Condition Basics
What are noroviruses?
Noroviruses are also called Norwalk-like viruses and caliciviruses. Noroviruses cause gastroenteritis, food infection, foodborne illness, and acute non-bacterial gastroenteritis.
What causes them?
Noroviruses typically spread through contaminated water and foods, although they can also pass from person to person. Water becomes contaminated if human waste enters drinking water because of flooding or from a sewage system that isn't working properly. You may become infected by:
- Eating foods or drinking liquids that are contaminated with norovirus. Shellfish and salad ingredients are the foods most often infected with the viruses. Food other than shellfish may be contaminated by food handlers.
- Touching surfaces or objects contaminated with norovirus, and then placing your hand in your mouth.
- Having direct contact with someone who is infected. For example, if you are a caregiver or share foods or utensils with someone who is ill, you may become infected.
Persons working in daycare centres or nursing homes should pay special attention to children or residents who have norovirus illnesses. This virus is very contagious and can spread rapidly throughout these environments.
Keep your child at home while they are sick and for a few days after feeling better. That's when the virus most likely can be spread to others. The virus can stay in your child's stool for weeks after the symptoms are gone.
What are the symptoms?
The symptoms of gastroenteritis caused by the noroviruses include nausea, vomiting, diarrhea, and abdominal (belly) pain. Diarrhea and vomiting can cause dehydration. You may have a headache and a fever. A mild and brief illness usually develops 24 to 48 hours after you eat or drink the contaminated food or water and lasts for 48 to 72 hours. Only in rare cases does a person get very sick or have to go to the hospital.
How are they diagnosed?
Most norovirus infections are mild and pass in a few days. So most people do not go to their doctors for a diagnosis. You can often diagnosis foodborne illness yourself if others who ate the same food as you also become ill.
If you do go to your doctor, they will make the diagnosis based on your symptoms, a medical history, and a physical examination. Your doctor will ask where you have been eating and whether anyone who ate the same foods has the same symptoms. A stool test is sometimes done.
How are norovirus infections treated?
You treat gastroenteritis caused by noroviruses by managing complications until it passes. Dehydration caused by diarrhea and vomiting is the most common complication. Do not use medicines, including antibiotics and other treatments, unless your doctor recommends them.
To prevent dehydration, drink plenty of fluids. Choose water and other clear liquids until you feel better. You can take frequent sips of a rehydration drink (such as Pedialyte). Soda, fruit juices, and sports drinks have too much sugar and not enough of the important electrolytes that are lost during diarrhea. These kinds of drinks should not be used to rehydrate. In cases of severe dehydration, fluids may need to be replaced through an IV (intravenously).
When you feel like eating again, start with small amounts of food.
If you had diarrhea caused by norovirus, you should stay home for 2 to 3 days after your symptoms end before going back to work or school. This will help prevent spread of the virus.
How can you prevent them?
You can help prevent infection by doing the following:
- Use soap and water to wash your hands often. (Alcohol-based hand sanitizers do not kill noroviruses.) It is especially important to wash your hands after using the toilet and before handling food.
- Wash fruits and vegetables and cook shellfish before eating them.
- If you suspect that your drinking water is contaminated, boil water for 1 minute (3 minutes at elevations above 1,500 metres [5,000 feet]). Then cool and refrigerate it. Water filters will not remove noroviruses.
- Clean and disinfect contaminated surfaces immediately after vomiting or having diarrhea by using a bleach-based household cleaner. To dilute household bleach, follow the directions on the label.
- Wear gloves to immediately remove and wash soiled clothing or linens after vomiting or having diarrhea. Use hot water and soap.
- Flush vomit and/or stool in the toilet. And make sure that the surrounding area is kept clean.
- Do not prepare food if you have symptoms of foodborne illness and for 2 to 3 days after you recover.
- Foodborne Illness and Safe Food Handling
- Travel Health
Credits
Current as of: October 31, 2022
Author: Healthwise Staff
Medical Review:
E. Gregory Thompson MD - Internal Medicine
Adam Husney MD - Family Medicine
Elizabeth T. Russo MD - Internal Medicine
Current as of: October 31, 2022
Author: Healthwise Staff
Medical Review:E. Gregory Thompson MD - Internal Medicine & Adam Husney MD - Family Medicine & Elizabeth T. Russo MD - Internal Medicine
FAQs
Norovirus outbreaks, also called the stomach flu, occur in B.C. communities every year. Symptoms include upset stomach and vomiting, followed by cramping, chills, fever and diarrhea. For more information about norovirus, see HealthLinkBC File #87 Norovirus (Stomach Flu).
