There have been roughly 900 confirmed and reported cases of the mumps among migrants being held at 57 federal and state detention facilities across 19 states since last September, according to a newly released government report.

A Centers for Disease Control and Prevention report set to be published Friday found outbreaks of the mumps among migrants, many of whom entered illegally, spiked between March and June, which is when the highest number of people were arriving at the border and being transferred from Customs and Border Protection to Immigration and Customs Enforcement centers where they are held up to three weeks.