Who proved the germ theory?

Proving the germ theory of disease was the crowning achievement of the French scientist Louis Pasteur. He was notthe first to propose that diseases were caused by microscopic organisms, but the view was controversial in the 19th century, and opposed the accepted theory of “spontaneous generation”.

How long has germ theory been around?

A transitional period began in the late 1850s with the work of Louis Pasteur. This work was later extended by Robert Koch in the 1880s. By the end of that decade, the miasma theory was struggling to compete with the germ theory of disease. Viruses were initially discovered in the 1890s.