Symbol of Asclepius

The Rod of Asclepius, symbol of medicine, is a single snake entwined around a stick. Originally, the symbol may have depicted the treatment of dracunculiasis (very common in the Ancient World) in which the long parasitic worm was traditionally extracted through the patient's skin by wrapping it around a stick over a period of days or weeks (because a faster procedure might break the worm).

Any symbol involving a snake would seem natural for medicine: The snake is a symbol of renewed life out of old shed skin, the perpetual renewal of life evoked by the ouroboros symbol (a snake feeding on its own tail). A snake around a walking stick is also an ancient symbol of supernatural powers which can triumph over death, like medicine can (biblically, the symbol of Moses' divine mission was his ability to change his walking stick into a snake).

In ancient times infection by parasitic worms was common. The filarial worm Dracunculus medinensis aka "the fiery serpent", aka "the dragon of Medina" aka "the guinea worm" crawled around the victim's body, just under the skin. Physicians treated this infection by cutting a slit in the patient's skin, just in front of the worm's path. As the worm crawled out the cut, the physician carefully wound the pest…