Health officials in Whatcom County, in northern Washington State, have received reports of outbreaks of suspected norovirus infections over the past couple of weeks involving a school, a nursing home, and a basketball team. While transmission has been stopped in the schools and nursing home, they anticipate that the community will see more cases during the holiday season.
Norovirus is a highly contagious virus that causes acute gastroenteritis (inflammation of the stomach and small intestines) which leads to abdominal pain, vomiting, and diarrhea. It is the most common cause of acute gastroenteritis in the USA and causes about 20 million cases per year. There are many strains of the virus and immunity is not long lasting, so it is possible to get infected multiple times.
People with norovirus infection can spread billions of viruses in their stool and vomit, and it takes very few viruses (less than 100) to cause infection in others. The virus can remain infectious on surfaces for days or weeks, and not all disinfectants inactivate it. Washing hands with soap and water is more effective than using alcohol-based hand sanitizers, and bleach solutions or steam cleaning are recommended for cleaning surfaces and carpets rather than standard disinfectants.
People become ill within 12-48 hours after exposure to norovirus, and the illness typically lasts 24 to 72 hours. Symptoms are usually acute onset of vomiting, watery, non-bloody diarrhea with abdominal cramping, and nausea. Some people may have low-grade fever, headaches, and generalized muscle aches. Some people who are infected never develop symptoms, but spread the virus in their stools.
Most people recover completely without any significant long-term problems. However, norovirus illness can be serious, especially for young children, older adults, and people with compromised immune systems and can lead to severe dehydration, hospitalization, and death.
There is no vaccine or specific treatment for norovirus. Antibiotics do not work against viruses, including norovirus. It is important to remain well hydrated when ill and to prevent the spread of infection to others. Careful handwashing and cleanup is important, and someone who is ill with norovirus should not prepare food for others to eat while they are ill and for 2-3 days after they recover.