Latrodectism

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Latrodectism is envenomation by bites of Latrodectus spp.. The venom causes extreme pain and potentially systemic effects, such as hypertension, seizure, or coma, leading rarely to death. The spider is common in most of the world, may be spread by man, and actually due to how common it is, probably causes the most deaths from spider bites. Typically the spider sub species are black and may have a stripe (white/red) on the abdomen.

Includes bites from:

  • Latrodectus tredecimguttatus (Mediterranean black widow spider, Steppe spider, Latrodectus lugubris, l'araignée malmignatte, qaraqurt - Mediterranean through to Asian steppes)
  • Latrodectus hesperus (Black widow spider, Western black widow- North America)
  • Latrodectus mactans (Southern black widow - Southern North America)
  • Latrodectus variolus (Northern black widow - Northeastern North America)
  • Latrodectus hasselti (Redback spider - Australia)
  • Latrodectus katipo (Katipo spider - New Zealand)

The primary toxins are latrotoxins with mammals being most sensitive to alpha-latrotoxin which is a 130 kDa neurotoxin that results in neurotransmitter release (acetylcholine and indirectly hormones such as insulin with the consequential severe pain and diaphoresis. Latrotoxins cause the formation of ion-permeable membrane pores in vertebrate or invertebrate cells. However the various toxin amounts vary across species to such a degree that the bite of the European widow spider can be painless but result in predominant systemic and cardiac toxicity. The characteristic pain and diaporesis have distributions that are also species specific. There are other components to the venom including short peptides, adenosine, guanosine, inosine and 2,4,6-trihydroxypurine. It has transpired that the genome of some varieties of the Wolbachia bacteriophage WO has incorporated the uninterrupted black widow latrotoxin C-terminal domain and this may allow the virus to enter the arthropod cells that contain the intracellular Wolbachia that it needs to infect[1].

Antivenom for Australian redback spider and the American black widow works well[2] and appear to work across Latrodectus species[3]

References

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