A common statement frequently heard when unwelcome diarrhea or vomiting occurs is, "It must be something I ate." Often it can be traced to improper handling of food; however, norovirus can be spread through both food and nonfood sources. You can get norovirus from eating contaminated food or water, coming into contact with someone who has norovirus, or touching contaminated surfaces and then putting unwashed hands in or around your mouth.
Symptoms of Illness
Usual symptoms include nausea, vomiting (often projectile), diarrhea, and abdominal pain. Headache, body aches, and/or a low-grade fever may also accompany this illness. Symptoms develop 12–48 hours after being exposed to norovirus and generally last between one and three days. Norovirus differs from other foodborne illnesses because vomiting is often forceful. It is also different from other illnesses in that infected individuals can continue to shed virus particles in stool for several weeks… and even months!
Public Health Consequences
The CDC estimates that in the United States, there are 19 million to 21 million cases of vomiting and diarrhea illnesses each year. Norovirus is the leading cause of foodborne illness in the United States, making up 58% of foodborne illnesses. Over 100,000 cases will be severe enough to require hospitalization, and approximately 900 deaths occur from norovirus illness each year. The exact number of norovirus cases that occur each year is difficult to determine because many people attribute their illness to the stomach flu. The local health department and the Centers for Disease Control and Prevention (CDC) cannot record the number of cases accurately unless the ill person seeks medical care or reports their illness to the local health department. The CDC estimates the number of norovirus cases based on corrections for underreporting, misdiagnosis, and the number of cases that are not caused by contaminated food.
Risk Factors
Anyone can get norovirus. The reason is that norovirus is found in vomit and diarrhea. Anyone who comes in contact with the vomit or diarrhea during an episode can become contaminated. The viral particles can spread through the air and, because they are microscopic, the places they land may not look like they have been contaminated. Someone who touches those surfaces and then handles food is at risk of contaminating the food or contracting the virus.
Older adults and children are at greater risk for complications from norovirus. The CDC states that norovirus is responsible for nearly 1 million pediatric medical visits each year. The majority of deaths caused from norovirus illness are primarily adults ages 65 years and older. Day care centers, aging facilities, healthcare settings, and cruise ships are all places where norovirus is known to spread due to the close proximity of large numbers of people.
Impacted Foods and Appropriate Food Preparation Practices
Any food can be contaminated with norovirus. Some foods can carry norovirus internally (e.g., raw and undercooked shellfish), while others become contaminated by human handling. Contaminated water is also a common source of norovirus outbreaks. Norovirus outbreaks can also occur when fresh fruits and vegetables (e.g., leafy greens) are sprayed with contaminated water in the field.
The good news about this virus is that it doesn't multiply in foods or water like bacteria. Also, this virus is destroyed by high heat. To prevent norovirus, make sure food is cooked completely. If you are traveling in an area that appears to have polluted water, drink pasteurized milk or bottled beverages without ice.
Prevention and Control
1. Wash hands with warm soapy water before and after handling raw foods.
a. First, wet your hands.
b. Add soap to your hands.
c. Rub both sides for at least 20 seconds.
d. Rinse thoroughly.
e. Air dry, or dry your hands with a clean towel or paper towel.
f. Always wash your hands.
• after using the toilet.
• after cleaning up from another infected person.
• after changing a baby's diaper.
• after touching pets or other animals.
• after sneezing or coughing.
h. Prepare food for yourself, but not others if ill with diarrhea.
2. Wash fruits and vegetables before eating them. Although washing fruits and vegetables cannot completely eliminate microbes, it helps remove soil or waxes where organisms may be attached.
a. Do not eat raw alfalfa and other raw sprouts.
b. Use water from a safe water supply for drinking and for washing fresh produce.
c. Remove outer wilted and damaged areas before washing.
d. Wash and prepare only the amount you will use in one meal.
e. Refrigerate remaining vegetables without washing, or dry with a paper towel or in a salad spinner.
3. Clean and disinfect kitchen surfaces.
a. Clean sinks and countertops with paper towels or clean cloths and hot soapy water before and after preparing food.
b. Wash knives, cutting boards, and countertops with hot water and soap before you prepare foods.
c. Scrub your cutting board with dish soap. If your cutting board is not made of wood, you can put it in the dishwasher.
4. Cook foods thoroughly.
a. Cook oysters and shellfish to at least 145 degrees Fahrenheit (quick steaming processes may not heat foods enough to kill norovirus).
How Should You Clean Up if Someone with Norovirus Vomits or Has Diarrhea?
Any clothing or linens that come into contact with infected vomit or fecal matter should be thoroughly washed with detergent using the washing machine’s longest cycles available and then dried in the dryer and not on a clothesline. Heat and detergent are important to remove the virus from the fabric. Proper and frequent handwashing is also key.
Proper cleaning and disinfection steps must be followed to minimize spread. You can find these steps and other resources at How to Prevent Norovirus (cdc.gov/norovirus/prevention).
Additional Resources
Check out the following resources to learn more about identifying, treating, and preventing norovirus:
Centers for Disease Control and Prevention (CDC). (n.d.). Clean up after someone with norovirus vomits or has diarrhea [YouTube video]. Retrieved from
youtube.com/watch?v=TAkH4jakLYA&t=11s
Centers for Disease Control and Prevention (CDC). (2023, July 31). Norovirus. Retrieved from
cdc.gov/norovirus/index.html
Hillers, V. N., Medeiros, L. C., Kendall, P., Chen, G., & DiMascola, S. (2003). Consumer food handling behaviors associated with prevention of 13 foodborne illnesses. Journal of Food Protection, 66(10), 1893–1899.
doi.org/10.4315/0362-028X-66.10.1893
Mayo Clinic. (2022, March 4). Norovirus infection. Retrieved from
mayoclinic.org/diseases-conditions/norovirus/symptoms-causes/syc-20355296#
Scallan, E., Hoekstra, R. M., Angulo, F. J., Tauxe, R. V., Widdowson, M. A., Roy, S. L., Jones, J. L., & Griffin, P. M. (2011). Foodborne illness acquired in the United States—Major pathogens. Emerging Infectious Diseases, 17(1), 7–15.
doi.org/10.3201/eid1701.p11101
Original reviewer (2012): Lydia C. Medeiros, Specialist, The Ohio State University, and Jeffrey LeJune, Professor, College of Veterinary Medicine
Original author (2012): Barbara Rohrs, Educator, Family and Consumer Sciences, Ohio State University Extension