Use of antivenoms for the treatment of envenomation by Elapidae snakes in Guinea, Sub-Saharan Africa

Abstract

BackgroundIn Guinea Elapids are responsible for 20% of envenomations. The associated case fatality rate (CFR) ranged 15-27%, irrespective of treatment.ResultsWe studied 77 neurotoxic envenomations divided in 3 groups: a set of patients that received only traditional or symptomatic treatments, and two other groups that received either 2 or 4 initial vials of Antivipmyn® Africa renewed as necessary. CFR was 27.3%, 15.4% and 17.6%, respectively. Although antivenom treatment was likely to reduce CFR, it didn’t seem to have an obvious clinical benefit for the patients, suggesting a low treatment efficacy. Mean delay to treatment or clinical stages were not significantly different between the patients who recovered and the patients who died, or between groups. Interpretation of these results is complicated by the lack of systematic studies under comparable conditions. Of particular importance is the absence of assisted ventilation, available to patients in all the other clinical studies of neurotoxic envenomation.ConclusionThe apparent lack of clinical benefit may have several causes. The hypothesis of a limited therapeutic window, i.e. an insufficient formation of antigen-antibody complexes once toxins are bound to their targets and/or distributed beyond the reach of antivenom, should be explored.

Retrospective study on the incidence of envenomation and accessibility to antivenom in Burkina Faso

“…For example, many patients preferred to consult a traditional healer as indicated by a previous study in the southwest of Burkina Faso in 2002 [ 7 ]. In addition, several patients bitten by Elapidae snakes die before reaching health centers due to a long delay between the bite and admission to hospitals [ 9 ].…”

Cost-Effectiveness of Antivenoms for Snakebite Envenoming in 16 Countries in West Africa

“…The likelihood of death from carpet viper and other snakebites among untreated victims was previously reported at 8.1–15.83% and 5–27.3% respectively [ 9 , 10 , 38 , 39 , 40 , 41 , 42 ] although these were varied in sensitivity analyses. When data on antivenom effectiveness was available for a given country, it was applied for that country.…”

“…Results from the meta-analysis suggested that an effective antivenom has a 75% (95% confidence interval: 55–86%) effectiveness in averting mortality from carpet viper bites [ 22 ]. Since the meta-analysis included studies wherein polyspecific antivenoms were used, these estimates of effectiveness were applied against non-carpet viper deaths except in Benin and Guinea-Conakry, where country-level effectiveness data exists for Antivipmyn antivenom against non-carpet viper (elapid) deaths, reported at 43.6% (0–80.5%) ( Table 1 ) [ 42 ]. However, in a scenario analysis antivenoms were assumed to be ineffective (0%) against non-carpet viper envenoming.…”

Immunological cross-reactivity and neutralization of the principal toxins of Naja sumatrana and related cobra venoms by a Thai polyvalent antivenom (Neuro Polyvalent Snake Antivenom)

“…Some authors suggested that it is due to the failure of antibodies to bind to the receptor-bound toxins which subsequently prevents the formation of toxin-antibody complex (Balde et al, 2013). Other suggested that it could be due to pharmacokinetic constraints -neurotoxins are present abundantly in extravascular compartment where their target receptors are located, whereas antibodies are likely to circulate in vascular compartment as their distribution to the extravascular compartment is restrained by their large molecular size (Gutierrez et al, 2003).…”