What is Germ Theory? As defined by the Encyclopedia Britanica, Germ Theory of disease is: “ The theory that certain diseases are caused by the invasion of the body by microorganisms.” This is based on three basic underlying principles that developed throughout the history of medicine(described by John Waller in The Discovery of the Germ : 1. Microbes can cause illnesses within the body. 2. Microbes (and thus the illness) can spread from one person to another. 3. A specific microbe exists for each illness which will always invoke the same illness.
When did it all begin? As is the case in many descriptions of history, Germ Theory is often summed up In a linear format. As we will soon discover, this was certainly not the case. The ideas that Germ Theory are based off were articulated far before the age of microscopes in 500 B.C. by Hippocrates who stated that disease originated in stagnant water in marshy areas travelled through the air, thus infecting nearby populations. This idea that certain “Miasmas” caused disease would both develop into and compete with the Germ Theory in later days. But, for the days until then, the promotion of good hygiene and sanitation were the cornerstones of warding off disease. It wasn't until the Bubonic Plague hit the Middle Ages that the idea that diseases could be transmitted from person to person was thought up, but would ultimately lay dormant until further scientific discoveries occured.
Miasma Moves Along Although still tied to Hippocratic dogma, in the 1600's Robert Boyle and Thomas Sydenham postulated that inorganic particles that come from the ground could be responsible for illness. This created a direct correlation between disease and sanitation therefore, even though the concept of particles causing illness had a long way to go and much support to gain, living conditions were now a top priority in public health.
The First Sense of Microbes Without much integration with the miasma theory, Anton Von Leeunhoek, a Dutch cloth merchant and lens grinder who made his own microscopes discovered the first microbe after examining white matter which he scraped from his own teeth. The questions that were asked surrounding Leeunhoek's discovery were not related to what the microbes did, but where they came from. Some people suggested that the microbes caused rotting (the idea that would eventually develop into Germ Theory) while others thought they simply gravitated towards rotting. The third idea that would most butt heads with the developing Germ Theory was that these microbes spontaneously generated.
18 th Century Hygiene In Britain, the 1750's saw: -The development of laws forbidding burials within city limits. -The revamping of sewer systems. -Street cleaning and the zoning of dairies and Slaughterhouses as suggested by the Quaker cloth merchant, John Bellers. But the growing populations and increasing urban density made these hygienic demands increasingly difficult to meet. As suggested by John Howard and his philanthropic tendencies, British prisons and hospitals began to improve their sanitation. The British Navy followed in hygiene as its growing fleet demanded better health conditions. Because diseases that we consider minor today created such a difficult conundrum, the American Physician Benjamin Rush suggested in 1793 that people “fly from it.”
New Century, New Ideas The immense growth of scientific thought of the 1800's is responsible for a massive paradigm shift in medicine that marked the transition from ancient dogma to the empirical ideology the western world so avidly embraces, but it was not a smooth switch and can claim no single scientist as its supreme founder. Up until 1800, illness was thought of as conditional, in that each instance was a different disease specific to its victim. This idea was contested by the Scottish William Cullen who claimed in his theory of “ Contagious Effluvia ” that diseases have specific traits that occur in each of their hosts. He did not, however, extend his theory to suggest that these specific illnesses were the result of microbes invading the body. The first strain of absolute proof for Germ Theory developed when Agostino Bassi, an Italian entomologist, discovered that a disease bringing death to silkworms by the name of “muscardine” was, in fact, caused by a parasitic fungus now known as Beauveria bassiana. Alas, there was still much work to be done by Germ Theorist in order to finally convince the opposition of its validity.
Times, They Are A' Changing As a new France was developing after its revolution, so were new ideas in science and medicine. The changing tides resulted in a huge growth in the effectiveness of hospitals. Previously, European hospitals were essentially places where the impoverished sick would go to die. They were responsible for little help and a high rate of defamation to those who survived their unsanitary conditions. 19 th century France began shaping hospitals into what they are today by linking them to universities and thus creating a place where students could learn medicine hands on and doctors could practice free from the restrictions (political and physical) of visiting their elite patients at home. The bridging of medicine and education also made way for the influx of innovative minds and the disposal of age old dogma. The industrial revolution happening in the Germany during the 1830's developed a new reason for medicine: Bigger industry dependent on a larger working class would require better medicine in order to keep things operating smoothly. Thus, the rationalization of labor could most certainly be interwoven with the rationalization of medicine.
