I read that at least some people believe that the Plague of Athens was Ebola, or perhaps a similar viral hemorrhagic fever (they think hiccups may be a telltale sign).
Is this a credible claim? Or are there other suspected massive outbreaks of VHFs in history?
It's a flat out guess.
If it was some hind of VHF, it didn't have the 90%+ fatality rate that one might expect from recent strains if they were the same back then.
This person suggests some kind of influenza: http://www.ancientgreece.com/essay/v/the_plague_of_athens/