It's actually plausible from the view of natural selection. When you eradicate diseases which are fatal, or where it's easy to explain the mechanism of symptoms

It's actually plausible from the view of natural selection. When you eradicate diseases which are fatal, or where it's easy to explain the mechanism of symptoms and block it... then parasitic "experts in stealth and distortion" can take over. In other words, modern medical science creates evolutionary pressure toward parasites/infections that have raft of unconnected mild symptoms with complicated underlying biology, which are impossible to replicate in vitro and make a career out of studying it. Or there are cultural taboos involved, for example Chlamydia might be similar silent killer but it's dismissed as trivial venereal disease and that isn't very respectful area of study. (compare https://www.cdc.gov/pneumonia/atypical/cpneumoniae/about/history.html https://www.cdc.gov/pneumonia/atypical/cpneumoniae/about/his... and https://www.sciencedirect.com/science/article/abs/pii/S0306987705001544 https://www.sciencedirect.com/science/article/abs/pii/S03069... ) The overall result is, only crackpots consider such a possibility seriously :(