An infant in Wisconsin has died of measles, the state health department said Thursday — the third measles-related death reported in the U.S. this week.

It’s Wisconsin’s first measles-related death since 1990, the health department said, adding that a coroner had listed measles as the infant’s immediate cause of death.

The news came just one day after Pennsylvania’s health department reported a measles-associated death there — the state’s sixth this year. The department said Wednesday that an unvaccinated resident in Jefferson County who tested positive for measles had died.

Two days before that, New York health officials announced that a child in Lewis County had died of measles. Gov. Kathy Hochul declared a statewide disaster emergency over measles in early October.

In total, the U.S. has recorded eight measles-associated deaths this year, according to state health department data. It’s the highest measles death toll in the country since 1991.

The Centers for Disease Control and Prevention has confirmed four of those deaths. The agency says it will update its count “as additional information becomes available and relevant reviews are completed.”

None of the eight people who have died were vaccinated, according to state health departments; some were ineligible because of their age or health status. Typically, the first dose of the vaccine is administered around a child’s first birthday.

Before the outbreaks in Wisconsin, New York and Pennsylvania, none of the states had recorded a measles death in more than 30 years.

Pennsylvania’s outbreak, which began in April, is by far the largest in the country, with a case total approaching 1,500 across 45 counties, according to the state health department. A Franklin County coroner reported an additional death last month possibly linked to measles, but the state health department said Wednesday that it has not yet confirmed any deaths as measles-associated in the county.

Nationally, the CDC has confirmed 4,852 measles cases this year — more than double last year’s count and the highest number since 1991. The dramatic rise is linked, in part, to a decline in vaccination rates across the country. Two doses of the measles vaccine are 97% effective against the disease.