Fourth measles death reported in Pennsylvania, all victims unvaccinated

Pennsylvania health officials reported a fourth measles-associated death in the state, involving an 18-year-old from Mifflin County. The death was caused by acute disseminated encephalomyelitis, a rare neurological complication of measles.

The previous three deaths this year included a 40-year-old woman in Jefferson County and two infants in Lancaster County. None of the four individuals had been vaccinated; the infants were too young for immunization under current guidelines.

The outbreak has now produced nearly 700 measles cases across 38 Pennsylvania counties, with about 100 cases reported in the past week. This marks the first measles deaths in the state in 35 years and contributes to the worst measles year in the U.S. since 1991, with seven deaths nationwide over the last two years.