Heloderma envenoming in the northern Midwest: the land of ice and snow!
Keyler, Daniel E.
SafetyCall International, LLC
Bloomington, Minnesota USA
Department of Experimental & Clinical Pharmacology
University of Minnesota
Minneapolis, Minnesota USA
Division of Clinical Pharmacology & Toxicology, Department of Medicine
Hennepin County Medical Center (retired)
Minneapolis, Minnesota USA
The Gila monster (Heloderma suspectum) is a colorful venomous tank-like lizard! It has been surprising to have provided toxicology consultation for four Gila "bites" far from their native geographic range, during the winter months of Minnesota when temps are below 0ºF, and outside your office window the wind is howling and snow flying! Consequently, the bite scenarios have been most intriguing. Victim bite circumstances have ranged from a high school biology teacher bare-handling a Gila in a classroom to an exotic dancer using a Gila as part of her act; both resulted in painful bite trauma and venom-induced toxicity. Although fatalities have been reported, their legitimacy is highly questionable. Bitten victims should be treated as medical emergencies. Heloderma deliver muscular bites that leave deep puncture wounds, and teeth may break off and dislodge into tissue when extricating the lizard. Despite puncture wound bruising, tissue necrosis is unlikely. Venom elicits intense pain that can radiate throughout the bitten extremity and progress to lymphadenopathy / lymphadenitis. Edema generally develops more slowly, and gradually become quite marked and tense, augmenting venom-induced pain. Systemic manifestations include generalized weakness, faintness/dizziness, diaphoresis, and nausea and vomiting. Profound hypotension and tachycardia, nonspecific electrocardiographic changes, ventricular arrhythmias, and myocardial infarction are potential severe medical complications. Diminished renal function may result from prolonged hypotension. Exaggerated swellings of the lips and tongue (angioedema) have been observed, and apparent anaphylaxis reactions from Heloderma envenomation have occurred in patients without a prior bite history. Parallel symptoms have been observed following beaded lizard (Heloderma horridum) envenomation. Thus, lip and tongue swelling may be direct venom-induced effects. Swift removal of the lizard is a necessary first aid measure since increased time of bite attachment increases severity of envenomation and trauma. Antivenom is not available and medical treatment is supportive and symptomatic. Heloderma bites in Minnesota have been an unexpected medical occurrence.