Germs. We've been hearing about them since we were toddlers. Our Moms nagged us to wash the dirt off our hands when we came to dinner, and to cover our mouths when we coughed. Teachers taught us about Lister, Pasteur, and the "germ" theory of disease. But who talks about the perils of kissing?

Worldwide, there are billions of kisses exchanged between people every year. The casual pecks on the cheek, the California air-kiss, or the cultured kiss on the hand aren't much of a threat. However, a kiss that exchanges saliva from one to another is an entirely different matter. Saliva carries microorganisms, bacteria and viruses. You've probably heard the mouth is the dirtiest place in the body: a human bite has more bacteria and is more dangerous than a dog bite, according to the Center for Disease Control. The CDC also preaches - and I agree - that hand washing is "the single most effective way to prevent the transmission of disease". However, they don't talk much about kissing. None of us likes to think that something we enjoy so much could be hazardous to our health.

The American Academy of Periodontology says more than 75% of adults over age 35 have some form of gum disease. The first signs of this infection are tender, swollen, bleeding gums. In their more advanced stages, periodontal diseases not only cause tooth loss but also put people at risk for many dangerous whole-body illnesses. In May 2000, the Surgeon General of the United States revealed studies linking bacterial infections of the mouth with heart attacks, strokes, diabetes complications, ulcers, respiratory problems, cancers, and many other serious diseases. Even premature childbirth and low birth weight babies were mentioned: pregnant women who have a severe gum infection could be nearly eight times more likely to have a premature baby, according to research done by Dr. Steven Offenbacher and colleagues from the University of North Carolina at Chapel Hill School of Dentistry

Unlike ordinary dirt, the hitch with germs is that they are invisible. Most of them are so small they can only be seen through a microscope. Their diminutive size, however, doesn't reduce their threat. Many different types of bacteria, like Strep Mutans, the bugs responsible for cavities, can be transferred from one mouth to another through kissing. Other organisms, like viruses, parasites, and yeasts, can be passed along as well.

In more than 35 years as a dental hygienist, I have harvested thousands of samples of bacterial plaque from the dark, moist, germ-friendly environments of the mouths of my patients. Under a microscope, the innocuous sticky white film I collected from between their teeth and gums transformed into a squiggling, undulating mass of organisms. This disturbing vision of highly-organized germ life was often all the motivation my patients needed to incorporate baking soda, salt, and diluted hydrogen peroxide into their daily oral care program along with a dental irrigator with a strong disinfectant. Germ warfare!

Since gum diseases are the equivalent of open wounds, kissing or having oral sex when you or your partner has bleeding gums, is a real invitation for transmission of unwanted organisms. Be careful: keep your mouth as healthy and germ-free as possible every day. Make sure your partner takes preventive actions too, so you can both enjoy those intimate smooches.

And don't forget Fido. When your beloved pet slobbers your face with kisses, he is not only demonstrating his love and affection, he is also gifting you his germs. Be sure to keep his mouth healthy too.