A growing number of Central Texas health departments are warning residents of possible exposure to measles, the latest sign that the outbreak in West Texas is spreading across the state. Why it matters: Measles is a highly contagious and potentially life-threatening disease that has surged in areas with high vaccination exemption rates.

The largest measles outbreak in decades has reached San Antonio and San Marcos. Officials say an individual who tested positive for the virus in West Texas traveled to two major universities and one of the nation's busiest tourist attractions — the San Antonio River Walk.

Texas is in the midst of the worst measles outbreak in decades, with 90 cases across 7 counties. Here’s what to know.