Noroviruses, a group of viruses which are responsible for more than half of all reported food borne gastroenteritis outbreaks, cause gastroenteritis including vomiting, diarrhea, fever, weakness, and dehydration in people of all ages. They can be spread through contact with infected people or through contaminated water, foods, or surfaces. In addition, noroviruses are very resistant to disinfection.

A new study conducted by researchers at Laval University in Quebec showed about 40 percent of commercial disinfectants used to clean surfaces are ineffective in eliminating noroviruses. Published recently in the Journal of Food Protection, researchers found only bleach-based disinfectants "drastically" reduce the concentration of these viruses by breaking down their genetic material into inactive fragments.

The team from Laval University led by Julie Jean, professor at the Faculty of Agriculture and Food Sciences, tested three types of household disinfectants: alcohol-based, ammonium-based, and bleach-based. The results indicated that alcohol-based and ammonium-based products were 100 times less effective than a simple mixture of water and bleach to eliminate noroviruses.

"Our results are particularly disturbing considering that nearly 40 percent of the commercial surface disinfectants on the market are alcohol or ammonium-based," said Jean. The researchers also noted it takes only 10 minutes for noroviruses to firmly latch onto a stainless steel surface. "Once attached, these viruses can survive for weeks and potentially contaminate anyone who comes in contact with them. And it's highly probable that our findings on stainless steel surfaces also apply to other materials," added Jean.

So how can one prevent a norovirus infection? Remember to wash hands with soap and warm water after using the bathroom, changing a diaper, blowing your nose, sneezing or coughing, caring for a sick person, playing with a pet, and also before preparing or eating food. Cook all shellfish thoroughly before eating; wash raw vegetables and fruits before eating. Food handlers should never contact ready-to-eat food with bare hands. Food preparation surfaces should be regularly disinfected using one tablespoon of bleach in one gallon of water. Solutions should be made fresh daily, and bleach solutions should never be mixed with ammonia-based cleaning products.

Finally, thoroughly clean and disinfect contaminated surfaces immediately after the appearance of bodily waste by first soaking up and securely discarding as much of the contaminated material as possible followed by thoroughly washing the surface and then disinfecting it using a chlorine bleach solution of ¼ cup bleach to one gallon of water. The person who cleans the area should follow up with proper hand washing and disinfection to avoid further spreading the virus.

(Chris Wiant, M.P.H., Ph.D., is president and CEO of the Caring for Colorado Foundation. He is also chair of the Water Quality & Health Council.)

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