Today the South Carolina Department of Health (DPH) said the state’s measles outbreak has grown to 789 cases, almost 30 more than the West Texas outbreak that took place from January to August last year and resulted in the death of two school-aged children.

The South Carolina outbreak, which grew by 89 cases in the past four days, is now the largest measles outbreak the United States has faced in nearly three decades.

The outbreak’s epicenter is Spartanburg County, where the virus spread in a series of elementary and middle schools in October of last year. Those schools, many of them private, Christian academies, havelargely unvaccinated student bodies. Holiday gatherings and travel accelerated the outbreak.

The majority of cases are close contacts of known cases.

“The majority of cases are close contacts of known cases,” the DPH said today in a statement. “However, the number ofpublic exposure sites indicates that measles is circulating in the community increasing the risk of exposure and the risk of infection for those who are not immune due to vaccination or natural infection.”

At least 18 hospitalized

There are currently 557 people in quarantine and 20 in isolation. The latest end of quarantine for these individuals is February 19, DPH said.

Of the 789 cases, 695 are in people who are unvaccinated, and 14 in people partially vaccinated. Twenty case-patients have been fully vaccinated, and 60 have unknown status. More than half, 493, are aged 5 to 17 years. Only 65 cases are known to be in adults over the age of 18; 203 cases are in children under the age of 5.

“Complications are not reportable to DPH, but we have learned that 18 people, including both adults and children, have required hospitalization for complications of the disease since the beginning of the outbreak. Additional cases required medical care for measles but were not hospitalized,” DPH said.

Last year the United States tracked 2,255 measles cases nationwide, with 760 cases recorded in the large West Texas outbreak, which originated in an under-vaccinated Mennonite community. In April, the US will meet with the Pan American Health Organization to see if the country has lost its measles elimination status, which was granted in 2000. Elimination status hinges on sustained, local transmission of the measles virus for 12 months or more.

Last week, Ralph Abraham MD, the Centers for Disease Control and Prevention’s principal deputy director, said during a press conference that the United States losing its measles elimination status is the “cost of doing business,” erroneously suggesting foreign, imported measles cases was causing the uptick in US activity.

“We have these communities that choose to be unvaccinated. That’s their personal freedom,” Abraham said.