The measles outbreak in Texas has grown to 124 cases mostly in children and in those who are unvaccinated, according to state data published Tuesday.

It can spread rapidly in communities with low vaccination rates, and initially results in symptoms including a high fever, a cough, a runny nose, and red or watery eyes, according to the U.S. Centers for Disease Control and Prevention ( CDC ).

The Texas health department said all but 23 of the cases are patients ages 17 and under. Eighteen people are hospitalized.