What is the meaning of the medical symbol with a snake?

This is a good question. There are two symbols which are often used in the medical profession to refer to medicine. These are the Caduceus (the winged staff of Hermes entwined with two snakes) and the Rod of Asclepius (A rod with one snake coiled around it in the process of shedding its skin). The latter is by far the more appropriate symbol, and is far more ancient in usage than the Caduceus which has been erroniously used as a symbol for medicine for some time due to confusion between the two symbols in the middle ages.

There are several theories about the snake on the rod. Several of which are based in symbolism or mythology. However the most likely theory has to do with a parasitic nematode, the Guinea worm (Dracunculus medinensis). The method of removal of the guinea worm is long an painful, and involves coiling it around a twig or stick to pul it slowly from the flesh which it is embedded.