The passage in question is Numbers 21.4-9. The story goes that the Israelites complained one time too many on the exodus, and God sent fiery serpents to besiege them. When the Israelite's were bitten they got sick and died. When the people repented, they went to Moses and begged him to get God to remove the snakes. Moses prayed, but God did not remove the snakes, choosing instead to effect healing to those who were bitten. We read, "And the LORD said to Moses, 'Make a fiery serpent, and set it on a pole; and everyone who is bitten shall look at it and live.' So Moses made a serpent of bronze, and put it upon a pole; and whenever a serpent bit someone, that person would look at the serpent of bronze and live" (Numbers 21:8-9).
The most common explanation of the event is that it was through the Israelite's faith in God that they lived after being bitten. God promised healing to those who looked upon the bronze icon (even though there was a clear biblical mandate against making such images in Deuteronomy 5.8).
However, I came across this explanation recently from a Dr. Victor Vorhees, M.D. He suggests that the fiery serpents weren't reptiles, but guinea worms (dracunculus medinensis), and the bronze image not a mystical object d'art, but a medical treatment plan.
Guinea worms are parasitical and enter the body through contaminated water. They release their larvae in the intestinal tract and the larvae pass into subcutaneous tissues (just under the skin) where they mature in about a year. At maturity, the female guinea worm is between 1/32 and 1/16 of an inch in diameter, and up to three feet long. The male worm is much smaller and is seldom discovered (and apparently not problematic). The female burrows her reproductive organs towards the surface of the skin and causes an ulcer or abscess. When that portion of the skin gets wet, the worm protrudes her organs and releases thousands of embryos.
The ancient method for removing the guinea worm was to wet the ulcer and when the worm protrudes through the skin it was caught and very slowlya few turns per daywound on a stick until it was removed. If, however, the worm was broken in the attempt to remove itoften because the patient tried to remove to worm too quicklysever poisoning occurred and additional larvae were released into the body. On the other hand, there were no serious aftereffects if the worm was removed successfully.
The bronze serpent on a stick, therefore, was made to teach and remind the infected Israelites to wind the worm around a stick slowly and patiently. If they did so, they would live. But if they did not, they would die. Thus the icon was not an image to be worshiped (according to 2nd Kings 18.4 it was later treated as an idol), nor a mystical object d'art, but a medical treatment plan outlining a cure for the infestation.
Whether the fiery serpents of Numbers 21 were actual snakes or guinea worms or . . . this fact remains: those who whine, carp, and complain incessantly do not win favor with God, and perhaps should consider the consequences of their words.