(ABC News) -- An Oregon teen has lost both her legs to a mysterious infection, leaving doctors searching for answers.
Tabitha Schulke, an 18-year-old woman who wanted to devote her future to helping others as a missionary, is now fighting for her life in the critical care unit of a Portland Hospital.
The teen first started feeling ill on Thanksgiving morning, when she came down with flu-like symptoms, but in a strange turn of events, she quickly developed gangrene on her feet.
"They looked like she'd been out in the snow, like they turned black," Katie Zimmerman, the teen's aunt, told ABC News affiliate KATU.
The teen was taken to a nearby hospital, but her condition quickly worsened to the point that doctors felt there was little else to be done to save her.
"They told the family that she was going to die, that you need to come say goodbye," said Amber Shoebridge, public relations officer at Legacy Emanuel Medical Center, where the teen would later be transferred.
In a last-ditch effort, the hospital contacted Legacy Emanuel, requesting that they send an emergency team to set up "extracorporeal membrane oxygenation," technology that provides support to patients whose heart and lungs are so severely damaged that they no longer function properly.
But the gangrene continued to spread, forcing surgeons to amputate her legs near each knee.
Doctors still do not know what exactly has transformed Schulke from a healthy-appearing young teen into a critically ill patient fighting for her life.
Photographs of her, bruised and swollen, breathing from a ventilator appear nothing like the beautiful young teen taken prior to that Thanksgiving morning.
Signs point to toxic shock syndrome, a disease with a 50 percent chance of survival caused by certain types of Staphylococcus bacteria. The syndrome can often initially look like a flu infection, but can quickly worsen with high fevers, dangerously low blood pressure and organ failure.
The rare condition is sometimes seen after superficial skin wounds become infected or when cloth is packed in the nose to stop a common nosebleed. And about half of all cases occur in menstruating women or women using barrier contraceptive devices, according to the New York City Bureau of Communicable Disease.
"I recommend that women use pads," said Dr. Philip Tierno, an expert on toxic shock syndrome and director of clinical microbiology and immunology at New York University's Langone Medical Center. "Or use tampons from the health food stores that are 100 percent pure cotton."
Lab studies will confirm whether Schulke's infection was caused by toxic shock.
Although Schulke is still in critical condition, hospital staff are hopeful that she'll recover.
"She's improving very much so. She's a little more responsive than she had been," said Shoebridge.
But family members are still devastated by what has happened to this young vibrant woman.
"She's beautiful on the outside, but she's even more beautiful on the inside," Schulke's aunt, Katie Zimmerman, told ABC affiliate KATU.
For the family, "just her surviving, that's all that matters," said Zimmerman.