Cholera- from miasma to germ Flashcards
cholera and john snow
many people used to die from outbreaks of cholera . Originally cooler was thought to be caused by miasma ‘bad air’. However John Snow made the obs on where the cholera outbreaks were ocruing and argued that waterborne germs caused cholera.
johns snow first clinical trial
-he marked homes who had those who had died on a map. Then removed the handle of the water pump on board street. Once the pump was out of commission, the epidemic seized.
example hypothesis of germ theory
‘The excretions of the sick at once suggest themselves as containing some material, which, being accidently swallowed, might attach itself to the mucous membrane of the small intestine, and there multiply itself by appropriation of surrounding matter.’
‘The excretions of the sick at once suggest themselves as containing some material, which, being accidently swallowed, might attach itself to the mucous membrane of the small intestine, and there multiply itself by appropriation of surrounding matter.’
the rationale for public health implications
‘ if the writers opinion be correct, cholera might be checked and kept at bay by simples measures.. it would only be necessary for all persons attending or waiting on the patient to wash their hands carefully and frequently, never omitting to do so before touching food, and for everybody to avoid drinking, or using for culinary purposes, water into which drains and sewers empty themselves, or to have water filtered and boiled before its use’.
Kochs postulates
1) microorganisms must be found in abundance in all organisms suffering from the disease and should not be present in healthy organism
2) microorganisms must be isolated from a diseased organism and grown in a pure culture
3) culture microorganism should cause disease when introduced to a healthy organism
4) microorganisms should be preisolated from the inoculated, disease host and identified as being identical to the original causative agent
who were the three men who created germ theory
Anton van Leuwenhoek
Louis Pastuer
Filippo Pacini
Anton van Leuwenhoek
1670
- microscope
- role of technology
- compared cells to cells in a church
Louis Pasteur
1870s
fermentation require micoorganisms
-no spontaneous generation
Filippo Pacini
- microscope
- identifies cholera vibri in 1853- seen in gut samples of victims
- prevailing miasma views meant it was ignored
- koch repeated in 1883 and got the credit
Thomas Kuhn related to
A PARADIGM SHIFT
What is a paradigm shift
Evidence builds up that contradict the prevailing theory (Miasma)
- the current there undergoes crisis
- new paradigm is established
- scientists work ‘normally within paradigms’
what is a paradigm
a normal pattern or model