Schwan Versus Liebig In 1839, a German chemist by the name of Justus Von Liebig developed a theory that microbes gravitate towards rotting substances and thus exploit decay. He went further to say that decay (both fermentation and disease related) are the result of chemical reactions. This theory was in contention with another theory, that of Theodore Schwann, an Austrian scientist. Schwann believed that it was airborne microbes caused decay, not gravitated towards it. It was through a series of extensive experimentation on beef broth that eventually disproved Liebig's theory, but believers of the idea that microbes spontaneously generate was still in contention and it would take much more experiments by many other scientists to disprove it. In 1842, a British doctor and statistician took the debate a step further in suggesting that microbes were organic particles similar to flower pollen that, upon ingesting or inhaling, caused disease in their newfound host. The idea that disease causing microbes could cause disease upon ingestion sparked international campaigns in further increasing the sanitization of sewer systems and the Germ Theory began to gain a little more support and momentum.
Childbed Fever Going back a few years, between 1789 and 1792 Alexander Gordon suggested that childbed fever, a deadly fever infecting women post-delivery, is contagious and transferred by midwives and doctors from one new birth to the next. In publicly naming specific midwives responsible for the transfer of this illness, Gordon provoked his medical community in Aberdeen, Scotland to slander his name and discredit his theory thus leaving the idea that contagions are responsible for childbed fever null until it was again pondered by a certain Oliver Wendell Holmes, an American physician. In 1855, Holmes pressured doctors to stop delivering children if three or more of their new mother patients consecutively died. Similar to Gordon, Holmes received negative responses from his medical community as no doctors wanted to be held responsible for the death of their patients. Contrary to Gordon, Holmes was not completely alone in the world with his postulation. Previously, during the 1840's, the Europeans had made some headway in the realm of childbed fever and found a way to tie it into the developing Germ Theory. Namely, James Young Simpson of Britain suggested that the minor vaginal abrasions caused by childbirth allowed for germs on doctor's hands to invade the mother's body and invoke the unfortunately familiar childbed fever.
Something Nice From Semmelweis In 1847, Ignaz Semmelwies, a Hungarian physician working in the Vienna General Hospital noticed a striking difference between the hospital's two maternity wards; one ward had an alarmingly higher rate of childbed fever than the other. He deducted that the reason for the high rate of childbed fever was due to the ward's student demographic; the ward was full of medical students who performed both autopsies and deliveries without much care to clean up. The low rate in the other ward was due to the fact that only students of midwifery performed deliveries. This theory was vindicated when a professor died of what was assumed to be childbed fever after cutting his finger in the midst of an autopsy. Childbed fever death decreased dramatically after the implementation of Semmelweis' suggestion that doctors wash their hands with a mixture of chlorine and water. Germ Theory's wheels of motion began accelerating as it was finally received positively by a medical community that diseases could be transmitted interpersonally. This developing science began laying its mental eggs in the brains of scientists throughout Euorpe.
Snowing Ideas in London In 1854, the British John Snow noticed that outbreaks of Cholera occurred around specific water sources. This led him to persuade authorities to remove the handle of a particular pump that was surrounded by an incredibly large outbreak of Cholera. This improvement in sanitation reduced the occurrence of Cholera surrounding the pump. In the same year, the Italian anatomist, Filippo Pacini, isolated the Cholera bacillus, however, many critics invoked the old argument that the bacterium could just arrive at the scene of Cholera, not necessarily cause it. Unfortunately, this discovery came far too soon to be widely accepted by science and it would not be until later in the century that Cholera would be conquered.
