Here are some key figures:
* Antonie van Leeuwenhoek (1632-1723): He was a Dutch scientist who used microscopes he built himself to observe tiny organisms in water, which he called "animalcules." He was the first to see and describe bacteria, though he didn't understand their role in disease.
* Louis Pasteur (1822-1895): A French chemist and microbiologist, Pasteur's experiments proved that microorganisms cause fermentation and disease, a concept known as the "germ theory of disease." He also developed pasteurization, a process of heating liquids to kill harmful bacteria.
* Robert Koch (1843-1910): A German physician, Koch established the "Koch's postulates," a set of rules to prove that a specific organism causes a specific disease. He was the first to isolate and identify the bacteria responsible for anthrax, tuberculosis, and cholera.
While van Leeuwenhoek made the initial observation of microscopic organisms, Pasteur and Koch's work provided strong evidence for the germ theory and its implications for disease.
