Venomous animals

Bites by venomous snakes cause more than 85,000 deaths and 150,000 permanent sequelae each year, while scorpion stings kill thousands of children. These are neglected environmental diseases of the rural tropics. Most species of medically-important venomous snakes are elapids (e.g. cobras), vipers, adders or pit vipers and rattlesnakes. Clinical effects of their bites include local swelling, blistering and necrosis, shock, haemostatic disturbances, descending flaccid paralysis, rhabdomyolysis, intravascular haemolysis and acute renal failure. Any of these may prove life-threatening. Scorpion stings cause intense pain and phaeochromocytoma-like cardiovascular effects which are particularly lethal in children. Spiders bites are necrotic or neurotoxic. Hypersensitization to bee, wasp and ant venoms is a common cause of anaphylaxis but mass attacks by African killer bees can kill by direct envenoming. Aquatic venomous animals include sea snakes, stinging fish, jellyfish, corals, cone shells, blue-ringed octopuses and sea urchins. Australian box jellyfish stings are particularly deadly. The intense pain of marine stings responds to immersion of the stung part in hot, but not scalding, water. Treatment of severe envenoming by all these groups of animals requires specific antivenom, supportive treatment for cardiorespiratory and renal failure and surgical management of wounds. Animal bites and stings can be prevented by learning about local venomous fauna, wearing protective clothing, using a light after dark, and sleeping off the ground and under a bed net.