What is Norovirus?
Norovirus is the most common cause of vomiting, diarrhea, and foodborne illnesses, leading to inflammation of the stomach or intestines, known as gastroenteritis. While many refer to norovirus as “stomach flu,” it has no relation to the known influenza that affects the respiratory system.
Norovirus is a term used for a group of viruses. It is a member of the Caliciviridae virus family. These viruses are responsible for about 90% of viral gastroenteritis outbreaks and roughly 50% of cases worldwide. According to statistical data, norovirus causes gastroenteritis in 19-21 million people annually in the United States. Additionally, it is responsible for 56,000-71,000 hospitalizations and 570-800 deaths each year.
Noroviruses are constantly undergoing genetic changes, have adapted to survive in various environments, and are resistant to many disinfectants. For this reason, it is generally accepted that people can be infected with norovirus more than once in their lifetime, although symptoms may be less severe each time.
Norovirus infection can cause sudden and severe vomiting and diarrhea. It is highly contagious. In addition to spreading through close contact with an infected person, it can also be transmitted via contaminated water, food, or surfaces.
What are the Symptoms of Norovirus Infection?
The infection is characterized by diarrhea, stomach pain, and vomiting, starting 12 to 48 hours after exposure to the virus, typically lasting 1 to 3 days. Most infected patients recover without needing treatment. However, in individuals with underlying health conditions, the elderly, young children, babies, and pregnant women, vomiting and diarrhea due to the infection can lead to severe fluid loss (dehydration). In such cases, monitoring and treatment at healthcare facilities are necessary.
Norovirus infections frequently occur in crowded settings where close contact is common, such as hospitals, daycare centers, nursing homes, schools, dormitories, or military barracks, leading to outbreaks.
The symptoms of a norovirus infection can start suddenly. Some of the common symptoms of norovirus infection include:
- Nausea
- Vomiting
- Diarrhea
- Muscle pain
- Fatigue
- Stomach pain or cramps
- Headache
Some individuals may have norovirus infection without showing any symptoms, yet the infection is still contagious, and infected individuals can spread the virus to others.
How is Norovirus Diagnosed?
Norovirus is typically diagnosed based on a thorough medical history and symptom evaluation. The presence of the virus can also be confirmed through stool sample testing, although this test is not always necessary.
How Does Norovirus Spread?
Norovirus is the leading cause of foodborne illnesses resulting from contaminated food, and it can spread to humans in various ways. The virus can enter the body through close contact with an infected person, touching contaminated surfaces and then touching the mouth, or consuming contaminated food or water. Certain foods, including oysters and other seafood, can naturally be contaminated with norovirus. Some of the ways norovirus spreads include:
- Eating contaminated food
- Drinking contaminated water
- Touching your mouth after contact with a contaminated surface or object
- Close contact with someone infected with norovirus
What Are the Risk Factors for Norovirus Infection?
There are several risk factors for norovirus infection. The main ones include:
- Having a weakened immune system (e.g., individuals who have had organ transplants or those with HIV).
- Eating in environments where someone with norovirus has handled food or where food has come into contact with contaminated surfaces or water.
- Being in daycare or childcare centers.
- Living in close-contact environments such as nursing homes.
- Staying in hotels, resorts, cruise ships, or environments with a high density of people.
- Close contact with someone who has a norovirus infection.
What Are the Complications Related to Norovirus Infection?
For most people, norovirus infection is not life-threatening, and discomfort generally subsides within a few days. However, in some individuals, particularly young children, the elderly, those with weakened immune systems, those with other health conditions, or pregnant women, norovirus infection can be severe. These cases may lead to serious dehydration and, in extreme cases, even death.
Less common complications may include:
- Malnutrition
- Constipation
- Indigestion
- Acid reflux
Signs of Dehydration from Norovirus Infection:
- Extreme fatigue
- Dry mouth and throat
- Dizziness
- Decreased urine output
- Sleepiness
How is Norovirus Infection Treated?
There is no specific treatment for norovirus gastroenteritis. Instead, the main goal of treatment is to prevent dehydration and manage symptoms. Recommendations for treating the infection may include:
- Drinking plenty of fluids
- Resting
- Eating light foods
Patients may be advised to follow a light diet consisting of easy-to-digest foods. Ensuring that lost fluids from vomiting or diarrhea are replaced is a crucial aspect of treatment and monitoring.
If fluid loss cannot be managed, dehydration can develop suddenly and may become life-threatening for some individuals. Those unable to drink enough fluids or experiencing severe dehydration may require intravenous (IV) fluids at healthcare facilities.
What is the Course of Norovirus Infection?
Most people with norovirus infection feel better after 2 to 3 days without long-term effects. The virus can be present in stool both before symptoms start and up to two weeks after symptoms resolve. Because norovirus includes many different virus types and can undergo genetic mutations, it is possible to contract the disease multiple times throughout one’s life.
How to Prevent Norovirus Infection?
Norovirus infection is highly contagious. To prevent infection, the following measures are recommended:
- Wash hands thoroughly with soap and water for at least 20 seconds after using the bathroom or changing diapers.
- Wash hands thoroughly with soap and water for at least 20 seconds before preparing food or eating.
- Avoid contaminated food and water, including food that may have been prepared by someone who is sick.
- Wash fruits and vegetables before eating.
- Cook seafood thoroughly.
- Disinfect surfaces that may be contaminated.
While traveling, especially in areas with a high risk of norovirus, take precautions by eating only cooked foods, avoiding raw or unwashed foods, drinking only hot beverages, and avoiding food from street vendors.
Preventing the Spread of Norovirus During Illness
To prevent spreading norovirus during illness and after symptoms have ended:
- Minimize contact with others as much as possible.
- Wash hands thoroughly with soap and water.
- Isolate oneself and any infected family members at home.
- Avoid touching food and items that others will use.
- Disinfect contaminated surfaces with a bleach-based household cleaner or a disinfectant effective against noroviruses.
- Dispose of vomit and stool carefully, using disposable gloves, cleaning with disposable towels, and placing contaminated items in sealed plastic bags. Wash potentially contaminated clothes and linens separately at a temperature of at least 60°C.
- Avoid travel for 2 to 3 days after symptoms have ceased.
If diarrhea lasts more than 2 days in an adult or 24 hours in an infant, if signs of dehydration appear, if there is a high fever, severe abdominal pain, or bloody or black diarrhea, it is essential to seek medical attention immediately.