
might spread the disease
• Published these ideas in 1849
• Provided evidence to support them
• Snow’s hypothesis not well received
• Always alternative, more plausible explanations
• 1854 cholera outbreak in London
• Snow suspected spread was due to contaminated
water
• Perfect natural experiment existed in the district
where he was working
• 2 different water companies supplied water to
the district
– One drew water from contaminated section of the
Thames River (Southwark & Vauxhall Co.)
– One drew water from above the sewage outlets
(Lambeth Co.)
• Snow traced local victims & determined who
had consumed water from which source
• Statistical analysis indicated 71:5 ratio of deaths
from Southwark & Vauxhall as opposed to
Lambeth
• Results still not accepted
• Alternative theories proposed by supporters of
miasma
• In late August, cholera broke out in Soho
• Water companies supplying water had a clean
source
• Snow speculated that a pump on Broad St.
might be contaminated
• Initial investigation of pump proved negative
• Snow mapped all cholera victims
• Used this evidence to persuade removal of the
handle of the Broad St. pump
• Epidemic stopped
• Subsequently, source of contamination found
• Several points must be made about Snow’s
contributions to germ theory
– He was often unwilling to go head to head with
colleagues who supported miasma
– He beat William Budd by 10 days in publishing his
theory of the spread of cholera
– Cholera bacillus was seen under a microscope in
1854 by Fillipo Pacini, whose findings were not
translated into English
• William Farr proposed an equally plausible
theory (for the times) as to why cholera deaths
were concentrated near the Thames River
• Some historians argue that Farr contributed far
more to epidemiology than did Snow
• Snow just happened to be correct
• By 1860s, germ theory accepted
• V. cholerae “rediscovered by Koch in 1884