Louis Pasteur proposed germ theory of disease, according to the theory he stated that micro-organisms are the causes of many diseases. This theory is also called as:
Pathogenic theory
The germ theory of disease states that some diseases are caused by microorganisms. These small organisms, too small to see without magnification, invade humans, animals, and other living hosts. Their growth and reproduction within their hosts can cause a disease. This is also called as Pathogenic Theory.