Some children affected by measles in the ongoing South Carolina outbreak have developed a serious complication of the disease called encephalitis, or swelling of the brain, state epidemiologist Linda Bell said on Wednesday.
The South Carolina measles outbreak began in October with a handful of infections. As of February 3, cases have climbed to 876, with 700 of those being reported since the beginning of the year. The surge could mean another bad year of measles for the United States, which had more than 2,267 cases—the highest in 30 years—in 2025. Declining vaccination rates across the country are driving the resurgence.
Encephalitis is a rare but severe complication of measles that can lead to convulsions and cause deafness or intellectual disability in children. It usually occurs within 30 days of an initial measles infection and can happen if the brain becomes infected with the virus or if an immune reaction to the virus causes inflammation in the brain. Among children who get measles encephalitis, 10 to 15 percent die.
It’s not known how many children in South Carolina have developed this serious complication. Under state law, measles cases must be reported to the South Carolina Department of Public Health, but measles hospitalizations and complications do not need to be disclosed.
“We don't comment on the outcomes of individuals, but we do know that inflammation of the brain, or encephalitis, is a known complication of measles,” Bell told reporters during a media briefing on Wednesday. “Anytime you have inflammation of the brain, there can be long-term consequences, things like developmental delay and impacts on the neurologic system that can be irreversible.”
The department is aware of 19 measles-related hospitalizations in the state, including some due to pneumonia, which occurs in about one in 20 children with measles and is the leading cause of death for children who get measles.
Bell also said that several pregnant women who were exposed to the virus required administration of immune globulin, a concentrated solution of antibodies. It provides temporary protection against measles for unvaccinated individuals. Measles exposure during pregnancy can cause preterm birth or miscarriage.
A rarer type of brain swelling called subacute sclerosing panencephalitis, or SSPE, can occur years after a measles infection. In September, the Los Angeles County Department of Public Health reported the death of a school-age child due to SSPE. The child was originally infected with measles as an infant before they were old enough to receive the measles vaccine, the first dose of which is recommended for children between 12 and 15 months old.
After recovering from the initial measles illness, the child developed SSPE, in which the virus remains dormant in the brain before triggering an inflammatory response that destroys brain tissue over time. The condition usually appears seven to 10 years after a person appears to recover from the initial measles infection. An estimated two in 10,000 people who get measles eventually develop SSPE.
The measles, mumps, and rubella (MMR) vaccine is the best way to prevent measles and serious complications associated with it.
Over 7,000 more doses of the MMR vaccine were given statewide in South Carolina this January compared to January 2025, a 72 percent increase. In Spartanburg County, the center of the outbreak, over 1,000 more doses were given this January compared to January 2025, a 162 percent increase. So far, January was the best month for measles vaccination during the outbreak, Bell said.
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