The measles outbreak in Texas has escalated sharply to 90 cases as health officials worry about the spread to more communities.

The largest measles outbreak in Texas in more than 30 years showed no signs of slowing down on Friday, rising to 90 cases across seven counties. The increase represents a jump of more than 50% since the Department of State Health Services last released an update on Tuesday.

The measles outbreak hasn't lightened up since its onset in late January, and some schools in West Texas may even be closing down in response. The Texas Department of State Health Services (DSHS) has confirmed 90 cases since late January, with 57 cases just in Gaines County. This is up from 58 cases in Texas earlier this week.