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.

At least six children at a day care in Lubbock, Texas, tested positive for measles amid the state's growing outbreak, local officials confirmed to CBS News Tuesday. On Monday, Lubbock Public Health issued immunization recommendations for the whole county following the cases at Tiny Tots U Learning Academy on South University Avenue.

In addition to these two children's deaths in Texas, a third death was reported in a New Mexico resident that was possibly linked to the outbreak. The Centers for Disease Control and Prevention (CDC) is still conducting an independent investigation to confirm that the third death is related to the outbreak.

A public health official in Texas recently warned that the state's ongoing measles outbreak could last a year. Why are cases expected to keep rising?

The multistate outbreak confirms health experts’ fears that the virus will take hold in other U.S. communities with low vaccination rates.

Much of the outbreak is concentrated in the districts of Texas House leaders, including Speaker Dustin Burrows. The crisis appears to have done little to change