A recent measles outbreak traced to Disney theme parks in California includes five park employees who were infected, officials said Tuesday.

Of the five employees at Disneyland and Disney California Adventure in Anaheim, three have fully recovered and returned to work, and two remain off, said Dr. Pamela Hymel, the chief medical officer for Walt Disney Parks and Resorts.

All of Disney's "cast members," as it calls park employees, have been offered immunity tests and vaccinations since the company first heard of the outbreak Jan. 7, Hymel said. Those who have been in close contact with infected employees are put on paid leave until their immunity can be established.

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

Oregon became the latest state affected Tuesday when state officials confirmed that a Eugene man in his 40s had contracted the disease after visiting Disney parks.

Orange County has confirmed 18 cases there in the past month, though six were not connected to the theme parks, said its health agency spokeswoman Deanne Thompson.

At nearby Huntington Beach High School, at least 23 unvaccinated students have been sent home after a student was confirmed to be infected with measles.

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.

"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 said.

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