Public health officials in California and Minnesota are warning about norovirus outbreaks, cautioning that the intestinal disease could sicken lots of people in those states this winter.

The California Department of Public Health announced last week that there had been 32 confirmed outbreaks of the disease since October, a number that greatly exceeds the total reported in the same window last year. Hundreds likely fell ill from the disease, officials said.

In Minnesota, the state Department of Health cautioned that the arrival of a new strain of the disease could cause some additional norovirus illnesses this winter. The department said it has investigated at least 20 outbreaks of the GII.17 Kawasaki strain since September. The strain is the same one that spurred many outbreaks in Asia last winter, officials said in a news release.

“Every few years, a new strain of norovirus emerges and causes many illnesses,” Amy Saupe, a foodborne disease epidemiologist with the department, said in a statement. “We don’t know yet if this new strain will lead to an increase in the number of outbreaks reported, but it could.”

According to the Centers for Disease Control and Prevention (CDC), norovirus is the top cause of stomach flu in the United States. The highly contagious virus sickens between 19 million and 21 million people, hospitalizes 56,000 to 71,000 and kills between 570 and 800 every year. Common symptoms include fever, diarrhea and vomiting. Most people recover within 1 to 3 days.

People get norovirus from eating tainted food or touching contaminated surfaces, making it relatively easy for the disease to spread in places like schools, daycares and nursing homes.

The Boston Globe reported a sick employee came to a Chipotle restaurant in the city earlier this month and 136 people — including some Boston College students — fell ill. There were some initial fears that outbreak was linked to an E. Coli outbreak at Chipotle restaurants in nine states, but the paper reported health officials ultimately determined that norovirus was at fault.

The CDC and other public health officials say proper disinfection, hand hygiene and food-handling techniques are vitally important to help prevent norovirus from spreading.

“One of the most important things you can do to avoid norovirus and other illnesses this holiday season is to wash your hands frequently with soap and running water for at least 20 seconds,” Dr. Karen Smith, the director of the California Department of Public Health, said in a statement. “This is especially important after using the bathroom, changing diapers, and before preparing or eating food. Hand sanitizers are not effective against norovirus.”