The team at Swedish Medical Center believe the woman was using a device called a neti pot to irrigate her sinuses, which likely introduced the amoeba into her system.
But the sore didn't go away even after treatment and multiple visits to the dermatologist.
With no diagnosis, her condition continued to decline and she developed more lesions on her brain.
Finally, a neurosurgeon at Swedish Medical Center, where the woman was being treated, opened her skull to examine her brain and found that it was infected with amoebae. This wasn't necessarily surprising, Cobbs told Live Science, as the woman had a history of breast cancer.
When Cobbs first operated on her, he discovered a tumor the size of a dime. A specimen was sent to Johns Hopkins University for analysis. "So that's what we suspect is the source of the infection", Cobbs said, according to KIRO. But the woman's condition was deteriorating. She entered surgery the next day.
The woman had been prescribed a neti pot to flush out her nasal cavity because she had a sinus infection, per a case report published in International Journal of Infectious Diseases. But unfortunately, the infection was too severe, and the woman died.
A 69-year-old woman from Seattle, Washington, died after contracting a rare brain-eating amoeba from using a neti pot to clean out her sinuses, according to the Seattle Times. But they weren't able to test her tap water to confirm the Balamuthia mandrillaris amoebas were there.
Cobbs said it's theoretically possible for other people to be infected with the same deadly amoeba, but that it's a very, very rare occurrence. That said, the woman's case was rare; there were only three similar cases in the USA from 2008 to 2017, according to the Center for Disease Control and Prevention (CDC). "I was pretty much shocked because I'd never seen that before", Cobbs told KIRO-TV. "There were these amoeba all over the place just eating brain cells".
The case is the second-ever reported in Seattle - the first was in 2013. It was microscopic amoebas that were feasting on her brain. It can only grow on mammalian cells and other amoebas, the report said.
"It's such an incredibly uncommon disease it was not on anyone's radar that this initial nose sore would be related to her brain", Piper said.
Still, Cobbs stressed that people should not panic about the possibility of this infection, given its rarity.