There is a painfully apt misunderstanding between the rod of Asclepius and a similar symbol.
Greek mythology featured a separate and entirely distinct symbolic rod wrapped with snakes, the caduceus—which has two snakes and is winged. The caduceus was carried by Hermes/Mercury, the god of merchants, thieves, messengers, and tricksters. Hermes used the rod to beguile mortals or to touch the eyes of the dead and lead them to the underworld.
In the United States the two rods have become confused because of a military mix-up in the early twentieth century (when a stubborn medical officer refused to listen to his subordinates and ordered the caduceus to be adopted as the symbol of the U.S. Medical Corps). Since then the caduceus has been extensively used by healthcare organizations in the United States and has come to replace the staff of Asclepius in the majority of uses. Commercial and for-profit medical organizations are particularly inclined to use the caduceus instead of the rod of Asclepius as the former is more visually arresting (although academic and professional medical organizations tend to use the staff of Asclepius).