Efficacy of North American crotalid antivenom against the African viper Bitis gabonica (Gaboon viper)

Abstract

Envenomations by exotic snakes occur from zoological collections and private individual collectors. Antivenoms to these snakes may not be readily available. The objective of this study is to determine the efficacy of North American crotalid antivenin in treating mice envenomated with venom of the African viper Bitis gabonica (Gaboon viper). The subjects of the study were Swiss Webster mice weighing approximately 30 g. The study was conducted in the University research laboratory. B. gabonica venom was obtained from Venom Supplies Pty Ltd (Tanunda, South Australia) and reconstituted in sterile water. North American Crotalid Fab2 antivenin (Anavyp®, Instituto Bioclon, Mexico) was donated by the manufacturer. The experimental groups were: Group I received two times an intraperitoneal LD50 dose of venom, 2.58 mg/kg. Group II received the same dose after incubation for 1 h with 10 mg of antivenin. Time to onset of toxicity defined as respiratory rate <10/min or absence of response to prodding. t test and Chi square with p<0.05 considered significant. Time to onset of toxicity was 7.040±4.334 h in group I, and 20.665±2.074 in group II (p=0.0064, 95% confidence interval of difference of means -2212;22.694 to -2212;4.556). Antivenin was efficacious to statistical significance at 4, 8, 12, and 16 h (p values of 0.062, 0.0067, 0.0067, and 0.0253, respectively). Improvement at 20 and 24 h (p values of 0.0673 and 0.0673, respectively) did not achieve statistical significance. North American Crotalid antivenin (Anavyp®, Instituto Bioclon, Mexico) demonstrated efficacy in increasing time to onset of distress in mice poisoned with B. gabonica (Gaboon viper) venom. Based on this result, treatment of humans envenomated with B. gabonica with North American Croatlid antivenin could be considered for severe envenomations if specific B. gabonica antivenin is unavailable. © American College of Medical Toxicology 2010.