Infectious Disease
Plague, Epidemic
noun, の adjective
An epidemic of sickness is going to come from an infectious disease. Perhaps a plague or epidemic of some kind?
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
その村の人々は、全員疫病で亡くなりました。
Everyone in that village died from the plague.