San Antonio officials warn of measles exposure at UTSA and other locations after a visitor tested positive for the virus.

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.

A Northwest Texas resident who has tested positive for measles potentially exposed University of Texas at San Antonio students and other residents while visiting San Antonio earlier this month. The San Antonio Metropolitan Health District said the Gaines County resident tested positive for the virus and traveled to multiple locations here on Feb.