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A representation by Robert Seymour of the cholera epidemic depicts the spread of the disease in the form of poisonous air.. The miasma theory was the predominant theory of disease transmission before the germ theory took hold towards the end of the 19th century; it is no longer accepted as a correct explanation for disease by the scientific community.
The germ theory was not yet established (Louis Pasteur proposed it in 1861). Snow did not understand the mechanism by which disease was transmitted, but the evidence led him to believe that it was not foul air. Based on the pattern of illness among residents, he hypothesized that cholera was spread by an agent in contaminated water. [7]
Epidemics of the 19th century were faced without the medical advances that made 20th-century epidemics much rarer and less lethal. Micro-organisms (viruses and bacteria) had been discovered in the 18th century, but it was not until the late 19th century that the experiments of Lazzaro Spallanzani and Louis Pasteur disproved spontaneous generation conclusively, allowing germ theory and Robert ...
The older theory of contagion said that germs spread disease, but this theory was increasingly out of fashion by the 1840s or 1850s for two reasons. [ 92 ] On the one hand it predicted too much— microscopes demonstrated so many various microorganisms that there was no particular reason to associate any one of them with a specific disease.
This began the path to germ specificity within the theory. [49] Louis Pasteur's contemporary Robert Koch devoted much of his scientific study to discovering certain pathogens and connecting them to specific diseases. These scientists were often in competition with one another and so the Koch-Pasteur rivalry is a well-known part of germ theory's ...
It was one of the first large-scale biological weapon trials that would be conducted under a "germ warfare testing program" that went on for 20 years, from 1949 to 1969.
Basing its sanitation beliefs on miasma theory (as opposed to germ theory), [2] its agenda was based on the construction of sewage systems, street-paving, and the provision of clean water. [1] The movement spread to the United States in the 1840s, reaching its peak in 1880 before declining in the 1890s. [3]
Ewald is known for his "theory of virulence”, suggesting that "the deadlier the germ, the less likely it is to spread", [1] and his theory that many common diseases of unknown origin are likely the result of chronic low-level infections from viruses, bacteria or protozoa.