Norovirus can survive in hard environmental conditions. They can be transmitted via food, water, person-to-person, and contact with contaminated surfaces. It is a leading cause of illness from contaminated food or water.


Norovirus can survive in hard environmental conditions. They can be transmitted via food, water, person-to-person, and contact with contaminated surfaces. Salads, fruits, and oysters are the foods most often linked to norovirus outbreaks. Current concentrations of commonly used disinfectants seem ineffective against these viruses. 

Norovirus is the leading cause of illness from contaminated food or water, but food is not the only way people get this disease. Norovirus can  also spread easily from person to person and spreads and in groups of people. Food prepared or handled by an infected person also can spread the illness. Oysters, when grown in contaminated water are another example of transmission of norovirus. 

Reservoirs & Transmission



Symptoms usually start within 1 or 2 days after eating the contaminated food, but it may start in as few as 12 hours. Explosive and projectile vomiting (that shoots out). Often vomiting is the first symptom, along with watery diarrhea that is not bloody, and cramps. Headache, mild fever, and muscle aches also may occur. Most people get better in a day or two, although it takes others a little longer. Occasionally, some people lose so much body fluid that it throws off the body’s balance of some important minerals and fluid, which can cause serious health problems. These people need to be treated by a health professional, and sometimes need to be hospitalized. Antibiotics don’t work against this or other viruses (they only work against bacteria), but health professionals can give the right fluids and minerals to put the body back in balance.

Susceptible Populations

Norovirus can cause illness to people of any age, but most vulnerable are children under the age of 5 years and the elderly. The virus spreads rapidly in a confined and enclosed environment, such as cruise ships, nursing homes, day-care, schools, and recreational camps. 

Prevention/ Food Handling/ Hand Washing

Separate Raw and Cooked: Use separate cutting boards, plates, and utensils for raw (uncooked) produce and raw (uncooked) meat, poultry, seafood, and eggs. Keep meat, poultry, seafood, and eggs separate from all other foods while shopping, and in the refrigerator.

Cook Thoroughly and Keep Food at Safe Temperature: Only a food thermometer can make sure meat, poultry, fish, and casseroles are cooked to a safe internal temperature. For example, internal temperatures should be 145°F or 63°C for whole meats (allow the meat to rest after cooking for 3 minutes at least) and fish, 160°F or 71°C for ground meats, and 165°F or 74°C for all poultry. Eggs should be cooked until the yolk is firm.

Chill: Use appliance thermometers to be sure your refrigerator is at or below 40ºF or  4°C and your freezer is 0ºF (-17.78°C) or below. Between 40ºF or 4°C and 140ºF or 60°, C is the Danger Zone, when bacteria can multiply rapidly. Generally, the more bacteria, the more likely someone will get sick. Most refrigerators have just a colder/ warmer adjustment, so the only way to know is to put a thermometer inside.

Hand Washing

  • Before, during, and after preparing food
  • Before eating food
  • Before and after caring for someone at home who is sick with vomiting or diarrhea
  • Before and after treating a cut or wound
  • After using the toilet
  • After blowing your nose, coughing, or sneezing
  • After touching an animal, animal feed, or animal waste
  • After handling pet food or pet treats
  • After touching garbage
  • Use Hand Sanitizer When You Can’t Use Soap and Water. Sanitizers can quickly reduce the number of germs on hands in many situations. Keep in mind, that sanitizers do not kill all types of germs. If your hands are visibly dirty, soap them then use a sanitizer. They also might not remove chemicals, pesticides, and heavy metals from your hands.

The presented information is an extract from the Guidelines for the Investigation and Control of Disease Outbreaks. Porirua: Institute of Environmental
Science & Research Limited; Updated 2011.