I should have seen this coming.
I may be a recovering science fiction novelist, I still know how to plot: you drop some casual fact or remark into the early story, it seems like just part of the background noise, and then at some critical point later in the story that fact or remark explodes into prominence and gives the whole story meaning. This is such an old gimmick that it has a classical Greek name: anagnorisis, which roughly translates as "learning up"—the aha! moment when we glimpse what reality really is.
Also known as the "shock of recognition," this sudden flash of insight seems to depend on connecting a newly learned fact with something already learned and assimilated. The Danish science writer Tor Nørretranders calls it exformation: the information you don't include in a message because your reader/listener knows it already. Exformation is also the principle behind the running gag: each time we see it, we flash back to the last time, and our brains reward us by dousing themselves in various euphoric chemicals.
But it's not always a euphoric process. Years ago I posted a lot about dengue in Brazil, and reports often mentioned official worry because a new strain had turned up for the first time in some region and posed a serious threat to those who'd recovered from another dengue strain. If you'd had serotype 1, for example, and then came down with serotype 3, you could well end up with hemorrhagic dengue and perhaps die of it.
Dengue not being a clear and present danger to residents of north temperate zone countries like the US, this unpleasant aspect of the disease went unnoticed. And when chikungunya showed up in the Americas, its dramatic spread distracted everyone—until Zika showed up and crowded chikungunya out.
Now it's beginning to look as if we've been distracted like rubes playing a shell game. Dengue and Zika are flaviviruses carried by Aedes aegypti. (Chikungunya, as Greg Folkers has just advised me, is an alphavirus.) In the last few days, it's beginning to look as if dengue and Zika have been giving us a one-two punch: if you've had dengue, and then catch Zika, your dengue antibodies will actually make your Zika worse. Mike Coston at Avian Flu Diary posted yesterday about several reports suggesting this.
And this is the point where the aha! moment (or Sistine Chapel facepalm) comes in. All those hundreds of thousands of Brazilians who caught routine "breakbone fever," and got on with their lives, were unknowingly at risk if ever Zika should turn up. And it did. Suddenly, starting last year, the microcephalic babies began to be born.
So the flaviviruses, without a molecule's worth of intelligence, appear to have taken our measure. Dengue sets us up, and Zika knocks us down. Chikungunya so far looks like an unindicted co-conspirator, along for the ride, but now that I'm in full-blown paranoid mode I expect it will soon be found to cause allergies and old age.
This dengue-Zika correlation may itself turn out to be yet another shell game, but it does not encourage a reductionist approach to dealing with each of these goddam arboviruses by itself. I hope I'm over-reacting, and would be grateful for others' thoughts on the matter.
