Ferdinand J. Cohn helps with the discovery of bacteriology. Cohn publishes his findings, calling it Bacillus.
Robert Koch publishes his work on the disease, Anthrax, which is caused directly by a bacterium.
Joseph Lister publishes his work on how milk souring is caused. Later called the bacteria, Bacterium lactis.
Louis Pasteur creates a way to attenuate (replicates in the host cell, but does not cause diseases) a virus pathogen for protection against different types of diseases. This concept was inspired by Jenner's smallpox vaccination.
ILya ILich (Elie) Metchnikoff introduced a theory of cellular immunity where certain body cells move to attack damaged cells.
Martinus Beijerinck demonstrates that using enrichment culture creates the conditions for bacterium growth.
Paul Ehrlich theorized that antibodies were a form of immunity to toxins and diseases.
Dmitri Ivanowski publishes his findings on the virus of tabacco mosaic disease.
December 27, 1899 - December 29, 1899, a meeting among the Society of American Bacteriologists was held at Yale. The Society of American Bacteriologist devoted their time to the promotion and service of bacteriology in the United States. Later known as the American Society for Microbiology.
Walter Reed indicated that yellow fever is caused by a virus transmitted by mosquitoes. Mosquitoes eradication programs began by the Yellow Fever Commission.
Francis Peyton Rous discovers that a virus causes cancer in chickens.
Frederick Twort had first discovered bacteriophage.
Sydney Brenner, Francois Jacob, and Matthew Meselson uses infected bacteria to demonstrate that ribosomes are where proteins synthesis occurs and show that messenger RNA exists.
Smallpox is officially announced eliminated
Stanley Prusiner finds an infection, he calls prions, causes a fatal neurodegenerative disease in sheeps', called scrapie.
Luc Montaigner and Robert Gallo broadcasts their findings of the human immunodeficiency virus (HIV), which is then believed to be the cause of AIDS