Spider Venom

spiders, atracine venoms are complex chemical cocktails, including a very large number of peptides and other molecules. For example, Palagi et al. used modern mass spectrometry methods to survey venoms of multiple atracine taxa and found a large number of peptides (800 peptides in female venoms, ~400 in male venoms), marked sexual differences, and clear species-level differences.

Despite this peptide diversity, primate-targeting δ-hexatoxins are a primary component of the atracine venom peptidome4, with some species possessing multiple δ-hexatoxin in-paralogs28. Even with minor differences at the protein level , bites of all atracines with these δ-hexatoxins cause a superficially similar envenomation syndrome in humans.Among known spider venom peptides, the δ-actinopoditoxin of male Missulena bradleyi is most similar to atracine δ-hexatoxins , and M. bradleyi venoms have a similarly selective mode of action on vertebrate sodium channels.

Furthermore, Missulena bites are sometimes of medical concern, and such bites are effectively treated using antivenoms developed for atracines. Our phylogenomic results indicate that all of these biological similarities reflect recent shared common ancestry of these spider lineages, rather than the alternatives of convergence or ancient phylogenetic conservation of venom composition.

Brown recluse spider bite? Consider this uniquely conservative treatment

What is the best way to treat the bite of a brown recluse spider? Having treated more than 185 bite wounds on 150 patients over the past 30 years, I have found that an oral antihistamine works best and makes surgery unnecessary.

I did not arrive at this treatment protocol immediately but, rather, developed it in 4 phases, which I describe in this article. Not only does this conservative approach consistently heal confirmed brown recluse bite wounds, but should a bite be mistakenly attributed to the brown recluse (or one of its relatives in the Loxosceles genus of spider), there is no harm to the patient, nor any big expense.

Is a brown recluse to blame?

Due to limited experience among the wider medical community in identifying spider envenomation, bite recognition and selection of appropriate therapy can be difficult.

Early findings can be confusing. Brown recluse bites typically feel like a pin prick. A vasoconstrictive halo may surround the bite, but this sign is inconsistent. Usually there is nothing to see immediately and pain from the bite goes away, so most patients dismiss the incident. Soon, however, pain from the envenomation begins and, importantly, becomes disproportionate to physical findings—the patient shows you where it hurts, but there is nothing visible to support a diagnosis or suggest a course of action.

Progression of the wound usually tells more than a captured specimen. If you are fortunate enough to examine an intact spider caught by the patient, a “fiddle” mark on the spider’s back confirms it is a brown recluse . However, most specimens brought in for examination are so misshapen from the patient’s retribution as to make identification futile. I focus instead on the resultant wound.

spider venom