Spanish Flu

Thanks to me (duh) you already know why the 1918 Spanish Flu has largely been ignored over the last century, and now we see that scientists are still baffled by the disease itself, presumably because they're fucking idiots:

There’s no single reason why the deadliest pandemic in modern history is still mysterious. Scientists have pinpointed the origins of recent influenza outbreaks like swine flu and bird flu with relative ease, arming the international health community with an arsenal of tests and vaccines to fight back. And a flu virus isn’t particularly complex; it’s just a stretch of RNA transmitted between animals, human and nonhuman, that has evolved to mutate quickly enough to outpace any long-term immunity.

There is one good thing about the flu: it clocked this bitch out.