Paradigm Shifts and the Germ Theory of Disease
The germ theory of disease is a theory that proposes that micro organisms are the cause of many diseases. Although highly controversial when introduced, it is now a cornerstone of modern medicine, leading to such important innovations as hand washing and antibiotics.
The historical view is that disease was spontaneously generated instead of being created by micro organisms which grow by reproduction. Anton van Leeuwenhoek first observed micro organisms. John Snow believed that the germ theory explained outbreaks of cholera, in opposition to the prevailing miasma theory of cholera.
A true germ theory of disease was spearheaded by the study of fermentation by French chemist Louis Pasteur, (who was more interested in wine making), beginning in 1879 and shown in a paper on wound infections published by the German bacteriologist Robert Koch in 1879. In general, the theory held that a pathogenic organism must be present in every case of the disease; that this organism could be grown or "cultured" outside the infected body; that an animal inoculated with this culture would get the same disease; and that the organism could be found again in the inoculated animal and re-cultured. Some pathogens may not meet all of these conditions, but they are the boiler plate for explaining scientifically how disease happens (Bidale).
Louis Pasteur demonstrated that fermentation and the growth of micro organisms in nutrient broths were not caused by spontaneous generation. He exposed freshly boiled broths to air in vessels that contained a filter to stop all particles passing through to the growth medium; and even with no filter at all, with air being admitted via a long tube that would not pass dust particles. Nothing grew in the broths, therefore living organisms that grew in such broths came from outside, as spores on dust, rather then being generated with the broth.
This discovery was a huge shift in the medical world. Louis Pasteur found a cure for chicken cholera, anthrax and rabies. He got doctors and surgeons to sterilize everything they used. He once and for all proved that germs existed and that they carried disease. But, Louis Pasteur's main contributions to microbiology and the world of medicine were much more then just those basics. Hospitals began instituting changes in their medical practices to minimize the spread of disease by microbes or germs. He discovered that the weak forms of disease could be used as an immunization against stronger forms. Pasteur also found that rabies was transmitted by viruses too small to be seen under a microscope. All in all, he introduced the medical world to viruses. His discovery that most infectious diseases are caused by germs, known as "germ theory of disease" is one of the most important in medical history.
Before the germ theory came about, it was said that disease arose from non living materials. Since it was believed to be so, it was also believed that micro organisms could arise from non living substances. Scientists and doctors then saw no reason to try and prevent these diseases. Doctors would do things like perform autopsies on the very people who died of these diseases and then go see other patients, even deliver babies, without washing their hands. They did not realize they were the ones spreading these diseases.
The previous paradigm takes us back to the days of our hunter-gatherer ancestors. As soon as they could they raised food crops as well as grew and gathered plants for medicinal purposes. These plants, as well as fresh water were the treatment for all ailments. By the time the great ancient civilization emerged, medicine was already well established. Different cultures and countries produced their own medical system.
Hippocrates was the start of Western medicine. He took health and disease out of the hands of the Gods. He argued that all diseases have natural causes and cures. He may have not made a discovery, but he envisioned and created the field of medicine as we know it. And this is why I say this was the paradigm shift before Pasteur's discovery. Hippocrates single handedly started the medical field as we know it today.
Before the germ theory, those in the medical community practiced a type of holistic medicine. They sought to make sense of illness in the context of patient's environment and lifestyle (Adler). Hippocrates would teach his students that it is the patient that matters the most. Spend time with them, get to know them and learn from them.
