Germ Theory of Disease

  • Germ theory states that specific microscopic organisms are the cause of specific diseases.
  • Germ theory is also called the pathogenic theory of medicine.
  • Germ theory led in to the development of antibiotics and hygienic practices.
  • It is considered as the cornerstone of modern medicine and clinical microbiology.
  • Major contributors to germ theory are:
    • Antoni van Leeuwenhoek
    • Francesco Redi
    • Rudolf Virchow
    • Louis Pasteur
    • Joseph Lister
    • Robert Koch
  • Microbes, or microorganisms - minute living things that are usually unable to be viewed with the naked eye.
  • Germ - refers to a rapidly growing cell.
  • Spontaneous generation - the hypothesis that living organisms arise from nonliving matter. It was an important early development in the germ theory.
  • Biogenesis:  living cells can arise only from preexisting cells.
  • Antibiotics - chemicals produced by bacteria and fungi that inhibit or kill other microbes.
Major Concepts
  • Explains the phenomenon of disease transmission
  • Means of speculative explanation and prediction of certain observable events
  • Allows us to effectively function to prevent transmission of communicable disease.
  • Viable basis upon which to make decisions about how to prevent certain illnesses.
  • There are phenomena we do not understand that are related to germ transmission, e.g. the communicability of cancer.
Antoni van Leeuwenhoek (1673-1723)
  • Microorganisms were first directly observed by Antoni van Leeuwenhoek, who is considered the father of microbiology.
Edward Jenner
  • In 1796, Edward Jenner inoculated a person with cowpox virus.
Agostino Bassi (1835)
  • Agostino Bassi showed a silkworm disease was caused by a fungus.
Ignaz Semmelwise (1840)
  • He advocated hand washing to prevent transmission of puerperal fever from one patient to another.
Louis Pasteur
  • Louis Pasteur was one of the first to link germs to disease.
  • In 1861, Louis Pasteur demonstrated that microorganisms are present in the air.
  • Pasteur discovered vaccines for chicken cholera. (1880), Anthrax (1881) and Rabies (1885).
  • Pasteur also showed that microbes are responsible for fermentation.
Joseph Lister
  • Joseph Lister is considered as inventor of antiseptic surgical techniques.
  • In 1860s, Joseph Lister used a chemical disinfectant to prevent surgical wound infections.
Robert Koch
  • In 1876, Robert Koch explained a bacterium causes anthrax.
  • In 1882, he discovered the germ that caused tuberculosis. (TB)
  • In 1883, he discovered the germ that caused cholera.
Alexander Fleming
  • In 1928, Alexander Fleming discovered the first antibiotic from Penicillium fungus.
  1. "The History of the Germ Theory". The British Medical Journal 1 (1415): 312. 1888.
  2. Germ Theory in Contagion: Historical Views of Diseases and Epidemics. Harvard University Library; accessed on 8/9/2011. Available at


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