Disease Theory Before Germ Theory

Hello.

My name is Michael Warbirds and I'm professor of the History of Science,

Technology and Medicine at the University of Manchester.

This course is about the germ theory of disease and the

batch technological revolution in the period 18 60 to 1900.

We begin by looking at theories of disease before the germ theory

and then

a lecture on the on the theory itself.

The third, The third lecture is on the Bacteriological Revolution,

and the fourth is on Pastors. Development of vaccines.

The Fifth Lecture is on Robert Cock

and the development of the Bacteriological Laboratory.

The sixth and final lecture

is on the changes in the understanding of tuberculosis over the 19th century,

which are used to revise

the whole aspect of the whole aspect of the course

and the way in which germs change medicine. Overall,

in this first module, I'm going to talk about disease theory before germ theory.

But what was the germ theory of disease?

Put simply, it was that microorganisms cause infectious disease.

German theory didn't apply to all diseases.

It doesn't apply to cancer

to heart disease or mental illnesses.

When was it developed? It was developed in the 18 sixties and 18 seventies

and really became bacteriology in the 18 eighties

18 nineties and in the 20th century.

It tends to now be called microbiology.

The main people involved in my period were Louis Pasteur in France,

Joseph Lister in Scotland

and in England,

and Robert Robert Cock in Germany.

So why was the germ theory of disease important?

Well,

in the view of some people,

it was the most radical change ever in the history of medicine.

It changed the whole way that doctors thought about disease

before the germ theory.

Doctors defined diseases by their symptoms.

After germ theory.

They they increasingly define them by their cause.

And nowadays, a disease without a cause

is often

not regarded as a disease and regarded as a syndrome or or something else.

One can see the change.

If one thinks about a very common illness

that many of us will suffer from tonsillitis

effectively, that just means inflamed tonsils. It's the symptoms of the disease,

but increasingly it's referred to a strep throat

that is that a specific microorganism streptococcal bacteria.

It's actually causing inflammation in the in the

throat and and and and in the tonsils.

But Joan theory did more than that. It changed where disease was studied.

The main focus of disease study nowadays is in the laboratory.

It used to be in the clinic, in the hospital, in the doctor's surgery,

but now it's in the laboratory,

and we've seen that we saw that in the Covid pandemic in 1920

subsequently where everybody looked for solutions to the laboratory,

um, and the production of vaccines,

treatments and other ways of in various ways of diagnosing,

diagnosing the disease.

So I'm going to be talking about infectious diseases or spreading diseases.

These are primarily defined by an inflammation,

and we see that most obviously in people suffering from a high temperature.

But there are also local effects are very common. Um, symptoms is spots rashes.

One can see the skin change.

But there are also other changes which one might regard,

which I might call eruptions, spots and

rashes or skin eruptions.

But they're also eruptions like vomiting and eruptions like diarrhoea

and characteristically infections have two levels of action.

They affect the whole body

and produce general malaise and tiredness. But they also have specific effects.

Local effects in different parts of the body

now before before germ theory.

It's often said that the dominant theory of disease was

the me asthmatic theory that my asthma's bad air,

bad smells caused, caused infectious disease.

Well, that's not quite right.

There were broadly two types of spreading disease.

There were those who caught by contact, like smallpox,

which people caught from the postures on the skin,

or sexually transmitted diseases like syphilis

that people caught from sexual intercourse.

And in these diseases,

there was a contagion

contagion that passed from person to person,

and it was often spoken about as a virus,

not a virus, as we know it,

but as a virus that was like a snake poison.

Indeed, the origins of the word virus come in part from venom

and and and and the virus in these types of diseases, um,

would would spread to the whole body and would grow and erupt, um,

and affect the whole the whole body.

My asthma's

applied to a different type of spreading disease.

Those that were spread through the environment by air by water,

Um, or that emerged emerged from the soil,

which which is one particular origin of enhancements

and these and characteristic of these, um,

in dark,

spreading diseases that spread indirectly through the environment was

that many of them seem to arise spontaneously.

There was no explanation as to where they came from,

other than that some malign force.

Um, and they acted.

They acted at a distance

that it would be just bad air would somehow affect the body.

Now many people think that this is absurd.

But actually at the time that my asthma's were a common explanation of disease.

Scientists were working on magnetism,

which is another phenomenon where you get action at a distance.

And there was also interests at the time in in Mesmer ism,

which is where something like hypnosis, where people can get into a mental state by,

um

working,

working with other people and mesmeric experiences were

a form of contagion contagion in a group.

But Jones theory didn't

come from medicine.

It came from studies on wine and beer,

and the person responsible

was Louis Pasteur in France,

and the key thing about pastor was that he was a chemist

and previously he had worked on crystals,

and one of the essential things about working on

crystals is being able to understand their shape.

And for these he used the microscope and he became very

adept at microscopy.

But he was.

He was brought in by the French winemakers to look

at why wine was deteriorating in bottles and in barrels,

and what was happening was the clear liquids were going cloudy.

So the first thing pastor did was to look

at some of the cloudy liquid through his microscope,

and he didn't find crystals. But rather he saw a small, micro,

tiny

microorganisms.

And the question was,

Were these microorganisms the cause

of the deterioration? Or were they the result of the deterioration?

If they were the result, then they had arisen spontaneously.

Now Pastor, like all scientists at the time,

disliked the idea of

spontaneous happenings.

Scientists wanted to give material naturalistic explanations for a phenomenon,

and pastor was also religious

and at the time to suggest that life could arise any time in writing beer or wine,

um was was almost kind of unthinkable for someone who was religious.

Life had been created once by God has described in

the early chapters in the early chapters of Genesis.

So what, Pastor?

What Pastor did was to try to understand where these microorganisms had come from.

And he did a whole series of experiments where he

where he tried different ways of sealing bottles of liquid,

um, so that they did not get contaminated.

And what he found is that in almost every case,

deterioration was due to contamination from the air.

He even took one of his, um,

bottles of fluid up until the high ups where he thought the air

would be would be absolutely pure and be unlikely to be contaminated.

And he was right. There was no contamination.

So Pasta's conclusion was that in the air

there were small organisms circulating all the time,

and he came up with what what

we can now call a germ theory of putrefaction.

That is a germ theory of deterioration, of rotting,

a germ theory of decay in organic materials.

And it was this theory

that was seen by Joseph Lister,

the London born surgeon who was then working in Glasgow

and thought, Well, if these microorganisms in the air can cause decay in wine

and beer,

then maybe they are the cause of the deterioration I am seeing in surgical wounds

surgeons at that time mainly dealt with people who were already injured or wounded.

Surgeons did not operate on people who were who were healthy.

So a lot of the surgeons work was cutting away dead or diseased tissue.

And what Lister did was when he was doing this,

he sprayed the air with something that he thought would kill germs carbolic acid.

And he put dressings on wounds to stop any germs that got in

developing

to kill the germs.

But that posed a question.

If germs were causing

diseases in wounds

and causing

sepsis because

people with disease wounds didn't just get local changes to the body,

these septic conditions spread to the whole body and cause fever, paralysis

and the type of the type of symptoms that you saw in a in an ordinary disease.

Then perhaps germs might just not be responsible for future faction.

They might actually be responsible for infection.

And that's the story I'm going to take up next time because

there isn't just one germ theory of disease.

So far, in fact, we haven't got a germ theory of disease.

We've got a germ theory of future function and a germ theory of infection