Hobo spider envenomation
Hobo spiders have been called "aggressive house spiders" because they can move fast and have been noted to run toward individuals when disturbed. However, this is now believed to be a misinterpretation of their behavior. When disturbed, hobo spiders often remain still. If they run away, given their poor eyesight, they sometimes run toward an individual. Hobo spiders, however, will bite in defense when caught against the skin but usually will not bite without clear provocation. The toxicity of the venom depends on the spider's age and sex. Young adults and male hobo spiders have the most toxic venom.
Hobo spider envenomation is thought to cause local skin necrosis similar to brown recluse spider (Loxosceles reclusa) envenomation. However, in the medical literature, there is only one verified hobo spider bite that resulted in a necrotic lesion in a woman with a pre-existing medical condition known to cause ulcerations. The remainder of the literature implicating the hobo spider is based on anecdotes, a rabbit model, and circumstantial evidence (ie, hobo spiders found in the home of a person with a necrotic lesion). In Europe, hobo spider bites are considered medically insignificant, and research shows that the venom of European and American hobo spiders is identical. No study has identified a necrotoxic component in the venom.
T63.391A – Toxic effect of venom of other spider, accidental, initial encounter
217665000 – Poisoning due to venomous spider
Differential Diagnosis & Pitfalls
- Abscess or furuncle caused by Staphylococcus (MRSA skin infection) or Streptococcus
- Herpes zoster (shingles)
- Herpes simplex
- Pyoderma gangrenosum
- Medication-induced drug reactions (Stevens-Johnson syndrome, toxic epidermal necrolysis)
- Other arthropod bites and stings (fleas, bedbugs)