With Soap and Water, a Cleaning to Stave Off the Flu

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With Soap and Water or Sanitizer, a Cleaning That Can Stave Off the Flu

September 15, 2009 Well By TARA PARKER-POPE

It sounds so simple as to be innocuous, a throwaway line in public-health

warnings about swine flu. But one of the most powerful weapons against the new

H1N1 virus is summed up in a three-word phrase you first heard from your mother:

wash your hands.

A host of recent studies have highlighted the importance and the scientific

underpinning of this most basic hygiene measure. One of the most graphic was

done at the University of California, Berkeley, where researchers focused video

cameras on 10 college students as they read and typed on their laptops.

The scientists counted the times the students touched their faces, documenting

every lip scratch, eye rub and nose pick. On average, the students touched their

eyes, noses and lips 47 times during a three-hour period, once every four

minutes.

Hand-to-face contact has a surprising impact on health. Germs can enter the body

through breaks in the skin or through the membranes of the eyes, mouth and nose.

The eyes appear to be a particularly vulnerable port of entry for viral

infections, said Mark Nicas, a professor of environmental health sciences at

Berkeley. Using mathematical models, Dr. Nicas and colleagues estimated that in

homes, schools and dorms, hand-to-face contact appears to account for about

one-third of the risk of flu infection, according to a report this month in the

journal Risk Analysis.

In one study of four residence halls at the University of Colorado, two of the

dorms had hand sanitizer dispensers installed in every dorm room, bathroom and

dining area, and students were given educational materials about the importance

of hand hygiene. The remaining two dorms were used as controls, and researchers

simply monitored illness rates.

During the eight-week study period, students in the dorms with ready access to

hand sanitizers had a third fewer complaints of coughs, chest congestion and

fever. Over all, the risk of getting sick was 20 percent lower in the dorms

where hand hygiene was emphasized, and those students missed 43 percent fewer

days of school.

Young children benefit, too. In a study of 6,000 elementary school students in

California, Delaware, Ohio and Tennessee, students in classrooms with hand

sanitizers had 20 percent fewer absences due to illness. Teacher absenteeism in

those schools dropped 10 percent.

Better hand hygiene also appears to make a difference in the home, lowering the

risk to other family members when one child is sick. Harvard researchers studied

nearly 300 families who had children 5 or younger in day care. Half the families

were given a supply of hand sanitizer and educational materials; the other half

were left to practice their normal hand washing habits.

In homes with hand sanitizers, the risk of catching a gastrointestinal illness

from a sick child dropped 60 percent compared with the control families. The two

groups did not differ in rates of respiratory illness rates, but families with

the highest rates of sanitizer use had a 20 percent lower risk of catching such

an illness from a sick child.

Regular soap and water and alcohol-based hand sanitizers are both effective in

eliminating the H1N1 virus from the hands. In February, researchers in Australia

coated the hands of 20 volunteers with copious amounts of a seasonal H1N1 flu

virus. The concentration of virus was equivalent to the amount that would occur

when an infected person used a hand to wipe a runny nose.

When the subjects did not wash their hands, large amounts of live virus remained

even after an hour, said the lead author, Dr. M. Grayson, a professor of

medicine at the University of Melbourne. But using soap and water or a sanitizer

virtually eliminated the presence of the virus.

Frequent hand washing will not eliminate risk. When an infected person coughs or

sneezes, a bystander might be splattered by large droplets or may inhale

airborne particles. In a recent Harvard study of hand sanitizer use in schools,

hand hygiene practices lowered risk for gastrointestinal illness but not upper

respiratory infections.

Still, it is a good idea to wash your hands regularly even if you're not in

contact people who are obviously ill. In a troubling finding, a recent study of

404 British commuters found that 28 percent had fecal bacteria on their hands.

In one city, 57 percent of the men sampled had contaminated hands, according to

the study, which was published this month in the journal Epidemiology and

Infection.

" We were surprised by the high level of contamination, " said Gaby Judah, a

researcher at the London School of Hygiene and Tropical Medicine. Ms. Judah

added that many of the contaminated commuters reported that they had washed

their hands that morning. They may have been embarrassed to admit they hadn't

washed, or they may have picked up the bacteria on their hands during their

commute.

For all those reasons, the Centers for Disease Control and Prevention, with

other health organizations around the world, urge frequent hand washing with

soap and water or alcohol-based hand sanitizers. (They also repeat some advice

you may not have heard from your mother: cough or sneeze into the crook of your

elbow, not your bare hands.)

And as hospitals put stricter hand hygiene programs in place, absentee rates

during cold and flu season also drop.

" Statistically, you can't determine a causal relationship, but it's very

suggestive, " said Dr. Neil O. Fishman, infectious disease specialist at the

University of Pennsylvania. " Our vaccination rates remained relatively stable,

so what else changed? The only thing different was that hand hygiene rates

increased. "

http://www.nytimes.com/2009/09/15/science/15well.html