Geographic variation in the clinical features of Mohave rattlesnake (Crotalus scutulatus) envenomations reported to the North American Snakebite Registry

The geographic variation of Mohave rattlesnake (Crotalus scutulatus) venom is well established. We reviewed all the Mohave rattlesnake bites reported to the Toxicology Investigators Consortium's North American Snakebite Registry between January 1, 2015 and 12/31/2021. Data reviewed for this study included details regarding the snake encounter, patient demographics, signs and symptoms, treatment, and outcomes. Our objective was to describe the epidemiology, clinical manifestations, and management of Mohave rattlesnake envenomations using prospective data from two geographically distinct sites. There were 20 subjects, including eight nonpregnant females. Ages ranged from seven to 75 years, median age 48. Nine of the bites were managed in Arizona and 11 in California. In Arizona, all envenomated patients had local swelling. None had neurological toxicity. In California, swelling was present in nine patients. Neurological effects were observed in five subjects. Four Arizona patients and one California patient had hypotension requiring treatment. Each site had one patient with thrombocytopenia. An Arizona patient who sustained a bite to the face was intubated. Rhabdomyolysis occurred in two California patients. All envenomated patients received antivenom. Mohave rattlesnakes have the potential to cause significant local and/or systemic toxicity. Neurotoxicity was not observed in envenomations from Mohave rattlesnakes that presumably lack Mohave toxin, but hypotension and gastrointestinal signs were more common than in bites from snakes believed to possess Mohave toxin. Neurological toxicity was limited to paresthesias and fasciculations. Significant skeletal or respiratory muscle weakness was not observed in our study population.