With annual flu season looming, enterovirus D68 spreading across the US, and Ebola still a threat in West Africa, there's never a better time to brush up on one of the easiest ways to avoid the spread of disease: proper hand hygiene.
Handwashing stops disease from spreading
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A person handwashing. (Shutterstock)
"There's more science behind hand hygiene than there is for other forms of infection control," says Elaine Larson, associate dean for nursing research at Columbia University.
There have been dozens of studies looking at how handwashing can prevent life-threatening diseases, particularly in developing countries.
In a 2008 review of the research, researchers looked at some of the best evidence for diarrhea-causing illnesses; they found that stringent handwashing protocols, on average, reduced incidents of diarrhea by 29 percent in high-income countries and 31 percent in low- and middle-income countries. Another 2008 review also found that improvements in hand hygiene reduced gastrointestinal illnesses by 31 percent and respiratory illnesses by 21 percent.
Those decreases can really matter: About 2.2 million children under 5 die each year from diarrhea-related diseases and pneumonia, a respiratory infection, according to the Centers for Disease Control and Prevention.
A multiyear study, from the University of Michigan, found that requiring students in residence halls to use surgical masks and alcohol-based sanitizers could reduce the spread of flu-like symptoms by up to 75 percent. The study found masks alone played no statistically significant role, indicating that hand hygiene was responsible for the results.
Other studies have found that hygiene interventions can reduce the number of sick days in schools. In a study of elementary schoolchildren in Denmark, researchers required the students to use hand sanitizer three times a day. Compared to the year before, there were 66 percent less schoolchildren with four or more sick days and 20 percent more with zero sick days.
Handwashing in particular can also clean off body fluids that contain viruses, such as the flu, enterovirus D68, and Ebola. That's why health organizations like the World Health Organization and Mayo Clinic recommend handwashing as one of the most important preventive measures for infectious diseases.
The bathroom is one particular area where these kind of hygienic practices are necessary. In the bathroom, people not only touch body parts that tend to have far more germs, but they also tend to contaminate the walls and floors with their own hands and splashing water.
But there's really good news about handwashing: It's really easy to do, even though a lot of people get it wrong.
You're probably washing your hands wrong. Fix that. 
A person uses hand sanitizer. (Shutterstock)
A previous study in the Journal of Environmental Health found only 5 percent of Americans wash their hands properly. Although the CDC recommends 20 seconds of handwashing, people on average wash their hands for about 6 seconds.
Obviously, handwashing isn't going to prevent disease if people aren't doing it right. Here are four tips for proper handwashing, from Larson and the CDC:
1) Wash your hands for at least 20 seconds. The amount of time spent handwashing is important, Larson explains, to thoroughly cover and scrub every surface of both hands. To do this right, the CDC provides a step-by-step guide: Wet your hands with clean water, lather soap on every surface, scrub your hands together for at least 20 seconds, and rinse before drying. If you need a timer, the CDC recommends humming the "Happy Birthday" song from beginning to end twice.
2) Wash your fingertips and under your nails. "If you think about it, most of the touching and most of the germs are on your fingertips and maybe under your finger nails," Larson says. "That's a part of the hand that's often skipped when people wash their hands."
3) Wash your hands after every trip to the bathroom. Even if you think you didn't get anything on your hands while using the bathroom, wash them. There are always germs on your hands, and, at the very least, the bathroom is a convenient place to make sure some of those germs are cleaned off.
4) Wash your hands quickly after coughing, sneezing, or dealing with sick people. A previous study co-authored by Larson found that the flu virus can survive on hands and other surfaces for five to 10 minutes before it dissipates. During that time frame, people risk contaminating others as long as they don't wash their hands.
For hand sanitizers, Larson says it's important to know that sanitizers are only active as long as they're on your hands. So even if it makes your hands feel annoyingly wet, keep the sanitizer on for at least 10 seconds.
As for whether to handwash or sanitize, the simple solution, according to the CDC, is to handwash in most occasions and use sanitizer when water and soap aren't available. Larson says that, for the typical healthy person, that should cover most hygiene needs.
"Handwashing is better for cleaning off stuff," Larson says. "If you have sputum, or if someone coughs, or if you have vomit, crap, or urine on your hands, soap and water are better cleaners. Alcohol is a better antiseptic. But in most cases, you can get the germs off your hands either way."
If you follow all these steps, stay cautious about coming into contact with sick people, and get vaccinated, you shouldn't have to worry too much about getting sick this holiday season.
