In the last three weeks, 48 cases of measles have been identified, sending 13 patients to the hospital, according to the Texas Department of State Health Services.

Most of the measles cases are still among school-aged children in Gaines County, Texas health officials said Friday.

Public health practitioners warn that measles outbreaks like the one hitting children in Texas will become more common because of scores of laws around the United States — pending and passed — that ultimately lower vaccine rates.