I believe one of the reason why there were few cats around is basically because they used to eat them. And every now and then the restaurant kitty catches would grab an pet cat they could find and take them back again to the restaurant. I remember seeing pet cats in glass displays out the front of the restaurants. But somewhere between then and today they restricted eating cats. So cats are now not on the menu and today there are felines everywhere. Most of them started off in someone's house and got thrown away, since many are very friendly. Also they may have this thing about stomach worms. And in those times China had not been as modern as now so tummy worms is a problem. Fleas are not really a problem because they have got tile surfaces and wooden furniture.
If this attitude towards cats dates back generations then one can understand why historians say the Dark colored Death started in China. Where there are rats and no cats then the rats dominate and that would have been a precursor for the disease to get near to people. Now as i go back to China there are still rats playing around but not so many in the real estate estates. There are various down by the river. Also they have a very efficient rubbish clean up system that continues the locations very clean. Where I stay the rubbish is accumulated everyday. That could also keep the rat human population down. And with so many discarded cats running around the rats don't possess much of the opportunity. I've never seen this but I believe the government picks up a whole lot of cats. There used to be colonies of stray felines living in some places but now I don't see them any more.