Lecture 14 - The Germ Theory of Disease - Lecture 14 The...

Lecture 14 - The Germ Theory of Disease
Friday, April 10, 2015
7:55 AM
Germ Theory of Disease

Taken us half a course to reach a period where one can see development of modern
scientific medicine
o
Enormous theory but to understand its magnitude, must compare 1789 with 1900

Before 1789 and Paris School of Medicine, conceptual framework was
dominated by Galen\Hippocrates\humoral medicine
o Humoral medicine weakening, seeing rise of ideas about different body systems
(circulatory\nervous) but medical philosophy, vocabulary and therapeutics , medical
education all cast in old framework

Supplemented by other developments in astrology or miasma causing
epidemic diseases (malaria was another name for miasma at the time)

1900, more change had occurred that in all of the centuries since Hippocrates combined
o Medical science had similar basic principles today and had emerged by this time

Speed of change accelerating during course of 19th century

End of century saw a revolution, germ theory of disease as its
central feature
o Theory was as important a revolution in medicine as Galileo's theory or Darwin's
theory was for their disciplines

What is the Germ theory\preconditions\decisive figures\decisive events linked with
Pasteur, Lister, Koch
o
Implications?

Avoid idea of a single genius coming up with one great idea (Nobel Prize)

These discoveries that culminate in germ theory had a long
gestation, were a collective progress that needed many preconditions
Preconditions

Were conceptual, technological, and institutional

Conceptual preconditions
o Germ theory of disease did not come directly from Paris School\hospital
medicine but it had important role

Had to have nosology (disease classification\specificity) instead of
localism

New development of pathological anatomy derived from post-
mortem in Paris hospitals
o Specificity was critical, further progress towards idea of microbial disease
depended on view that diseases did not transform from one to another

Before Paris school, many people believed that cholera was a worse form
of endemic summer diarrhea

Not a specific disease, grew out of another pre-existing condition

Germ theory: stable\unchanging disease entities, each
specific with specific microbial cause

Pierre Louis and his followers did classify\distinguish different diseases
from each other but did not advance much towards idea of causative
pathogens behind them
o
Not all figures in the advance of disease specificity were French

William Gerhard= distinguished typhus from typhoid, studied in Paris
under Louis but returned to Philadelphia where he was from


Dissected cadavers of those who died from typhus, lesions not
similar to those ill from typhoid

William Budd wrote Typhoid Fever and Its Nature, Mode of Spreading
and Prevention in 1873

Disease specific and unchanging, like animals and plants (but this
was not acknowledged before)

Pierre Bretonneau believed that there were morbid seeds that cause
special disease
