Snake bites in today’s world: three challenging questions after a century of antivenom
How big a problem is snake bite?
Attempts to quantitate the global burden of human suffering attributable to snake bites have failed through lack of reliable, representative data. Well designed epidemiological studies have succeeded in proving the importance of snake bites in several selected geographical foci and revealed why official epidemiological returns have been misleading.
However, these figures cannot be extrapolated to create national incidences. Perhaps results of research such as India’s “Million Death Study, 2001-2003”, employing Representative, Re-sampled, Routine Household Interview of Mortality with Medical Evaluation (“RHIME”) may at last silence the doubters who claim that the importance of snake bite has been exaggerated.
Is there any effective first-aid treatment?
First-aid is to delay life-threatening effects of envenoming, notably respiratory muscle paralysis and shock, until the patient has reached medical care. Efficacy is difficult to prove, but most traditional methods have been rejected because they are too dangerous. Pressure-immobilisation, initially promising in animal studies, has been criticised for its impracticability in developing countries.
How can antivenom treatment be optimised and delivered to all who need it?
Antivenoms are at last accepted as essential drugs. They can convincingly reverse anti-haemostatic and cardiovascular effects of envenoming, but their role against neurotoxicity and renal and local tissue damage is less certain. Antivenom’s limitations must be recognised. Patients must not be allowed to die for lack of ancillary treatment for respiratory, circulatory and renal failure.
Antivenom’s efficacy is determined by its quality (specificity, potency, safety), the timing of the initial dose after appearance of envenoming, its dosage, route of administration, pharmacokinetics and pharmaco¬dynamics. Antivenoms are the least investigated of all therapeutic agents, their production and use shrouded in un-substantiated concepts, such as the need for enzyme digestion, their efficacy and safety rarely subjected to clinical trials.
Fundamental to modern snake bite management is appropriate distribution of sufficient, appropriately-designed antivenom, correctly stored to prolong its activity for use by properly trained staff. A WHO initiative aims to help existing manufacturers to improve the quality and quantity of their products.
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