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Germ Theory UNIVERSITY OF TENNESSEE Research Assistant: Yurdagül BOĞAR

Germ theory presentation

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Page 1: Germ theory presentation

Germ TheoryUNIVERSITY OF TENNESSEE

Research Assistant: Yurdagül BOĞAR

Page 2: Germ theory presentation

● The germ theory states that many diseases are caused by the growth and reproduction of specific microorganisms within a host body.

● The germ theory was proposed in the mid-16th century and gained popular acceptance through the work of many scientists during the 17th through 19th centuries.

The Germ Theory

Page 3: Germ theory presentation

Historical Perspective● One of the earliest theories of how disease is

transmitted is the miasma theory that was accepted in ancient times in Europe, India and China.

● The miasma theory held that diseases such as cholera, chlamydia and Black Death were caused by miasma which is a noxious form of bad air, also knownas night air.

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Pre 19th-Century● Caraka, Susruta, and Vagbhata, all practitioners of

Hindu medicine, all agreed that there were pathogens in the blood that were invisible.

● Girolamo Fracastoro proposed in 1546 that epidemic diseases were transmitted by direct or indirect contact, or even without contact at times.

● Later, in 1668, Francisco Redi of Italy performed an experiment from which he concluded spontaneous generation was not possible.

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Pre 19th- Century● In the 1670s, Anton van Leeuwenhoek was the first

person to directly observe microorganisms.

● Building on Leeuwenhoek’s work, Nicolas Andry states in 1700 that microorganisms were like “worms” that were responsible for various diseases.

● Richard Bradley proposed that disease was caused by living creatures that could only be seen through a microscope in 1720.

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Agostino Bassi● Bassi was the first person to prove that a disease was

caused by a microorganism when he conducted experiments between 1808 and 1813

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Ignaz Semmelweis● Hungarian obstetrician who noticed unusually high rate

of childbed fever in women who delivered in the hospital compared to women who delivered at home with a midwife

● Research revealed that the doctors assisting with birth had recently completed autopsies which led Semmelweis to realize disease can be contagious

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John Snow● Skeptical of miasma theory and did not understand how

disease was spread

● Studied cholera outbreak in France and discovered it was due to water supply

● Government rejected his research because they viewed the idea of fecal-oral transmission as “too depressing”

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Louis Pasteur● Conducted more formal experiments on the relationship

between germs and disease from 1860-1864o discovered the pathology of childbed fever and suggested

boric acid be used to kill microorganisms causing it

o demonstrated that microorganisms do not continue due to spontaneous generation

o discovered another disease that affects silkworms and developed method to screen silkworm eggs that is still used today

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Robert Koch● Known for developing four basic criteria for

demonstrating that a disease is caused by a particular organismo Koch’s Postulates

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Recent Germ Theory•The discoveries made during the 19th century, by scientists like Pasteur, Koch, Lister, Iwanowski, Fleming, many others, and the scientists before them, built the foundation for the scientific field we have today.

•Old theories and the spread of disease had to be reformed by necessity.

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Recent Germ Theory Diseases

•“Old” infectious diseases,❖ such as tuberculosis, cholera, thypus❖ more virulent strains,

•“Newer” diseases, such as West Nile virus and Severe Acute Respiratory Syndrome (SARS), have emerged.•Infectious agents can travel faster – and farther – than ever before

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The reemergence of infectious diseases

West Nile virus–First appeared in New York City in the summer of 1999–Initially puzzled medical personnel and public health officials, since the disease had not been seen before in the Western hemisphere–Eventually spread throughout the U.S.–Peak cases/mortality in 2006

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The reemergence of infectious diseases

•The anthrax crisis of 2001•Sudden Acute Respiratory Syndrome (SARS)•Monkey virus

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The reemergence of infectious diseases

➢ Sexually transmitted diseases (HIV/AIDS)–Represents greatest threat to worldwide health

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Haiti cholera epidemic 2010

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The reemergence of infectious diseases

Bioterrorism–Relatively new threat of infectious diseases–Takes place when people knowingly prepare biological agents or gases and use them to deliberately induce illness and death among other people•Overt - the perpetrator announces responsibility for the event or is revealed by the attack•Covert - characterized by the unannounced or unrecognized release of agents; the presence of sick people may be the first sign of an attack

–Examples: •1995 release of sarin gas in Japan by the Aum Shinrikyo cult in the Tokyo subway•1996 outbreak of gastroenteritis when a disgruntled coworker put dysentery bacteria in pastries

consumed by staff members in a large medical center laboratory•2001 anthrax sent through the U.S. mail

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Finally“The winners of past wars were not always the armies with the best generals and weapons , but were often merely those bearing the nastiest germs to transmit to their enemies.”Jared Diamond in Guns, Germs and Steel

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Future Implications● The germ theory has saved countless

lives and impacted the way we live our lives today.

● It is also having an impact on how our lives will be lived in the future. o Super-germso gene therapyoHealthy microbiomes

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Immunity and Super-germs ● “Antibiotics...are prescribed in a reflex

manner like old-fashioned palliting to mollify patients and/or their concerned parents” (Morrell, 2001).o This has potential to weaken

immune systems (Abernathy, 2015).

oMorrell (2001) suggests that antibiotics are becoming obsolete in treating diseases due to adaptations of target germs such as MRSA.

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Case Study● Overuse of antibiotics has led to multidrug resistant tuberculosis.

o The documentary "Cure from the crypt: Fighting tuberculosis again" produced by Naomi Lunsdaine (2009) stated, “⅓ of the world is infected with TB” and “the world is losing the battle with TB”.

o Case looked at discovery of hidden burial chamber from the 1800’s. Over 200 corpses were found well preserved and studied to identify old strains of TB and DNA analysis to locate mutated genes. This could lead to improved antibiotics, however, this could only help short term.

Simon

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Gene Therapy● Additionally, scientists were able to

locate human DNA from both infected and non-infected corpses.o By locating the genome that

allows individuals to resist TB infection, scientist can create treatment through gene therapy. Individuals without the

gene can be inoculated with the proper protein to eradicate TB infections in the future.

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Microbiomes● The “old” germ theory led medical practices to view

all germs as bad and thus, attempt to destroy them all. Not Good!

● The “new” germ theory suggests that a balanced understanding be deployed.o “There are more microbial genomes within

us than we have human cells” (Harking). o “Humans are walking ecosystems” (Dove,

2013).● By understanding the relationship between

microorganisms and humans, scientists can clarify the boundaries between diseased and healthy individuals.

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Ethical Concerns The future of medicine may about to be turned upside down. By understanding the germ theory and how microorganisms cause diseases, new scientific revolutions would allow for DNA engineering. Bacteria, such as TB, can be eliminated by altering their very own DNA sequences. This, however, comes with some concerns!

● techniques can be used for engineering super-germs for war.

● techniques can also be used for germ-line engineering, e.g. engineered babies.

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ReferencesAbernathy, D. (2015). Germ theory: Discovery, history, and new developments in health. Retrieved

from http://thephantomwriters.com/free_content/db/a/germ-theory-and-your-health.shtml.

Dove, A. (2013). Microbiomics: The germ theory of everything.Science,DOI:10.1126/science.opms.p1300075.

Cure from the crypt: Fighting tuberculosis, again [Video file]. (2000). In Films On Demand. RetrievedFebruary 5, 2015, fromhttp://digital.films.com.proxy.lib.utk.edu:90/PortalPlaylists.aspx?aid=17730&xtid=11850

Morrell, P. (2001). Concerning antibiotics and the germ theory of disease. Retrieved fromhttp:// www.homeoint.org/morrell/otherarticles/antibiotic.htm