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College of Food, Agricultural, and Environmental Sciences


Chow Line: Keep viruses at bay by washing hands (for 9/9/07)

August 31, 2007

What are "noroviruses," and how can they be prevented?

Noroviruses are very common viruses that can cause gastroenteritis, or the stomach flu. Even though the illness is called the "flu," these viruses are different from the influenza virus, which causes a respiratory illness, not a digestive problem.

Noroviruses are often spread through improper food handling and, along with hepatitis A -- also caused by a virus -- they are the most common type of food-borne illness. Unfortunately, just a small number of the microorganisms can make you ill. Any kind of food can become contaminated, but ready-to-eat foods, such as salads, cut fruit and deli meats, are among the most common.

Although noroviruses are destroyed with thorough cooking, they can survive freezing temperatures. Some outbreaks have been associated with ice made from contaminated water.

Noroviruses are also called "Norwalk-like" viruses because they were first identified in an outbreak in Norwalk, Ohio, in 1972. Symptoms usually appear suddenly and last about one or two days. Common symptoms are nausea, vomiting, diarrhea and some stomach cramping. You might also experience fever, chills, headache, muscle aches and fatigue.

The illness is usually relatively mild, but cases can be more serious. Those most at risk for severe illness are the elderly, children, and anyone with a compromised immune system.

Recently, the Centers for Disease Control and Prevention identified two new strains of norovirus that can be fatal. A 90-year-old patient in a nursing home died from a norovirus last year, and the CDC suspects it in 18 other fatalities as well as thousands of illnesses.

Washing hands, and doing so properly, is the best way to prevent the spread of norovirus. This is especially important for anyone who handles food for a large number of people. When washing your hands:

  • Run hot water over your hands -- at least 100 degrees. It should be as hot as you can stand.
  • Apply soap, and scrub hands, wrists and forearms for 10 to 15 seconds. Time yourself -- it's longer than you might think. Be sure to get under your fingernails and between fingers.
  • Rinse thoroughly in running water, allowing any microorganisms to be washed away.
  • Use a fresh paper towel or warm-air dryer to dry your hands. Don't use a cloth towel which may have been used before (and contaminated by someone else).

September is National Food Safety Education Month. More information on noroviruses and hepatitis A is available at

Chow Line is a service of Ohio State University Extension and the Ohio Agricultural Research and Development Center. Send questions to Chow Line, c/o Martha Filipic, 2021 Coffey Road, Columbus, OH, 43210-1044, or

Editor: This column was reviewed by Lydia Medeiros, associate professor of human nutrition in the College of Education and Human Ecology, a state specialist with Ohio State University Extension, and a researcher with the Ohio Agricultural Research and Development Center.

Martha Filipic
Lydia Medeiros