The staff and the “fiery serpent”

I write concerning the recent letter by H.J. Scott concerning Asklepios' staff (the karykeion) and Hermes' winged 2-serpent wand (the caduceus).1 Perhaps I can spoil the broth or symbol further. Several years ago I read in a book on surgical history, the title of which I have now unfortunately forgotten, that the serpent on the staff may in fact represent the guinea worm (Dracunculus medinensis), commonly called the fiery serpent. The serpent and staff are symbolic of the removal of the worm by winding it around a staff and slowly withdrawing it from the unfortunate victim's tissues.