Louis, Louis The man who would come to be thought of as the pioner of Germ Theory, although this is not entirely true, was a man by the name of Louis Pasteur. He was a chemist professor in Lille, France when he first stumbled upon the ideas that would eventually shatter dogma. Lille was a region stocked full of breweries, wineries, and vinegar distilleries; all which were institutions of a mysterious science at that time. Contrary to Liebig's theory that fermentation was a result inorganic molecules causing chemical reactions, Pasteur set out to prove that establish that yeasts are comprised of microorganisms. Pasteur began experimenting with fermentation and eventually discovered that different microorganisms create different effects. He was eventually invited by Napoleon III to study the problems of winemaking. This led to the discovery of several different types of bacteria and the ability to kill them with heat (a process now known as pasteurization). Pasteur eventually convinced most of France that spontaneous generation was impossible through a series of experiments with beef broth and swan-necked flasks. It is now known that Pasteur's notebooks did not always line up with his public statements. His main intention was disproving Felix Pouchet, a strong advocate of the spontaneous generation theory.
Joseph Lister In 1854 the assistant surgeon at Glasgow Royal Infirmary naemd Joseph Lister combined the ideas of past proponents of surgical cleanliness with Pasteur's ideas that airborne germs cause fermentation and began using the antiseptic Phenol (Carbolic Acid) to disinfect the air and wounds before, during, and after surgery. This innovation decreased the post-operative mortality rate by 30%. Imagine the effects if he had also disinfected the bedclothes of patients and garments of surgeons. On a global scale, physicians took after Lister's success and ran with it by disinfecting midwives thoroughly between operations to reduced the still prevalent childbed fever and doing the same with surgeons to reduce the occurrence of gangreen. Hospitals all over Europe (especially in Germany) began improving their sanitation by invoking the use of gapless metal instruments, glass operating tables, increased antisepsis, and disallowing outside clothes in operating rooms.
Laying the Framework With Farm Work Pasteur was called to the South of France to investigate the cause of Pébrine, a disease responsible for killing a large number of silkworms – devastating in the times of a booming silk industry. Contrary to both his discoveries of fermentation and work done by others (including that of his assistants), Pasteur rebuked the idea that Pébrine was caused by microbes. It was only after solving the pandemic conundrum through eugenics (selective reproduction) did he realize his reasons were discounting the evidence for pathogens was faulty. This sparked Pasteur's embarkment on a journey into the abyss of disease causing bacteria.
Early Work From 1863 to 1870, Casimir-Joseph Davaine, a French physician, performed critical work in the understanding the nature of Bacillus anthracis , the bacterium that causes Anthrax, a fatal disease responsible for the death of many farm animals. In 1873, the German physician Robert Koch took the ideas of Davaine much further after working as a surgeon during the Franco-Prussian War. He isolated Bacillus anthracis and proved that it had a lifecycle in which produced spores that (he assumed) settle in the grass which were capable of causing sudden outbreaks of Anthrax. Koch also performed more work in proving that different microbes had different effects on their hosts thus answering some of the questions related to Germ Theory at the time such as “why don't bacteria in the stomach cause disease?” Koch would go onto to do an incredible amount of work on Germ Theory and become one of the most remembered scientists in the field, but for now, it was unto Louis Pasteur to solve the problem.
The Sheep Trial Between 1876 and 1881, Pasteur and his team isolate Bacillus anthracis in their own right and claim, although prematurely, that they have developed a vaccine. A French veterinarian put Pasteur to the test by inviting to demonstrate the effectiveness of his vaccine in hopes of proving him wrong. Fortunately for Pasteur, his vaccine worked. He vaccinated 25 of 50 sheep and then injected them all with an extremely potent strain of the bacillus. Of the 25 vaccinated, 1 died. This convinced herds of non-believers and the Germ Theory's investment grew more. Although the textbook account of this episode in science often denotes Pasteur as the forerunner of vaccination, much credit is due to a veterinarian competitor in the field by the name of Jean-Joseph Henri Touissant who made the discovery that Bacillus anthracis was better weakened by carbolic acid. Charles Chamberland, a man working for Pasteur, built upon Touissant's idea and weakened the bacillus more effectively with potassium-bichromate. It is now known that it was actually Chamberland's vaccine that was used by Pasteur in the public trial. Nonetheless, Pasteur reaped the monetary benefits and eventually developed a more powerful vaccine using heat instead of antiseptics to weaken the bacillus.
