A 39-year-old unvaccinated woman in Franklin County, Pennsylvania, has become the sixth person to die of the highly infectious virus amid a state outbreak that has stricken over a thousand people since it began in April.

The woman died on Saturday, October 10. She had several underlying health conditions and had recently tested positive for measles, according to an advisory posted on social media by Franklin County Coroner Jordan Conner. The advisory noted that the woman’s death meets the definition of a measles death set by the state’s health department.

In an emailed statement to The Washington Post, the coroner’s office said the primary cause of death was listed as “probable acute cardiac event due to possible complications of the measles.”

The previous five deaths amid the state’s measles outbreak included a newborn, a 6-week-old, an 18-year-old, a 20-year-old, and a 40-year-old. All the deceased were unvaccinated; the two infants were too young to have been vaccinated.

As of the latest measles update from Pennsylvania’s health department on Friday, October 9, there have been 1,136 cases in the state since the start of the year—1,124 of which are from the current outbreak. Overall, 218 people have been hospitalized. The outbreak, which now spans 41 of the state’s 67 counties, shows no signs of slowing. There had been 157 new cases reported just in the previous week.