A measles outbreak that originated at Disneyland has grown to 87 cases.

The California Department of Public Health said Monday most of the infections—73— are in California. The rest are in Arizona, Utah, Washington, Colorado, Oregon, Nebraska and Mexico.

Measles has been spreading since an outbreak linked to visits to California Disney parks last month. Most of those infected were not vaccinated, and have urged people to get the measles shot.

Measles is a contagious illness spread through the air by coughing and sneezing. It was largely eliminated in the U.S. in 2000, but it can enter the country from abroad.

The U.S. experienced a record number of measles cases last year, with 644 infections reported from 27 states.