The Texas health department reported 422 cases of measles in the state on Tuesday, an increase from 400 on March 28, as the United States battles one of the largest outbreaks of the disease in the past decade.

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.