A 39-year-old unvaccinated woman has become the sixth person to die from measles in Pennsylvania amid a state outbreak affecting over a thousand individuals.

According to the Franklin County Coroner’s office, the woman had several underlying health conditions and had recently tested positive for measles, which was confirmed by the state’s health department.

The primary cause of death was listed as “probable acute cardiac event due to possible complications of the measles,” highlighting the severe impact of the virus even in adults with underlying health issues.

The previous five deaths in the state’s outbreak included a newborn, a 6-week-old, an 18-year-old, a 20-year-old, and a 40-year-old, all unvaccinated with the exception of the two infants, who were too young to have been vaccinated.

As of the latest update, there have been 1,136 cases in Pennsylvania since the start of the year, with 218 people hospitalized, and the outbreak, which now spans 41 of the state’s 67 counties, shows no signs of slowing.