HUNTINGTON BEACH, Calif. (AP) – At least 23 unvaccinated students have been sent home from an Orange County high school after a student was confirmed to be infected with measles. The disease has been spreading since an outbreak last month was traced to Disney theme parks in the county.

Matt Zahn, medical director for epidemiology at the Orange County Health Care Agency, sent a letter to parents saying an infected student was at Huntington Beach High School from Jan. 6 to 8.

“Simply being in the same room with someone who has measles is sufficient to become infected,” Zahn said in the letter.

Students without a measles vaccination were told to stay home until Jan. 29 to avoid a spread of the disease that has symptoms including fever and a blotchy body rash.

State law requires schoolchildren to get vaccinated to protect against measles, mumps and rubella. But parents can get an exemption by signing a personal belief waiver.

Many parents who reject vaccines or delay them fear there are links between the vaccines and medical conditions such as autism. Numerous studies have dismissed an autism link.

Huntington Beach High School Principal Rocky Murray previously told public radio station KPCC-FM that 24 students were sent home, including one who was infected. It was not clear if the infected student had been vaccinated. The other 23 students had not been vaccinated against the illness.

Several dozen measles cases have emerged in California, three other states and Mexico in the outbreak linked to December visits to Disney theme parks in Orange County.

The county has confirmed 16 cases in the past month, including six that were not connected to Disney theme parks, said Deanne Thompson, spokeswoman for the Orange County Health Care Agency.

“It is at large in the community now, and particularly infants too young to be immunized, people with other health conditions and, of course, people who aren’t immunized need to be very concerned,” Thompson told the newspaper.

She added that unvaccinated people “really should rethink that and consider getting vaccinated.”