WASHINGTON, United States (AFP)—Authorities in Pennsylvania confirmed Wednesday a fifth death linked to measles, as thousands of cases spread in the worst US outbreak in 35 years.

Lancaster County health officials confirmed an unvaccinated resident died of the highly contagious disease, without offering further details.

The region is known for its large Amish population, a traditionalist Christian community that avoids modern society and has lower vaccination rates than the general population.

The outbreak in Pennsylvania has affected 943 patients in 29 counties, state officials said.

Across the United States, as of September 24 there were 3,642 cases reported in 47 states, according to the Centers for Disease Control and Prevention.

Measles was declared eradicated in the US in 2000 after years of effective vaccination campaigns. The disease killed hundreds of children every year in the US before a vaccine was developed in the 1960s.

But the illness has made a worrying comeback in recent years as vaccine skepticism rose alongside growing mistrust of health authorities, spurred on by President Donald Trump’s vitriol against public health leadership during the Covid-19 pandemic.

More recently, Trump’s health secretary, Robert Kennedy Jr., has voiced vaccine skepticism, repeatedly spreading false information about the measles vaccine and downplaying the severity of the life-threatening disease.

Kennedy has also publicly questioned whether some recent deaths were actually caused by the illness, without providing evidence.

In Pennsylvania all the deaths have occurred in unvaccinated people.

Measles causes fever, respiratory symptoms, painful rashes and in severe cases complications can include pneumonia and brain inflammation, which can lead to death.

The disease continues to claim tens of thousands of lives around the world every year.