Monday, February 21, 2011

African Viper Envenomation Needs to be Treated with Antivenom - Despite Delay Time to Treatment

Recently this blog reported on a forthcoming article by  P. Chippaux that suggests snake bite mortality in sub-Sahara Africa is much lower than previously thought - about 7000 deaths per annum. Now, a new study by Sebastien Larreche and colleagues examined 12-years of viper bite data from the Republic of Djibouti, and compared the impact of an early administration of antivenin versus a delayed administration on restoring the victims’ normal blood chemistry. The study looked at 73 cases (from 1994-2006), where patients presented with symptoms of viper bites in the intensive care unit of the French military Hospital, in Djibouti. Snakes involved in the bites were Echis pyramidum and Bitis arietans, and patients treated prior to 2001 received Echis-Bitis-Naja serum (Pasteur-Mérieux, Lyon, France), those treated after 2001 received FAV-Africa (Aventis-Pasteur), which is useful against Echis, Bitis, Naja, and Dendroaspis venoms. The research team examined antivenin efficiency in correcting blood chemistry to the time of treatment - before or after the 24th hour after the bite. Forty-two patients (58%) presented with bleeding - blood in their urine, coughing blood, or bleeding gums. Larreche and colleagues found antivenin was effective in improving hemostasis, and the time to normalization of blood chemistry was similar, whether the treatment was started before or after the 24th hour after the bite. They authors report that antivenin should ideally be administered as early as possible. In Africa, time to treatment often exceeds 24 hours because of the distances and transportation available. However, the results suggest that antivenom should be used despite the delay in getting treatment, and that the fact that time has elapsed between the envenomation and treatment should in no way prevent the use of antivenin immunotherapy for treatment of  African viper bites.
Larréché, S., G. Mion,  A. Mayet, C. Verret, M. Puidupin, A. Benois, F. Petitjeans, N. Libert, and M. Goyffon. 2011. Antivenin remains effective against African Viperidae bites despite a delayed treatment. The American Journal of Emergency Medicine, 29(2):155-161.

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