Microbiology started with Dutch scientist Antonie van Leeuwenhoek in 1676. Microbiology is the study of microorganisms and includes the fields of bacteriology, virology and mycology.
Van Leeuwenhoek was the first to describe a single-celled organism that he named an “animalcule”. He was using a microscope to examine a sample of plaque he had scraped from his own teeth and made this observation:
I then most always saw, with great wonder, that in the said matter there were many very little living animalcules, very prettily a-moving. The biggest sort… had a very strong and swift motion, and shot through the water (or spittle) like a pike does through the water. The second sort… oft-times spun round like a top… and these were far more in number.
It was almost two hundred years after this discovery of bacteria that Louis Pasteur and Robert Koch proved that some bacteria could cause disease. In 1838, the name animalcule was changed to bacterium, which comes from the Greek word ‘bakterion’, meaning ‘a small rod or staff’. (It was only later discovered that bacteria can come in a variety of shapes - rod-shaped, spherical and curved.)
Viruses were not identified until 1898 when a solution from which bacteria had been removed by filtration was still able to transmit disease.