Harvard Men's Health Watch

Wash your hands

Harvard Medical School can claim many important discoveries in its more than 220 years of research and education. One of its most important contributions, though, is often overlooked amid the glitter of today's dramatic advances in science and technology. In 1843 Dr. Oliver Wendell Holmes, the school's eighth dean, discovered that childbirth fever was spread by contamination on the hands of doctors and nurses. It took decades for scientists to discover that the bacteria transmitted by health care personnel were streptococci. Even then, the profession was slow to adopt handwashing to prevent infection. In fact, the struggle to ensure proper handwashing in hospitals is still in progress. But you should combine Dr. Holmes's sentinel observation with the insights of 21st-century microbiology to protect yourself from infection.

Skin and bacteria

Human skin — even in the most healthy and fastidious of us — is teeming with bacteria. Most of those bacteria are rather wimpy critters that cause disease only under special circumstances. But everyone also carries potentially dangerous germs from time to time, such as staph, strep, and the intestinal bacteria that cause food poisoning and diarrhea. Sad to say, health care personnel — including your doctors and nurses — are particularly likely to carry the most troublesome bacteria, especially on their hands. In fact, health care workers carry up to five million bacteria on each hand. And although viruses don't set up shop on the skin the way bacteria do, the viruses that cause diarrhea and respiratory infections — from the sniffles to the flu — can hang around on the hands long enough to spread from person to person.

If your skin is covered with so many bacteria, why don't they make you sick more often? Although the skin is a hospitable resting place for bacteria, it is also a tough barrier that prevents hostile bugs from reaching the body's vulnerable internal tissues. Ironically, perhaps, some of the traditional methods of removing bacteria from the skin can disrupt the skin's own defenses. Scrubbing, for example, can produce minute abrasions that allow bacteria to sneak into your tissues. Detergents can remove the skin's oils, which have important antibacterial properties. Even plain water can remove oil, leaving the skin dry and vulnerable.

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