Thomas S. Kuhn defines anomalies as deviations from the common rule, failures of the current paradigm to take into account the observed phenomena also; anomalies expose the limitations of existing paradigms and drive the search for new ones. (Kuhn). There were many anomalies that brought about the paradigm shift of germ theory. Before Hippocrates, health and disease were in the hands of the Gods. Hippocrates' focus was on the patient. Herophilus dissected the human body from head to toe; he distinguished the two parts of the human brain. He also discovered and described the prostate, the spermatic duct, the Fallopian tubes, and the ovaries which he linked to the testes in men (Adler). Soranus of Ephesus did the most to bring the ancient practice of midwifery into the medical field and to teach doctors that women have unique medical needs. Galen of Pergamon did dissections and experiments which led him to new understandings of the heart, the nervous systems and the mechanics of breathing (Adler). Abu Bakr al-Razi was the first to divide all substances into classifications using animal, vegetable, and mineral. Galen discovered and tested the way blood flowed through the body. His emphasis was on the liver and the right side of the heart. Andreas Vesalius wrote the book that gave man its first look at the structure and workings of the human body. All of these men strayed away from what once was known, coming up with their own theory, thus creating a new paradigm and change in the medical world. Each one of these events led up to Pasteur and his discovery of germ theory.
Kuhn defines crisis as a turning point, change and instability in the paradigm shifts. The period of crisis in reference to the germ theory of disease was the fact that there was an absence of understanding of how germs cause infection. Until Joseph Lister discovered the antiseptic methods - inspired by Pasteur's work on fermentation and putrefaction- won gradual acceptance, almost any surgical procedure carried significant risk of death. Surgery and childbirth were nightmares. A compound fracture, with the bone coming out of the skin, proved to be fatal at least half the time. Women were ten times safer giving birth on the street then in the hospital. Fatal infections stalked the halls and decimated the wards of every hospital in the world, and were accepted by most doctors as sad but inevitable. (Adler)
People in those times did not find it easy to accept the idea that there was something they could not see that was causing disease and death. They could not accept the idea that infected diseases were brought about by germs which could be passed from one person to another and then would cause them to have that disease. It wasn't until people realized that infected diseases were caused by these micro organisms that they could really hope to find a cure for diseases.
Because of Pasteur's discovery of the germ theory there have been many changes in society today. If not for Pasteur and his work, we may not have the treatment for rabies. Pasteur was able to open the Pasteur Institute where younger researchers trained. Roux's work in the institute led to the development of antitoxins; Elie Metchnikoff discovered the role of white blood cells in immunity; and Alexander Yersin discovered the microbe responsible for plague (Adler). Pasteur led the way to discoveries of cholera, diphtheria, typhoid fever, bubonic plague, malaria, and tuberculosis. Once these discoveries were made, scientists then could go on to find ways in which to prevent or treat these diseases.
Alexander Fleming and World War I was another big change in society. Fleming saw thousands of soldiers dying from tetanus, blood poisoning, and gangrene. Fleming realized that antiseptic was not working for war wounds. He tried cleaning the wounds with boric acid, carbolic acid and hydrogen peroxide. These antiseptics did not kill the bacteria or heal the wounds. Fleming then tried flushing the wound with sterile saline solution. This seemed to minimize the infections and get the body to produce more white blood cells. The white blood cells would speed up healing. So as we can see Louis Pasteur and his germ theory of disease has changed the medical world into what we know it for today.
In conclusion, today there are three different types of vaccines: live attenuated virus vaccines, inactivated virus vaccines, and acellular vaccines (Bakalar). If not for Pasteur's germ theory, it is possible that these vaccines would not exist today, or they would have been discovered many years after Pasteur, which would cause a shift in another direction in the medical and scientific world. In theory one would think that if the germ theory was discovered at a later date by someone else, then there would have been many people that died of diseases in Pasteur's era that did not have to. There would not have been a Pasteur's Institute in which those young scientists were able to study and make their discoveries. I believe that if research continues to stem from the past germ theory and move forward the way it has for hundreds of years, it is possible we may see the cure to AIDS.
References:
Adler, Robert E. (2004) Medical firsts: from hippocrates to the human genome. Hoboken, New Jersey: John Wiley and Sons, Inc.
Bakalar, Nicholas. (2003) Where the germs are: a scientific discovery. Hoboken, New Jersey: John Wiley and Sons, Inc.
Biddle, Wayne. (1995) A field guide to germs. New York: Henry Holt and Company.
Kuhn, Thomas S. (1962) The structure of scientific revolutions. Chicago: The University of Chicago Press.