In the United States, the poisonous snakes naturally found include the rattlesnake, copperhead, water moccasin (cottonmouth) and the coral snake. All of these, except for the coral snake, are of the pit viper (Viperidae) family. The coral snake is of the Elapidae family. 99% of snake bites in the United States are caused by the pit viper family. Of people bitten by poisonous snakes, less than half are poisoned and few of those poisoned will die. The danger is when a bite occurs that allows the snake to inject a large dose of venom; the patient can get very sick and has a much higher risk of dying.
The most important thing to keep in mind in a snakebite situation is that of avoiding panic. Most snake bites require no management at all. The toxin from the pit vipers- rattlesnake, copperhead,and water moccasin are hemotoxic (attacks tissue and blood). The toxin from the coral snake is neurotoxic (damaging or destroying nerve tissue). Most snake bites (96%) are to extremities. Painful fang marks with swelling are seen with pit viper bites and coral snake bites are often painless tiny puncture wounds with minimal swelling.
Pit vipers are characterized by triangular shaped head, nostril pits (which are heat sensing organs), elliptical pupils, and subcaudal scales arranged in a single row. Coral snakes have heads that are only slightly larger than neck, round pupils, and subcaudal scales arranged in double rows. Coral snakes may be confused with another brightly colored snake – the king snake. Remember: “red on yellow will kill a fellow, red on black venom lack.” Also, “if red touches yellow then like a stop light -STOP” it is poisonous.
The venom effects from the pit vipers are hemotoxic, and symptoms are pain and swelling at bite site, bleeding disorders (like bleeding from the bite site and gums and bruising), and local tissue destruction. Copperhead venom is the least potent of the pit vipers. The coral snake toxin is neurotoxic, and symptoms involve worsening weakness – Ptosis (drooping eyelids), inability to cough or protrude tongue, eventually paralysis and respiratory arrest due to weakness of muscles of respiration. Coral snake toxin paralysis may occur up to 24 hours after the bite, therefore the patient should be watched for this time.
Treatment of snake bites includes:
- preventing the bitten region from being dependent and probably keeping it mildly elevated.
- It should also be immobilized.
- Remove jewelry from affected extremity, as swelling of the extremity may allow jewelry to become dangerously tight.
- Activity such as walking should be restricted.
- The bitten site may be gently wiped.
- A suctioning device (without cutting the skin) may be applied to the bite site with some benefit but only if it is used within several minutes of the bite and left in place for 30 minutes.
- Do not apply tourniquet, ice packs, cut the puncture wounds, use mouth suctioning or apply electric shock/current.
- At a hospital setting antivenin may be given depending upon the degree of envenomation.
- IV fluids, blood products and respiratory support (ventilator use) may be given in a hospital setting as needed.
- Cutting away dead tissue may be needed.