India, Sept. 16 -- A fourth person has died of measles in Pennsylvania within a month, the worst case in the United States in more than three decades.

The last time four measles deaths were reported in one year in the country was in 1992.

The latest death in Pennsylvania was reported in Mifflin County. The county coroner said the victim was an 18-year-old person who died from acute disseminated encephalomyelitis, a rare neurological condition that can occur after an infection. She did not disclose the deceased person's identity.

On August 25, Pennsylvania's Department of Health reported two measles-associated deaths in Lancaster County, which it said was the first deaths of this kind in the state in 35 years. And on Tuesday it confirmed ...