Germs In Space

"Germs in space: Keeping astronauts healthy".

For instance:

[W]ithout gravity, germs launched by coughs and sneezes no longer fall to the ground within an earthly three to six feet, but continue to float around, increasing the distance and time for astronauts to inhale them or for them to settle on a wider variety of surfaces. 

(Via @Medgadget.)