PASSIVE HEMAGGLUTINATION INHIBITION TEST FOR DIAGNOSIS OF BROWN RECLUSE SPIDER BITE ENVENOMATION

Our goal was to recreate a passive hemagglutination inhibition (PHAI) test to diagnose brown recluse spider (BRS; Loxosceles reclusa) bite e nvenomation for treatment trials. Guinea pigs received intradermal inj ections of concentrated spider venom from the following species: Loxos celes reclusa, Argiope aurantia, Argiope trifasciata, Phidippus audax, and Lycosa frondicola. Skin lesion exudate was collected and tested w ith the BRS venom PHAI assay. From 51 separate collections of exudate, test sensitivity was 90% as long as 3 days after venom injection. Spe cificity was 100% with venom from the other spider species listed abov e in vivo (7 test samples) and in vitro (5 test samples), as well as w ith random bacterial exudate with and without added serial dilutions o f BRS venom (1 0 test samples). The test was reproducible over repetit ive assays to within one 10-fold dilution. A positive PHAI test result could function as an entry criterion for BRS bite victims in human tr eatment trials.