>>Key word there being "Noticed".....I fail to understand how that's precise.
It's part of the definition. ;-) I agree that symptoms are subjective, but in the old days we believed that history is 80% of the diagnosis- meaning that patients are quite observant about themselves and symptoms can be highly prognostic. These days they just test the heck out of everybody and drive up insurance premiums. ;-)
The early symptoms of Ebola are familiar enough: fever, severe headache, musculoskeletal aches and pains, shivering chills, weakness. He *might* have had weakness when he rode the train but fever didn't begin until the following day.
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1