<P> By extension of its association with Mercury and Hermes, the caduceus is also a recognized symbol of commerce and negotiation, two realms in which balanced exchange and reciprocity are recognized as ideals . This association is ancient, and consistent from the Classical period to modern times . The caduceus is also used as a symbol representing printing, again by extension of the attributes of Mercury (in this case associated with writing and eloquence). </P> <P> The caduceus is often incorrectly used as a symbol of healthcare organizations and medical practice, particularly in North America, due to confusion with the traditional medical symbol, the Rod of Asclepius, which has only one snake and is never depicted with wings . </P> <P> It is thought that this symbol's long lasting association with the medical profession stems from early use of twigs to draw out long bodied inter muscular parasitic worms by wrapping them slowly around the twig so as not to break them or allow them to escape back into the body, a successful treatment still in use today, see Dracunculiasis . </P> <P> The term kerukeion denoted any herald's staff, not necessarily associated with Hermes in particular . </P>

Why is there a snake in medical symbol