STORY HIGHLIGHTS

Atlanta (CNN) -- Dr. Kent Brantly answered a calling.

That's what friends and colleagues say about the man who garnered national headlines when he became the first known Ebola hemorrhagic fever patient in the United States.

Brantly, 33, arrived Saturday in Atlanta from Liberia, where he and another American missionary worker contracted the deadly virus while caring for Ebola patients.

From an early age, Brantly was driven by his faith in God to make a difference, friends and former colleagues said. He took mission trips to Uganda, Honduras, Nicaragua, Tanzania and Haiti, they said.

"He intended to be a missionary before he became a doctor," friend Kent Smith, an elder at Southside Church of Christ in Fort Worth, Texas, told CNN.

"Eventually, he decided medical mission is what he wanted to do."

Brantly went to Liberia with his wife and two children last year to serve a two-year fellowship through Samaritan's Purse post-residency program.

He was there initially to practice general medicine. But when the Ebola outbreak began, he took on the role of medical director for the Samaritan's Purse Ebola Consolidated Case Management Center in Monrovia. It's there that he tested positive for the virus, according to the evangelical Christian relief charity.

There is no known cure or vaccine for Ebola, and it has a mortality rate of up to 90%.

More here:
Dr. Kent Brantly