When Texas officials first discovered measles cases this year, they were among the Mennonite population. Now, officials say cases are spreading to other communities.

Texas has reached 400 cases of measles in an outbreak that started two months ago. Texas, New Mexico, Ohio, Kansas and Oklahoma all have active measles outbreaks.

Texas and New Mexico health departments said on Friday that the number of measles cases in their states rose 20% since their last reports three days ago, as experts warn they expect the outbreak to further spread in coming weeks.