1. Emerging Diseases Lecture 1:
Historical Ideas About Infectious Diseases
1.1 Overview
1.2 Historical Ideas About Infectious Disease
Supernatural
B. Humoral
C. Miasma
D. Germs

2. 1.1 Overview: Types of Diseases There are many types
Nutritional or dietary diseases-scurvy, or vitamin C deficiency
Genetic diseases-hemophilia
Behavioral diseases-addictions such as alcoholism
Mental illnesses-bipolar disorder
Infectious diseases-you can catch them from someone or something-BIOL 119 Emerging Diseases is about this type of disease only!! 

3. 1.2: Some Historical Ideas About the Causes of Infectious Disease
Supernatural – the anger of the gods
Humoral – balance of body fluids
Miasma - bad air
Germs – microscopic particles called germs because they can “germinate” like a plant seed
These four have been historically important.

4. of disease-an early idea
A. Supernatural origin
of disease-an early idea
Not a useful idea

5. B. Humoral
Greek physician Hippocrates formulated “humoral” medicine or “humorism”
Body fluids were known as “humors”
When humors got out of balance-disease followed
The four humors were yellow bile, black bile, phlegm and blood
They were connected to “elements” earth, air, fire, water

6. Humoral Hypothesis Humor = body fluid
Hippocrates
Humoral Hypothesis
Humor = body fluid
Mood, personality are determined by your own individual mix of humors
Disruption leads to illness

7. Restoring the balance of Humors
Many things might force the humors out of balance-
The important thing was to restore balance
“bleeding” or “bloodletting” was a key treatment
Used up until about 1900 for almost any ailment including hemorrhage
There were other treatments to adjust other humors

8. Hippocrates is honored as the founder of the western medical profession
He lived and practiced around 400 BCE
Main contribution was the idea that disease had natural causes-not supernatural-so physicians actually had a chance to cure disease
He was the first major figure to draw a distinction between medicine and religion
Hippocratic medicine is very different from modern medicine but this was a huge step forward
His ideas persisted for over 2000 years in Western society

9. C. Miasma Humorism did not explain everything well
For example-it was easy to see that certain diseases were more prevalent in areas with bad sanitation and this was hard to explain based only on the balance of humors
It was proposed that rotting sewage and other materials gave off a polluted vapor or mist that caused various diseases when inhaled
The mist was called a “miasma”
“Bad air”, “Night air”, “nebula”, “malaria” or “Cold air” were other names for this horrible agent
“Miasma” explanation for disease seemed to fit the facts

10. Miasma idea about infectious disease
Disease is associated with bad air-”miasmas” with a sort of spiritual or ghostly component-not a physical thing

11. “Miasmas” resulted from the chemical
breakdown of living material
19th Century cities were a
good place
for this

12. Sanitarians were determined to clean up the filthy cities

13. Sanitarian movement of the 19th Century
19th Century cities had many diseases of filth
Sanitarians operated under the idea that cleanup would reduce miasmas and therefore disease
But even if that didn’t work everyone was better off if the cities were cleaner
They convinced city governments to act
Built privies and sewers, paved streets and tried to keep them clean

14. Sanitarian ideas were fuzzy
They thought disease resulted spontaneously from garbage, filth and dirt
Thought chemical interactions produced miasmas and no
host was necessary for miasmas to proliferate
But they thought cleaning up was generally a good idea
And some key medical people of the mid-1800s agreed
Cleaning up the garbage, sewage and dirt did make a difference! Sanitarians helped to improve public health!
Their ideas were wrong but their actions were helpful.

15. D. Germ Theory of Disease Many other 19th Century medical professionals suspected that something more defined than a miasma was responsible for some diseases
The “contagionists” felt that physical things caused disease-not mysterious vapors
Actually an old idea (smallpox germ warfare used against Native Americans)
But this explanation ran into trouble because no one could see or demonstrate the existence of these physical things
Improvements in microscopes and in science methodology changed all that in the second half of the 19th Century

16. Louis Pasteur
Showed that microorganisms always occur in infectious disease or in spoilage
And that they always come from pre-existing microbes-
not miasmas
Specific microbes are always associated with
specific diseases

17. Robert Koch Anthrax Koch showed that germs caused diseases
Koch’s Postulates-rules for demonstrating
causation
Endospores of anthrax
are very stable-
A bioterror weapon used
against the US in 2001

18. In 1854 Dr. John Snow halted a deadly cholera outbreak in London by preventing contact with contaminated water –showed something physical must be involved

19. Semmelweis-”The Savior of Mothers”
Puerperal fever or childbed fever
Semmelweis notices higher incidence when doctors deliver-not midwives
Suspects dirty hands or instruments
Cleaning instruments, hands and clothing reduced post partum infections

20. Lister-Antiseptic Surgery
Used strong chemicals to kill germs
“Carbolic acid” = phenol = paint stripper
“Antiseptics” = chemicals that kill germs on surfaces
Achieved a significant reduction in
post-surgical complications and infections

21. The Germ Theory of Disease is the accepted theory today.
Through the work of Pasteur, Koch, Snow, Semmelweis, Lister and many others The Germ Theory of Disease
Became accepted by scientific and medical community around 1900.
The Germ Theory of Disease
is the accepted theory today.
Infectious diseases are caused by germs!

22. IT WORKS! Why is the Germ Theory of Disease
so successful and still so widely accepted?
Because it is based on a lot of evidence and………
IT WORKS!
If it didn’t work we would have to come up with a new theory.

23. Types of Germs and Their Diseases
Parasites-tapeworms, amoebas, protozoa
Fungi- athlete’s foot, yeast infections
Bacteria-anthrax, syphilis, Staph infections
Viruses- AIDS, cervical cancer (HPV), influenza
Sub-viral- Mad Cow, Hepatitis D
These are just some examples of five important types of germs