It's 1 AM material, this one. There's a mold called Cladophialophora bantiana, and unlike virtually every other fungal pathogen on Earth, it seems to have a taste for the brain. Not the lungs, not the skin, not the warm damp places mold usually settles. The brain. The infection it causes is described as seldom seen but often deadly, and rare plus lethal is a grim enough combination that I'd understand if you closed this tab now.

Gizmodo reports that cases of this infection appear to be increasing, and the honest answer from researchers is that nobody fully knows why. It's still rare. But rare and rising is a different category of problem than rare and stable, and that's the part I can't stop turning over.

What's strange here is the target. C. bantiana goes after the brain in a way other fungal infections don't, and per the reporting, scientists aren't sure why it has that preference at all. The prevailing question isn't only how to treat it, though by all accounts it is often deadly. The question is why any mold would be built to reach the brain, a boundary most pathogens never manage to cross. There's no obvious evolutionary logic I can point to. The brain isn't an easy place for a fungus to end up.

Unless it's easier than we think, and we just haven't figured out the mechanism yet.

That's the rabbit hole part, and I'll admit it freely: I don't have an answer, and neither do the researchers. I'm not going to enumerate the standard explanations, better diagnostics, changing environments, shifting patient populations, as though they came from the source, because the source doesn't say that. What it says is simpler and stranger: cases are rising, and scientists aren't sure why. I've written enough of these pieces to know that "we're not sure" is sometimes a temporary condition and sometimes a load-bearing wall. Time tells you which.

And I keep coming back to the preference itself, because it touches a bigger unease I've circled before, the same itch I get with prions and with that strange class of organisms that seem adapted to hosts they shouldn't be able to reach. A mold that goes after the brain is a mold that solved a very hard biological problem for no clear reward. Evolution doesn't usually do that. When it does, either we're missing part of the story or the story is missing us.

I'll be following this one. When the researchers themselves publish on what's driving the increase, rather than the rewrite desks, I want to read the actual data. Until then the honest position is the uncomfortable one: a brain-seeking mold is becoming more common, and the best explanation anyone has so far is a shrug.

Sleep well.