Viperine envenomation

Introduction

With more than 80% of cases of envenomation by ophidians, vipers represent worldwide a real public health problem, especially in developing countries where medical care is often non-existent, absent (out of reach) or self- made.

Composition & symptoms

Their bites cause inflammatory, hemorrhagic and local necrosis disorders that can spread to the extremity of the bitten limb. In some cases, neurotoxic symptoms are also observed. Their venoms are composed of enzymes that transform substrates (a generic term for the target object of an enzyme) into a new component.
Apart from the symptomatic rapidity, the toxicity is only slightly influenced by the quantity injected, however, the toxic action can be visible during several days with late repercussions that can have a non-negligible effect on the vitality or the functional aspect of the bitten member (CHIPPAUX, JP, & Goyffon, M. (2006)).

Venoms have elements favoring their diffusion in the body, this is particularly the case of phospholipase. However, with Phospholipase A2, the mode of action differs according to their concentrations: weakly concentrated, the facilitating effect is reinforced. At high concentrations, they will inhibit membrane function, nervous infflux (presynaptic neurotoxic effect), or even cytolysis (blood platelet destruction) (Goyffon, M., & Chippaux, J. P. (1990)).

The components of the venom are not all toxic; for example, phospholipases are responsible for hydrolysis of free and membrane phospholipids. It is also possible, during bites, to have molecules exogenous to the venoms, typically by introducing saliva, for example serotonin, during the penetration of the hooks and sometimes favoring benign infections (Chippaux, JP (2016) , personal exchange).

The venom of vipers has the particularity of acting on blood clotting. Haemorragins cause local vascular lesions associated with inhibition of haemostasis. This causes bleeding at the place of the bite.

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