Forty-three: That's the total number of the measles cases now in the Western United States.
Of those cases, 39 are in California. Most of those patients visited Disneyland or Disney's California Adventure last month.
The measles illness was eliminated in the U.S. in 2000, but it's still prevalent in a number of countries.
Health officials don't have information on all of these new cases, but at least 18 people were unvaccinated, and a few of them had received the measles vaccine.
Southern California Public Radio health reporter Rebecca Plevin explains how these people came down with measles.
Read Rebecca Plevin's full story: Measles tally at Disney parks jumps to 33