Avoiding the Rat Plague is a book found in Dishonored.
[Excerpt from a government protocol on disease practices]
Much of the public still harbors false beliefs related to the plague. It is NOT true that the bile from river krusts will protect against contraction of the disease. Nor is it true that crushed Morley orchids act as a remedy, though it is speculated that both of these ingredients are used in both Sokolov's Elixir and Piero's Remedy. Consumption of these products, before exposure to the plague, constitutes the only known means of resisting the disease.
Further, the Abbey of the Everyman warns against superstitious practices. Not only is it ineffective to burn two hagfish and a cat together, inhaling vapors while chanting the names of the plague-dead, but it is also considered heresy by the Overseers and will be met with the full measure of the Abbey's laws.
Tell your neighbors and practice these things yourself: Avoid contact with the infected. Consume your ration of elixir daily, preferably in the morning. And report anyone suspected of carrying the plague. Everyone must work together to stop the spread of the dreaded contagion.