Some children infected with measles in an ongoing outbreak in South Carolina have developed a serious complication of the disease called encephalitis, or inflammation of the brain, epidemiologist Linda Bell said Wednesday.
A measles outbreak in South Carolina began in October with a few cases. As of February 3, cases have increased to 876, 700 of which have been reported since the beginning of the year. The move could mean another bad year for measles in the United States, which had more than 2,267 cases—the highest rate in 30 years—in 2025. Declining vaccination rates across the country are causing a resurgence.
Encephalitis is a rare but serious complication of measles that can lead to seizures and cause deafness or mental retardation in children. It usually occurs within 30 days of the first measles infection and can occur if the brain becomes infected with the virus or if the immune response to the virus causes inflammation in the brain. Among children who develop measles encephalitis, 10 to 15 percent die.
It is not known how many children in South Carolina started this serious problem. Under state law, measles must be reported to the South Carolina Department of Health, but hospitalization for measles and measles does not need to be disclosed.
“We don’t comment on human outcomes, but we know that inflammation of the brain, or encephalitis, is a known complication of measles,” Bell told reporters during a press conference Wednesday. “Anytime you have inflammation of the brain, it can have long-term effects, things like developmental delays and effects on the nervous system that are irreversible.”
The department is aware of 19 measles-related hospitalizations in the province, including pneumonia, which is found in about 20 children with measles and is the cause of death for children affected by measles.
Bell also said that several pregnant women who were exposed to the virus need to be administered immune globulin, a concentrated solution of antibodies. It provides temporary protection against measles in unvaccinated people. Exposure to measles during pregnancy can cause premature birth or miscarriage.
A rare form of brain inflammation called subacute sclerosing panencephalitis, or SSPE, can occur years after measles infection. In September, the Los Angeles County Department of Public Health reported the death of a school-aged child due to SSPE. The child first contracted measles as an infant before he was old enough to receive the measles vaccine, the first dose of which is recommended for children between twelve and 15 months of age.
After recovering from the first bout of measles, the child developed SSPE, where the virus remains dormant in the brain before causing an inflammatory response that eventually destroys brain tissue. The condition usually appears seven to ten years after a person appears to have recovered from the initial measles infection. An average of two in 10,000 people who get moles end up with SSPE.
The measles, mumps, and rubella (MMR) vaccine is the best way to prevent measles and its serious complications.
More than 7,000 additional 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 epicenter of the outbreak, more than 1,000 doses were given this January compared to January 2025, a 162 percent increase. So far, January has been the best month to get a measles vaccine during an outbreak, Bell said.
