Everything You Never Wanted to Know About Germs

"If you're going to worry about germs, the number one thing to worry about is contact with other people," says Dr. Philip Tierno, Director of Clinical Microbiology and Immunology at New York University Medical Center. In his book, The Secret Life of Germs, he says that 80 percent of all infectious disease is transmitted by touching—either another person or an object that has been touched by someone else.

The problem is germs can hang around on fingertips for hours and surfaces for days. Most of us unconsciously touch our eyes, nose or mouth several times a day, which can spread germs that cause the common cold, flu, even some forms of hepatitis. Fortunately, most germs can be shrugged off by our immune systems, explains Dr. Tierno, who believes, "Handwashing is the single most important thing that people can do to safeguard their health." Some especially important handwashing occasions: after using the bathroom, handling raw foods, money or bodily fluids (like runny noses), and before eating or drinking.