Fang Factors

Few commonly encountered creatures evoke greater fear than snakes.  However, of the 45,000 bites inflicted annually in the United States only 7,000-8,000 are from venomous snakes, accounting for 9-15 deaths.  Most often these bites involve members of the cotalidae, or pit viper family, which include rattle snakes, copper heads and water moccasins.  Much rarer are the bites from the elapid family of snakes including the Eastern coral snake.

Although I do not recommend leaning in for a close look, some features can help identify a venomous snake.  Pit vipers have triangular shaped heads, elongated or elliptical pupils and most consistently, a pit midway between the eye and nostril.  This is a heat-sensing organ used to locate prey.  Color and skin patterns are often misleading in the identification of pit vipers.  Coral snakes are recognizable by their colorful bands with red and yellow bands lying adjacent to one another.

The venom of both families is carried within glands and delivered through hollowed fangs.  To some degree the amount of venom can be controlled by the snake, though the coral snake generally has to hold on and chew its victim in order to envonomate.  Up to 25% of pit viper bites do not result in envenomation, so-called “dry bites.”

Pit viper venom contains multiple toxins, which primarily injure cells, blood vessels and the body’s ability to form clots and control bleeding.  Coral snake venom acts primarily as a nerve toxin.

Early signs of pit viper envenomation occur locally and include burning pain, swelling and discoloration of the injured area.  This may progress to weakness, nausea, fever, sweating, muscle contractions and ultimately shock.  Coral snake poisoning may involve little or no pain locally, but can result in numbness and local or widespread muscle weakness and paralysis.  These symptoms can take hours to develop.

First aid for snake bites begins with getting away from the snake and avoiding multiple bites.  Identification of the snake is only important if it can be done safely.  To reduce spread of the venom remain calm and immobilize the injured extremity, preferably at or below the level of the heart.  Next seek medical attention immediately. 

Tourniquets are no longer recommended, though for coral snake bites a thick pressure dressing over the bite may reduce venom spread as long as it is not tight enough to cut off circulation.  Commercial suctioning devices are available and are useful if applied within fifteen minutes of the bite.

Do not apply tourniquets that cut off the patient’s circulation or immerse the extremity in ice water.  These methods are dangerous and worsen tissue damage.

If these steps are followed and medical care is reached promptly, a variety of treatments ranging from infection prevention, pain control and anti-venin administration are available depending on the severity of the envenomation.  Overall the chances of a full recovery in an otherwise healthy patient are excellent.

--Andres J. Exposito, M.D.

Dr. Exposito is Board Certified in Emergency Medicine.  He graduated from the University of Massachusetts Medical Center and completed his Emergency Medicine residency at the University of North Carolina at Chapel Hill.  He currently is employed with Medac Health Services, P.A., and can be reached at (910) 791-0075.