Once upon a time, humans lived outdoors in harmony with vast and diverse populations of bacteria, fungi, and viruses, largely unaware of the presence of these microbes.
As ever-curious humans, however, we eventually created magnifying lenses to see more than our naked eyes were capable of. In the 1500s, tiny moving “germs” were spotted in pus oozing from infections, so we gladly blamed diseases on these microbes. This was a relief because we could now theoretically control devastating human losses from cholera and the “Black Death” plague. By 1880, the germ theory of disease was widely accepted, and our war against microbes was energetically underway. By the 1940s, we had created the first flu vaccine, and the first antibiotic, penicillin, was being produced in mass. The 1962 Nobel Prize winner in medicine boldly (and incorrectly) stated, “To write about infectious diseases is almost to write of something that has passed into history.”