However, instead of using sterile water, she used tap water that had been run through a store-bought filter. "I think she was using water that had been through a water filter and had been doing that for about a year previously", Dr. Cobb said.
The study concluded that the woman contracted the infection about a year earlier.
"When I operated on this lady, a section of her brain about the size of a golf ball was bloody mush", Charles Cobbs, a neurosurgeon at Seattle's Swedish Medical Center, told the Times.
"We didn't have any clue what was going on", he added. The CDC found evidence of the amoeba in both the woman's brain tissue and tissue from the rash on her nose, Cobbs said. That said, the woman's case was rare; there were only three similar cases in the US from 2008 to 2017, according to the Center for Disease Control and Prevention (CDC).
She used the device over the span of a year. "There were these amoeba all over the place just eating brain cells". This single-celled organism is not to be confused with Naegleria fowleri, another brain-eating amoeba that also lives in freshwater.
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In the case report, the doctors said there was evidence of amoeba infection from neti pots before, but that they did not test the water their patients had been using, and so they could not be sure. It was declared a distinct species in 1993, according to the report.
As in the Seattle woman's case, the infections are "almost uniformly fatal", with a death rate of more than 89%, according to the doctors who treated her and the CDC. It was sent to a lab at the prestigious Johns Hopkins University in Baltimore, where a scientists said he suspected an amoeba infection. They hope her case will let other doctors know to consider an amoeba infection if a patient gets a sore or rash on the nose after rinsing their sinuses.
"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", Keenan Piper, a Swedish Medical Center employee and co-author of the study, told the newspaper.
A CT scan revealed a 1.5-centimeter (0.6 inches) lesion in her brain.
The woman filled the neti pot with tap water, doctors said. "At this point, the family made a decision to withdraw support".
The Centers for Disease Control and Prevention says the devices are safe, but recommends people use only boiled water or saline.