Germ Theory


The germ theory of disease is also refereed to as the pathogenic theory of medicine. It is the sole most significant input by the science of microbiology to the common welfare of the people of the world. It is perhaps the sole most significant input of the scientific discipline in modern times. It may be the sole most significant input to the modern medicine practice, fundamentally illustrating the expression with the discovery of antimicrobial chemotherapeutics (Rezende 15).

The theory has represented a larger late 19th century[1] break point between modern and traditional medicine, which is difficult to get hold of but easy to perceive (Windelspecht 3). This has mostly been evident to the medical historians, the healthcare professionals and the public.


The germ theory proposes that diseases are caused by small organisms (can only be viewed by very powerful microscopes) known as microorganisms in the body (Goldstein 4, Hyde 7). This theory superseded the theories of contagion and miasma. The miasma theory proposed that diseases were caused by a poisonous vapor (Garner 1). The particles of decaying matter overcame the vapor, which the characteristic of foul smell.

According to the above explanation, it is revealed that the ancient people believed that diseases were brought into existence through spontaneous generation. This was in place of creation of microorganisms, which multiply by reproducing. A sacred text of Hinduism known as Athaevaveda was one of the olden manuscript dealing with medicine. The diseases believed to be caused by the durnama, krimi, kimidi and yatudhanya[2], were treated using various drugs (Mazumdar 15). These drugs were believed to kill these agents.

The germ theory is credited to Agostino Bassi, an Italian, who is said to have initially stated this disease (Reynoldson 50). He stated this disease after observing the epidemic and lethal muscardine silkworm disease. He alleged that the death of the insect was caused by powdery spore masses, which were visible to the eye and a contagious living agent. This was in the year 1835. This fungus was later referred to as Beauveria bassiana[3] (Madigan & Martinko 65).

Anton van Leeuwenhoek also referred to as the father of microbiology, was the first person to observe microorganisms. Nicolas Andy, a physician, built on Leeuwenhoek’s work and argued that microorganisms were responsible for the emergence of the disease known as smallpox. He called these microorganisms “worms” (Herbst 25). Ignaz Semmelweis observed that women giving birth with the help of the doctors either got puerperal fever or were at a higher chance of getting it as compared to the women who delivered with the help of the midwives (Simpson 28). After much investigation, Semmelweis realized that the doctors helping in the delivery usually came from autopsies. He realized that the doctors got contagious matter from the dead bodies, which in turn caused the women to get the puerperal fever (Gillen 45). He asked doctors to clean their hands in chlorinated lime prior to attending to the women.

John Snow proved the miasma theory inconsistent as he identified the Cholera disease to be a vessel of the disease’s transmission. Francesco Redid disapproved the spontaneous generation evidence. Through an experiment where he put meat loaf and eggs in three jars (one open, one tightly covered and one covered with gauze), he observed that there were maggots in the open jar and the jar with gauze (Waller 18). He also observed that the maggots were on the places that had contact with flies. By this observation, he concluded that it was not a plausible theory.

One man who is very significant to the history of microbiology is Louis Pasteur[4]. He demonstrated that the development of microorganisms and fermentation did not take place through spontaneous generation (Bellis 2011). After exposing freshly boiled soup to air in containers that has a filter, he found no growth took place in the growth. Air was channeled in these containers using long tortuous tubes (Waller 38). He concluded that what grew in these soups came from without and not within.

Pasteur further contributed to the discovery that weaker forms of a disease could be used as an immunization towards stronger forms of the same disease (Chiras 280). He further dwelled on Andy’s work and discovered the silkworm’s disease. He had to work very closely with the clothing industry in order to make this possible. The peak of his time was when he discovered the fermentation method as a way of killing germs. This process was named pasteurization (coming from the word Pasteur). He also put up a big campaign, including a school in order to emphasize on the need of using clean instruments, hands as dirty instruments and as agents of spreading germs, which caused diseases.

Another important person in the history of the germ theory is Robert Koch. This scientist came up with the tests, which were used in the evaluation of the germ theory (Gillen, Douglas & Frank, 2010). Through his works, the publication of the Koch’s Postulates demonstrated that bacterium Bacillus antharacis[5] caused the disease known as Anthrax. These tests are still used in order to identify whether a disease has been caused by microorganisms (Gradmann 56). Joseph Lister is also acknowledged for coming up with practical applications of the theory in elation surgical techniques.

