Rare Brain Complication Kills Pennsylvania Teen In Fourth Measles Death

WEDNESDAY, Sept. 16, 2026 (HealthDay News) — An 18-year-old from central Pennsylvania has died of a rare complication of measles that attacks the brain and spinal cord, the fourth death tied to the state's growing outbreak.

The Mifflin County coroner's office reported the death in a Facebook post, listing the cause as acute disseminated encephalomyelitis, the Associated Press reports. 

In that condition, the immune system mistakenly attacks the protective coating around nerves in the brain and spinal cord after an infection. The damage comes on quickly, usually days to weeks after the original illness. 

Early signs can resemble a viral infection, with fever, headache, nausea and vomiting. However, this quickly shifts to confusion, unusual sleepiness, weakness or numbness in the arms and legs, vision changes, trouble with balance and sometimes, seizures.

Doctors say families should call a physician right away if someone becomes confused, weak or unsteady after a viral illness, because treatment works best when it starts early.

The condition is rare, affecting fewer than 1 child in 100,000 each year. 

Before vaccines came into wide use, measles was its most common trigger, and the outlook for those cases was worse than those linked to other germs. Today, it more often follows common stomach or respiratory viruses.

None of the four Pennsylvanians who died had received the measles, mumps and rubella (MMR) vaccine, the state health department said. 

Two infants who died last month in Lancaster County were too young for the shot under current recommendations. A 40-year-old woman from Jefferson County, in rural western Pennsylvania, died of measles complications Saturday.

"My thoughts are with the two families who lost loved ones to this highly contagious virus, as Pennsylvania faces the worst measles outbreak in more than three decades," Dr. Debra Bogen, the state health secretary, said Tuesday in a statement about the two recent adult deaths.

"We remain committed to working with our partners across Pennsylvania to stem this outbreak and prevent more deaths," Bogen said. "That means ensuring people have the facts about measles and access to the MMR vaccine, which kept measles outbreaks at bay for decades."

The state has counted nearly 700 measles cases in 38 counties this year, including about 100 in the past week, as of Sept. 15. The four deaths are the state's first from measles in 35 years.

Nationally, 2026 is the worst year for measles since 1991, AP News reported. 

Seven measles-related deaths have been reported across the country in the past two years, more than the total reported over the previous three decades.

The United States halted the continuous spread of measles within its borders in 2000, but childhood vaccination rates have since dropped below the 95% coverage needed to head off outbreaks, AP News reports. 

International health officials will decide in November whether the United States and Mexico still qualify as measles-free.

More information

Visit the Cleveland Clinic for more information about acute disseminated encephalomyelitis.

SOURCES: AP News, Sept. 15, 2026; StatPearls, Jan. 26, 2024