The United States reported its first death from measles in 12 years, health officials said Thursday. An autopsy of a Washington state woman who died in the spring revealed her measles infection.

The cause of her death was pneumonia due to measles, but she had not developed the typical symptoms of the disease such as rash, the Washington State Department of Health said Thursday in a statement. Because of this the infection was not detected until her death, the officials said.

The identity of the woman was not revealed, but the authorities said she was from Clallam County. "The woman was most likely exposed to measles at a local medical facility during a recent outbreak in Clallam County. She was there at the same time as a person who later developed a rash and was contagious for measles," the state health department said in the statement.

The health department also noted that the woman had various health problems and was on medication that led to a suppressed immune system.

The last death due to measles in the country was recorded in 2003, according to the Centers for Disease Control and Protection.

This marked the 11th measles case in Washington and the sixth in Clallam County, the press release stated. The last active case of measles in the state was recorded in late April, the officials said.

Measles is a highly communicable disease and can spread when an infected person breathes, coughs or sneezes.

"It's very sad that we have a death from measles in the U.S.," Anne Schuchat, director of the National Center for Immunization and Respiratory Diseases at the Centers for Disease Control and Prevention told the Associated Press. "We really rely on people who can be vaccinated to protect those for whom vaccine protection isn't available."

According to USA Today, measles recurred in the country lately after some parents chose not to fully vaccinate their children. In 2014, about 644 people were reportedly infected with the disease.

Recently, some states made it compulsory to get children vaccinated. This year, California and Vermont states barred unvaccinated children from attending school.