An ancient Greek symbol used internationally today for the practice and profession of medicine, the Asklepian (or Aesculapian) shows what is typically believed to be a single serpent coiled around a staff. There is a theory among parasitologists, however, that it is really a worm and not a snake featured in the symbol. Some medical historians believe that the plague of "fiery serpents" that afflicted the Hebrews as they fled from Egypt in the Book of Numbers really refers to guinea worm infection. The ancient Greeks would have been familiar with the method for extracting the parasitic worm: winding it slowly on a stick to ease it out intact. The staff of Asclepius, which shows a single snake (or worm), is used around the world, while the caduceus, the wand of the Greek god Hermes, entwined by two snakes and topped with wings, is often used in the United States.
—Taryn L. Salinas