In the US, it's common to hear phrases such as:
I caught a stomach bug
There's a bug going around
I was sick with a 24-hour bug
When did bug start being used in such a manner?
Specifically, when did this definition (pulled from M-W.com) come into usage:
3 a : a germ or microorganism especially when causing disease
b : an unspecified or nonspecific sickness usually presumed due to a bug
For further background information:
M-W.com and other dictionaries indicate a first-usage for "bug" in general to be around 1622.
Microorganisms were considered discovered in either 1655 by Robert Hook, or around 1675 by Antonie Van Leeuwenhoek.
So, I wonder if the microorganisms were viewed as "bugs" rather early in the history of the word and the history of microorganisms, or if that terminology was maybe applied later as our understanding and imagery of microorganisms improved.