Minnesota health officials are warning of an outbreak of a highly contagious illness: norovirus. The Minnesota Department of Health is reporting 40 cases of norovirus, otherwise known as the stomach flu.

The department defines an outbreak as an incident in which two or more persons experience a similar illness after a common exposure.

ST. PAUL, Minn. – So far in December, over 40 outbreaks of norovirus have been reported in Minnesota. The state’s Department of Health (MDH) says that is almost twice the usual number.

A contagious virus that causes vomiting and diarrhea is on the surge, according to new data from the US Centers for Disease Control and Prevention (CDC). A confirmation of 91 cases were reported during the week of December 5,