Transmission & Vectors
Once reaching the ripe old age of 400, Dwarves start to naturally deteriorate. There is no known cure, but it does seem to be linked to genetics.
Genetics and old age are the proponents of Stone Jitters. It might come from something in the rocks in Mil Bazon, for none that have been gone from the place for a generation experience it.
The afflicted person feels as if a large stone sat on their chest. It's akin to allergies, but heavier and deeper. It feels as if one if stayed in bed. Then the jitters some. The jitters are the worse of the two side effects. One with the jitters looks as if they are cold, but the bodily convulsions are not from any chill. The limbs will vibrate violently and uncontrollably. In extreme cases, full range of motion is achieved, one even reported half-walking, half-dragging herself through her house to the other room.
Several salves seem to give temporary aid, but nothing in Mil Bazon besides the release of death seems to help anything. Of course, there are those who went outside of Mil Bazon and traveled. Those still had symptoms but not as awful, and their children born outside of the great city never experienced any issues when they eventually grew up, even after going back under the stone.
It is very likely some sort of dust is released in Mil Bazon from the mining that is constant. It could also very well be the constant furnaces, but try telling a Dwarf to darken his kiln or furnace! The Dwarves think it to be a dust, or simply bad genes. They note that no new cases occur from those outside of families who already have it.
Those Dwarves over the age of 400 are most keenly affected. There is no male or female bias.
Any good surgeon or scholar will tell you to leave Mil Bazon for a bit if you are a guaranteed carrier of Stone Jitters. They say to have your child in the open (i.e. not in Mil Bazon) and wait until they are about ten before returning. There is no known full cure as of now, just ideas that could be extrapolated to mean more.
The first case was a thousand years after the Dwarves came to Mil Bazon. Some poor smith noted his chest felt flat, which garnered a laugh. When he earnestly told them he had trouble breathing they took it seriously. He laid on his bed and heaved great sighs then started shaking violently. The family, scared of their minds, fled and retrieved clerics. It was thought a sad case, but an outlier, an odd case but nothing more. Since then it has affected a good majority of the Dwarves. The main issue is that it cannot be detected until its symptoms are in effect. This makes targeting it an issue as well.
Thank Kord the Dwarves are more stoic-minded and not flighty. For this instance almost any Dwarf will stomach the pain of seeing a loved one suffer in this way.