Controversies about the Theory  

Due to his main contributions, the germ theory is referred to as Pasteur’s germ theory of disease. However, some scientists have argued that he should not be given all the credit for coming up with the theory given the fact that there are very important scientists who played a major role before (Bellis, 2011) as indicated earlier. In another perspective, he was not the only one experimenting about the fermentation process. His contemporary, Antoine Beauchamp was also in the same course. Nevertheless, he never acknowledged Beauchamp’s contribution to the discovery when he finally discovered about the fermentation of sugars concept. This is why some scientists refer to him as a plagiarist (Fry 527).

Another controversy about the theory lies in the way it is taught in medical schools. There are scientists who argue that it should not be taught as the main truth about microbial science. Since it is still a theory, tests are still being done to prove its validity. The theory has not yet been made a fact (Alhardhi & Weinwright 312). The theory still has inconsistencies, which have not been scientifically proven.

It has also been argued that Pasteur admitted to his own mistake. He realized that microbial species undergo transformations and thus making the germ theory inconsistent. It was discovered that germs could be able to penetrate a territory when the territory conditions change, the host enfeebled after the exaltation of the virulence. Since bacteria are not permanent monomorphic, the theory becomes a fallacy as bacteria have been proved to pleomorphic or inconsistent in form (Gaynes 120).

Importance and Applications of the Germ Theory

As earlier identified, the tests introduced by Robert Koch and Joseph Lister are widely used in identifying whether an emerging disease has been caused by microorganisms or not. The use of using weaker forms microorganisms in order to cure the strong ones has widely used in vaccination and curing of diseases all over the world. Diseases such as rabies, small pox, the silkworm disease, just to mention but a few have been controlled for many years.

Fermentation, which had been used for thousands of years in the wine industry for example, was a process that had been researched on by many scientists but was never understood. When it was finally understood between the years 1860-1864[6], it started being used commercially in such processes as fermentation of milk. The process has continued being used for other commercial purposes.

Above all, the discovery of the theory played a major role in the reduction of disease spreading. When the doctors and scientists finally got convinced of the disease, they did such acts as cleaning medical instruments before using them on patients, cleaning their hands and other general sanitation precautions.

Germs’ Epidemics

Epidemics involving germs include the Black Death, which was encountered in the 1300s, the syphilis epidemic the small pox epidemic, the fever epidemics, just to mention but a few. The fever epidemics have been given different names for they have come up a couple of times killing millions of people worldwide (Worboys 327). The fever epidemic is one of the major germ caused epidemic still recurring even today. All these epidemics were caused by bacteria and viruses (Rodgers 1)[7]. The virus caused diseases are more difficult to handle that the virus caused disease. In most cases, they are fatal if not controlled in time.

The discovery of the germ theory has brought forth the innovation of cures and explanations pertaining to the cause of many diseases (Havard, 2011). With the theory’s weakness of microbial transformations in relation to their environment, scientists have been able to do more research and thus finding ways of curing the diseases caused by the changing microorganisms.

Terms Relating to the Theory  

Such terms as antibiotics, chemotherapy, aseptic technique, chemotherapeutic agent, synthetic drugs, pasteurization and spontaneous generation revolve around this theory (Gradle 75). All of the named apart from the latter two are used in the curing of the various diseases caused by either bacteria or viruses.


Although research is being carried out, it can be appreciated that the discovery of the germ theory has greatly contributed to where the world is today in the scientific and especially the medical field. It is true that the Americans took a longer time to accept this theory, but when they accepted it, the reduction level in diseases was significant. Nevertheless, it can be regarded as the only theory that has played a major role in the identification of diseases and their cures. The spontaneous theory and other theories in the scientific field have also played major roles in the microbial research. As the bacteria change in relation to their environment, the research will continue to help scientists come up with the cures of the various diseases.


Works Cited

Alharbi, S.A, and M Wainwright. “The Story of a Largely Unknown Evolution – Germ Theory Hoax.” Saudi Journal of Biological Sciences. 18.4 (2011): 311-316. Print.

