Ironrot (5e Disease)
From D&D Wiki
Ironrot is the name given to the effects of a particular strain of bacteria that subsists by facilitating the corrosion of ferrous metals.
Ironrot spreads easily. If any affected gear or constructs come into physical contact with viable hosts for the disease, it could spread to them.
Constructs and gear made of ferrous metal slowly rust away into piles of red flakes, as the bacteria consumes their components.
Ironrot has a few methods of being treated. The first is to remove and replace all metal pieces afflicted with the disease. The second is if the metal pieces hosting ironrot are heated to a red-hot temperature, killing the bacteria.