When was Germ Theory?

Germ theory, which posits that many diseases are caused by microorganisms, was developed in the mid to late 19th century. Key figures like Louis Pasteur and Robert Koch significantly advanced this theory through their research in the 1860s to 1880s. Pasteur's experiments debunked the idea of spontaneous generation, while Koch established methods for identifying specific pathogens. By the late 19th century, germ theory became widely accepted in the medical community.