Ideas About Causes of Disease in 18th & 19th Century (Edexcel GCSE History): Revision Note

Developments in ideas about disease in the 18th and 19th centuries - Timeline & Summary

• The 18th and 19th centuries were part of the 'Scientific Revolution'

  • This was a period of major breakthroughs in understanding disease

• Improvements in technology, especially microscopes, allowed scientists to see microbes clearly

• Key scientists such as Pasteur and Koch changed medical thinking forever by showing that germs caused disease

  • In the 19th century, they faced resistance to their findings

    • The public and some doctors did not want to abandon well-established theories such as Spontaneous Generation or miasma

    • The government had a laissez-faire attitude to the health of the people, meaning that they did not interfere

  • Applying Germ Theory, such as Joseph Lister's use of carbolic acid, began to change public and government opinion

Miasma

• Many members of society still believed that miasma caused disease

  • Miasma seemed logical, as people got ill in dirty areas

• The government continued to believe in miasma until the end of the 19th century

Spontaneous Generation

• Scientists developed Spontaneous Generation theory in the early 18th century

• The theory states that, when matter decays, the process produces microorganisms 

Why did people believe in Spontaneous Generation?

• It explained the microbes that scientists could see using a microscope

• Scientists also stated that microbes spread through miasma, linking their new ideas to a well-known and trusted explanation

• However, scientists did not have the evidence to prove that decay caused germs

Pasteur and Germ Theory

Louis Pasteur and the development of Germ Theory

• Louis Pasteur was a French scientist

• He entered a competition in 1860 to either prove or disprove Spontaneous Generation

• By 1861, Pasteur's Germ Theory stated that:

  • Air contains microbes

  • Decaying matter did not create microbes; instead, microbes caused decay

• Germ Theory proved Spontaneous Generation was incorrect because:

  • Microbes would not grow on sterilised matter which was left in an airtight container

  • Microbes could be killed by processes like boiling

• In 1878, Pasteur published his findings, linking germs to human illness

Pasteur's influence in Britain

• Germ Theory faced resistance in Britain

  • Doctors like Dr Henry Bastian still supported Spontaneous Generation

  • The general public did not like change, preferring to believe in miasma

• Some scientists supported Pasteur’s ideas

  • Joseph Lister used Germ Theory to link germs with surgical infection

    • Lister could not prove his theory, as some microbes are good, for example, those in the gut

  • John Tyndall linked the discovery of particles in the air to Germ Theory

    • Tyndall was a physicist, not a doctor. Many medical professionals ignored his suggestions

Koch and bacteria

Robert Koch's work on microbes

• German scientist Koch built on Pasteur’s work

• In the 1880s, he proved that specific microbes caused specific diseases, such as:

  • Tuberculosis (1882)

  • Cholera (1883)

    • In 1884, he confirmed that water spread the disease, supporting John Snow’s earlier theory

Koch's influence in Britain

• He inspired scientists to identify the bacteria behind:

  • Diphtheria

  • Plague

• Scientists began treating the bacteria causing diseases, not the symptoms

• Koch developed techniques that made microbes easier to see under a microscope:

  • He promoted the use of agar jelly to grow bacteria

  • He also stained the bacteria with dye

• He received the Nobel Prize for Medicine in 1905

• Some still doubted the importance of Koch’s discovery

  • The British government ignored Koch’s work on cholera being waterborne

  • The government still believed that miasma spread the disease

Factors influencing the understanding of disease