If you're like many office workers, your workday may begin something like this. You arrive a little tired, so you make a beeline for the break room, grab a coffee cup (yours or any handy one that looks clean) and pour a full cup of Joe. In no time, you tell yourself, the java will kick in and your brain will shift into gear.

If this sounds familiar, you may be setting the stage for a sick day, according to research by University of Arizona microbiologist Chuck Gerba, PhD. In his recent study of germs around the office, the coffee mug was a star, but in the worst way.

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Twenty percent of the mugs he tested were contaminated with fecal bacteria. And 90 percent were covered in other germs, says Gerba, who's been affectionately called Dr. Germ thanks to his years of research focusing on bacteria and viruses and how to stay well in a germy world.

Here's another interesting, although disgusting, finding: "The higher up the administrative chain, the more fecal bacteria [on that person's cup]," he says. He wonders: were disgruntled secretaries washing out the big bosses' coffee cups in the toilet? He can’t account for this phenomenon.

The findings about germy coffee cups make sense, he says. "Most coffee break rooms don't have a dishwasher. People use sponges to wipe them out." Or they may use scrub brushes. Both may still contain bacteria and viruses, he says, either from food products left behind or perhaps people's hands. In some cases, the same sponge that has just been used to wipe up the counter is used to wash the coffee cups. Ugh.

Related: Germ-Proof Your Commute

Good coffee cup hygiene

What to do? Gerba says to tote that coffee cup home and put it in the dishwasher. Every day would be ideal. Be sure to let the cup go through the dishwasher's drying cycle, Gerba says, to kill as many germs as possible. If you forget to take it home, wash it with hot water and soap and rinse it well, he says. Then dry it with a paper towel.

Another bad habit is leaving your coffee cup unwashed on your desk. Germs flock to it immediately, Gerba says. Little cities of germs can sprout, even if you've slurped every last drop and all that’s left is a coffee ring.

What if you're on a job interview and offered coffee? Gerba's suggestion may be tricky to pull off, as your potential boss may wonder if you're a germaphobe, environmentally unfriendly or both. But still, it's your health. "Always ask for a disposable cup."

Where else germs lurk

Once you've got the germy coffee cup under control, look around. Germs are everywhere at work. If you think the bathroom is the worst area, you're wrong. Office workers face 400 times the level of contamination sitting at their desk than on a toilet seat, research suggests.

Your desk has about 10 million germs. The phone, 25,000 a square inch. The keyboard, more than 3,000 and your mouse 1,600. The toilet seat? A measly 49 per square inch.

What else to do?

  • Don't eat lunch at your desk. If you must, wipe down the surface with soap and water or antibacterial wipes before and after eating.
  • Use the wipes to zap germs on you keyboard, phone and mouse — especially if you have been eating lunch and working away.
  • Wash your hands frequently with soap and water or wipes. If that's not possible, use hand sanitizer.

Germs travel faster than…

You might also consider giving a sick co-worker a very wide berth. If a single co-worker comes to work sick with a virus, by lunchtime about half of the commonly touched surfaces around the office will be infected, Gerba found in another study. He recruited 80 workers, giving all but one harmless droplets on their hand at the day's start. One got a droplet containing several artificial viruses. Workers were told to work as usual.

After four hours, Gerba's crew sampled commonly touched surfaces such as doorknobs, the refrigerator and the copy machine buttons. He also sampled the workers' hands. More than half the surfaces and the workers' hands were infected with at least one of the viruses. 

Kathleen Doheny is a Los Angeles journalist specializing in health, behavior and fitness topics.