[Sensori]

Regeneration appears to help with disease, so planting regen rings on folks (or if you have a nature blessing, that shroud should do it too) might help a bit once you already have disease. I think I saw some guys with 1 hp living a couple of turns just fine with disease in one game I was about to sub in.

And, if you happen to have Nature in general, getting Faery Queens (it's that Faery Court summon) will work too, they have the Heal ability. They're 3N3A mages that can summon (crappy) allies which makes them good even when you don't need 'em to be healing disease, and since their numbers aren't limited like with those tree guys, bigger demons and elemental royals you can get as many as you want or can. Gift of Health can fix afflictions, too.