Emergency: requires immediate attention
Widow spider envenomation in Adult
Alerts and Notices
Synopsis
Widow spider venoms are all very similar and contain a neurotoxic component called alpha-latrotoxin. This toxin inserts itself into calcium channels in the presynaptic neuron creating a Ca2+ pore leading to neurotransmitter release. The specific synaptic cleft involved dictates the neurotransmitter released; however, all neurotransmitters can be affected. Massive release of acetylcholine and catecholamines into the central nervous system are theorized to produce the specific clinical symptoms of envenomation. The result is initial stimulation of neuromuscular transmissions followed by depletion of synaptic vesicles. Local tissue changes are minimal as the venom lacks locally active toxins capable of producing inflammation.
A bite from a widow spider is typically severe, painful, and often described as "burning." If not immediate, symptoms can be expected within 60 minutes of the bite. Tiny fang marks with a local inflammatory reaction may be evident, and so most envenomated patients are aware they were bitten by some type of spider or insect. Local toxicity is classically manifested through a triad of diaphoresis, local pain, and piloerection with a concomitant target lesion. Most of the time symptoms do not progress beyond this local reaction. However, with significant envenomation, a wide range of systemic symptoms can be observed.
Systemic symptoms include myalgias, fever, hypertension and tachycardia, vomiting, tremor, and paresthesia. Muscle spasms can be seen in the chest, legs, and back, and patients classically exhibit abdominal rigidity. Less commonly, altered mental status, myocarditis, elevated troponin levels, leukocytosis, and rhabdomyolysis can be a sequalae of alpha-latrotoxin toxicity.
Symptoms usually resolve over a 3- to 7-day period, and deaths are exceedingly rare.
Codes
ICD10CM:T63.314A – Toxic effect of venom of black widow spider, undetermined, initial encounter
SNOMEDCT:
217666004 – Latrodectism
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Differential Diagnosis & Pitfalls
- Scorpion sting
- Cellulitis
- Centipede envenomation
- Contact dermatitis
- Ecthyma
- Hymenoptera stings (bee sting, wasp sting)
- Influenza or other viral infectious process
- Hypertension-related emergencies
- Skin infections or abscess
- Tetanus
- Tularemia
- Ergotism
- Acute coronary syndrome
- Abdominal aneurysm
- Acute appendicitis
- Mesenteric ischemia
- Ectopic pregnancy
- Pancreatitis
- Pneumoperitoneum or perforated hollow viscus
- Allergic reaction
- Anxiety
- Hypocalcemia
- Muscle spasms
- Primary priapism
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Last Reviewed:08/07/2022
Last Updated:01/05/2023
Last Updated:01/05/2023
Emergency: requires immediate attention
Widow spider envenomation in Adult