South Carolina health officials said Friday that the state’s measles caseload had jumped almost 30% in four days, reaching 558 total infections in what has become the worst active measles outbreak in the United States. The state health department reported 124 new cases since Tuesday, with the wave of infections centered on Spartanburg County.
The accelerating outbreak comes as the United States faces growing risk of losing its measles-eliminated status, a public health designation held since 2000, with the disease now reported across nine states so far this year.
South Carolina health officials said Friday the state’s measles caseload had jumped almost 30% in four days, with 124 new cases reported since Tuesday bringing the total to 558, the worst active measles outbreak in the United States.
The outbreak is centered on Spartanburg County and has accelerated since the holiday season, the Associated Press reported.
The spread has not remained confined to South Carolina. The Centers for Disease Control and Prevention has recorded measles cases this year in eight additional states: Arizona, Florida, Georgia, North Carolina, Ohio, Oregon, Utah and Virginia.
The widening caseload follows a historically severe year nationally. The CDC confirmed 2,144 measles cases across 44 states in 2025, the country’s worst year for the disease since 1991. Three people died, all of them unvaccinated.
Measles is caused by a highly contagious airborne virus that spreads when an infected person breathes, sneezes or coughs. The disease is preventable through vaccination. The United States has held eliminated status for measles — meaning the disease is no longer endemic — since 2000, though health officials have warned the country is at risk of losing that designation.