The Caduces is a symbolic staff surmounted by two wings and entwined with two snakes. Today, variations of it adorns cheques, office stationary, and uniforms of medical personnel around the world.

Amongst the ancient Greeks it was carried by heralds and ambassadors as a badge of office and a mark of personal inviolability. How those snakes got there is the story of a remarkable helminthic worm and a treatment for it devised by the Mesopotamians still used today.

First, the snake isn't a snake. It is the guinea worm and when it infects humans, the disease is called Draconculiasis. It is common in Egypt, the Near East, India and in the southern part of Russia. It is unsurpassed by any parasite for its remarkable behavior.


Despite a 12-year campaign to eradicate it, there are still 150,000 known cases as of 1998. Today guinea worm has been reduced to 16 African countries, in addition to India and Yemen. At least a third of the cases are known in southern Sudan. The life cycle of the organism is like something from a Stephen King novel.

The infection begins with drinking water contaminated with tiny aquatic crustaceans called cyclops which carry the larvae of the guinea worm. Male and female exit the cyclops when digestive juices kill the cyclops. They burrow through the wall of the intestine and make their way into the abdominal cavity where they rendezvous and the female is impregnated. The male dies shortly after mating. The female matures in about a year.

The female grows to a meter in length and embarks on a subdermal voyage. The task of the female is to discharge its larvae into water. In barefooted natives, the worm works its way under the skin to the tissues of the foot. It then engages in an exquisite bit of host manipulation: it secretes a substance that causes an itch. The person scratches, opening the skin allowing the discharge of the larvae from the head of the Guinea worm. Water cools the itch, so the instinctive thing to do is to pour water on the wound. The free-swimming larvae are thus off to infect a cyclops crustatean and complete the life cycle, ready to infect anew.

In Europeans with shoes, the worms go to the hands. The worms have been known to seek the back of persons who routinely carry moist canvas or animal skin waterbags on their backs.

If the worm dies or if the larvae are liberated into the host's body as the result of a botched removal, there may be severe inflammation and abcess formation. The Mesopotamians devised a technique for removal that is still in use today. The worm must be removed slowly in order to get it out intact. The solution is to roll up the worm daily on a stick. A carefully rolled worm was a symbol of technical know-how, something that in time became a symbol of the physician's practical skill.

Medical scholars suspect that the worms were the 'fiery serpents' that afflicted the Children of Israel in the migration from Egypt. Moses demonstrated the winding of the 'serpent' and made a model in brass of the procedure.

..... CJ '98


Boyd, W. A Text-Book of Pathology, 5th ed. Philadelphia: Lea and Febiger, 1950.

Dellios, H. "Guinea worm still challenges Africa's health experts" Chicago Tribune April 2, 1998.

Ewald, P. Evolution of Infectious Disease. New York: Oxford University Press, 1994.