CLEVELAND — A terrifying word circulated Tuesday at the Republican National Convention: Norovirus.

A dozen staffers in the California delegation who had arrived in Cleveland early have fallen ill with the extremely contagious virus, California GOP chairman Jim Brulte said.

The virus causes vomiting and diarrhea and has been known to spread quickly in closed places, such as cruise ships, schools and nursing homes, according to the Centers for Disease Control and Prevention.

Brulte said that, so far, no delegates or alternates have shown symptoms.

The delegates from California are staying at the Kalahari Resort in Sandusky, Ohio, nearly 60 miles away from Cleveland. Brulte said the delegates and their guests were spending the day Tuesday at the Cedar Point amusement park in Sandusky or at the Pro Football Hall of Fame in Canton, Ohio — or just relaxing at the Kalahari Resort.

Brulte said he believes one staffer brought the virus to Ohio from California and then passed it to the staffer’s spouse. Soon, 12 of the 36 staffers were sick. The infected individuals first began showing symptoms on Thursday, The (Cleveland) Plain Dealer reported. State party officials alerted the delegation Monday to the outbreak and briefed attendees again Tuesday. They also informed Ohio health officials.