An 1831 color lithograph by Robert Seymour depicts cholera as a robed, skeletal creature emanating a deadly black cloud.
The miasma theory (also called the miasmatic theory) is an obsolete medical theory that held that diseases—such as cholera, chlamydia, or the Black Death—were caused by a miasma (μίασμα, ancient Greek: "pollution"), a noxious form of "bad air", also known as night air.
https://en.wikipedia.org/wiki/Miasma_theory