The Emerging Koch In 1881, Robert Koch developed four postulates in order to effectively prove the undiscovered truths of the effects of bacteria. This is how John Waller articulates them in his book The Discovery of the Germ : 1. Bacterium must be present in every case of the disease. 2. Bacterium must be isolated from the diseased host and grown in a pure culture. 3. The specific diseases must be reproduced when a pure culture is inoculated into a healthy susceptible host. 4. The bacterium must be recoverable from experimentally infected hosts. Koch went further into his methods and began using potatoes, gelatin, and agar (from seaweed) as solid mediums on which to cultivate colonies of bacteria with far less risk of contamination as was the case with previously popular liquid mediums. Taking advantage of the booming German dye industry (a result of the occurring Industrial Revolution), Koch and other German scientists began using dyes to identify bacteria that could not otherwise be seen.
Erysipelas In 1881, one of Koch's stalwarts by the name of Firedrich Fehleison used Koch's methods to isolate and identify the bacterium causing Erysipelas, a commong disease in the 19 th century. After experimenting on rabbits, Fehleison moved onto tumor patients, as it was known that the onset of Erysipelas benefited their health. These experiments luckily did not kill any patients and were done in order to prove the isolation of the bacillus as the disease brought on different effects in rabbits than it did in humans. This discovery, then, advanced belief in the Germ Theory in the international scene, but it still faced some serious opposition that wouldn't be convinced until further discovery.
Altering the Tuberculosis Prognosis In 1865, a French military doctor by the name of Jean-Antoine Villemin suggested that Tuberculosis is contagious after observing its passing from humans to rabbits and then along to more rabbits. Due to opposition and Villemin's inability to locate a specific germ, it was unto the familiar Robert Koch in 1882 to prove this theory. Thanks to his sheer industriousness, Koch was able to identify, cultivate, and test the bacterium responsible for causing tuberculosis; a definitively difficult task. Unfortunately, the German physician assumed too soon that he had developed a cure for the disease by isolating the protein tuberculin and injecting it into infected guinea pigs, which cleared up their symptoms after a short terrible reaction occurred where the injection took place. Hyping this false alarm led to a great downfall in his credibility which triggered his retreat to Cairo, Egypt, although he would eventually return home to teach.
The Call to Calm Cholera In 1883, the Cholera epidemic in Egypt was investigated by British, German, and French medical teams. The British medical team was assembled to be a group who would not determine the a germ as the cause for the political purpose of keeping trade routes Suez Canal trade route open. The Birtish blamed unusual weather patterns and a dormant Cholera poison in the soil leftover from a previous epidemic in 1865. But where did this dormant poison originate? After the British returned home, the French team, assembled by Louis Pasteur and led by Emile Roux, arrived in Egypt. By this time, however, the epidemic was settling down and (along with the German team led by Koch) relocated to Calcutta, India where a new epidemic was on the rise. Koch and his team found inside the intestines of Cholera victims the same bacillus that was discovered by Filippo Pacini in 1854. Still, the age old question still drawing from miasmatic theory of whether or not the bacillus alone could cause Cholera or if it was dependent on a set of environmental factors was on public debate. Although many men labored to find a cure and thus prove the cause of this violent disease, it was a politically radical young Russian scientis by the name of Waldemar Heffkine who was responsible for the final culmination of Germ Theory meets Cholera.
Waldemar Haffkine After leaving his native Russia due to political oppression and fear of losing his life for being a radical, Haffkine eventually found himself working for Emile Roux in 1890. By 1893, he had created a vaccine by concentrating the bacterium in guinea pigs and then weakening it. In 1894, he vaccinated 20,000 Indians in Assam triumphantly protecting all but 400 of them (an incredibly low 2% death rate).
