What is Norovirus, and How Can You Protect Yourself and Others?

What it is?

Norovirus is a very contagious virus that causes vomiting and diarrhea. In fact, it is the leading cause of vomiting, diarrhea, and foodborne illness in the United States. People of all ages can get infected and sick with norovirus.

It is sometimes called the "stomach flu" or the "stomach bug." However, norovirus illness is not related to the flu. The flu is caused by the influenza virus. Norovirus causes acute gastroenteritis, an inflammation of the stomach or intestines.

Most people with norovirus illness get better within 1 to 3 days, but they can still spread the virus for a few days after.  

Types of Norovirus

You can get norovirus illness many times in your life because there are many different types of noroviruses. Infection with one type of norovirus may not protect you against other types.

It is possible to develop protection against specific types, but it is not known exactly how long protection lasts. This may explain why so many people of all ages get infected during norovirus outbreaks.

Who is at risk?

Anyone can get infected and sick with norovirus, and people of all ages get infected during norovirus outbreaks. Your likelihood of getting a norovirus infection is also determined in part by your genes.

*Shellfish: If eaten raw, oysters and other filter-feeding shellfish can contain viruses and bacteria that can cause illness or death. Anyone who consumes raw shellfish is at risk of contracting norovirus. Children younger than 5 years old, older adults, and people with weakened immune systems are more likely to develop severe infections.

To avoid getting norovirus, do not eat raw or undercooked shellfish.

How does it spread?

Norovirus spreads very easily and quickly in different ways. You can get norovirus by:

• Having direct contact with someone with norovirus, like caring for them, sharing food or eating utensils with them, or eating food handled by them.
• Eating food or drinking liquids that are contaminated with norovirus.
• Touching contaminated objects or surfaces and then putting your unwashed fingers in your mouth.   

*You can still spread norovirus for 2 weeks or more after you feel better.

Signs and Symptoms

A person usually develops symptoms 12 to 48 hours after being exposed to norovirus.

Most common symptoms: Diarrhea, vomiting, nausea, stomach pain/cramping

Other symptoms: Fever, headache, and body aches

Dehydration

If you have norovirus illness, you can feel extremely ill, and vomit or have diarrhea many times a day. This can lead to dehydration (loss of body fluids), especially in young children, older adults, and people with other illnesses. Symptoms of dehydration include:

• Decreased urination
• Dry mouth and throat
• Feeling dizzy when standing up
• Crying with few or no tears
• Unusual sleepiness or fussiness

Drink plenty of liquids

• If you have norovirus illness, you should drink plenty of liquids to replace fluid lost from vomiting and diarrhea. This will help prevent dehydration.

• Sports drinks and other drinks without caffeine or alcohol can help with mild dehydration. However, these drinks may not replace important nutrients and minerals. Oral rehydration fluids that you can get over the counter are most helpful for mild dehydration.

*Seek medical care for severe dehydration

Dehydration can lead to serious problems. Severe dehydration may require hospitalization for treatment with fluids given through your vein (intravenous or IV fluids). If you think you or someone you are caring for is severely dehydrated, call your doctor.

Treatment and recovery

Most people with norovirus illness get better within 1 to 3 days. There is no specific medicine to treat people with norovirus illness. Antibiotic drugs will not help treat norovirus infections because they fight bacteria, not viruses.

A good rule to follow when treating someone with norovirus is The Rule of Three: 

1. Nothing by mouth (such as food or beverages) for three hours.
2. Then ice chips or small sips of water for three hours, 
3. Then clear liquids for three hours.
4. Continue as needed.
5. If at any point you vomit, restart with the first step (“nothing by mouth’) for three hours. 
6. Take Tylenol or ibuprofen for body aches.
7. Get plenty of rest!

How can you prevent getting norovirus?

Norovirus is very contagious, but you can take steps to protect yourself and others, including:

• Wash your hands well and often with soap and water for at least 20 seconds; especially:
  • After using the toilet or changing diapers
  • Before eating, preparing, or handling food.
  • Before giving yourself or someone else medicine.

Be aware that hand sanitizer alone doesn’t work well against norovirus. You can use hand sanitizers in addition to hand washing, but hand sanitizer is not a substitute for handwashing, which is best.

• If you’re sick, don’t prepare or handle food, or care for others. Wait at least 2 days (48 hours) after your symptoms stop.

• Handle and prepare food safely:
  • Carefully wash fruits and vegetables well.
  • Cook oysters and other shellfish thoroughly to an internal temperature of at least 145°F.
  • Routinely clean and sanitize kitchen utensils, cutting boards, counters, and surfaces, especially after handling shellfish.
  • Keep raw oysters away from ready-to-eat food in the grocery cart, refrigerator, and on cutting boards.
  • Throw away food that might contain norovirus.

Noroviruses are relatively resistant to heat and can survive temperatures as high as 145°F. Quick-steaming processes will not heat foods enough to kill noroviruses.        Food contaminated with norovirus may look, smell, or taste normal.

• Clean and disinfect contaminated surfaces.
  • Always clean well and disinfect the entire area immediately.
  • After someone vomits or has diarrhea:
    • Wear rubber or disposable gloves and wipe the entire area with paper towels and throw them in a plastic trash bag.
    • Disinfect the area as directed on the product label.
    • To disinfect, use a chlorine bleach solution with a concentration of 1,000 to 5,000 ppm (5 to 25 tablespoons of household bleach [5% to 8%] per gallon of water) or use an EPA-registered disinfecting product against norovirus.
    • Leave bleach disinfectant on the affected area for at least 5 minutes.
    • Clean the entire area again with soap and hot water.
    • Wash laundry, take out the trash, and wash your hands.
       

• Wash laundry in hot water.
  • Immediately remove and wash clothes or linens that may have vomit or feces on them.
    • Wear rubber or disposable gloves.
    • Handle items carefully without shaking them.
    • Wash the items with detergent and hot water at the maximum available cycle length, then machine dry them at the highest heat setting.
    • Wash your hands after with soap and water.