Sept. 5, 2012 -- When Jennifer Benewiat first came down with a fever on Christmas 2010 at her home in Wichita, Kansas, she thought it was the flu.
What she didn't know was that she had a deadly illness called hantavirus, which would stop her heart three times in ten days.
"I get upset still because I had no idea, and it's just a mouse," Benewiat said. Hantavirus is carried in airborne particles of urine or feces from infected mice, which can be inhaled by people. "It's really scary, and people don't realize the danger that comes from something so little."
As the number of Yosemite campers at risk for hantavirus climbs to 10,000, including people in 39 countries outside the United States, those who have survived the deadly airborne disease are reminded what they went through and the struggle that still lies ahead.
"There's a perception that once a patient has left the hospital, that the patient has completely recovered and can go about their normal routines just like before, but that's not really the case," said Marjorie McConnell, a medical sociologist at the University of New Mexico who founded the Hantavirus Survivors group on Facebook and Twitter.
McConnell started the group a few years ago to give survivors a place to support one another. It now includes 42 survivors and their family members, including a few new faces in light of the outbreak at Yosemite.
Benewiat, 29, said the hantavirus group on Facebook first alerted her to this summer's Yosemite outbreak, which has already killed two people and infected four others. As she read, overwhelming fear passed over her for a moment. It's the same sensation she gets every time she reads about a new hantavirus case as a result of her post-traumatic stress disorder, she said.
It all started with a 104-degree fever and flu symptoms that wouldn't go away for nearly two years ago, Benewiat said. It's still not clear where she inhaled the virus. The first time she went to her doctor's office, he ran a number of tests, but found nothing. He sent her home with medicine for nausea.
When nothing changed the next day, he told her to go to the emergency room, where doctors performed more tests. But they still didn't know the mystery illness they were treating, and Benewiat was beginning to fear passing it to her 2-year-old twins, her infant, her mother or her sister.
"The first doctor she saw in the ER was just going to send her home," said Benewiat's mother, Gayle Collins, 52, as she fought off tears. "If she would have went home, she would have died in her sleep that night." Benewiat's oxygen level dropped while she was at the hospital. Within a few hours, Collins was signing paperwork to put her on a ventilator.
A doctor friend from New Mexico, where hantavirus is more common, recognized the symptoms right away. They tested Benewiat for hantavirus, but the results would take more than a week to process before they could get an actual diagnosis.
That was time she didn't have, but sure enough, a chest X-ray revealed that her lungs were full of fluid, a common symptom of hantavirus pulmonary syndrome. Of the 587 reported hantavirus cases in the United States, 36 percent of them resulted in death as of December 2011, according to the Centers for Disease Control.
Benewiat's fever reached 107 degrees and she fell into a coma. Doctors decided to keep her unconscious as they pumped her full of medicine and steroids. Collins stayed by her daughter's bedside the whole time except when doctors inserted a chest tube to drain Benewiat's lungs. Collins said she was afraid her daughter would feel pain even in her comatose state and couldn't watch.
Benewiat's recovery was touch and go for ten days as her kidneys and liver failed, Collins said. Doctors had to resuscitate her three times. Finally, her body began to fight the virus on its own and doctors brought her out of the coma. She was temporarily paralyzed from the neck down because of the steroids, and would have to learn again to walk and feed herself in a rehabilitation center after she left the intensive care unit on January 20, 2011.
"She didn't understand where she was," Collins said. "She knew she had had that flu at one time, but she didn't understand where she was. She thought she'd been kidnapped."
Even though Benewiat has returned to a normal life, she said people don't realize how much physical and emotional pain she's faced in the aftermath of hantavirus pulmonary syndrome. Her life now includes depression, PTSD, anemia, and chronic pain. Her mother also worries about her kidney function, which is regularly tested.
When Benewiat's therapist suggested she find a support group for survivors, she learned that she wasn't alone.
"I think it's particularly important for folks dealing with these processes to be able to discuss the issues since recoveries may be similar but not identical," McConnell said of the group. "The Facebook survivors can empathize and offer advice to one another, which is an important part of the recovery process."
One survivor, Charlotte Winter of Santa Fe, New Mexico said doctors told her family that if she'd been airlifted to the University of New Mexico Hospital just ten minutes later, she would have died. When she arrived there, her heart stopped, and she was blue from head to toe. She, too, was in a coma and on heart and lung bypass for a number of days.
It has been five years now since she was stricken. "While I look okay today, the overwhelming fatigue and other aftereffects of HPS cause me to be disabled," Winter wrote in an email to ABCNews.com.
Idelette Nutma, of Hague in the Netherlands, joined the group after coming down with a European strain of hantavirus in Belgium in 2007. Her strain was carried by a red bank vole instead of deer mice, but it essentially does the same thing. She started with flu-like symptoms, but progressively developed back pain and breathing problems.
Despite abnormal lab findings related to Nutma's kidney and liver function, doctors misdiagnosed her with bilateral pneumonia and sent her home a week later. But four weeks after that, she was back in the hospital and in critical condition. Although a doctor thought it could be hantavirus, he dismissed the notion and kept her in the ICU on steroids another five days.
Four weeks later, test results came back showing hantavirus antibodies in Nutma's blood, but doctors concluded the infection wasn't recent. She blames the fact that they didn't test her until two weeks after she was admitted to the ICU for the second time.
Given the acute nature of her illness, Nutma, a nurse, said she is sure she was battling hantavirus, but doctors considered her case closed and never proved it.
She said she now suffers from fatigue, muscle and joint pain, and "weird immune system reactions," which she explains as her body overreacting as if there is a constant hantavirus threat.
Nutma's mother called her this month from Holland after hearing about the Yosemite outbreak on the news, so she read about it herself.
She said an unpleasant feeling hit her right in the stomach, and she had the same mix of emotions she felt in 2007 -- uncertainty and a sense of "losing all grip." She said she was overwhelmed by the idea of going through chills, back pain and a fever and not knowing that four weeks later, she would be in an ICU on a ventilator fighting for her life.
"I felt how unpredictable and dangerous this illness is and what fear people may feel being exposed to this virus," she said.
Like many survivors, she wanted to emphasize increasing hantavirus awareness among doctors. In light of the Yosemite outbreak, McConnell's group of survivors have started a Tumblr page, which includes news articles and updates from government health departments.
Health officials have already emailed 3,000 people who camped at Yosemite's now-closed signature cabins from June through August, urging them to keep an eye out for symptoms, seek medical attention early, and let doctors know about their hantavirus risk. The number of people at risk is reported to be 10,000.
"The Facebook survivors are keen on getting education and awareness out into the public so appropriate cleaning methods are utilized," McConnell said. "Survivors don't want anyone else to go through what they experienced, or perhaps lose a life."