Been thinking about this and only Mr Duncan knows the truth and he seems to be keeping the truth to himself. However ... he fled Liberia knowing he had been exposed to Ebola and then went to stay with friends/relatives in Dallas. I'm quite sure he didn't tell them he had Ebola and probably didn't want to admit to anyone that he knew he had Ebola because that would mean that deliberately put friends/relatives to a high risk of exposure. He started lying about his exposure with that CDC form at the airport when he departed Liberia and he never changed his story. Just my opinion, but it seems to be corroborated with the reports out of Liberia and the fact that the folks in Dallas let him stay. Desperate people lie.