Some children affected by measles during the ongoing outbreak in South Carolina have developed a stern complication of the disease called encephalitis, or swelling of the brain, state epidemiologist Linda Bell said Wednesday.
The measles outbreak in South Carolina began in October with several infections. As of February 3, the number of cases climbed to 876with 700 such cases reported since the beginning of the year. The surge could mean another bad year for measles cases in the United States, where more than 2,267 measles cases have been reported in 2025 – the highest number in 30 years. A decline in vaccination rates across the country is causing a resurgence of the disease.
Encephalitis is a uncommon but stern complication of measles that can lead to seizures and cause deafness or intellectual disability in children. It usually occurs within 30 days of the initial measles infection and can occur if the brain becomes infected with the virus or if an immune reaction to the virus causes inflammation of the brain. Among children suffering from measles encephalitis 10 to 15 percent die.
It is unknown how many children in South Carolina developed this stern complication. Under state law, measles cases must be reported to the South Carolina Department of Public Health, but measles hospitalizations and complications do not have to be disclosed.
“We do not comment on individual outcomes, but we do know that encephalitis, or encephalitis, is a known complication of measles,” Bell told reporters during a press conference Wednesday. “Whenever you have encephalitis, there can be long-term consequences such as developmental delay and effects on the neurological system that may be irreversible.”
The department is aware of 19 hospitalizations in the state due to measles, including pneumonia, which occurs in about one in 20 children with measles and is the leading cause of death in children with measles.
Bell also said that several pregnant women who had been exposed to the virus required administration of immunoglobulin, a concentrated antibody solution. Provides transient protection against measles for unvaccinated people. Exposure to measles during pregnancy can cause premature birth or miscarriage.
A rarer type of brain swelling, called subacute sclerosing encephalitis (SSPE), can occur many years after measles infection. In September, the Los Angeles County Department of Public Health reported death of a school-age child due to SSPE. The child was originally infected with measles as an infant, before he was ancient enough to receive the measles vaccine, the first dose of which is recommended for children aged 12 to 15 months.
After recovering from the initial measles illness, the child developed SSPE, during which the virus lies dormant in the brain before triggering an inflammatory response that destroys brain tissue over time. The disease usually appears 7 to 10 years after the person appears to have recovered from the initial measles infection. It is estimated that two in 10,000 people with measles eventually develop SSPE.
The measles, mumps and rubella (MMR) vaccine is the best way to prevent measles and its stern complications.
In January, more than 7,000 more doses of the MMR vaccine were administered across the state of South Carolina than in January 2025, a 72% raise. In Spartanburg County, the center of the outbreak, more than 1,000 more doses were administered in January compared to January 2025, a 162% raise. Bell said January has so far been the best month for measles vaccination during the outbreak.