Germ theory of disease, Wikipedia:
"Basic forms of germ theory were proposed by Girolamo Fracastoro in 1546, and expanded upon by Marcus von Plenciz in 1762. However, such views were held in disdain in Europe, where Galen's miasma theory remained dominant among scientists and doctors. "
On that page, check out the "development" section, covers what I was talking about with the rudimentary understanding of contagious illnesses. Keyword rudimentary.
Germ theory of disease, Wikipedia: "Basic forms of germ theory were proposed by Girolamo Fracastoro in 1546, and expanded upon by Marcus von Plenciz in 1762. However, such views were held in disdain in Europe, where Galen's miasma theory remained dominant among scientists and doctors. "
On that page, check out the "development" section, covers what I was talking about with the rudimentary understanding of contagious illnesses. Keyword rudimentary.