California child dies years after measles infection from rare brain complication

Los Angeles County health officials announced Thursday that a school-age child has died from subacute sclerosing panencephalitis (SSPE), a rare and fatal brain disorder that developed years after the child contracted measles as an infant.

Authorities said the child had been infected before becoming eligible for the measles, mumps and rubella (MMR) vaccine, which is first recommended between 12 and 15 months of age. No further details, including the child’s age or sex or the timing of the initial infection, were released. Dr. Muntu Davis, Los Angeles County health officer, called the case "a painful reminder of how dangerous measles can be, especially for our most vulnerable community members," and urged vaccination to protect infants who are too young to be immunized.

SSPE is a progressive, degenerative condition caused by persistent measles virus in the central nervous system. It typically appears years after the initial infection and is characterized by cognitive decline, seizures, personality changes and involuntary movements that lead to severe neurological impairment and, in most cases, death. There is no cure; treatment focuses on supportive care and anticonvulsant medications to control seizures. Public health agencies estimate SSPE affects about one in 10,000 people who contract measles, and the risk rises to roughly one in 600 for those infected as infants.

The Los Angeles announcement comes amid a near-record U.S. measles outbreak in 2025. As of this year, federal data show 1,454 confirmed cases across 42 states, the highest tally since 1992 when 2,126 cases were reported. The majority of cases have been in Texas, which has reported 803. California had reported 20 cases. Three deaths attributed to measles were reported this year, including two children in Texas and one person in Colorado.

Public health officials stress that vaccination protects both individuals and communities. The two-dose MMR series is recommended at 12 to 15 months and again at 4 to 6 years and is about 97% effective at preventing measles. The U.S. Centers for Disease Control and Prevention deems 95% coverage among school-age children necessary to maintain herd immunity. California kindergarten immunization data show about 96% of students have received both MMR doses, slightly above that threshold. Nationally, however, coverage has declined: CDC figures for the 2024–2025 school year indicate about 92.5% of kindergarteners were fully vaccinated against measles, mumps and rubella.

Measles is a highly contagious respiratory virus spread through direct contact with infectious droplets or airborne transmission. Infected persons are contagious from roughly four days before a rash appears until four days after. Unvaccinated people exposed to the virus have about a 90% chance of becoming infected; roughly three of every 1,000 people who contract measles die, most commonly from acute encephalitis or pneumonia.

Before the widespread use of the two-dose vaccine introduced in 1968, measles caused substantial annual morbidity and mortality in the United States, with up to 500 deaths, 48,000 hospitalizations and 1,000 cases of brain swelling reported each year. Vaccination dramatically reduced that burden and led public health officials to declare measles eliminated in the U.S. in 2000, a status challenged by recent outbreaks tied to declining vaccine coverage and international importations.

SSPE is rare in the modern era because measles itself has become uncommon where vaccination coverage is high; the CDC estimates no more than about 10 SSPE cases are reported in the United States each year. The disorder typically has a lengthy silent period during which the virus persists in the brain without symptoms, then progresses to fatal neurological decline over a period that can range from months to a few years.

Los Angeles County health officials reiterated guidance that infants younger than six months are too young to receive the MMR vaccine and rely on maternal antibodies and community immunity to reduce their risk of exposure. "By getting vaccinated, individuals not only protect themselves but also help shield vulnerable populations — including infants, pregnant people, and those with weakened immune systems — from measles infection," the county statement said.