Epidemiology

• Only 2 of the almost 3000 lizard species in the world are venomous
  • Gila Monster (Heloderma suspectum): present in southwestern US and Mexico
  • Mexican Beaded Lizard (Heloderma horridum): present in Mexico
• These lizards are not aggressive and most bites are related to human-initiated interaction with the lizard

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Etiology

• Gila Monster (Heloderma suspectum)

• Mexican Beaded Lizard (Heloderma horridum)

  

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Physiology

• Mechanism of Envenomation
  • Venom is elaborated from 8 glands in the floor of the lizard’s mouth and bathes the oral cavity
  • Teeth are grooved posteriorly
  • Lizard bites tenaciously and is often difficult to dislodge: may require removal of head, submersion in water, application of fire to dislodge
• Venom Components
  • VIP-Like Biopeptides
  • Kallikrein-like substances
  • Neurotoxin: causes neuropathy

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Clinical Manifestations

• Local Wound
  • Excruciating pain with massive tissue edema, and erythrema
    • Intense hyperesthesia of the wound may persist for weeks
• Systemic Symptoms
  • Blurred Vision
  • Dizziness
  • Dysphonia
  • Dyspnea/Acute Hypoventilation (see Acute Hypoventilation) -> Respiratory Failure
  • Hematemesis
  • Nausea/Vomiting (see Nausea and Vomiting)
  • Tachycardia (see Sinus Tachycardia)
  • Weakness (see Acute Motor Deficit): may be profound

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Treatment

• Removal of Lizard: may require removal of head, submersion in water, application of fire to dislodge lizard
• No Antivenin Available
• Constriction Band
• Cooling of the Wound Area
• Antibiotics
  • Including coverage for Tetanus (Tetanus Toxoid or Immune Globulin)
• Analgesia: necessary
  • Local
  • Parenteral

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References

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