Cholera in 1849 and the
Biopsychosocial Model:
Historical Analysis or
Anachronism?
The Snowflakes of MSU:
Peter Vinten-Johansen
Howard Brody
Nigel Paneth
Steve Rachman
Michael Rip
The Argument
 One
can draw useful analogies
between:
– Today’s biopsychosocial model of
human health, and
– The scientific approaches used by John
Snow to study both cholera
transmission and inhalation anesthesia
in 1846-56?
The Argument--II

The BPS model
 John Snow and his career
 Methods of studying anesthesia
 Methods of studying cholera
transmission
 Snow’s theoretical synthesis (“continuous
molecular changes”)
Engel, 1977: BPS Model
 Systems
(part-whole relations)
 Multilevel hierarchy (atoms to
biosphere)
 “Ripple effects” among levels
 Patterns of information flow
(feedback loops)
 Anti-reductionistic
BPS: Sources
 General
systems theory (von
Bertalanffy, Laszlo)
– Cybernetics (von Neumann),
information theory, game theory
 “Holistic”
biology (Dubos, Mayr)
 All grounded in mid-20th-century
thought
John Snow: Early Life

Born 1813, York
 Father: Laborer/farmer
 Mother: Illegitimate
 Apprentice in Newcastle, 1827-32
 Cared for coal miners in 1831-32 cholera
epidemic
John Snow: Life (cont.)

Newcastle medical school, 1832-34
 Assistant, Newcastle and Yorkshire, 183436
 Walked to London (via Bath), 1836
 Hunterian school and Westminster
Hospital, 1836-38
 MRCS/LSA, 1838
 General practice, Soho, 1838
John Snow: Later life
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Active in Westminster Medical Society
MD, Univ. of London, 1844
Begins anesthetic research and practice, 1847
On the Mode of Communication of Cholera,
1849
Attends Queen Victoria, 1853, 1857
Broad Street Pump, 1854
President, Medical Society of London, 1855
Completes On Chloroform, 1858
Death of apoplexy, 1858
Snow on Ether

Dec. 1846: Sees ether used in London
 Jan. 1847: Displays data on relation
between concentration and temperature;
working on apparatus
 September 1847: Publishes On Ether, 80
cases, describes degrees of anesthesia
How?

Snow’s research, 1838-46, ideally
prepared him for ether:
– Studies of respiration and asphyxia
– Studies of chemistry and physics of gases
– Properties of inhaled medications and
poisons
– Design of new apparatus
Snow’s Approach to Ether

Chemical level: problem in defining
physics and chemistry e.g. concentrationtemperature relationships
 Physiological level: animal experiments
with different concentrations of gases
 Clinical level: correlate bedside
observations with animal experiments to
predict degrees of anesthesia
Ether and Chloroform

Define a class of agents with similar properties
(“narcotism”), of which anesthesia only one
effect
 Calculate precise serum concentrations of
agent when inhaled at given concentration in
air
 Correlate serum concentration with clinically
observed effects
 Hardly anyone else doing this work in 1847-58
Snow and Cholera: 1848-9

Cholera must be communicable personto-person based on geographic
distribution
 A local affection of alimentary canal;
dehydration produces systemic symptoms
 Assumed to be inhaled by lungs– why
must this be true?
Snow’s Theory

Causal agent of cholera ingested
 Multiplies in gut
 Causes symptoms of disease by irritating
mucous membrane
 Shed in evacuations
 Household spread: dirty hands
 Area spread: drinking water
Budd, Brittain, Swayne 1849
 Microscopic
particle must cause
cholera
 Therefore must search for evidence
at microscopic level
 Identified “cholera fungus”
 Identification quickly refuted
Snow, 1849
Community
Household
Organ/System
Spread by contaminated drinking
water
Spread by poor hygiene
Irritation > Diarrhea > Dehydration
Cellular
Can’t identify agent; analogy to
ova of intestinal worms
Molecular
“Continuous molecular changes”
(self-replication of vital processes)
Snow on Cholera, 1849
Move from levels where “collateral
sciences” least developed to levels
allowing better tools for investigation
 Ova of worms: analogy of functional
properties
 Cf. “Cholera fungus”: identified a
structure but had no idea of function

Cholera Deaths per 10,000
Households (Snow, 1855)
80
70
60
50
(first weeks of
epidemic)
40
30
20
10
0
Lambeth Co. Southwark & Vauxhall Co.
Snow’s Method, 1849-1855

Ultimately discovered that statistics was a
sounder basis for investigation than
microscopy
 Reasoned across levels to deduce likely
effects at neighborhood and community
levels
 Then gathered data to confirm or
disconfirm hypotheses
Continuous Molecular
Changes, 1853
CMC, 1853

Annual oration to Medical Society of
London
 Rare opportunity to speak at theoreticalspeculative level
 Opportunity to link (successful)
anesthesia research with (so far rejected)
cholera theory
CMC, 1853-- II
“Molecular” = smallest level of
organization, “insensible” (very small)
distances between particles acting on
each other
 “Change” = constant flux at molecular
level in either living or non-living matter
(common chemical basis of vital and nonvital)

CMC, 1853--III
“Continuous” = molecular processes
peculiar to living things; never commence
anew without continuity with previous
processes of same type
 Combustion/oxidation– a bridging
process, exists in both living and nonliving matter

Anesthesia: Counter-Affinity
B
A
C
C exerts pull on A
and prevents A from
combining with B,
without itself
combining
Anesthesia Theory
C
= anesthetic agent
 A <-> B = oxidation process
responsible for maintaining
consciousness and sensation
 Reversible interference with normal
bodily process
CMC and Epidemic
Diseases

Causative agent of disease enters body
 By CMC, replicates itself inside body
 Hijacks normal body processes of
oxidation, etc. to support its own
replication
 Disruption of normal body processes
causes symptoms of disease (irreversible
in extreme cases)
“Communication”
“Mode of Communication” of epidemic
diseases
 “Communication” among molecules
accounting for continuity of vital
processes– infections agents as packets of
information (computer viruses?)
 Social and cultural communication as
analogous flows of information

The communication of certain molecular changes
taking place in the brain is by no means confined
to…parents and offspring, but extends collaterally
in all directions, by means of vibrations in the air…
If the brain of an animal is in a particular state of
molecular action, from any object that excites fear
or joy, it may cause a similar state in the brain of
others of the species, by uttering a cry or merely
assuming a particular demeanour.
The faculty of speech gives man a power of
communicating his complex feelings and ideas,
far exceeding that of lower animals; and the
invention of literature has greatly increased this
power in civilized nations. By speech, not only
can fresh sensations and ideas be communicated,
but also that continuation of them called
remembrance, by which they revive after, it may
be a long interval of suspended animation.
Snow’s Social Vision
According to Snow, his oration “On
Continuous Molecular Changes” was
itself an example of continuous molecular
change in human organisms and human
society
 Both chemical and social processes
viewed as governed by patterns of
information flow (“communication”)
