@doctorsex @HunDriverWidow @hittitezombie @gorskon @ankokukishi @m0rglee @Gab_Refugee @WoodenDoorInspector @jeffcliff @LaylaAlexandrovna Correct me if I'm wrong, @nosat , but I think it would be from introduction or accumulation of something that was harmful or toxic to many people, making the environment very bad for humans and causing the response. A genuinely interesting thing is the presence of comets before the plague, and historically comets were a bad omen. It's possible they brought something into the area that contributed to plague. There's also the an interesting thing about new illnesses corresponding with big technological changes. Major electrical infrastructure starts up in Europe in 1889 and The Russian Flu suddenly develops the same year. It can be both/and IMO, and disease could spread via germ theory even if it seemingly emerges because of environmental conditions. We have a ton of "viruses" in our genetic code that are sort of folded in, and who's to say they can't suddenly pop out from new stimuli.