If you're the type who already dreads trudging to your cubicle on Monday mornings, here's another reason to stay home: Your desk may be a veritable zoo for bacteria.

In a recent study, a British consumer advocacy group tested a few dozen of its office keyboards for harmful bacteria. Four were deemed health hazards, and one was five times dirtier than a toilet seat in the same office.

And that's just the keyboard — there's also the computer mouse, the telephone, the coffee mug, the work refrigerator and all the other surfaces on which workers touch, breathe, cough and spill crumbs of food.

In the keyboard study, the British magazine Which? (similar to Consumer Reports) commissioned microbiologist James Francis to test more than 30 office keyboards for a handful of nasty bugs that indicate poor hygiene.

Two keyboards had staphylococcus aureus — associated with skin infections and food poisoning — at "warning levels," and one keyboard was removed from the office because its bacteria levels were 150 times higher than normal.

"That keyboard is increasing the risk of its user becoming ill," Francis told the magazine. "I haven't seen a reading like that in a very long time. It was off the scale."

It's not terribly surprising that keyboards and other office equipment are crawling with bacteria — after all, these one-celled microorganisms are already crawling inside our bodies and on our skin at massive levels. One study last year found evidence of 182 species of bacteria on skin samples.

Besides bacteria, workers also have to worry about viruses, the smaller infectious agents that cause, among other things, the common cold.