In medicine, the word pathogen means an organism that causes diseases that are harmful to you if you are exposed to it, such as a harmful virus, bacteria, and fungi (in contrast to a micro-organism that might be good for you like a pro-biotic gut bacteria, or bad for you like strep).
I am looking for a single word that is a memetic analogy to a pathogen, i.e. an idea or emotion or other meme (in the memetic sense) that is harmful or toxic to be exposed to, such as a conspiracy theory or hate or an idea that makes you feel inferior.
I'm looking for something close to the social work term "adverse childhood experiences" (ACEs) which a standardized indicia of childhood traumatic experience that can lead to negative life outcomes, but not specific to children.
It might also be an echo of the idea of the "seven deadly sins" (lust, gluttony, greed, sloth, wrath, envy, and pride) without the religious connotations and with an emphasis on being something that can be spread rather than something that is an inherent character flaw.