Elsevier

Toxicon

Volume 151, 1 September 2018, Pages 84-88
Toxicon

Case report
Arizona Ridge-nosed rattlesnake envenomation: Case report of a personal encounter with the official state reptile of Arizona, Crotalus willardi willardi

https://doi.org/10.1016/j.toxicon.2018.07.001Get rights and content

Highlights

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    Describes human envenomation by the Arizona Ridge-nosed Rattlesnake, Crotalus willardi willardi.

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    Although C. w. willardi is generally regarded as a rattlesnake species with relatively mild venom, this patient required treatment with antivenom.

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    The primary venom effects were local: progression of swelling, tenderness to palpitation, erythema and diminished range of motion.

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    The patient experienced complete recovery of the venom effects within three days.

Abstract

This case report describes the effects of an envenomation from one of the most infrequently encountered species of rattlesnake in the United States, Crotalus willardi willardi (C. w. willardi), the Arizona Ridge-nosed Rattlesnake. A previously healthy 57-year-old male sustained a bite to his non-dominant hand from a C. w. willardi. The most pronounced effect from the envenomation was edema and progression of edema that extended from his hand to the mid bicep. He also experienced erythema and tenderness to palpation in the affected limb, and some diminished range of motion in the hand. He expressed only minimal pain. Other than a mildly positive D-Dimer and leukocytosis, he had no significant hematologic effects and no systemic effects. He was treated with standard doses of Crotalidae Polyvalent Immune Fab (Ovine). He reported complete recovery from the envenomation within three days of the bite.

Although envenomation from rattlesnakes is somewhat common in Arizona, knowing the exact species of snake is not. Confirmed documentation is exceedingly rare as most people do not recognize the different rattlesnake species. In addition, some species of rattlesnake (such as C. w. willardi) are especially reclusive and found only in isolated mountainous regions. Being able to confirm an envenomation by C. w. willardi would require not only someone knowledgeable in herpetology, but also, preferably, photographic evidence. This case has both.

Section snippets

Background

From 2013 to 2016 approximately 4000 pit viper envenomations were reported annually to the American Association of Poison Control Centers (AAPCC) (Mowry et al., 2014, 2015, 2016; Gummin et al., 2017). It is estimated that the true number of pit viper envenomations in the United States each year is closer to 7000 to 8000, as reporting exposures to the AAPCC is voluntary (Centers for Disease Control and Prevention, ). In Arizona, the indigenous pit vipers are all rattlesnakes, genera Crotalus and

Case presentation

A 57-year-old male with no underlying health issues presented to a community hospital approximately one hour after sustaining a rattlesnake bite to his nondominant, left hand while hiking in the hills west of the Huachuca Mountains in southeastern Arizona. With a background in biology, he had a special interest in reptiles and amphibians. Upon finding an Arizona Ridge-nosed Rattlesnake, he began photographing it (Fig. 1). When he went to move a piece of grass that was obstructing the photo

Discussion

Various factors have been proposed as contributing to the severity of a rattlesnake bite. For example, the amount of venom injected may be dependent on size of the snake, how recently the snake has fed, the snake's perceived threat level and interference of clothing (Hayes, 2008; Hayes and Mackessy, 2010; Herbert, 1998). Venom composition can vary by snake species and geographic location of the snake (some species show venom variation based on geographic range even within the same species) (

Conclusion

Reports of human envenomation by Crotalus w. willardi are scarce. And, envenomation by this snake has commonly been regarded as presenting only a relatively mild threat for humans. In this case report, the patient experienced predominantly local venom effects. He met one of the three criteria for antivenom administration based on the degree of his progression of swelling. This was accompanied by other local effects: erythema, mild pain and some decrease in range of motion. It is notable that he

Acknowledgement

Philip C. Rosen, Research Scientist, School of Natural Resources & Environment, University of Arizona, for providing identification of the rattlesnake and editorial assistance.

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