Crotalidae polyvalent immune Fab (ovine) antivenom is efficacious for envenomations by Southern Pacific rattlesnakes (Crotalus helleri).
OBJECTIVE
Southern Pacific rattlesnake (Crotalus helleri ) venom is not 1 of the 4 venoms used to produce Crotalidae polyvalent immune Fab (ovine) (CroFab; FabAV). There is currently no published clinical experience regarding the efficacy of this new antivenom for confirmed C helleri envenomation, and animal data suggest greatly diminished efficacy. We assessed the efficacy of FabAV for patients with confirmed C helleri envenomation.


METHODS
We conducted a prospective observational study of 23 consecutive rattlesnake envenomations that were treated with FabAV at our center. Patients were excluded if the species of snake could not be confirmed, if FabAV antivenom was not given, or if Antivenin (Crotalidae) polyvalent (equine) was given. We collected serial physical examination and laboratory data over a 24-hour period to serially evaluate the severity score and performed follow-up to evaluate delayed reactions.


RESULTS
There were 15 patients who received FabAV and had the species of rattlesnake confirmed (9 C helleri, 4 C scutulatus scutulatus, 1 C mitchellii pyrrhus, 1 C ruber ruber ). C helleri envenomations demonstrated similar improvement in serial snakebite severity scores to those of other species. Three patients treated with scheduled dosing had recurrence of progressive swelling (2 C helleri and 1 C mitchellii pyrrhus ) during the 24-hour study period.


CONCLUSIONS
We observed similar improvement in FabAV-treated patients with C helleri envenomation compared with those of other species and conclude that this treatment in standard doses appears efficacious for bites by this species. Progressive swelling may recur despite scheduled dosing.
Bush
Sean P
SP
Department of Emergency Medicine, Loma Linda University School of Medicine, Medical Center and Children's Hospital, Loma Linda, CA, USA. famensean@aol.com
Green
Steven M
SM
Moynihan
James A
JA
Hayes
William K
WK
Cardwell
Michael D
MD
D000818:Animals; D000997:Antivenins; D003435:Crotalid Venoms / Q000037:antagonists & inhibitors*; D017839:Crotalus; D006801:Humans; D007140:Immunoglobulin Fab Fragments; D007128:Immunoglobulin Fragments / Q000009:adverse effects / Q000627:therapeutic use*; D011446:Prospective Studies; D012720:Severity of Illness Index; D012909:Snake Bites / Q000145:classification / Q000628:therapy*; D016896:Treatment Outcome
D000997:Antivenins; D003435:Crotalid Venoms; C431183:Crotalidae Polyvalent immune Fab; D007140:Immunoglobulin Fab Fragments; D007128:Immunoglobulin Fragments