Elarikan Plague

The Plague is an acid base substance, which emits gas. Therefore, contact, even with just the gaseous substance will cause burn inflictions so it's not something that can be protected against in regards to lore. More information on the Elarikan Plague here.

As far as mechanics go, the Ring of Era'Vosh can protect your character against the plague stacks. The ring is an endgame Felgarth item.

(Information from Espen from the AoC Discord)

The scourged creatures in AoC are creatures injected with a form of the Elarikan Plague, making them linger in a dying state for an uncertain period of time.

During this, they're driven mad and extremely dangerous to their surroundings with a few exceptions.

Upon the final stage of their demise, the plague will seep out of their bodies and be dispersed to their immediate surroundings.