To be quite blunt about it, Ebola is a very scary disease. Among those infected, the mortality rate is, as is perhaps now widely known, an appallingly high 90 percent. That would seem a very good reason to keep our borders closed to this scourge- and the consequences to the poor souls who already have it be damned. That, apparently, was just the kind of thinking behind at least one rather high-profile tweet.
But perhaps we might characterize this thinking as the subjugation of epidemiology to hyperbole. And like all rabid opposition, it is the product of anxiety rather than analysis.