Benchmark 10I
Historical Perspectives: Discovering Germs
Grades 6-8, page 257

Throughout history, people have created explanations for disease. Some have held that disease has spiritual causes, but the most persistent biological theory over the centuries was that illness resulted from an imbalance in the body fluids. The introduction of germ theory by Louis Pasteur and others in the 19th century led to the modern belief that many diseases are caused by microorganisms--bacteria, viruses, yeasts, and parasites.
 

See Content Standard G History and Nature of Science (grades 9-12): Historical Perspectives