Spider bites
Types
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Differential Diagnosis
Envenomations, bites and stings
- Hymenoptera stings (bees, wasps, ants)
- Mammalian bites
- Closed fist infection (Fight bite)
- Dog bite
- Marine toxins and envenomations
- Toxins (ciguatera, neurotoxic shellfish poisoning, paralytic shellfish poisoning, scombroid, tetrodotoxin
- Stingers (stingray injury)
- Venomous fish (catfish, zebrafish, scorpion fish, stonefish, cone shells, lionfish, sea urchins)
- Nematocysts (coral reef, fire coral, box jellyfish, sea wasp, portuguese man-of-war, sea anemones)
- Phylum porifera (sponges)
- Bites (alligator/crocodile, octopus, shark)
- Scorpion envenomation
- Reptile envenomation
- Spider bites
History
- Determine circumstances of bite to assess consistency with spider habitat and behavior
- Indoors vs outdoors
- Day vs night
- Geographic location (recent travel)
- Appearance of the spider if seen
- Dead spiders can be preserved in 70% EtOH and later identified by arachnologists or entomologist
Clinically important spider genera by geographic region
- North America
- Loxosceles
- Latrodectus
- Tegenaria
- South America
- Loxosceles
- Latrodectus
- Phoneutria
- Africa
- Loxosceles
- Latrodectus
- Europe
- Loxosceles
- Latrodectus
- Australia
- Atrax
- Hadronyche
- Latrodectus
- Asia
- Latrodectus
Physical Exam
- No pathognomonic signs proving lesion is a spider bite
- Assess both bite site and for systemic signs
- Bite Site
- Location
- Spider bites more common when clothing is tight against skin
- Number of bites
- Multiple bites suggest parasitic insect and not spider
- Appearance of bite
- Erythema, pallor, hemorrhage, induration, tenderness, paresthesia, vesicles
- Location
- Systemic findings
- Abnormal vital signs
- Altered mental status
- Abdominal pain
- Diaphoresis
- Generalized rash
- Muscle fasciculations, spasm, or tenderness
Treatment
- Clean area of bite
- Tetanus prophylaxis
- Analgesics
- Hydration
- Surgical follow up if indicated for debridement of necrotic area
- Antivenom is indicated only for specific envenomation
- No proven benefit for corticosteroids
- No indication for antibiotics unless concern for cellulitis
See Also
References
- Boyer LV, Binford GJ, Degan JA. Spider Bites. In Auerbach PS, Cushing TA, Harris NS. Auerbach’s Wilderness Medicine. 7th ed. Philadelphia, PA: Elsevier; 2017: 993-1016.