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.

Good handwashing, then, involves two potentially conflicting goals, removing microbes while still keeping your skin healthy.

Preached but not practiced

Cleanliness may not actually be next to godliness, but handwashing is an important part of many religious rituals. Handwashing is also preached by civic authorities, ranging from your mother ("Wash your hands before you eat, dear") to the local board of health ("Employees must wash their hands before returning to work"). It's good advice — but do Americans follow it?

Often, we don't. When intrepid investigators from the American Society for Microbiology surveyed public restrooms around the country, they found that only 83% of people washed up after using the toilet. Do posted reminders to "Please Wash Your Hands" help? When researchers from Pennsylvania State University tested this simple strategy, they found that handwashing improved in women but not in men.

The gender gap applies to hospitals, too. In one study, female physicians washed their hands after 88% of patient contacts, but male doctors washed after just 54%. Without specifically comparing men and women, another study added confirmation when it reported that nurses washed after 50% of encounters, while the rate for doctors was a rather pathetic 15%. And in another gender-blind hospital study, the overall rate of handwashing was just 48%. Even in Switzerland, a land famous for cleanliness, doctors adhered to hand hygiene guidelines only 57% of the time.

Does it work?

Yes.

Just 30 seconds of simple handwashing with soap and water reduces the bacterial count on health care workers' hands by 58%. And there is an even better way: Alcohol-based handrubs (discussed below) reduce counts by 83%.

Reducing the number of germs is one thing, actually preventing infection another. But a two-year study of Navy recruits shows that handwashing pays big dividends. A simple soap and water handwashing campaign reduced clinic visits for respiratory infections by 45%, and the sailors who washed most often enjoyed the greatest protection.

What's best?

Soap and water is the time-honored technique, and it does work. In fact, it's still the best way to remove visible soilage and particulate material. But as the public has become concerned about the risk of infection, soaps with antibacterial additives have gradually taken over 45% of the market. It's understandable, but it's not helpful; antibacterial soap is no better than ordinary soap, and the additives actually increase the risk of allergic reactions and other side effects. The only exception is that the spores of the anthrax bacillus are more susceptible to antimicrobial soap than ordinary soap. Unless the bioterrorism of 2001 resurfaces, however, that's not a worry for ordinary folks.

Plain soap will do the job — and so will plain water. Tap water is excellent, and cool or lukewarm temperatures serve as well as hot water. In fact, excessively warm water may do more harm than good by damaging skin.

If soap and water are not available, antibacterial wipes can help. Although they are not as effective, they will reduce bacterial counts. Antibacterial towelettes are particularly convenient for travel and picnics.

Washing with soap and water is the best way to remove dirt, but waterless, alcohol-based handrubs are even better at killing germs. Handrubbing is faster and more convenient than handwashing, and it's also easier on the skin. Hospitals are switching to handrubs because they kill more bacteria and viruses and they are used more regularly. Alcohol-based rubs and gels are also available for use at home. The best products contain 60%–95% isopropanol or ethanol.

When and how

Without succumbing to the corruption of machine politics, you should apply the legendary method of rigged voting to handwashing: Do it early and often.

Wash your hands before each trip to the dining room and after each trip to the bathroom. Wash after handling diapers and animals. Wash before and after you handle food. Wash after you take out the trash, work in the yard, clean the house, repair the car, or do other messy chores. Wash before and after sex. Wash after you come in contact with anyone who is sick, particularly if they have a respiratory infection or diarrhea. Wash your hands whenever they look or feel dirty, but use common sense. If you follow reasonable guidelines you'll be washing often, but you won't become obsessive or compulsive. Be careful, not fearful.

How should you wash? Liquid, bar, powdered, and lather forms of plain soap are all acceptable. Wet your hands with water, then apply the soap to your palms. Rub your hands together briskly for at least 15 seconds before rinsing. In most cases, removing jewelry is not necessary. If your nails are dirty, scrub under them with a nailbrush, but unless you are a surgeon preparing to operate, don't scrub your skin. Whenever possible, use a disposable towel to dry your hands thoroughly, then use the towel to turn off the faucet.

Alcohol-based handrubs are preferred for health care workers, and you should consider using them at home when dirt is not an issue but infection is a particular worry. Apply the recommended amount of the gel or rub to the palm of one hand, then rub your hands and fingers until your hands are dry. If your hands dry in less than 15 seconds you have not used enough rub; if it takes 30 seconds or longer, you've applied more than you need.

Skin care is also important. Alcohol-based rubs are easy on the skin, but if you use a lot of soap and water, your skin may get dry, itchy, or cracked. Soaps that contain bath oil may help, but the best protection is to apply a moisturizer after each wash.

Protect yourself

In today's world, infections are more worrisome than ever. Fortunately, simple precautions can go a long way toward protecting you. Do your best to minimize close contact with anyone who has an infection, and protect others by coughing or sneezing into a tissue. Keep up with your immunization; for most American adults, that means a tetanus-diphtheria-pertussis booster every 10 years, a flu shot each fall, and a pneumococcal pneumonia vaccine at age 65. Check with your doctor about immunizations and medications for travel. Always practice safer sex. Avoid exotic pets and unnecessary animal contact. Be alert for infectious agents and travel advisories. Consider wearing a high-quality respirator mask (N95) if there is a realistic worry about exposure to a virulent respiratory agent such as bird flu or tuberculosis. And above all, wash your hands. It's the most common and obvious precaution — but for all its simplicity, it's the most important.