Early Symptoms of Norovirus

The early symptoms of norovirus usually appear 12-48 hours after exposure to the virus, and can last between 1 and 3 days. Norovirus causes gastroenteritis (inflammation of the stomach and/or intestines).

Norovirus symptoms include the following:

·         Nausea.

·         Vomiting.

·         Abdominal cramps or pain.

·         Watery or loose diarrhea.

·         Ill-feeling.

·         Low-grade fever.

·         Muscle pain.

·         Headache.

·         Body aches.

Diarrhea in particular can result in dehydration, mainly in young children and older adults. Symptoms of dehydration include:

·         Decreased urination.

·         Dry mouth and throat.

·         Dizziness when standing up.

Noroviruses – for they are Legion-like – are extremely contagious and resistant to heat and cold and to the majority of disinfectants. A single person can become sick with this bug several times throughout his or her life – prior infection with one type of norovirus does not protect against future infection with another type. The main source of norovirus is food, and that applies to food at both ends of the digestion process. People can get sick with norovirus by accidentally – or at least one should hope it is accidental – getting feces or vomit from an infected person in their mouths. Next time you’re about to say grace ask the lord thy god whether these thy gifts thou art about to receive have been touched by the bare hands of infected food workers. Additionally, any food served raw or handled after being cooked can be tainted with norovirus. Food can also be tainted at the source, for example oysters, fruits, and vegetables.

Transmission may also occur thusly:

·         Drinking contaminated liquids.

·         Touching surfaces or objects contaminated with norovirus and then putting your fingers in your mouth.

·         Having close contact with someone infected with norovirus – e.g., caring for, or sharing food or eating utensils.

The virus can spread rapidly in closed quarters such as daycare centers, nursing homes, schools, cruise ships, and buildings. Furthermore, these risk factors can increase your risk of becoming infected with this bug:

·         An impaired immune system.

·         Residing in a place where food is handled unsanitarily.

·         Living with a child who goes to preschool or a day care center.

·         Living in a nursing home or another closed environment.

·         Staying in hotels, resorts, cruise ships or other destinations with many people in closed spaces.

Infection is generally diagnosed based on the early symptoms of norovirus or by testing a stool sample. The illness more often than not disappears in a few days without further complications – though children and older immune-compromised adults in hospitals or nursing homes have a higher risk of severe dehydration, malnutrition, and death, and as such may need to be hospitalized. There are no medications nor vaccines that specifically target norovirus – and especially not antibiotics. Therefore, treatment revolves around preventing dehydration. An oral rehydration drink can help replace the electrolytes and water lost to vomiting and diarrhea.

Preventing norovirus transmission

Hand hygiene

·         Wash hands with soap and water after using the toilet and changing diapers, and before eating, and preparing or handling food.

·         Alcohol-based hand sanitizers can be used in addition to but not instead of soap and water.

Fruits, vegetables, and seafood

·         Wash fruits and vegetables before preparing and eating them.

·         Cook oysters and other shellfish thoroughly before eating them.*

·         Throw out food that might be contaminated with norovirus.

Cleaning and disinfecting surfaces

·         Clean and disinfect contaminated surfaces immediately after vomiting or having diarrhea with a chlorine bleach solution with a concentration of 1000–5000ppm or other disinfectant registered as effective against norovirus by the Environmental Protection Agency (EPA).


  • Handle soiled items carefully without agitating them.
  • Wear rubber or disposable gloves while handling soiled items and wash your hands afterward.
  • Wash items with detergent at the maximum available cycle length and then machine-dry them.

Food workers

  • Avoid preparing food for others while sick and for at least 48 hours after symptoms stop.
  • Wash hands carefully and often with soap and water.
  • Rinse fruits and vegetables and cook shellfish thoroughly.
  • Clean and sanitize kitchen utensils, counters, and surfaces routinely.
  • Wash table linens, napkins, and other laundry carefully.


*Norovirus can survive up to 140 F of temperature as well as the quick steaming frequently used to cook shellfish.

People who are sick – and thus at their most contagious – should be take good care not to cook for or provide healthcare for others up to and including the first few days after recovery. Then again, there is no excuse for anybody healthy or sick not to practice basic prevention measures – after all, on the one hand infected people may not display the early symptoms of norovirus (and still be infectious), and on the other, the virus has been found in stool collected up to 2 weeks following a patient’s recovery.

Related: Food for thought: How to make food safer across state lines