September 5, 2020

Snake Bites

By ejschwartz

By: Ashley Jacobson, MD

Dr. Jacobson is a resident physician at Mayo Clinic in Rochester, MN.

As more and more people explore the outdoors with summer and quarantine, physicians must refresh snakebite presentations and treatment options. 2018 data from the American Association of Poison Control Centers documented a reported 7,110 snakebites (including nonvenomous bites) resulting in one death. While mortality is low, morbidity is high. The two families of  venomous snakes native to the United States (U.S.) are: Viperidae and Elapidae.

The Viperidae family includes the Crotalinae subfamily, or crotalids. Crotalids native to the U.S. includes rattlesnakes, cottonmouths, and copperheads. Venom from crotalids contains a hemotoxin, neurotoxin, cardiotoxin, and necrotizing factors, which can lead to severe complications, including hypotension, respiratory distress, tissue destruction, coagulopathy, paresthesias, and fasciculations. Treatment consists of CroFab or Anavip. Anavip is only approved for rattlesnake envenomation.

Coral snakes are the only member of the Elapidae family native to the U.S. and are associated with the famous saying, “Red on yellow, kill a fellow.” Please be aware that outside of the U.S. this may not be accurate. Coral snakes are typically not as aggressive and will only attack if threatened. Their venom results in neurotoxicity that may result in descending paralysis and respiratory failure. Unfortunately, the U.S. does not have any antivenom available for coral snake envenomation. The current recommendation is to contact your local Poison Center and zoo to determine other antivenom options. A Phase 3 FDA clinical trial for a new coral snake antivenom (sponsored by the University of Arizona) was completed in 2018 with final results still pending.

Overall, when giving antivenom, closely monitor for anaphylaxis since the serum is either sheep or horse-based. Workup in the Emergency Department should include complete blood count, comprehensive metabolic panel, coagulation studies, type and screen, urinalysis, and EKG. Patients should be admitted for monitoring with concern for delayed presentation of neurotoxic symptoms.

Full book chapter by Dr. Ashley Jacobson and Dr. Neha Raukar can be reviewed at Ferri’s Clinical Advisor 2021.

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