Although norovirus circulates year round, cases and outbreaks tend to peak from November through April. Norovirus is extremely infectious – ingesting as few as 18 viral particles can cause someone to get sick. The virus spreads easily via contaminated food and surfaces, or directly from person to person.
If you are experiencing vomiting and diarrhea, stay home while ill and not prepare food for others. Hand washing is the best way to prevent the spread of norovirus, which can remain in the stool of an infected individual for two weeks or more after symptoms resolve. Hand sanitizer is not as effective as hand washing for norovirus. Surfaces contaminated by ill individuals should be cleaned thoroughly with bleach-based products, as other products may not be effective against norovirus.
For more information about norovirus, visit http://www.cdc.gov/norovirus/index.html