The only way to prevent measles infection is with the measles, mumps and rubella (or MMR) vaccine, said Dr. Zachary Most, an assistant professor of pediatrics at UT Southwestern Medical Center, who specializes in pediatric infectious disease.

The measles outbreak that started in late January in West Texas has infected dozens of people and killed a school-aged child according to the Texas Department of State Health Services. It comes as health officials released exposure concerns in San Antonio and Central Texas.

The main measles outbreak has been in the South Plains region of West Texas, where 124 cases have been confirmed. Most of the cases have been among unvaccinated children, although five people who are vaccinated have been among the cases, according to health officials.

The measles case reported in Rockwall County is unrelated to the outbreak in West Texas, officials said, but they're monitoring and preparing in case the disease spreads in North Texas.

Dr. Jeffrey Kahn, the chief of infectious diseases at Children's Health in Dallas believes the reason for the cases is the low vaccination rate. Kahn said about 95% of the population needs to be vaccinated against measles to avoid an outbreak, and the vaccination rates in the affected areas range between 20% to 50%.