(Updates with quotes, details throughout)
By Rich McKay
ATLANTA, Aug 21 (Reuters) - Appearing thin but smiling, a Texas doctor who weeks ago entered an Atlanta hospital in a full-body biohazard suit to be treated for Ebola said on Thursday he was "thrilled to be alive" as doctors declared him virus-free and safe for release.
Dr. Kent Brantly's release came two days after a second U.S. missionary, Nancy Writebol, was quietly allowed to leave Emory University Hospital, where both had been treated after contracting the deadly virus in July while working for Christian organizations in Liberia.
They were each cleared for discharge from the hospital's isolation unit after their symptoms eased and blood and urine tests showed no evidence of the virus, a doctor who treated them said on Thursday.
The announcement of their release and expected full recovery from a disease that has killed 1,350 people in West Africa prompted an emotional scene in Atlanta. Hospital workers cheered, clapped and cried as a thin but steady Brantly entered a news conference holding his wife Amber's hand.
"Today is a miraculous day," said Brantly, a 33-year-old medical missionary for the Christian relief group Samaritan's Purse. "I am thrilled to be alive, to be well and to be reunited with my family."
Brantly thanked the health teams at Emory and in Liberia for their care "during the most difficult experience of my life," recalling how he grew sicker each day before being evacuated to the United States earlier this month.
"I am forever thankful to God for sparing my life and am glad for any attention my sickness has attracted to the plight of West Africa in the midst of this epidemic," he said.
Writebol did not attend. The 59-year-old from Charlotte, North Carolina, left the hospital on Tuesday and was resting in an undisclosed location with her husband, Christian mission group SIM USA said in a statement.
The couple was smiling and hugging in photos released by the organization on Thursday, but Nancy Writebol endured "dark hours of fear and loneliness" during the course of her fight, her husband said.
"Nancy is free of the virus, but the lingering effects of the battle have left her in a significantly weakened condition," her husband, fellow missionary David Writebol, said in a statement. "We decided it would be best to leave the hospital privately to be able to give her the rest and recuperation she needs at this time."
QUESTIONS LINGER ABOUT EXPERIMENTAL DRUG
Dr. Bruce Ribner, medical director of the infectious disease unit at Emory's hospital, credited aggressive supportive care and the fact that both Brantly and Writebol were healthy and well-nourished with helping them recover.
The pair received an experimental therapy called ZMapp, a cocktail of antibodies made by tiny California biotech Mapp Biopharmaceutical. Health experts cautioned against declaring the drug a medical breakthrough based on two patients.
"The honest answer is we have no idea," Ribner said, when asked if the experimental drugs helped the missionaries' survival. He said early studies in primates suggest the drug has few long-term side effects.
The scale of the Ebola outbreak in West Africa, the largest in history with 2,473 people infected and at least 1,350 dead, has prompted a scramble for experimental drugs, most of which have only been tested in monkeys and cell cultures.
Last week, the World Health Organization backed the use of untested drugs and vaccines, but the scarcity of supplies has raised questions about who gets the treatments.
ZMapp was also given to a third patient, a Spanish priest, who has now died from his infection, as well as two doctors in Liberia and a nurse. Sources in Liberia told the WHO that two of those patients have shown marked improvement following their treatment.
But about 50 percent of people survive Ebola anyway, even under poor medical conditions, Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Disease at the National Institutes of Health, said on MSNBC on Thursday.
"I'd say we have a couple of people who've recovered, they've gotten excellent medical care and the specific therapy, ZMapp ... may have had a role in it but we don't know," Fauci said.
Scientists who have studied Ebola say the virus can remain in certain areas of the body, including the eyes and seminal fluid, for seven to eight weeks after recovery.
Ribner said Brantly and Writebol were released in consultation with the U.S. Centers for Disease Control and Prevention and pose no health risk to the public.
Brantly, the father of two young children, said he planned to spend time in private with his family after more than a month apart. (Additional reporting by Joe Bavier in Abidjan, Daniel Flynn in Dakar, Julie Steenhuysen in Chicago and Susan Heavey in Washington; Writing by Colleen Jenkins; Editing by Louise Ireland, Bill Trott, Susan Heavey and Eric Walsh)