Kael, sorry, but I was wrong in my last post, Monkeyfinger is right. I'm almost positive now I was right the first time. I've attached two saves. The first is two turns before the blight hit, when I went into the worldbuilder and got myself a bunch of AV priests. The second is after the blight.
The fact that the blight health hit is FAR greater than population + rand (1-15) is clear. Some examples: in my first save, Khazak, my capital, has a population of 27, Rylad has a population of 19, and Celo, for instance, has a popualtion of 13. The blight effects for them are 67! (just from blight), 19, and 31; therefore, it is logical to conclude that we are getting hit with double the population impact or something on the same order of magnitude. The other cities appear to have similar impacts.
Note that the total unhealth in Khazak is now 96; despite people's protestations to the contrary, this is an absolute game killer, I will have a popualtion of 1 for a VERY long time in my capital.
Best wishes,
Breunor