Germ theory is the scientific theory that certain diseases are caused by microorganisms known as pathogens or “germs.” The theory was developed, proved, and popularized in Europe and North America between about 1850 and 1920. The French chemist and microbiologist Louis Pasteur, the English surgeon Joseph Lister, and the German physician Robert Koch are given much of the credit for development and acceptance of the theory. Koch conclusively established that a particular germ could cause a specific disease by experimentation with anthrax. He observed rod-shaped bacteria and suspected they caused anthrax. When Koch infected mice with blood from anthrax-stricken cows, the mice also developed anthrax. This led Koch to list four criteria to determine that a certain germ causes a particular disease. These criteria are known as Koch’s postulates. Germ theory revolutionized the theory and practice of medicine and the understanding of disease. It was, however, compatible with existing ideas about health. [1][2][3][4][5]
At the time of this writing it has been 51,843 days (142 years, not long really) since “The germ theory and its applications to medicine and surgery” was read before the French Academy of Sciences, on April 29th, 1878 by Louis Pasteur. This theory revolutionized public health by proving that certain diseases are caused by microorganisms, and that they can be prevented by prophylactic vaccination and treated by antiseptic surgery[6][10]. Pasteur’s experiments showed that food spoiled because of contamination by invisible bacteria, not because of spontaneous generation. He also proved that anthrax disease in sheep and cattle was caused by bacteria, and that injecting healthy animals with killed bacteria gave them immunity to the disease if he later injected them with living bacteria, which is the foundation of vaccines[8].
About Pasteur
Louis Pasteur was a French biologist, microbiologist and chemist. He did not just throw out some made up theory about germs causing diseases, he did experiments and he proved his theory. The stakes were high. He used what he learned to save sheep and cattle from anthrax disease caused by bacteria.
He showed that Anthrax was not caused by “cursed fields” as the people before him thought, it was caused by a bacteria. He showed that this bacteria, after being isolated in the lab and grown, could be killed by what he called “pure air” which was oxygen.
He showed that injecting healthy animals with killed bacteria gave them immunity to the disease if he later injected them with living bacteria! This was huge. It worked. This is the simple foundation of vaccines. Regardless of what you think about current vaccines, the first vaccines came about originally because they saved lives. Even before Louis Pasteur, it was common practice in Europe to give people cow pox because it was known that getting this weaker disease somehow protected people from the much more deadly small pox. No one understood why, they just knew this worked at a time when many were dying of small pox.
Childbed Fever
The truth is horrible to us today, but before germ theory, doctor’s did not wash their hands before delivering babies, because they did not understand the need. One thing that proved germ theory, the discovery, and rejection, and rediscovery of it by trial and error, was that if doctors washed their hands delivering a baby, the mother died in childbirth less. Deaths of mothers who had babies delivered by doctors who had been doing autopsies prior to the delivery without washing their hands was particularly high.
The importance of handwashing for doctors was discovered by Ignaz Semmelweis in the 19th century. Semmelweis, a Hungarian obstetrician, observed that the mortality rate from childbed fever was significantly higher in the ward where doctors conducted autopsies compared to the ward where midwives worked. He hypothesized that “cadaverous particles” were being transmitted from the autopsy room to the maternity ward, leading to the higher death rate. To test his hypothesis, he implemented a policy of handwashing with a chlorine solution for physicians and medical students. The result was a significant decrease in the mortality rate in the ward where handwashing was practiced, providing evidence of the effectiveness of hand hygiene in preventing infections[11][13][14].
Semmelweis’s work, although not initially accepted (which is putting it mildly, since he was in fact, confined to an insane asylum) laid the foundation for the importance of hand hygiene in healthcare. His observations and the subsequent decrease in mortality rates demonstrated the critical role of handwashing in preventing the transmission of harmful particles and reducing the spread of infection in medical settings[15].
Many doctors back then refused accept that they were harming patients with their lack of understanding. Read this modern answer rife with denial.
Childbed fever, also known as puerperal fever, was historically attributed to various causes, including the belief that it was transmitted by doctors. However, it is now understood to be caused by a bacterial infection of the upper genital tract, with the most common causative organism being the Beta-hemolytic streptococcus. Ignaz Semmelweis, a pioneering figure in the field of medicine, demonstrated that puerperal fever was contagious and that it was associated with the lack of hand hygiene among doctors and medical students. His work was instrumental in highlighting the importance of hand-washing and disinfection in medical settings, ultimately leading to a significant reduction in the incidence of childbed fever. Therefore, while doctors were once believed to be the cause of childbed fever, it is now known to be a result of bacterial infection, and proper hygiene practices have been crucial in preventing its spread.
Doctors and med students spread bacteria with lack of hygiene, but it was not their fault, it was the bacteria’s fault!? The above is an example of the absurd arrogant denial which is still alive in some places today.
Hopefully you have from this article understood germ theory, how it was proven to exist, and what the first reactions to it were. In the future you may encounter germ theory deniers. It will help to understand the evidence which lead to this theory being widely accepted by the medical community today. To be proven incorrect, past experimental results from around the world for over 100 years would need to be explained in a different way. This is possible, but it is not likely to happen.
Citations:
[1] https://www.ncbi.nlm.nih.gov/books/NBK24649/
[2] https://en.wikipedia.org/wiki/Germ_theory_of_disease
[3] https://curiosity.lib.harvard.edu/contagion/feature/germ-theory
[4] https://www.britannica.com/science/germ-theory
[5] https://www.sciencedirect.com/topics/immunology-and-microbiology/germ-theory-of-disease
[6] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3342039/
[7] https://www.amazon.com/Applications-Medicine-Antiseptic-Principle-Practice/dp/1573920657
[8] https://ourstory.jnj.com/louis-pasteur-discovers-germ-theory
[9] https://sourcebooks.fordham.edu/mod/1878pasteur-germ.asp
[10] https://www.britannica.com/science/germ-theory
[11] https://en.wikipedia.org/wiki/Ignaz_Semmelweis
[12] https://www.npr.org/sections/health-shots/2015/01/12/375663920/the-doctor-who-championed-hand-washing-and-saved-women-s-lives
[13] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7240806/
[14] https://globalhandwashing.org/about-handwashing/history-of-handwashing/
[15] https://theconversation.com/ignaz-semmelweis-the-doctor-who-discovered-the-disease-fighting-power-of-hand-washing-in-1847-135528
[16] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1088248/
[17] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3881728/
[18] https://www.ogmagazine.org.au/11/1-11/childbed-fever-major-cause-maternal-mortality/