State the observation. In your own words, explain Koch’s germ theory of infection.
In 1874 a man by the name of Dr. Trudeau knew all too well that a large number of people diagnosed with consumption (now called Tuberculosis) ultimately died. Crowded together in cities like New York, where he was living with his young family, were tens of thousands of immigrants who were trying to adapt to life in the U.S. They worked long days in crowded factories and lived in inadequate housing with poor ventilation, sanitation, and very little food. Despite being ill, they labored for as long as they could draw breath as the bacterial infection in their lungs worsened and spread, eroding blood vessels and causing bleeding and poor oxygenation, or causing the lungs to fill with fluid until the sufferer might literally drown. After work, they would retire to their dank, crowded apartments to be nursed by their families until they died. Often family members would themselves become infected from their close contact and constant inhalation of organisms expelled by their sneezing, coughing, bleeding loved one.
E.L. Trudeau, however, was not poor, nor was he a member of the factory-worker class. He decided to travel to a place where he had spent a lot of time as a boy and a young man, the Adirondack Mountains of upstate New York. There he could rest a bit, think, take long walks in the open air, and make a plan.
Dr. Trudeau’s condition worsened during the arduous trek north by rail and carriage. In fact, the young man was so frail and sick that he had to be carried into the house of an Adirondack outdoorsman and wilderness guide. But a remarkable thing happened. Dr. Trudeau began to feel better and in time, he could hike and hunt and enjoy life with his friends once
again. Eventually, he resumed his correspondence with doctors and scientists and sent for his wife and child. After some time, he began to build a medical practice in the distant little outpost of Saranac Lake and began to think about the cause and cure of what more and more scientists were calling Tuberculosis.
In the 19th century, a portion of the medical community believed that diseases like Tuberculosis were caused by an unfortunate combination of bad “family blood” (after all, the poor were certainly not well-bred, and they were more likely to become sick and to die early) and mysterious causative agents including ill-defined environments that included dank conditions, bad “humours,” obnoxious smells, and miasmas. But, in 1882, Robert Koch demonstrated to most of the scientific establishment’s satisfaction that the tiny bacterium Mycobacterium tuberculosis (MTb) was in fact the cause of the disease. Moreover, he could grow pure cultures of the finicky MTb and infect cells of experimental animals and animals themselves, causing the disease. Koch said: “If the importance of a disease for mankind is measured by the number of fatalities it causes, then Tuberculosis must be considered much more important than those most feared infectious diseases, plague, cholera and the like. One in seven of all human beings dies from tuberculosis. If one only considers the productive middle-age groups, Tuberculosis carries away one-third, and often more.” Koch’s work led to the more general “germ theory of infection,” which stated that infectious diseases were caused by germs (microscopic organisms we know now as viruses, bacteria,
Dr. Trudeau had followed Dr. Koch’s work with interest. He worked hard to learn how to culture MTb organisms, and was the first to do so in the United States. Intrigued by the correlation between healthy outdoor lifestyle and efficient anti-tubercular defense in his own case, he devised a simple experiment. The experiment spoke to both the MTb “germ” as the sole causative agent of Tuberculosis and a possible therapy for the disease. The experiment was described in his 1886 paper, “Environment in its Relation to the Progress of Bacterial Invasion in Tuberculosis.” The following is an excerpt from that paper.
- State the observation.
- In your own words, explain Koch’s germ theory of infection.
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