Story highlights Nancy Writebol was diagnosed with Ebola on July 25 while in Liberia

The mother of two has been in Africa as part of her missionary work

Her pastor described Nancy and her husband as "the salt of the Earth"

Despite the high mortality rate, her son says: "We feel like Mom has a chance"

Nancy Writebol is a loving mother. A devoted wife. A woman of faith. A missionary who has traveled the world to help others.

And now, the world knows her as an Ebola patient.

Last month, while working in Liberia, Writebol contracted the deadly virus. She's one of three Americans known to contract Ebola during the outbreak that has ravaged West Africa.

The others are colleague Dr. Kent Brantly and Patrick Sawyer, a naturalized citizen and Liberian government official who died from the disease earlier this week.

The missionary is expected to be picked up in West Africa and flown back to the United States, where she is expected to join Brantly -- who arrived Saturday -- in a special isolation unit at Atlanta's Emory University Hospital. According to Todd Shearer, a spokesman for the Christian charity Samaritan's Purse, she should be in Georgia early next week.

The trip will be the latest of many journeys for Writebol, whose other missionary ventures include Ecuador and 14 years ministering to orphans and vulnerable children in Africa.

Since August 2013, the Writebols have been in Monrovia, Liberia, with the Serving in Mission group, which worked with Samaritan's Purse.

Nancy guided missionaries and teams and worked with nurses at ELWA hospital, where her husband is the technical services manager, according to the Christian group's website . Nancy was diagnosed with Ebola on July 25.

Those who know Nancy best say that she's motivated not by any quest for personal glory or thirst for adventure, but because she and her husband feel compelled to act because of their faith.

As husband David explained from Africa via Skype to members of Calvary Church in Charlotte, North Carolina, at a recent vigil for Nancy: "We have been blessed because of what Christ has done for us, (by giving) us eternal life and salvation.

"What else could we do (but help)?"

The fact the Writebols left the comforts of America to live in an area rife with poverty, instability and disease, the fact they put their lives at risk to assist those suffering everyday, isn't surprising to those who know them.

John Munro, their friend and pastor at Calvary Church, describes the couple as "the salt of the Earth," the kind of people who wouldn't give a second thought to dropping everything to help.

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The only thing perhaps ironic about what's happening now is how such an "unassuming" and "very humble" woman has become international news.

"She is ... not someone who would ever make the headlines," Munro said, "apart from something like this."

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That doesn't change the fact the Writebols have extraordinary lives.

Wherever they've gone, their lives have been centered on their church and their family, including two now-adult sons who live in the United States.

One of those sons, Jeremy Writebol, told CNN's Chris Cuomo that the recent ordeal has been hard on his father. Nancy Writebol has been isolated in the couple's Liberia home; she and David talk by phone but, given fears she might pass on Ebola to him, they can't touch.

"It's very difficult, and we feel the emotion of that," Jeremy Writebol said of his parents' physical separation.

Then, of course, there's the inherent danger of Ebola. The World Health Organization reports that there have been at least 1,322 cases in recent weeks in West Africa, some 729 of which have resulted in death.

Even before it was known his mother would return to the United States, where she'll get top-notch care at Emory, Jeremy Writebol took solace the mortality rate isn't even higher.

"We feel like Mom has a chance," he told CNN affiliate WCCB.