Bellis, Mary. Louis Pasteur. Web. About.Com, 2011. Web. 3 Nov. 2011.

Rogers, Kara. Bactria and Viruses. . New York, NY: Britanica Educational Publishing, 2010. Print.

Chiras, Daniel D. Human Biology. New York, NY: Jones and Bartlett Learning, 2005. Print.

Contagion History Views of Diseases and Epidemics. Germ Theory. Havard University Library Open Collections Progaram, 2011. Web. 3 Nov. 2011. <>

Dr. Gillen, Alan L., Dr. J. Douglas Oliver & Frank Sherwin. “Robert Koch, Creation, and the Specificity of Germs”. Answers Research Magazine, April 7, 2010. Web. 3 Nov. 2011.

Fry, D.E. “Prions: Reassessment of the Germ Theory of Disease.” Journal of the American College of Surgeons. 211. 4 (2010): 546-552. Print.

Garner, Stanton B. “Artaud, Germ Theory, and the Theatre of Contagion.” Theatre Journal. 58. 1 (2006): 1-14. Print.

Gaynes, Robert P. Germ Theory: Medical Pioneers in Infectious Diseases. Washington, DC: ASM Press, 2011. Print.

Gillen, Alan. L. The Genesis of Germs: Disease and the Coming Plagues in a Fallen World, Green Forest, AR: Master Books, 2007. Print.

Goldstein, Natalie. Germ Theory. New York: Chelsea House, 2011. Print.

Gradle, Henry. Bacteria and the Germ Theory of Disease. New York, NY: BiblioLife, 2009. Print

Gradmann, C. Laboratory disease: Robert Koch’s Medical Bacteriology. Baltimore, MD The Johns Hopkins University Press, 2009. Print.

Herbst, Judith. Germ Theory. Minneapolis, MA: A Division of Learner Publishing Group, Inc, 2008. Print.

Hyde, Natalie. What is Germ Theory. CRABTREE PUB, 2011. Print

Maclagan, T. The Germ Theory – Applied to the Explanation of the Phenomena of Disease – The Specific Fevers. Read Books Design, 2010. Print.

Madigan, M. & J. Martinko. Brock Biology of Microorganisms ,11th ed. New York: Prentice Hall, 2005. Print.

Mazumdar, P. M. H. Species and Specificity: An Interpretation of the History of Immunology. Cambridge, United Kingdom. Cambridge University Press, 2002. Print.

Mitchell, R. T. Evolution and medicine. Web. Answers genesis, Nov. 22, 2005. Web. 3 Nov. 2011. <>

Reynoldson, Fiona. Medicine Through Time. Oxford: Heinemann Education Publishers, 2002. Print.

Rezende, Lisa. Chronology of Science. New York, NY: Infobase Publishing, 2006. Print.

Simpson, Ruth E. & Rutgers The State University of New Jersey- New Brunswick. The Germ Culture: Metaphor, modernity, and epidemic disease. Ann Arbor, MI: ProQuest Information and Learning Company, 2006. Print.

Waller, J. The Discovery of the Germ. New York, Columbia University Press, 2002. Print.

Windelspecht, Michael. Groundbreaking scientific experiments, inventions, and discoveries of the 19th Century. Westport, CT: Greenwood Press, 2003. Print. 122

Worboys, Michael. Spreading germs: diseases, theories, and medical practice in Britain, 1865-1900. Cambridge, Press Syndicate of the University of Cambridge, 2000. Print. 327

[1] The research on disease and medicine started as early as 36 BC.

[2] These are Hindu phrases published in Marcus Terentius Varro, a journal in the Hindu medicinal field.

[3] This fungus was named after Agostino Bassi.

[4] This scientist has brought controversy in regards to the germ theory as his discoveries are referred to as fraudulent and plagiarized from works of previous scientists.

[5] This bacteria was discovered by Robert Koch.

[6] This is the period when Pasteur was most active in his research work.

[7] The 1918 fever, the avian flu also known as the H1N1 fever, were some of the deadliest epidemics caused by viruses in the 20th and the 21st centuries.

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