A Rabid Germ Theorist In 1884, Pasteur and Roux set out to find a Rabies vaccine. Because Rabies is a viral infection, the two could not find a germ that caused. Nonetheless, they formulated an extremely potent strain of the virus through a lineage of extractions from the spinal cords of dogs. They heated and dried this strain, entitled the virus fixe , only to discover a 60% success rate in protecting dogs against rabies. Into 1885, the two refined their vaccine through a series of experiments on dogs in which increasingly stronger strains of rabies were injected. Two tests on humans who had been diagnosed with rabies (and were assumed to be gravebound anyway) were performed by demand of the patients and before they had actually perfected their vaccine. The results were inconclusive; one man lived and one girl died. It was impossible to determine whether the survivor had actually been infected and whether the girl was reached in time. Undeterred, the scientists carried on. Twice again, the vaccine was put to the test by two young boys who had been bitten by positively rabid dogs. Neither contracted the disease and many attested the efficacy of the vaccine, especially the young boys. One of the boys even went onto run the Pasteur Institute (built in with donations in gratitude of this life-saving rabies vaccine) after Pasteur's death in 1895, by which time the vaccine had been effectively used at least 20,000 times.
Typhoid Fever In 1861, the first postulation that Typhoid Fever is caused by a bacterium popped up in the doctor from Bristol, William Bald's “Typhoid Fever.” In which, Bald suggested that a microbe found in dirty water caused the disease, but once again, the world was not ready to hear such a thing. It would not be until 1880 and 1881 that this idea was resurrected by the Swiss morbid anatomist by the name Carl J. Eberth made headway on identifying the bacillus that caused tyhpoid fever by examining intestinal lymph nodes and spleens of patients who feel victim to it. To his chagrin, he could not locate the bacillus in all the patients he examined. One of Koch's students, George Gaffky, began working on identify this elusive bacillus. More successful than Eberth, Gaffky found the bacillus in 26 of 28 patients. He then isolated it on gelatin and grew a colony, but was unable to prove it as the cause of Typhoid Fever within the framework of Koch's postulates because animals did not react to the bacillus in the same manner as humans.
The Science Continues... Both a team of two British scientists and a French scientist discovered (independently of each other) that when the blood serum extracted from sufferers of Typhoid Fever was mixed with the Eberth and Gaffky's bacillus, it curdled. This suggested that antibodies were present in the blood. This came to be known as the Widal test (named after the French scientist who ultimately published the idea) and was used to determine if patients had Typhoid Fever. But alas, the race for proof continued...
Life Saver Although the bacillus had not been entirely proven to cause the disease, the British Scientist Almroth Wright set out to weaken the bacillus in order to develop a vaccine. Taking from the German physician Richard Pfeiffer's discovery that the bacillus could be killed entirely by heat and then injected into subjects whilst still provoking immunity, Wright fought opposition and worked tirelessly to test and as he had hoped, prove this vaccine's efficacy. Beginning in 1896, he travelled to a small town to convince civilians to be vaccinated when rates of the disease were high. Successful there, he moved along to a mental institution were an outbreak was happening. Most of the people he vaccinated there did not contract Typhoid Fever. Wright's perseverance paid off for the British during WWI when near-mandatory vaccinations saved all but 7,000 British soldiers from Typhoid Fever. Both the French and the Germans experienced over 100,000 cases of the disease who had also invented vaccines, but were not as eager to use it.
So... After a roller coaster history, Germ Theorist finally prevailed in proving to the world that disease is, in fact, often caused by microorganisms procreating in their host. They went on to develop vaccines to several other diseases. By deconstructing the dogma written by Hippocrates and Galen, the 19 th century scientists created one of their own. This new dogma was relevant to the growth of industry and the paradigm's shift to the quest for the objective and the growing body of empirical data. The 1900's saw the rise of many germophobic campaigns, some over the top and some not. Although it was not their intention, the empirically based view the Germ Theory invoked severely altered medicine into what it is today which, unfortunately for many people, compromises many age-old philosophies on health and healing. The growing return to herbal medicine now has the ability to combine with the body of knowledge modern science has developed and understand health in a myriad of perspectives never before thought up. To say that the train of thought provided by Germ Theory is superior to all previous conceptualizations of health and body restricts room for growth, but to discount it based on what it has evolved into limits its ability to promote health and foster life. Only the future will inform mankind what these discoveries will become next. Let's just hope it's for the benefit of all and not the few.
Gotta Say Thanks to John Waller for writing his book on Germ Theory called The Discovery of the Germ , where the information from this project came from, with some help from wikipedia for clarifying job titles of certain Germ Theorists and opposers. Hope you enjoyed this text heavy summary of historical haps, you are a trooper for going all the way to the end.