A child’s death this past week in Texas is the first U.S. death from measles, a highly contagious but preventable respiratory disease since 2015, according to the U.S. Centers for Disease

With the number of highly contagious measles cases rising in Texas, the San Antonio Metropolitan Health District shared more details about the possible exposure in the city after an individual who tested positive for the virus visited multiple locations in the city.

While a measles case has yet to be confirmed in San Antonio and Bexar County, hundreds of thousands of residents may have been exposed to the virus spreading rapidly throughout the state.