One thing that comes to mind and has not been discussed anywhere that I have seen:
China is filthy, and culturally they don't seem to give a damn. They blow their nose with their fingers and wipe the snot whereever, kids run around with crotchless pants, tainted/doctored food supplies, but most of all, air pollution.
The smog in Chinese industrial cities-- just google 'chinese smog'-- is the stuff that 21st century Americans cannot fathom unless you bought a building lot on Love Canal. I cannot believe that none of this is an epidemiological factor.
Now imagine this:
https://www.youtube.com/watch?v=M0NcWj-e....Gillions of Chinese packed into pools, who have no qualms excreting in them... culture.fucking.matters.