Norovirus
What is Norovirus?
Norovirus is a group of viruses that cause severe vomiting and diarrhea. Highly contagious and widespread, it is one of the most common causes of foodborne illness in the United States. Norovirus outbreaks are typically seasonal, occurring more often in colder months. The first recorded outbreak took place in a school in Norwalk, Ohio, in 1968, which is why the original strain was called the Norwalk virus.
Norovirus vs. Stomach Flu
Although some refer to norovirus as the “stomach flu,” it is different from the flu caused by the influenza virus, which primarily affects the respiratory system. Norovirus, on the other hand, leads to gastroenteritis, causing inflammation in the stomach and intestines.
Types of Norovirus
Norovirus belongs to the Caliciviridae family of viruses, which includes 10 groups and 48 types. The most common strain affecting humans is GII.4.
Prevalence and Seasonality
Norovirus is extremely common, with about 685 million cases reported globally each year, including over 200 million in children. Outbreaks typically occur between November and April in countries north of the equator and between April and September in countries south of it. In equatorial regions, outbreaks can happen year-round.
Symptoms and Causes
Common Symptoms
Symptoms appear 12 to 48 hours after exposure and typically last 1 to 3 days.
Causes and Transmission
Norovirus spreads via:
- Close contact with infected individuals
- Contaminated surfaces
- Ingesting contaminated food or drinks
Foods like oysters and other seafood can sometimes naturally carry the virus. Norovirus is highly contagious, with only a few particles needed to infect someone.
Risk Factors and Complications
Anyone can contract norovirus, but risk increases with direct exposure to infected individuals. Severe cases can lead to dehydration, with symptoms such as:
Children may also exhibit fussiness, lethargy, or cry without tears.
Diagnosis and Treatment
Diagnosis
Norovirus is typically diagnosed based on symptoms. In certain cases, such as when underlying conditions are present, stool samples may be tested.
Treatment
There is no specific cure. Management focuses on:
- Drinking fluids with electrolytes
- Eating soft, bland foods
- Resting
Vaccination
Currently, there is no vaccine for norovirus, although research is ongoing.
Prevention
To reduce the risk of norovirus:
- Wash hands frequently with soap and water.
- Rinse fruits and vegetables thoroughly.
- Cook seafood to at least 145°F (62.77°C).
- Clean surfaces and wash soiled clothing thoroughly.
Hand sanitizer is less effective than soap and water in killing norovirus particles.
Frequently Asked Questions
Can you get norovirus more than once?
Yes, reinfection is possible since immunity to one strain does not protect against others.
How long does norovirus stay in the body?
The virus can remain in your stool for up to two weeks after symptoms subside, although you’re contagious for only about 48 hours after symptoms stop.
Norovirus vs. Rotavirus
Both viruses cause gastroenteritis, but they are distinct infections caused by different pathogens.
When to See a Healthcare Provider
Consult a healthcare provider if:
- Symptoms last longer than three days.
- You are unable to eat or drink, as this can lead to severe dehydration.
Key Questions for Your Doctor
- Is this norovirus or another infection?
- How can I safely eat or drink while sick?
- What precautions should I take to protect my family?