Supposedly, at no time when Duncan was on any aircraft was he contagious because he was not yet exhibiting any symptoms.
And after he was turned away from the hospital, he went back home, stayed in his room and cleaned up after himself in the bathroom. Still, hard to believe that one of his family didn’t get it. But there is still time.
That seems to be the accepted fact. But I would add this --
Duncan was in Africa. He cared for a dying pregnant woman.
He then seems to have said, "Hmmmm. I've been exposed. I'm sure I'm going to die. I should quit my job, fly to America, and seek top medical help. Certainly I feel fine, there's no trace of any symptom, but I know I've received a death sentence."
And he was right about that. He got infected from his exposure. He thought he had a death sentence, and he did.
Why was he so vulnerable and caught it from the exposure he had, yet his family seems to have been less vulnerable and did not receive the immediate death sentence when they cared for him?
I know you get more contagious as time goes by, but he seems to have been darn sick before he finally got admitted to the hospital.