Prior to this outbreak, this Ziare strain of Ebolavirus, now formally known as "Ebola virus", has never infected more than 318 people at a time, and not a whole lot more than a thousand total: https://en.wikipedia.org/wiki/List_of_Ebola_outbreaks#List_o...
I guarantee that at least one of the things the usual suspects like the CDC "know" about its transmission is wrong. Consequentially wrong? Well, we'll see.
As for this case, he was not feeling well (also described as "sluggish") for a couple of days before his self-monitored temperature spiked. Which is prompting the usual suspects to say that that wasn't a "symptom" ... which is open to question.