Measles has returned to Texas, with two cases confirmed in Houston last week. No cases have been found in Central Texas, but measles is a worry for health officials, causing Austin Public Health and the Texas Department of State Health Services to issue alerts.

Two children were hospitalized with measles in West Texas the same month the highly contagious respiratory illness was also found in two Houston residents.

Two of the four cases are in Lubbock, which hasn’t seen a case in more than 20 years. Measles vaccination rates in Texas have fallen over the last four years.

Two cases were reported in Harris County, and an additional two were in Lubbock, according to The Texas Tribune.