تسجيل الدخول

تسجيل

Vertebrates Snakes

المؤلف:  Sue Jickells , Adam Negrusz (Editors)

المصدر:  Clarkes Analytical Forensic Toxicology

الجزء والصفحة:  p128-129

2026-10-01

20

Vertebrates

Snakes

Three main families of poisonous snakes exist the Elapidae (cobras), the Viperidae (vipers) and the Crotalidae (pit vipers). The elapids comprise about half the world’s species of venomous snakes and include the cobras and the mambas. Genera of the elapid family are found in Asia, the Pacific, the Americas and Africa. The true vipers, Viperidae, of which the common viper is the best known, inhabit Europe, Asia and Africa. The pit vipers, Crotalidae, are mainly found in North, Central and South America and include the rattlesnake genera Crotalus and Sistrurus. An estimated 30 000 lethal cases of snakebite occur annually in Asia and 1000 in Africa and South America (WHO 1995). The symptoms of snakebites in humans vary greatly depending on the species, but in general consist of local pain, oedema, blistering and necrosis. Systemic effects of neurotoxic species include blurred vision, ptosis and respiratory paralysis. Haemostatic toxins, such as the haem orrhagins, cause spontaneous bleeding in the gingival sulci, nose, skin and gastrointestinal tract. Fatalities result from cerebral haemorrhage or massive retroperitoneal bleeding. Renal lesions include glomerulopathy, vasculopathy, tubular necrosis and interstitial nephritis, and often accompany snakebites with haematotoxic and neurotoxic venoms. The only specific and effective treatment for systemic and severe local envenomation is the administration of antivenom, a hyperimmune immunoglobulin (Warrell and Fenner 1993; Moroz 1998). For administration of the proper antivenom, the species that has bitten the patient must be known, and panacea antivenom is not and will not be available. Purification and characterisation of snake venoms is important not only for the elucidation of their mechanism of action but also for the preparation of these antivenoms. A future development in reducing snakebite fatalities may be active immunisation of populations at risk (Chippaux and Goyffon 1998).