The historical progression from the ancient miasma theory to the modern germ theory of disease spans centuries of scientific discovery. Key milestones include Girolamo Fracastoro's early contagion proposals in 1546, microscopic observations by Robert Hooke in 1665 and Antonie van Leeuwenhoek in 1674, Ignaz Semmelweis's handwashing studies in 1847, and John Snow's demonstration of waterborne cholera transmission in 1854. The paradigm shift was solidified in the late 19th century through Louis Pasteur's discovery of microbial fermentation in 1856 and refutation of spontaneous generation in 1862, Joseph Lister's use of surgical disinfectants in 1867, and Robert Koch's identification of specific bacterial causative agents between 1867 and 1906.