What was the ‘Germ Theory?’ Our learning objectives today are: To explain ideas about disease in the 18th C. To investigate how Pasteur discovered germs To explain why this discovery was an important development

How did people explain disease before 1750? God People had thought it was a punishment from God. However the church’s power was weakened and this idea was fading 4 Humours Like spiritual explanations, this idea of humour imbalances was fading fast Why had these theories been so popular? Bad air (miasma) People could see rotting food and waste in the streets and knew they smelt terrible. They assumed it must be the smell that caused disease

People thought that bad air caused disease. This was called a “miasma”. Industrial towns were more crowded and dirtier than ever. There were epidemics of diseases like TB, diphtheria and cholera and this theory seemed very logical.

Spontaneous Generation! Bad air (miasma) People could see rotting food and waste in the streets and knew they smelt terrible. They assumed it must be the smell that caused disease Spontaneous Generation! The latest theory. The microscopes picked up bacteria on decaying matter. Scientists thought that the germs were spontaneously (automatically) generated (created) by the decay and then spread the disease further. Is this right? What is wrong with this theory?

Louis Pasteur! The Daddy of Bacteriology.

He thought it was because of germs. Pasteur was a French scientist, asked by a brewery to investigate why their alcohol was going sour. He thought it was because of germs. He proved that germs in the air were causing the decay – not the other way around …

100 years later, it was still sterile (no germs)! He took two flasks – he heated the liquid in one flask to kill the germs and make it sterile. He then drove the air out so no more bacteria could grow, and sealed the flask. 100 years later, it was still sterile (no germs)! The other flask soured with the bacteria.

He called this method of heating and sterilising liquids … Pasteurisation! Many foods are pasteurised, such as milk. This method also paved the way for air-tight food storage such as vacuum packing and air-tight jars, tin cans etc.

He was asked to investigate a disease in silkworm. He proved that bacteria was spreading the disease and therefore linked germs to disease (in animals)

He proved that germs caused diseases in other animals too. He accidentally injected a chicken with some old chicken cholera germs. The chicken did not die! He then injected the chicken with fresh germs, and it still didn’t die! He had proved how Jenner’s vaccination worked. He now wanted to prove germs caused human diseases too …

Learning check: Title – Louis Pasteur and Germ Theory Write down these key words (underline) and a definition for each: Miasma Spontaneous generation Germ Theory

Watch the Powerpoint on Pasteur and answer the question below. http://www.youtube.com/watch?v=Wo-ewybcG-Y&feature=related How did Pasteur work out his Germ theory? Explain in your own words Clue: Milk and beer

How would Pasteur’s discovery influence the world of medicine?

Robert Koch Built on the work of Louis Pasteur IDENTIFIED bacteria that caused specific diseases. Scientific Method Paved the way for vaccines and magic bullets to be invented.

Diseases Koch Identified TB (1882) – a major killer in 19th Century caused the death of 1/7. High mortality rate (if untreated 50%) Now vaccinations and antibiotics. (Although 1/3 of the world’s population have it) Cholera (1883) – A quick and lethal killer which struck big cities often. Diseases Koch Identified Anthrax (1877) – Now rare thanks to eradication programme. Spores still survive however. Treatable with antibiotics. Developed as a biological weapon by UK (ww2).

Legacy of Koch From his work Pasteur developed vaccines for Cholera, Anthrax and Rabies His students went on to identify the bacteria that causes: Diphtheria, pneumonia, Typhoid, Gonorrhoea, Meningitis, Leprosy, Plague, Tetanus, Syphilis. Won Nobel Prize (later, 2 other members of his team would also).

Team Spirit Paul Ehrlich (German): Nobel Prize winner and inventor of the first magic bullet. Gerhard Domagk (German): Nobel Prize winner and inventor of the first sulphonomide. Julius Richard Petri (German): Obvious! Koch’s team of scientists would be perhaps the most successful in the history of medicine.

Make a CV for Koch Name Job Location Main influences Discoveries Achievements

GERM THEORY Identifying Bacteria Pasteur convinced other scientists that diseases are caused by microbes (bacteria or Germs) Identifying Bacteria Koch was the first scientist to identify specific microbes that caused individual diseases

Anti-biotic medicines Vaccines Cleaner hospitals Public Health EXPLAIN THE LINK: Anti-biotic medicines Vaccines Cleaner hospitals Public Health Antiseptic surgery Training of Doctors and Nurses More investment in Science Higher life expectancy

Koch or Pasteur? A French scientist PASTEUR

Koch or Pasteur? Worked with Paul Ehrlich KOCH

Koch or Pasteur? Investigated a disease in silkworm PASTEUR

Koch or Pasteur? Discovered what caused TB KOCH

Koch or Pasteur? Discovered GERMS PASTEUR

http://www.youtube.com/watch?v=rR4sC9RDaKY&safe=active