Like many victims, Janelle Hansberger's symptoms progressed rapidly. She dropped a computer on her left foot in late 2010. Within hours, her foot had swelled and she simultaneously developed what felt like a stomach flu, she said.
Unable to endure the pain and illness, she went to the hospital within 24 hours. Hansberger, a 37-year-old mother of two young boys, eventually had her left leg amputated below the knee.
Only about 1 in every 400,000 people is diagnosed with necrotizing faciitis each year in the United States, said Dr. Chris Van Beneden, a medical epidemiologist with the CDC's Division of Bacterial Diseases. In Georgia, that would translate into roughly 25 cases each year.
A number of different bacteria can cause the infection, Van Beneden said, including Klebsiella, E. coli, Staphylococcus aureus and group A Streptococcus. Strep A is among the most common, especially in cases occurring among young, healthy people.
About 20 percent of cases caused by Strep A are fatal, according to the CDC.
The infection can start with a trivial injury -- a cut, scrape or burn on the skin. In some cases, patients and doctors never determine how the infection began.
Symptoms include small, painful red bumps or lumps; bruise-like areas that grow rapidly or turn black; and skin that may break open and ooze, according to the U.S. National Library of Medicine. Victims might also have fever, nausea, weakness, chills, dizziness or shock.
And, of course, the pain.
"A common denominator in most cases appears to be pain that is disproportionate to the size of the rash or trauma on the skin," reports an article on the website of the American Academy of Orthotists and Prosthetists.
Or, in Walker's more colorful words: "It’s the worst pain you could possibly imagine."
Survivor Bill Brust, 60, echoes that.
"I had never ever been through any pain like that. It's indescribable," said Brust, of Roswell, who developed the infection following knee surgery in 2001. "I have fallen off a bicycle and broken my arm, but that was nothing [compared to this]."
Robert Vaughn, a Cartersville man currently battling necrotizing fasciitis, said the infection "hit me like a ton of bricks." Vaughn, 33, remains hospitalized at the Joseph M. Still Burn Center in Augusta, where Aimee Copeland is being treated. Copeland, whose multiple amputations have made worldwide headlines, remains in critical condition, according to a burn center spokeswoman.
Vaughn doesn't know what triggered his infection. It seemingly began with a small bump near his groin that grew from the size of a pea to a grapefruit overnight, he said.
"I don’t know how I got it," said Vaughn, who admits he at first didn't want to tell doctors about the "bump" because of its location. His wife insisted, he said.
Vaughn is grateful he was spared amputation, but is still reeling from the "what-ifs" of his medical nightmare. "I think about it a lot ... what if my wife hadn't been there?"
Most of all, he said, "I hope I never get it again."
Doctors believe Copeland's case began with the bacterium Aeromonas hydrophila, typically found in warm climates and waters. The University of West Georgia student likely contracted the bug when a home-made zipline near the Little Tallapossa River broke and she tumbled into rocks and water below, cutting her leg.
The survivors interviewed for this story said Copeland's case has brought back vivid memories. At the same time, they said others with the condition should take heart, recognizing that life after necrotizing fasciitis is possible.
Brust, who lost a ligament in his knee to the infection, is still able to ride bicycles, though he's given up skiing.
Walker, 43, who credits her doctors and the power of prayer for her survival, eventually learned to walk again. She can now run and play with her three children.
And Hansberger, an avid runner before her amputation, completed her first triathlon less than a year after her 40-day hospitalization in Atlanta.
"There are a lot of blessings that have come out of all of this," said Hansberger, who has since moved to Charlotte. "It might sound weird, but I am very grateful for everything I have now, and I enjoy all the things I get to do with my children, whereas I maybe took it for granted before."
And Walker said that while the illness changed her life, she refuses to live in fear -- even though she has to battle against it when her children incur the inevitable scrapes and bruises of childhood.
"I cannot live every day in fear that someone else I love is going to get this," Walker said. "You can't live like that."