Protection Against Norovirus

Norovirus illustration


It’s hard to miss the media blitz when a widespread outbreak of vomiting or diarrhea erupts. Whether it’s hundreds of cruise ship passengers or dozens of restaurant patrons suddenly afflicted with gastric distress, reports of mass illness are always breaking news.

After these mass outbreaks, I always get questions from my patients as to how they can get infections, such as the Norovirus, and what they can do to avoid it. The Norovirus, not to be confused with the flu, is a gastrointestinal virus. It is actually more common than most people realize and chances are you have likely suffered at least one episode at some point during your life because it is so contagious. 


Norovirus outbreaks are notorious for spreading like wildfires, which explains why many people become suddenly sick all at once. In fact, the CDC reports that it only takes a small amount—as few as 18 viral particles—of norovirus to cause illness. This means that the amount of virus that could be found on the head of a pin could infect up to 1000 people!

Community outbreaks of Norovirus infections are commonly associated with areas of shared food or close contact including; schools, daycare, nursing homes, overnight camps, restaurants, cruise ships, or any other location where people share close quarters. 

Transmission can occur in a variety of ways:

  • Eating food or drinking liquid contaminated with the virus
  • Touching a contaminated surface and then spreading the virus by touching your eyes, nose, or mouth
  • Sharing utensils or food with someone who is infected
  • Shaking hands with someone whose hand is contaminated
  • Exposure to airborne droplets after an infected person has vomited
  • Cleaning up after an infected person has vomited or had diarrhea

Food-borne contamination is most commonly associated with either raw fruits or leafy vegetables (common culprits include celery, melon, and raspberries) or with raw or undercooked oysters and shellfish. Other foods associated with the Norovirus include salad ingredients or sandwiches. However, food-related outbreaks can also be traced to an infected food worker who has handled any food prepared for others and unknowingly passed the virus to many.


Norovirus is known to be an extremely hardy and resistant microbe. This means that the usual methods of killing germs are not always effective in destroying this virus. In fact, Norovirus particles are able to survive heat and water exposure up to 140 degrees. They are also able to live on hard surfaces for weeks, on contaminated fabrics for days, and even survive in contaminated water for months. Because the virus is highly contagious and only a micro amount of exposure is needed to cause infection, prevention is key.

Here are some tips to prevent exposure to Norovirus:

  1. Practice good handwashing, with soap and water, after using the restroom, changing a diaper, and before preparing or eating food. Alcohol-based sanitizers can be used in addition but never instead of proper handwashing.
  2. Wash raw fruits and vegetables well before consuming.
  3. Cook oysters and shellfish thoroughly.
  4. Do not share food or eating utensils with others.
  5. Throw out any food items suspected of contamination.
  6. Disinfect contaminated surfaces with a chlorine bleach solution. Recommended concentration is 5-25 tablespoons of bleach per gallon of water.
  7. Handle infected laundry or other articles carefully by using rubber or disposable gloves. Wash laundry using maximum cycle length and machine dry.
  8. Replace toothbrushes if the illness is suspected to avoid re-contamination or spread of infection.

If you do become ill with a suspected Norovirus infection, you are considered most contagious while symptomatic and for two days following the resolution of symptoms. During this time, you should not prepare food or provide personal care for others. Many local and state health departments outline specific policies regarding Norovirus illness, but in general, for those whose occupation involves these tasks (e.g. food preparers, ​health care workers, teachers, etc.) it is not recommended to return to work until symptoms have resolved for at least 48 hours.

Although most cases clear up on their own, the Norovirus is not an illness to be taken lightly. Over 60,000 hospitalizations and more than 600 deaths occur in the United States per year from Norovirus. However, you can prevent your chances of contracting the virus by practicing good hygiene and by being smart about cleanliness when preparing and eating foods.

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