Pennsylvania measles outbreak nears 700 cases as fourth death reported

A fourth person has died in Pennsylvania from a measles-associated illness as the United States faces its worst measles year in decades, health officials said.

The most recent victim, an 18-year-old resident of Mifflin County, died from acute disseminated encephalomyelitis, a rare neurologic complication of measles, the Pennsylvania Department of Health and county coroner said.

That comes after the deaths last month of a 40-year-old woman in Jefferson County and two infants in Lancaster County. The infants were too young to receive the measles vaccine, but none of the four had been immunized, according to the Associated Press.

Pennsylvania has reported nearly 700 measles cases in 38 counties, including about 100 new cases in the past week. The Centers for Disease Control and Prevention(CDC) reported 3,294 confirmed cases across the US as of Sept. 10.

The CDC has not included the four deaths in its national 2026 death toll, saying it is working with health officials to develop a standard definition for measles deaths.

The outbreak comes as measles cases are rising across the country, raising fears of declining vaccination coverage.