North American Pit Viper Envenomation

In the United States, 98% of venomous snakebites―also known as envenomation―are from the North American pit viper and have been reported in all states, with the exception of Hawaii1-3:

  • According to the Department of Wildlife Ecology & Conservation, approximately 8,000 venomous snakebites occur each year in the United States4
  • Between 2000 and 2007, the number of pit viper bites reported to poison control centers has increased 243%5
    • The reported increase may partially reflect an increased use of US poison control centers


Since the consequences of pit viper envenomation may be severe, it’s important to understand the impact of venom on the patient and follow an established treatment protocol.

Pit Viper Envenomation Overview

North American pit viper envenomations progress over time. Outcomes vary from patient to patient, depending on many variables, including timeliness of treatment.6

Envenomation can affect 3 critical—and potentially life- or limb-threatening—areas6:

  • Local
  • Systemic
  • Hematologic

Learn more about the effects of envenomation

Pit Viper Venom Effects

North American pit viper venom contains a complex mixture of toxins that often includes6-8*:

  • Procoagulants
  • Anticoagulants
  • Hemotoxins
  • Neurotoxins
  • Cytotoxins

Each toxin may have distinct actions on diverse body systems, and different toxins may work synergistically to increase toxicity.6-8

  • Effects can range from no apparent clinical effects or local effects at the bite site to life-threatening effects that can affect every major organ in the body
  • Effects may begin within minutes or be delayed for hours, with the more severe effects not becoming evident for many hours
  • Locally active toxins may show clinical effects almost immediately
  • Systemically active toxins must first reach the bloodstream, where they will rapidly exert their effect
  • Toxins with extravascular targets, such as neurotoxins and myotoxins, generally have a more delayed onset
  • Rapidity of effect can also be influenced by any latency period between time of binding to the target tissue and onset of detectable activity

After envenomation, a depot of venom often remains at the site of the bite, which may prolong the clinical effects of the venom.8

  • Following intramuscular injection of venom in animal models, absorption of venom has been shown to last for 72 hours8
 

*Venom toxins vary from species to species.

Learn about halting progression and treating the effects of envenomation.

References:

1. Gummin DD, Mowry JB, Spyker DA, Brooks DE, Fraser MO, Banner W. 2016 Annual Report of the American Association of Poison Control Centers National Poison Data System (NPDS): 34th Annual Report. Clin Toxicol. 2017;55(10):1072-1252. 2. Gold BS, Barish RA, Dart RC. North American snake envenomation: diagnosis, treatment, and management. Emerg Med Clin N Am. 2004;22(2):423-443. 3. Seifert SA, Boyer LV, Benson BE, Rogers JJ. AAPCC database characterization of native U.S. venomous snake exposures, 2001-2005. Clin Toxicol. 2009;47(4):327-335. 4. Frequently Asked Questions. Department of Wildlife Ecology and Conservation website. Ufwildlife.ifas.ufl.edu/venomous_snake_faqs.shtml. Accessed May 23, 2018. 5. Spiller HA, Bosse GM, Ryan ML. Use of antivenom for snakebites reported to United States poison centers. Am J Emerg Med. 2010;28(7):780-785. 6. Lavonas EJ, Ruha A-M, Banner W, et al. Unified treatment algorithm for the management of crotaline snakebite in the United States: results of an evidence-informed consensus workshop. BMC Emerg Med. 2011;11:2. 7. Rattlesnake Envenomation. EMed website. www.emed.ie/Trauma/Environmental/Snakebite.php. Accessed May 23, 2018. 8. Smith J, Bush S. Envenomations by reptiles in the United States. In: Mackessy SP, ed. Handbook of Venoms and Toxins of Reptiles. Boca Raton, FL: CRC Press; 2010:475-488.