Health authorities say five cases of measles have been confirmed among Los Angeles County residents so far this year.
The Los Angeles County Department of Public Health says four cases are linked to one another after international travel, and there's been an additional single case of measles following international travel.
The five cases are unrelated to four cases of measles among non-residents who traveled through Los Angeles County earlier this year.
The department says the majority of the cases involve people who were not vaccinated against measles.
About 90% of people who have never been immunized against measles become ill seven to 21 days after exposure.
Twenty-two states have reported measles cases this year, but the vast majority have been in New York.