What is cryptosporidium, anyway? I know it can turn up in water, but that's about it. I asked a friend who works in public radio, and she said, "It's a parasite. It eats your body." That didn't sound very scientific to me. But what does it do?
From its bad press and scary-sounding name, you might suppose cryptosporidium is some sort of Andromeda strain that combines the worst characteristics of toxoplasmosis (the disease pregnant ladies get from mistaking cat litter for Almond Roca), triffids and the Illudium Q-36 Explosive Space Modulator.
The truth is more mundane. If you just want a quick handle on what it does to you, here's a gross oversimplification: think of cryptosporidium, functionally, as basically the same as E. coli.
Like E. coli, crypto is a microscopic organism that gets in your gut when you ingest a tiny amount (or a large amount, I guess, if that's your thing) of infected poo in your food or water. Also like E. coli, it will give you diarrhea for several days, but probably won't kill you if you're an adult in good health.
Mind you, from a scientific standpoint this explanation is roughly equivalent to saying that, functionally, a migraine is the same thing as being hit on the head with a cast-iron skillet. Taxonomically, crypto and E. coli are less closely related than cows and algae.
One of the most salient differences between the two bugs is that chlorine, Western civilization's go-to solution for disinfecting water, won't kill crypto, which is one reason the latter is such a headache for treatment-plant officials and folks who own water parks.
The back-and-forth over how best to keep crypto out of Portland's water is well-documented elsewhere. In the meantime, I'd remind you that we don't swim in your colon, so please don't crap in our reservoir.