18-year-old dies of measles in Pennsylvania from severe neurological complication

Pennsylvania has confirmed a fourth death related to measles, the state health department announced Tuesday. The latest fatality was an unvaccinated 18-year-old male from Mifflin County.

The state health department also confirmed a coroner's report that the death was caused by acute disseminated encephalomyelitis (ADEM), a rare but known severe complication of measles. ADEM is characterized by a rapidly progressing autoimmune disorder where inflammation strips away the protective coverings of nerve cells in the brain and spinal cord.

Mifflin County coroner Andrea L. Alcalde determined that ADEM was the cause of death for the 18-year-old. Prior to widespread measles vaccination, ADEM was commonly associated with measles, though other viral infections can also trigger the condition.

The state had previously reported two deaths in Lancaster County, both infants too young to be vaccinated: a newborn boy and a six-week-old girl.