While personal habits at the desk -- eat lunch there and some crumbs may fall into the keyboard, feeding germs there -- personal habits elsewhere carry some of the blame (and plenty of the germs) too.
Studies indicate that one in three adults don't wash their hands after using a public restroom -- don't wash at all, not even the ineffectual fingerwave under a trickle of water, much less the twenty seconds of warm water, soap and scrubbing that the Centers for Disease Control recommends.
So when one in three of us (at least) returns to doing business at the keyboard after, well, doing business elsewhere...
You get the picture -- and I'd apologize for bringing it to your attention, except for the fact that careful, frequent handwashing is one of the key defenses against disease, and not just at the keyboard (although thinking of one third of business's busily typing fingers busily spreading who-knows-what is something we should all be aware of.)
Think of how much time and money your business lost to sick-time last year, and ask yourself if twenty seconds of soap and water isn't a far less expensive and, obviously, far healthier approach.
There's more to keeping your business safe than keeping your computers secure -- you also need to keep them clean, and that means keeping your hands clean.
A suggestion that applies ten or a hundredfold to -- I shudder to think -- at least one in three of the readers of this blog.