Taxonomy and geographical distribution
Only a small percentage of the almost 3000 known species of snakes are venomous, and thus potentially dangerous to humans (1). Venomous snakes are classified into four families: Viperidae, Atractaspididae, Elapidae, and Colubridae.Viperidae (vipers, pit vipers) are distributed over The Americas, Europe, Africa, and Asia (2-4). There are more than 200 species of Viperidae. Among these are some of the most dangerous snakes to human beings, including the Russellรs viper (Daboia russelli), the carpet viper (Echis carinatus), the puff adder (Bitis arietans), the rattlesnakes (Crotalus sp. and Sistrurus sp.), and the lance-head pit vipers (Bothrops sp. and Bothropoides sp.).Atractaspididae (mole vipers, burrowing vipers) are mainly found in Africa and the Middle East (5). This family includes over 50 species. Most Atractaspididae are harmless; however, the venom of Atractapis engaddensis has potent cardiotoxins, called safarotoxins, that are potentially lethal to humans (6).Elapidae are widely distributed over tropical and subtropical regions of The Americas, Africa, Asia, and Australia (3, 7). In addition, some species inhabit the Pacific and Indian Oceans and are known as sea snakes (formerly classified as a different family called Hydrophiidae). Examples of