A previously undetected measles infection was found by an autopsy to be the underlying cause of a Washington state woman's death this spring, marking the first known U.S. fatality from the disease in 12 years, public health officials said on Thursday.
The woman from Clallam County, in northwestern Washington, was most likely exposed to measles at a medical facility during a recent outbreak in the area, the state Health Department said in a statement on its website.
She was there at the same time as another person who turned out to have been contagious with the virus. But the woman never developed some of the common symptoms of measles, such as a rash, so her infection was not discovered until after her death, the agency said.
Her precise immunization status was unknown, and though she had measles anti-bodies, the woman also had several other health conditions and was on medications that suppressed her immune system, Health Department spokesman Donn Moyer said.
The cause of her death was ruled by medical examiners as pneumonia due to measles, according to the agency.
People with compromised immune systems often cannot be vaccinated, and even if they are inoculated, such individuals may lack a strong immune response when exposed to infection, making them especially susceptible to outbreaks.
The agency cited the death to illustrate how vaccines for highly infectious diseases are important not just to protect the individual but to provide "herd" immunity for those most vulnerable among the public.
The last confirmed measles death in the United States was reported in 2003, according to the U.S. Centers for Disease Control and Prevention in Atlanta.
The latest death was reported two days after California Governor Jerry Brown signed a bill into law making it harder for parents in his state to opt out of vaccinating their children for communicable diseases.
That measure, passed by the Legislature in the aftermath of a measles outbreak at Disneyland that was linked to low inoculation rates, makes California the third state to abolish religious and other personal exemptions to vaccinations.
The bill generated staunch opposition from some parents, many of whom feared a now-debunked link between childhood vaccines and autism and others who objected to what they saw as an intrusion on their religious faith.
State Senator Richard Pan, a Democrat and pediatrician who sponsored the bill, said the Washington death underscored the need to maximize vaccination rates.
He also pointed to a 4-year-old patient in hospice care in Los Altos, California, who he said was suffering complications from a measles infection contracted when the child was 5 months old and too young to be immunized.
(Writing and additional reporting by Steve Gorman from Los Angeles, additional reporting by Sharon Bernstein in Sacramento, California; Editing by Eric Walsh)