What You Need to Know About Norovirus

Running to the bathroom due to vomiting, diarrhea, or both is no one’s idea of a good time. But “stomach bugs” are a fact of life, and norovirus is often the cause.

Norovirus is a highly contagious virus that causes vomiting and diarrhea. It gets attention for outbreaks on cruise ships, but 99% of cases happen off-ship—anywhere people get together. Anyone can get infected and sick with norovirus.

“Initially described as ‘winter vomiting disease,’ norovirus is one of the most common causes of vomiting and diarrhea in adults and children,” says Ava Anklesaria, MD, gastroenterologist and assistant professor of medicine at Columbia University Irving Medical Center. She treats dozens of cases every year. “Norovirus is extremely stable in the environment and only a small amount of virus is needed to transmit the disease, making it easy for the disease to spread. However, by washing hands for 20 seconds with soap and water and by avoiding contact with sick people, you can prevent the spread of this disease.”

In the United States, norovirus causes about 21 million illnesses, 400,000 emergency room visits, and about 570 to 800 deaths a year. 

We asked Anklesaria to explain more about norovirus, including how to prevent it and how to treat anyone who gets it.  

What Is Norovirus?

Norovirus is actually a group of RNA viruses with different strains that cause gastroenteritis.

Symptoms

Norovirus can make you feel extremely ill, vomit, or have frequent diarrhea. Symptoms usually develop one to two days after exposure.

The common symptoms of norovirus are:

• Nausea
• Vomiting (non-bloody)
• Diarrhea (watery)
• Stomach pain
• Dehydration (rare but possible)
• Fever
• Headache
• Body aches

Most people get better within one to three days. But they can still spread the virus for up to two weeks after symptoms resolve.

Who Gets Norovirus

Everyone! In the United States, norovirus is the leading cause of vomiting and diarrhea from acute gastroenteritis (inflammation of the stomach and intestines) in people of all ages.

Young children, older adults, pregnant people, and people with other illnesses are the most susceptible.

How Norovirus Spreads

Norovirus spreads through:

• Contaminated water and foods, especially leafy vegetables, fresh fruit, and shellfish, including oysters.
• Direct contact: person-to-person, usually via the fecal-oral route—spreading pathogenic microorganisms from the feces of someone infected to someone else—contact between contaminated hands or objects (forks, spoons, toys, and more) and the mouth.

It spreads easily as it is extremely stable in the environment and requires only a small amount of the virus to transmit the disease. There are enough norovirus particles on the head of a pin to infect more than 1,000 people.

How to Stop Norovirus Spread

Norovirus can resist disinfectants and hand sanitizers and can have a long life on food, utensils, hands, and other surfaces (especially in the kitchen and bathroom).

While norovirus is highly contagious, there are steps we can take to stop its spread. Here are a few tips:

• Wash hands often, especially after going to the bathroom.
  • Use soap and warm water when washing hands.
  • Lather for at least 20 seconds each time.
• If possible, avoid contact with people who are sick.
• Block off, clean, and disinfect areas where someone vomited or had diarrhea as soon as possible. Norovirus is not killed by alcohol or standard cleaning agents; contaminated environmental surfaces should be killed with bleach.
• If you are sick, do not make food or drinks for other people.
• Clean and sanitize kitchen surfaces and frequently touched objects with bleach.
• Cook food to above 140°F.
• Stay home from school or work for at least 48 hours after your symptoms stop.
• Wash hands, wash hands, wash hands—we cannot say this enough!

How to Treat Norovirus

Adequate hydration is the best treatment for gastroenteritis. Drink plenty of fluids with electrolytes, particularly oral rehydration solutions, sports drinks, or broth. Some studies show better improvement in electrolytes with oral rehydration solutions than with sports drinks.  When you are actively sick, do not take anti-diarrhea or cold medicines, which can dehydrate you. 

When to Seek Medical Help

Most cases of norovirus resolve on their own with supportive treatment. However, you should seek early medical help if:

• You have any signs of dehydration; this includes excessive fatigue or tiredness, severe thirst, or signs of confusion.
• If you have not been able to keep anything down for a few hours.
• If you have not been able to urinate in 6-8 hours.
• Severe abdominal pain.
• If you have blood in the vomit or stool.
• If symptoms have lasted more than a few days.