Overview

Norovirus infection can cause the sudden onset of severe vomiting and diarrhea. The virus is highly contagious and commonly spread through food or water that is contaminated during preparation or contaminated surfaces. You can also be infected through close contact with an infected person.

Diarrhea, abdominal pain and vomiting typically begin 12 to 48 hours after exposure. Norovirus symptoms last one to three days, and most people recover completely without treatment. However, for some people — especially infants, older adults and people with underlying disease — vomiting and diarrhea can be severely dehydrating and require medical attention.

Norovirus infection occurs most frequently in closed and crowded environments such as hospitals, nursing homes, child care centers, schools and cruise ships.

Symptoms

Signs and symptoms of norovirus infection include:

  • Nausea
  • Vomiting
  • Abdominal pain or cramps
  • Watery or loose diarrhea
  • Malaise
  • Low-grade fever
  • Muscle pain

Signs and symptoms usually begin 12 to 48 hours after first exposure to the virus and last one to three days. You may continue to shed virus in your feces for up to two weeks after recovery. Viral shedding may last several weeks to several months if you have an underlying health condition.

Some people with norovirus infection may show no signs or symptoms. However, they are still contagious and can spread the virus to others.

When to see a doctor

Seek medical attention if you develop diarrhea that doesn't go away within several days. Also call your doctor if you experience severe vomiting, bloody stools, abdominal pain or dehydration.

Causes

Noroviruses are highly contagious and are shed in the feces of infected humans and animals. Methods of transmission include:

  • Eating contaminated food
  • Drinking contaminated water
  • Touching your hand to your mouth after your hand has been in contact with a contaminated surface or object
  • Being in close contact with a person who has a norovirus infection

Noroviruses are difficult to wipe out because they can withstand hot and cold temperatures as well as most disinfectants.

Risk factors

Risk factors for becoming infected with norovirus include:

  • Eating in a place where food is handled with unsanitary procedures
  • Attending preschool or a child care center
  • Living in close quarters, such as in nursing homes
  • Staying in hotels, resorts, cruise ships or other destinations with many people in close quarters
  • Having contact with someone who has norovirus infection

Complications

For most people, norovirus infection clears up within a few days and isn't life-threatening. But in some people — especially children and older adults with compromised immune systems in hospitals or nursing homes — norovirus infection can cause severe dehydration, malnutrition and even death.

Warning signs of dehydration include:

  • Fatigue
  • Dry mouth and throat
  • Listlessness
  • Dizziness
  • Decreased urine output

Children who are dehydrated may cry with few or no tears. They may also be unusually sleepy or fussy.

Prevention

Norovirus infection is highly contagious, and anyone can become infected more than once. To help prevent its spread:

  • Wash your hands thoroughly, especially after using the toilet or changing a diaper.
  • Avoid contaminated food and water, including food that may have been prepared by someone who was sick.
  • Wash fruits and vegetables before eating.
  • Cook seafood thoroughly.
  • Dispose of vomit and fecal matter carefully, to avoid spreading norovirus by air. Soak up material with disposable towels, using minimal agitation, and place them in plastic disposal bags.
  • Disinfect virus-contaminated areas with a chlorine bleach solution. Wear gloves.
  • Stay home from work, especially if your job involves handling food. You may be contagious as long as three days after your symptoms end. Children should stay home from school or child care.
  • Avoid traveling until signs and symptoms have ended.