The Texas health department reported 663 cases of measles in the state on Tuesday, an increase of 17 cases since April 25, as the U.S. battles one of its worst outbreaks of the childhood disease.

The number of cases reported in Texas’ historic measles outbreak has risen to 597, an increase of 36 cases since Friday, according to state officials on Friday. Of those, 62

Nearly all measles infections seen during the Texas outbreak are among individuals who have not been vaccinated, or whose vaccination status is unknown.