Norovirus: Symptoms and Treatment

Nothing can ruin a vacation like a bout of vomiting, diarrhea, and stomach cramps. Noroviruses have become notorious for sending hundreds of cruise ship passengers at a time running for their respective bathrooms and for steering entire ships back to port early.

Back on dry land, noroviruses also have a big impact on people's health. The CDC estimates that noroviruses are responsible for more than half of all food-borne disease outbreaks each year. And noroviruses are the most common cause of diarrhea in adults and children.

What Are Noroviruses?

Noroviruses are a group of viruses that cause inflammation of the stomach and large intestine lining (gastroenteritis); they are the leading cause of gastroenteritis in the U.S. The norovirus was originally called the Norwalk virus after the town of Norwalk, Ohio, the location of the first confirmed outbreak in 1972.

Noroviruses are sometimes called food poisoning, because they can be transmitted through food that's been contaminated with the virus. They aren't always the result of food contamination, though. Noroviruses are also sometimes called the stomach flu, although they aren't the influenza virus.

What Causes Infection With Noroviruses?

People become infected with noroviruses when they eat food or drink liquids that have been contaminated; raw or undercooked oysters and raw fruits and vegetables have been implicated in some outbreaks. You can also get infected if you touch an object or surface that has been infected with the virus and then touch your nose, mouth, or eyes.

Noroviruses thrive on cruise ships (as well as in daycare centers, restaurants, nursing homes, and other close quarters), because they are very hardy and highly contagious. They can survive temperature extremes in water and on surfaces.

Once someone is infected from contaminated food, the virus can quickly pass from person to person through shared food or utensils, by shaking hands or through other close contact. People who have a weakened immune system are particularly susceptible to catching noroviruses.

What Are the Symptoms of a Norovirus Infection?

If you come down with a norovirus infection, you'll probably go from being completely healthy to feeling absolutely miserable within a day or two after being exposed to the virus. Typical symptoms include nausea, vomiting (more often in children), watery diarrhea (more often in adults), and stomach cramps.

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Other norovirus symptoms include:

Most of these symptoms aren't serious, but diarrhea and vomiting can deplete your body of the fluid it needs and you can become dehydrated. Children and the elderly are most susceptible to dehydration, as well as malnutrition from not getting enough nutrients.

If you have symptoms of norovirus, your doctor can give you a stool test to confirm that you have the illness. However, norovirus diagnosis is usually made based solely on symptoms.

A small percentage of people who are infected with norovirus never have any symptoms, which suggests they might have some natural protection from the virus.

Norovirus Treatment

Noroviruses, like other viruses, don't respond to antibiotics, which are designed to kill bacteria. No antiviral drug can treat noroviruses, but in healthy people the illness should go away on its own within a couple of days. Most people don't have any long-term problems from the virus.

To prevent dehydration, make sure to drink plenty of liquids, especially water and juices. Give children an oral rehydration solution (such as Pedialyte) to replace lost fluids and electrolytes. Avoid sugary drinks, which can make diarrhea worse, as well as alcohol and caffeinated beverages, which can dehydrate you further.

Symptoms of dehydration include dizziness when standing, dry mouth, and a decrease in urination. If severe dehydration develops, contact your doctor. Severe dehydration is sometimes treated with intravenous (IV) fluids.

How to Prevent Norovirus Infection

Good hygiene is the key to preventing an infection with norovirus, especially when you are in close surroundings with a lot of other people.

  • Wash your hands often with soap and water for at least 15 seconds, or use an alcohol-based hand sanitizer, especially after going to the bathroom or changing a baby's diaper, and before you prepare or eat food.
  • Carefully dispose of any contaminated items (such as dirty diapers).
  • Wash raw fruits and vegetables thoroughly. Cook oysters and other shellfish before eating them.
  • Clean and disinfect surfaces with a mixture of detergent and chlorine bleach after someone is sick.
  • If you have norovirus, don't prepare food for at least two to three days after you feel better. Try not to eat food that has been prepared by someone else who is sick.

 

WebMD Medical Reference Reviewed by Roy Benaroch, MD on June 07, 2015

Sources

SOURCES:

CDC: "Norovirus: Q&A" and "Norovirus: Technical Fact Sheet."

American Medical Association: "Diagnosis and Management of Foodborne Illnesses, Norovirus Infection."

Goldman L, Ausiello D, eds. Cecil Medicine. Philadelphia, Saunders Elsevier, 2007.

Glass, R.I. New England Journal of Medicine, Oct. 29, 2009.

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