he is isolated after walking into the emergency room with a fever and gastrointestinal symptoms. he had recently traveled to a west african country struggling with the outbreak. >> we'll be able to hopefully find there is a more common cause of fever and other symptoms that the patient has. but using an abundance of caution, we're going to work carefully with the cdc to make certain this patient does not have the ebola virus disease. >> reporter: only 40% of ebola patients survive. and the atlanta doctors treating brantly are hopeful he will be one of them. he arrived stateside saturday, climbing down from this ambulance in a full biosuit and walked into emory university hospital. he's been taking an experimental drug that his missionary organization tells us is working wonders, after he was on the brink of death. we learned his fever is lower. the 33-year-old doctor from tennessee had just moved his family to liberia. his aid organization tells us he and others at his field hospital were infected by someone who was sick on their cleaning crew. nancy writebol from charlotte helped decontaminate doctors --