ghosts and spirits (鬼神)
Many people in early China believed that ghosts of the dead and other spirits caused illness.
Discourse on Epidemic Qi, and a Brother's Letter
Cao Zhi and Cao Pi, quoted in the Taiping yulan (Imperial Readings of the Taiping Era), chapter 742 · 217 or soon after (the essay, on the epidemic of Jian'an 22); 218 (Cao Pi's letter)