SACRAMENTO – The California Department of Public Health (CDPH) is working with local public health departments across the state to help control norovirus outbreaks that have increased in the past few weeks, and are occurring in schools and other institutional settings. Norovirus is highly contagious and can spread quickly in settings where people come in close contact with each other such as cruise ships, daycare centers, schools and health care facilities. It is the leading cause of gastrointestinal illness in the U.S.

“Norovirus outbreaks usually have an annual peak like we are seeing now. They can be particularly large and disruptive in schools, affecting both students and teachers,” said CDPH Director and State Public Health Officer Dr. Karen Smith. “Norovirus is very infectious and can spread rapidly wherever people congregate and share food and bathroom facilities. Fortunately, most people with norovirus infection will recover quickly, usually in one to three days.” 

Norovirus activity is seasonal and typically peaks in late winter or spring each year. A peak in May is somewhat later than usual. CDPH is working with local health departments to help ensure the impacted schools are properly disinfected to contain the virus. Norovirus can remain in a person’s body for up to two weeks after that person feels better. It can also stay on surfaces for a long time so proper disinfection is essential to stop the spread.

Most norovirus illnesses do not require medical care and go undiagnosed. Data on the current number of norovirus disease cases, is therefore, not available. The Centers for Disease Control and Prevention (CDC) estimates that there are between 19-21 million cases of norovirus illness each year in the U.S. Additionally, CDC estimates that norovirus contributes to 56,000-71,000 hospitalizations and 570-800 deaths each year in the U.S. CDPH does not have data on the number of cases in the state during this current outbreak because state and local health departments are not required to report individual norovirus cases.

Norovirus causes inflammation of the stomach and intestines. Common symptoms include diarrhea, vomiting, nausea and stomach pain. While most people with norovirus get better within 1 to 3 days, the virus can make a person feel extremely ill with vomiting and diarrhea many times a day. This can lead to dehydration, especially in young children, older adults and people with other illnesses. Symptoms of dehydration include decreased urination, dry mouth and throat, and feeling dizzy when standing up. Children who are dehydrated may cry with few or no tears and be unusually sleepy or fussy. It is important that children with norovirus stay well-hydrated.  Fortunately, norovirus illnesses are usually self-limiting and resolve with supportive care.   

The best ways to stop transmission from occurring is to properly wash hands and handle food safely. Infected people should stay at home when they’re sick, and avoid caring for other people and preparing food for others during illness and for at least two days after symptoms stop. Surfaces and objects in contact with vomit or diarrhea should be disinfected with a bleach solution or washed in a washing machine with detergent. Wear gloves and wash hands carefully after any contact with contaminated objects.