Noroviruses are a group of viruses that can cause inflammation of the stomach and intestines, leading to vomiting, diarrhea and stomach cramping. Other symptoms can include low-grade fever or chills, headache, and muscle aches.
Noroviruses are very contagious and are the leading cause of foodborne illness outbreaks in Minnesota, infecting thousands of people each year, said state health officials. Found in the stool (feces) or vomit of infected people, the viruses are transferred to food, water or surfaces by the hands of infected people who have not washed adequately after using the bathroom.
November through January is the peak time of year for norovirus infections in Minnesota. It's not unusual to see a spike in cases around the holidays, according to foodborne disease specialists at the Minnesota Department of Health (MDH). People become infected with norovirus by:
• Eating food or drinking liquids contaminated by an infected person.
• Eating uncooked shellfish that has been harvested from contaminated waters.
• Touching contaminated surfaces or objects and then touching their mouth or eating without washing their hands first.
Several recent large outbreaks in the state are reminders of how contagious norovirus can be and how important it is to take steps to prevent it. Things you can do include:
• Wash your hands with warm, soapy water for 20 seconds:
o After using the bathroom.
o After changing diapers.
o Before preparing foods
o Before eating
• Wash your hands more often when someone in your household is sick.
• Clean and disinfect surfaces with a household bleach solution immediately after vomiting or diarrheal accidents.
• Steam oysters before eating them.
• Avoid preparing food for others while you have symptoms and for at least three days after you recover.
“If everyone followed these guidelines diligently, we could eliminate the majority of the norovirus outbreaks in Minnesota,” said Dr. Kirk Smith, foodborne disease supervisor at MDH. “The season of giving should also be the season of good handwashing,” he said.
Symptoms of norovirus usually begin 1 or 2 days after ingesting the virus, but may appear as early as 12 hours after exposure. The illness typically comes on suddenly. The infected person may feel very sick and vomit often, sometimes without warning, many times a day. Sometimes people infected with norovirus have no symptoms at all, but can still pass the virus to others.
Most people recover in 1 or 2 days and have no long-term health effects. Dehydration can be a concern in the very young, the elderly, or people with weakened immune systems. Occasionally infected people may experience milder symptoms for a week or more. Of note, even after people recover they still remain infectious to others for at least several days.
If you develop norovirus symptoms, drink plenty of fluids so you don't become dehydrated, wash your hands often and don't prepare food for others, and contact your health care provider.
For more information on norovirus, visit the MDH website at: http://www.health.state.mn.us/divs/idepc/diseases/norovirus/index.html.
To report a suspected foodborne illness, call the Minnesota Department of Health Foodborne Illness Hotline at 1-877 FOODILL (OR 651-201-5655 from the Twin Cities).