The measles outbreak that began in the South Plains region of Texas rose to 422 cases and spread to two new counties on Tuesday, according to health officials. The update from the Texas Department of State Health Services added 22 infections since the agency’s last update on Friday.

A local medical official is warning against the unsupervised use of vitamin A to treat measles as Texas sees a growing number of cases. Here's what to know.

The Texas health department said on Friday that the number of measles cases in the state rose 20% since its last report three days ago, as experts warn they expect the outbreak to further spread in coming weeks.