A measles outbreak that has caused the deaths of two school-aged children has now surpassed more than 500 cases across Texas, according to health officials. The latest update from the Texas Department of State Health Services shows that 505 people have been infected with measles since the outbreak began in late January in the South Plains region.

The number of measles cases exceeded 500 in Texas on Tuesday, according to the state’s health department, which made the update days after a second Texas child died after contracting the highly contagious illness that has been confirmed in at least 20 states.