Are norovirus and Norwalk virus the same thing? ›
What is norovirus infection? Noroviruses are a group of related viruses that cause acute gastrointestinal illness sporadically or in outbreaks. Noroviruses are sometimes referred to as "Norwalk virus" or "Norwalk-like virus," based on the name given to the first strain identified in the 1970s.
How contagious is Norwalk virus? ›
Norovirus is very contagious
And the virus can linger on objects and surfaces for days or even weeks, spreading easily in crowded environments such as nursing homes, day care centers and cruise ships.
What is the main symptom of Norwalk viruses? ›
What are the symptoms? Common symptoms of norovirus infection include vomiting, diarrhea, and stomach cramping. Less common symptoms can include low-grade fever or chills, headache, and muscle aches.
How long is a person contagious with norovirus? ›
Particular care should be taken with young children in diapers who have diarrhea. 8. How long are people contagious? - People infected with norovirus are contagious from the moment they begin feeling ill until at least three days after recovery. Some people may be contagious for as long as two weeks after recovery.
What is the difference between the stomach flu and the Norwalk virus? ›
Norovirus is a very contagious virus that causes vomiting and diarrhea. Anyone can get infected and sick with norovirus. Norovirus is sometimes called the “stomach flu” or “stomach bug”. However, norovirus illness is not related to the flu, which is caused by influenza virus.
How do you confirm you have norovirus? ›
Norovirus infection is usually diagnosed based on your symptoms, but noroviruses can be identified from a stool sample. If you have a weakened immune system or have other medical conditions, your health care provider might recommend a stool test to confirm the presence of norovirus.
What kills norovirus? ›
To disinfect, you should use a chlorine bleach solution with a concentration of 1,000 to 5,000 ppm (5 to 25 tablespoons of household bleach [5% to 8%] per gallon of water) or use an EPA-registered disinfecting product against norovirus.
How long can Norwalk virus last? ›
Norovirus causes an acute illness that commonly lasts 1 to 2 days for most people, although some people may be ill or feel the effects for up to 6 days. After the period of illness your body gradually gets rid of the entire virus. Norovirus is not known to create a long term 'carrier' state in a person.
What food is norovirus found in? ›
Norovirus outbreaks can also occur from food that is contaminated at the source or on the farm, such as oysters harvested from contaminated water, or fruit and vegetables sprayed with contaminated water in the field. Foods that are commonly involved in norovirus outbreaks include: Leafy greens (such as lettuce)
There is no prescription medication to treat norovirus infections. Most people begin to feel better on their own within 2 or 3 days and do not experience any long-term health effects. You can get norovirus more than once.
Do you always vomit with norovirus? ›
Norovirus symptoms are usually sudden and harsh. You'll likely be throwing up (vomiting) or having diarrhea for a few days until the infection runs its course. The thought of eating or drinking can be nauseating.
What is the fastest way to cure norovirus? ›
There's no treatment for norovirus, so you have to let it run its course. You don't usually need to get medical advice unless there's a risk of a more serious problem. To help ease your own or your child's symptoms drink plenty of fluids to avoid dehydration.
How to tell if norovirus or food poisoning? ›
However, the key distinction is time: The symptoms of a stomach bug will take 12 to 48 hours to develop, while the symptoms of food poisoning typically develop much faster, usually within 6 hours of consuming an infected dish. Another common difference between the two is the length of illness.
Is the stomach bug going around in 2024? ›
Outbreaks have also been rising steadily in recent months. During Aug. 1, 2023 to April 9, 2024, there were 1,208 norovirus outbreaks reported by the 15 states participating in the CDC's NoroSTAT surveillance program. During the same period the last seasonal year, 986 norovirus outbreaks were reported by these states.
How serious is the Norwalk virus? ›
Most people recover completely without treatment. However, for some people — especially young children, older adults and people with other medical conditions — vomiting and diarrhea can be severely dehydrating and require medical attention. Norovirus infection occurs most frequently in closed and crowded environments.
What stomach bug is going around in BC? ›
Norovirus outbreaks occur in BC communities every year. Outbreaks of illness are common in long term care homes, daycare centres, schools, hospitals and on cruise ships. The virus can be spread among people if they do not wash their hands or if someone with this illness handles food, water or ice.
What are the symptoms of Norwalk virus in Canada? ›
Norovirus can make you vomit and have diarrhea several times a day. This can lead to dehydration (loss of fluids). Drink plenty of liquids to replace lost fluids. If you have a severe case, you may need to be admitted to hospital and given fluids intravenously (through a needle inserted in a vein).
