The widening outbreak has been reported in the northwest part of the state, which includes Greenville and Spartanburg, according to the South Carolina Department of Public Health.
The three new cases resulted from a previously reported school exposure.
There are currently 252 people in quarantine and three in isolation, the department said. Of those infected, 148 were unvaccinated, three were partially vaccinated with one of the recommended two-dose measles-mumps-rubella vaccines, one was fully vaccinated and four had unknown vaccination status.
Most cases were reported in children in the five to 17 age group followed by those below five years of age.
Measles is a highly contagious viral infection that causes symptoms such as fever, cough and a characteristic rash. It can also lead to severe complications like pneumonia and encephalitis.
