You've been traveling for hours. All you want to do is check in to your hotel, stretch out on the bed and flip on the television. You walk in, throw your bag down and take a look around. It's sparkling clean.

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To the naked eye, that is. Germs are teeming on those surfaces, ready to attack your tired immune system if you don't take some easy-to-implement precautions and carry a few extra pieces of gear with you to combat these "hot zones," says Dr. Philip Tierno, director of Clinical Microbiology & Immunology at New York University Langone Medical Center and author of The Secret Life Of Germs: Observations and Lessons From a Microbe Hunter. 

"The worst offenders are basically anything that is touched by multiple people," says Tierno, who has participated in many undercover hotel sting operations. Even in the nicest of places, Tierno has found E. coli, Candida albicans (the virus that causes yeast infections), rhinovirus (the common cold), norovirus (that awful "24 hour" bug that often really lasts 48 hours) and more. 

Here, then, is the way Tierno sees a hotel room.

Germ Hot Zone A: The Never Cleaned

Watch out for door handles, telephones, remote controls, the clock radio and the light switch. 

You walked in the room, flicked on the switch, then, perhaps, you pulled back the door handle to allow your spouse in. Wash your hands now.

"The inside doorknob of your room," says Tierno, "is rarely cleaned by anyone — not the service people nor anyone else who might be coming in periodically to do some heavy cleaning."

He suggests carrying Clorox or other disinfecting wipes and wiping down doorknobs, the entire phone and the remote control. Some hotel rooms, he says, have remote controls that are caked with food from snacking channel surfers. Dr. Charles Gerba, professor of microbiology at the University of Arizona, agrees. In his studies, the remote control is often filled with E. coli.

Germ Hot Zone B: The Bathroom

The bathroom often looks pristine, but what's dirty isn't what you might have imagined. The worst offender is the underside of the toilet seat; it can be literally swarming with E. coli. 

"Men tend to lift it and women touch it to put it down, so your hands have touched the dirtiest part of the toilet bowl," Tierno says. Next dirtiest: the flush button or handle, and the sink taps. Both places are likely to be wiped with a cloth, but not disinfected. 

The shower floor is also a hot zone. Tierno suggests never going barefoot; athlete's foot grows rampant in hotel room shower floors and drains can carry bacteria. 

He also recommends skipping that hot bath — the tub may look clean, but you don't know what's on the surface of the tub. If you insist, he says, you should first wipe down the surface with a chlorine bleach wipe. 

And every microbiologist in America knows that you should never use a whirlpool bath in a hotel room. One 2000 study showed that 100 percent of the samples found nasty viruses, including those that cause urinary tract infections. Why? Because those pipes aren't ever disinfected.

Next: See the germs in hotel bathrooms. >>