What Is Norovirus? What Are Causes and Symptoms?
Highly contagious virus affects the digestive system
Highly contagious virus affects the digestive system
Norovirus is a highly contagious virus that causes acute gastroenteritis, which is inflammation of the stomach and intestines. It leads to symptoms like vomiting and diarrhea.
People often confuse norovirus with the flu, but they are not the same. Influenza viruses cause respiratory illness. Norovirus primarily affects the gastrointestinal tract.
Norovirus spreads through close contact with infected people. It can also spread through contaminated food, water and surfaces. It is the leading cause of foodborne illness in the United States.
“Preventing norovirus transmission is crucial because it is highly contagious and can spread quickly in crowded environments,” says Stephanie Posadas, DO, a family medicine physician at Scripps Coastal Medical Center San Marcos.
How to prevent norovirus
You can lower the risk of getting or spreading norovirus by:
- Washing your hands regularly with soap and water, especially after using the bathroom, changing diapers, and before eating or cooking
- Cooking seafood thoroughly
- Washing fruits and vegetables before eating them
- Not cooking for others if you are sick
- Cleaning any surfaces that might be dirty
- Handling laundry carefully
- Staying home if sick and limiting contact with others
How common is norovirus?
The virus can affect anyone, regardless of age or health. Each year, about 2,500 norovirus outbreaks occur in the U.S. affecting millions of people, according to the Centers for Disease Control and Prevention (CDC). These outbreaks can happen any time of the year, but they are most common in the colder winter months when more people are indoors and person-to-person spread is more likely.
High-risk groups
While norovirus can affect anyone, some people are at higher risk. Young children often have worse symptoms. Their developing immune systems put them at higher risk of dehydration.
Older adults are also at high risk. As people age, their immune systems weaken, which can reduce their ability to fight infections, leading to more severe illness from norovirus.
People with weakened immune systems in general need to be cautious. Chronic illnesses or certain medications can weaken the immune system and make it harder to recover from norovirus.
People in high-risk groups can take steps to prevent and manage norovirus, including:
- Drinking water regularly
- Practicing good hygiene
- Staying away from crowded places during outbreaks
- Seeing a doctor if sick and symptoms get worse
Symptoms of norovirus
Norovirus symptoms typically begin suddenly. In addition to diarrhea and vomiting, nausea and stomach pain are main symptoms. In some cases, people also experience fever, headaches and body aches.
Symptoms usually start 12 to 48 hours after being exposed to the virus. Most people feel better in one to three days and recover fully. However, some symptoms may last longer or get worse, especially in high-risk groups.
Even after symptoms go away, people can still spread the virus.
“Even after symptoms subside continue practicing good hygiene as the virus may still be in your system. Thorough handwashing and avoiding close contact can help prevent the spread,” Dr. Posadas says.
There is no specific treatment or vaccine for norovirus. Antibiotics do not help because they target bacteria, not viruses.
Immunity from norovirus can be short-lived and people can get infected multiple times.
How norovirus spreads
Most outbreaks happen when infected people spread the virus to other people through close contact. Common settings for norovirus outbreaks include schools, day care facilities, cruise ships, nursing homes and health care facilities.
People infected with norovirus can shed virus particles through vomit and feces. The virus can survive for extended periods on surfaces, including doorknobs, toilet handles, sinks and counters. This makes it easy to spread through indirect contact.
Contaminated food is a leading cause of outbreaks and can occur at any stage of the food supply chain. Infected people can contaminate food. Inadequate washing of fruits and vegetables and undercooked seafood further increase the risk.
Recognizing and treating dehydration
Dehydration is a key concern with norovirus because the body can lose fluids quickly. It's important to recognize the signs.
“While most symptoms are mild to moderate, dehydration is a major concern because of the loss of fluids through vomiting or diarrhea,” Dr. Posadas says.
Signs of dehydration include dry mouth, increased thirst and reduced urine output that is darker than usual. These signs indicate a need for more fluids.
Staying hydrated is important for recovery and preventing complications. “Address dehydration early to help the body's healing process,” Dr. Posadas says. Stay hydrated with water, sports drinks or oral rehydration solutions to replace electrolytes and maintain body balance.
Monitor for severe dehydration signs and seek medical help if symptoms persist.
To help prevent dehydration:
- Take small sips of fluids frequently to maintain a steady intake
- Avoid caffeine and alcohol, which can dehydrate you
- Monitor your urine color and frequency; dark urine or infrequent trips may indicate dehydration.
When to seek medical help
Most people with norovirus get better on their own without medical help. However, it is important to recognize when symptoms become serious. If symptoms persist for more than a few days, seek medical attention. Prolonged symptoms may mean there is a more serious problem that requires medical care.
Severe dehydration, including persistent vomiting, dizziness or the inability to keep fluids down, is especially concerning. Seek medical help immediately if these symptoms occur.
“Monitor your symptoms closely. If you have severe or long-lasting symptoms or any signs of dehydration, seek medical help,” Dr. Posadas says. “Getting help early can prevent problems and lead to a faster recovery.”