Dust Plague

A Dust Plague begins sweeping the North-East corner of the continent, decimating settlements that had started to inhabit the area north east of the Dwarven Mountains.
The Dust Plague is caused by an incredibly tiny creature known as a Dust Micrit. Like a Dust Mephit it originates from the demiplane of dust (which sits "between" the elemental planes of air and earth). Once it makes contact with a living creature, it turns it, cell by cell, into dust. Or, rather, into more Micrits, which look like dust when piled up (such as, after they have consumed a creature).
It is not certain how these creatures came to the material plane, but they appear likely to destroy all living creatures on the surface of the planet.

Transmission & Vectors

The Dust Micrits are tiny, self-replicating organisms. They may be carried on clothing and equipment, or in the body of a living creature. They can be carried on the wind, in the same way as dust particles. They are inactive while wet, but reactivate when dried out.

Causes

When a Micrit comes into contact with a living creature it begins to convert that matter that makes up that creature's body into more Micrits.

Symptoms

Initial symptoms of exposure to Micrits causes itching on the part of the body exposed as the flesh is converted, one tiny bit at a time, into Micrits. If the skin is exposed, it is just an itching and burning sensation, which becomes more and more painful as it progresses deeper.
If the lungs have been exposed (inhaling airborne Micrits, carried on the wind) then it will cause coughing (which may project Micrits into the air). This will turn to aching lungs, burning and finally an inability to breathe.
Other, more sensitive parts of the body may become painful faster. Micrits in the eyes are often flushed out by tears, but if not then blindness can come on quickly.

Treatment

The spread of the condition can be slowed or even halted by washing with water. If all the Micrits are dislodged, this should end the infection. Unfortunately, if some have penetrated within the wounds they will reactivate once they dry out, and will likely restart the infection.

Prognosis

The condition is almost always fatal. It starts with itching skin or throat or lungs. Then the affected surface burns with pain. The flesh turns into dust (actually Micrits). Limbs fall off and crumble to dust. The stump continues to erode until it reaches the body. The process takes about a day from initial contact to total consumption. As vital organs disintegrate, death is inevitable.
The only way to end this slow-moving disaster is to find something that will irradicate the Micrits en-mass.

Prevention

To avoid being affected, people are advised to keep away from affected areas, people and animals. The Micrit dust is being carried east on the wind, so all settlements on the northern coast are likely to be infected eventually. Those who don't evacuate now may find themselves on the outside of quarantine.
Those who absolutely must enter an affected area could try enclosing themselves fully in an arcane barrier of some sort, or using a dustproof wrapping with a glass view-port and some very effective air filter. By all reports thus far the Micrits only consume living matter. It would be pretty awful if that changed though.

Type

Nanite / Mechanical

On Tuesday some travellers arrived, having fled an infected town. We carried out a careful quarantine at the edge of town.
On Wednesday one of the travellers was coughing.
On Thursday the town was in the ravages of the plague, people disintegrating in the streets, fresh victims trying to scrape the dusted skin from their bodies in the hope of stopping the spread.
On Friday it rained. A miraculous thunderstorm. The downpour drenched the streets and everyone who went out and soaked found relief. We washed and washed and then set off to find sanctuary in another town.
On Saturday we arrived, one town over. They were suspicious, but we told our tale and they let us in. We warmed ourselves by the fire. As we dried off, one by one we began to itch, began to cough.
I carve this warning, sitting in the town well, dunking myself from time to time to keep the plague at bay. I can't make it much longer, but I will try to place this stone somewhere it will be found.
Be warned though, if you have found this stone, you have probably already been exposed to the plague. If you haven't started coughing, seek water and never stop washing.

- Elerly Halbin