Almost 900 migrants have been sick with mumps in 57 detention centers in 19 states, according to a Centers for Disease Control and Prevention report. The Associated Press reports that 898 adult migrants have gotten ill since September, along with 33 detention center employees. As of last week, 15 facilities in seven states were still dealing with sick inmates or staffers—with the spread being attributed to the transfer of migrants to different facilities and new ones being taken in. The agency concluded that over 80 percent of mumps patients were exposed to the illness while in government custody, and at least 13 were hospitalized. Many of the cases reportedly have occurred in Texas.

Immigration and Customs Enforcement spokesman Bryan Cox told the AP medical professionals at facilities screen all new detainees within a day to ensure no contagious diseases are spread. ICE also has given over 25,000 measles-mumps-rubella vaccine doses in detention centers hit by the illness.