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Spider Bite, Black Widow

Spider Bite, Black Widow is a topic covered in the 5-Minute Emergency Consult.

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  • Syndromes caused by envenomation by black widow spider bite
  • Mechanism of toxicity:
    • Females are responsible for human envenomations
    • Venom contains potent neurotoxin, α-latrotoxin:
      • Causes cation-channel opening presynaptically, resulting in increased neurotransmitter release into synapses and neuromuscular junctions
      • Increased neurotransmitter release causes increased neurologic, motor, and autonomic effects
  • Morbidity and mortality are dose dependent
  • Severity of envenomation depends on:
    • Premorbid health of victim:
      • HTN or cardiovascular disease increase risk
    • Size and age of victim:
      • Children (i.e., smaller size for a given dose of venom) are at greater risk of morbidity and mortality.
    • Number of bites
    • Location of bite wounds
    • Size and condition of spider
  • Rarely fatal


Black widow spider features:
  • Appearance:
    • Glossy black with red markings shaped like an hourglass or a pair of spots on the ventral aspect of the globular abdomen
    • Females have 25–50 mm leg spans and 15 mm long bodies
  • Found throughout North America, except the far north and Alaska
  • Prefer dark sheltered hideaways such as garages, barns, outhouses, woodpiles, and low-lying foliage
  • Most bites occur during the warmer months when spiders are defending their webs and egg clutches

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Rosen, Peter, et al., editors. "Spider Bite, Black Widow." 5-Minute Emergency Consult, 5th ed., Lippincott Williams & Wilkins, 2016. Emergency Central, emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307568/1.3/Spider_Bite_Black_Widow.
Spider Bite, Black Widow. In: Rosen P, Shayne P, Barkin AZ, et al, eds. 5-Minute Emergency Consult. 5th ed. Lippincott Williams & Wilkins; 2016. https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307568/1.3/Spider_Bite_Black_Widow. Accessed June 18, 2019.
Spider Bite, Black Widow. (2016). In Rosen, P., Shayne, P., Barkin, A. Z., Wolfe, R. E., Hayden, S. R., Barkin, R. M., & Schaider, J. J. (Eds.), 5-Minute Emergency Consult. Available from https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307568/1.3/Spider_Bite_Black_Widow
Spider Bite, Black Widow [Internet]. In: Rosen P, Shayne P, Barkin AZ, Wolfe RE, Hayden SR, Barkin RM, Schaider JJ, editors. 5-Minute Emergency Consult. Lippincott Williams & Wilkins; 2016. [cited 2019 June 18]. Available from: https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307568/1.3/Spider_Bite_Black_Widow.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Spider Bite, Black Widow ID - 307568 ED - Rosen,Peter, ED - Shayne,Philip, ED - Barkin,Adam Z, ED - Wolfe,Richard E, ED - Hayden,Stephen R, ED - Barkin,Roger M, ED - Schaider,Jeffrey J, BT - 5-Minute Emergency Consult UR - https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307568/1.3/Spider_Bite_Black_Widow PB - Lippincott Williams & Wilkins ET - 5 DB - Emergency Central DP - Unbound Medicine ER -