Preventing Norovirus Infection
Common settings for norovirus outbreaks include restaurants and events with catered meals (36%), nursing homes (23%), schools (13%), and vacation settings or cruise ships (10%) (CDC, 2006, August 3). Proper hand washing is the best way to prevent the spread of norovirus.
The good news about norovirus is that it does not multiply in foods as many bacteria do. In addition, thorough cooking destroys this virus. To avoid norovirus, make sure the food you eat is cooked completely.
Shellfish (oysters, clams, mussels) pose the greatest risk and any particular serving may be contaminated with norovirus; there is no way to detect a contaminated oyster, clam, or mussel from a safe one. Shellfish become contaminated when their waters become contaminated (e.g. when raw sewage is dumped overboard by recreational and/or commercial boaters). Shellfish are filter feeders and will concentrate virus particles present in their environment. With shellfish, only complete cooking offers reliable protection; steaming does not kill the virus or prevent its transmission (Kirkland, et al., 1996).
Raw vegetables should be washed thoroughly before being served, and travelers should drink only boiled drinks or carbonated bottled beverages without ice when in areas that have polluted water sources.
Immunity to calciviruses is not permanent and re-infection can occur. Infection may also spread from person-to-person. So, if you or another household member suffer a bout of gastroenteritis, be absolutely sure to wash hands with soap and warm water after toilet visits, before preparing or eating food, and after caring for the sick. Exclude persons with gastroenteritis from the kitchen, and always dispose of sewage in a sanitary manner.
Recently, outbreaks of norovirus have become synonymous with cruise ships (CDC, 2006, August 3; MMWR Weekly, 2002, December 13). Healthcare facilities also experience a high incidence of norovirus outbreaks. The CDC has published information regarding the prevention of norovirus outbreaks on cruise ships and in healthcare facilities on its website (CDC, 2006, December 21; CDC, 2007).