chrisnlisa03, please read the thread.

There is no "definitive" set of words to a folk rhyme; one of the essential characteristics of folklore is that it changes all the time.

There is usually no way to definitively establish the exact origin, either. Folklorists used to do research to establish the "Ur-form," what they believed to be the initial form a piece of folklore, and to establish its origin. Problem was, the results were always more or less speculative.

Beyond that, if you DO read the thread you'll find there is no evidence for the rhyme being as old as the Plague. Therefore the scholarly abilities of plague victims are irrelevant.