ATLANTA - Dr. Kent Brantly answered a call to help.
That's what friends and family members 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 aid worker contracted the deadly virus while caring for Ebola patients.
The news has prompted many to ask why would he put himself at risk.
The answer might be difficult for some to understand, his former college and medical school professor wrote in an op-ed published this week in The Indianapolis Star.
"Simply put, he would say that he had been called to care for the patients in Liberia," Richard Gunderman wrote in the newspaper.
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.
Brantly 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 charity.
Before heading to Liberia, Brantly did his residency at John Peter Smith Hospital in Fort Worth, Texas.
"We're kind of proud that there was a hero out there trying to do his best to make life better for other folks under the circumstances," a physician who knows him, Dr. Paul Pepe of Dallas' UT Southwestern Medical Center, told CNN affiliate WFAA this week.
From an early age, Brantly was driven by his faith in God to make a difference. He took mission trips to Uganda, Honduras, Nicaragua and Haiti, according to accounts offered by family members and former colleagues.
Brantly attended high school in Indianapolis before graduating from Abilene Christian University (Texas) in 2003 and Indiana University's medical school in 2009.
While at Abilene Christian, he spent a summer interning overseas with a program focused on vocational missions experiences, ACU's online alumni magazine reported.
"Everyone here who has been connected with Kent knows him to be someone who is very compassionate, considerate and always upbeat in all he does," the program's director, Dr. Gary Green, told the magazine.
"... Kent's the kind of guy who would weigh benefits versus risk, then try to take himself out of the equation so that he would be thinking, 'What do I bring to the table? Is the risk worth taking because I can benefit so many people?'"
Though Brantly's wife and children had been in Liberia with him, they were in the United States when he became ill.
"Many people have been asking how I am doing," Amber Brantly said in a statement released earlier this week. "The children and I are physically fine."
The U.S. Centers for Disease Control and Prevention has said neither Brantly's wife or his children are symptomatic.
Brantly's wife, parents and sister cried when they saw him on CNN, walking from the ambulance into the hospital, a family representative said on condition of anonymity. His wife, Amber, later said she was relieved that her husband was back in the United States.
"I spoke with him, and he is glad to be back in the U.S.," she said in statement sent to CNN. "I am thankful to God for his safe transport and for giving him the strength to walk into the hospital."
Brantly's wife visited with him from behind a glass wall for about 45 minutes, the family representative said. Kent Brantly was described as being "in great spirits and so grateful."