Norovirus is an infectious disease caused by a group of highly contagious viruses that spread through contaminated food, water, surfaces, or objects and direct contact with an infected person.
Norovirus is a highly contagious infection caused by a group of viruses. Infection with these viruses is the most common cause of acute gastroenteritis in humans.
Most people get norovirus from contaminated food or water. It can also spread by touching contaminated surfaces or direct contact with an infected person.
Symptoms typically begin 12–48 hours after exposure and commonly include watery diarrhea and vomiting. Other symptoms, such as abdominal pain, may also occur.
In most cases, norovirus infection goes away with home care in about one to three days.
Infection with these viruses leads to acute gastroenteritis in humans and can occur in people of any age. Symptoms typically appear 12-48 hours after exposure to the virus, and most people fully recover with home treatment in about one to three days.
What are noroviruses?
Noroviruses are a group of highly contagious viruses that cause norovirus infection. Many kinds of noroviruses can infect humans, and anyone can get infected with them. Once infected, noroviruses can make people sick with a gut (digestive tract) illness called gastroenteritis.
Gastroenteritis is a general term for inflammation of the stomach and intestines. It’s sometimes also referred to as food poisoning. People also commonly call it “stomach flu.” However, it isn’t related to the flu, a respiratory illness caused by influenza viruses.
There are many causes of gastroenteritis, but it most often occurs due to infection with certain viruses, bacteria (such as E. coli), or parasites. When viruses cause it, it’s known as viral gastroenteritis. When bacteria causes it, it’s known as bacterial gastroenteritis.
Viral gastroenteritis is an acute illness, which means it starts suddenly and lasts for a short time. Globally, noroviruses are the most common cause of acute gastroenteritis.
How does norovirus spread?
Norovirus is found in an infected person’s feces (stool) or vomit and spreads quickly and easily between people. Food, water, surfaces, and objects can get contaminated with tiny particles of feces or vomit that can’t be seen and enter another person’s body in the following ways:
- Swallowing contaminated food or water.
- Putting unwashed hands in the mouth after touching contaminated surfaces or objects.
- Putting unwashed hands in the mouth after direct contact with an infected person (for example, after shaking hands or sharing eating utensils with an infected person).
Most people get infected with norovirus through food or water contaminated with feces or vomit. Contamination of food and water can occur in several ways. Some examples include:
An infected person doesn’t wash their hands well after using the bathroom and then prepares food or serves drinks with their bare hands.
Food touches a surface that has tiny particles of feces or vomit on it.
An infected person vomits, and small bits of vomit land on another person’s food.
Although people are most contagious when they have symptoms, and during the first few days after they feel better, they can infect others even if they don’t have symptoms. Specifically, an infected person remains contagious for two weeks or more after they feel better.
Additionally, although norovirus outbreaks can occur anywhere, the virus often spreads quickly in crowded places or places where many people live closely together. These settings include:
- Healthcare facilities such as nursing homes or hospitals.
- Daycare centers.
- Cruise ships
Who can get sick from norovirus?
Anyone can get sick from norovirus infection. However, certain groups are more likely to develop severe symptoms or medical complications. These people include:
- Infants and young children.
- Older adults.
- People with weak immune systems.
What symptoms does norovirus infection cause?
Symptoms of norovirus infection range from mild to severe, usually beginning 12-48 hours after exposure to the virus and lasting for one to three days. Although the most common symptoms are watery diarrhea and vomiting, abdominal pain often occurs. Additionally, some people may experience a general feeling of being unwell (malaise), fever, headaches, and body aches.
If diarrhea and vomiting are severe, it can lead to dehydration, the most complication of norovirus infection. Dehydration occurs when a person loses fluids and electrolytes very quickly or doesn’t drink enough fluids to replace what’s lost. Symptoms of dehydration may include decreased urination, intense thirst, a dry mouth, and feeling dizzy or lightheaded.
How do you treat norovirus infection?
No specific medication is available to treat norovirus infection, and antibiotics aren’t effective because a virus causes it. However, most people fully recover at home by resting and drinking lots of fluids to prevent dehydration. Depending on the symptoms a person is experiencing, healthcare providers may also recommend over-the-counter medications to control diarrhea and pain or prescription medications to manage nausea to help reduce the discomfort.
For people with severe vomiting and diarrhea, it may be challenging to keep fluids down to prevent dehydration. In these cases, treatment may require a hospital stay to receive IV fluids.
While norovirus symptoms are unpleasant, most infections go away on their own at home within about one to three days and with lots of fluids and rest. However, a person with severe dehydration due to vomiting and diarrhea may need treatment at a hospital. This complication often occurs in the very young, the very old, and people with weak immune systems.
Anyone with severe symptoms or signs of dehydration should seek immediate medical care.
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