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A snakebite is an injury caused by the bite of a snake. It often results in two puncture wounds from the animal's fangs.〔 Sometimes poisoning from the bite may occur.〔 This may result in redness, swelling, and severe pain at the area, which may take up to an hour to appear. Vomiting, trouble seeing, tingling of the limbs, and sweating may result.〔〔 Most bites are on the hands or arms. Fear following a bite is common with symptoms of a racing heart and feeling faint.〔 The venom may cause bleeding, kidney failure, a severe allergic reaction, tissue death around the bite, or breathing problems.〔〔(【引用サイトリンク】url=http://www.cdc.gov/niosh/topics/snakes/ )〕 Bites may result in the loss of a limb or other chronic problems.〔 The outcome depends on the type of snake, the area of the body bitten, the amount of venom injected, and the health conditions of the person. Problems are often worse in children than adults.〔 Snakes bite both as a method of hunting and as a means of protection.〔 Risk factors for bites include working outside with one's hand such as in farming, forestry, and construction.〔〔 Snakes commonly involved in poisonings include the elapids, vipers, and sea snakes.〔(【引用サイトリンク】title=Neglected tropical diseases Snakebite )〕 The majority of snake species do not have venom and kill their prey by squeezing them.〔 Venomous snakes can be found on every continent except Antarctica.〔 Determining the type of snake that caused a bite is often not possible.〔 The World Health Organisation lists snakebite as a neglected disease. Prevention of snake bites can involve wearing protective footwear, avoiding areas where snakes live, and not handling snakes. Treatment partly depends on the type of snake.〔 Washing the wound with soap and water and holding the limb still is recommended.〔〔 Trying to suck out the venom, cutting the wound with a knife, or using a tourniquet is not recommended.〔 Antivenom is effective at preventing death from bites; however, antivenoms frequently have side effects.〔〔 The type of antivenom needed depends on the type of snake involved. When the type of snake is unknown, antivenom is often given based on the types known to be in the area.〔 In some areas of the world getting the right type of antivenom is difficult and this partly contributes to why they sometimes do not work. An additional issue is the cost of these medications.〔 Antivenom has little effect on the area around the bite itself. Supporting the person's breathing is sometimes also required.〔 The number of snakebites that occur each year may be as high as five million. They result in about 2.5 million poisonings and 20,000 to 125,000 deaths.〔〔 The frequency of bites varies greatly among different parts of the world. They occur most commonly in Africa, Asia, and Latin America,〔 with rural areas more greatly affected.〔 About seven to eight thousand people per year in the United States are bitten by venomous snakes.〔 Deaths are relatively rare in Australia, Europe and North America.〔 == Signs and symptoms == The most common symptom of all snakebites is overwhelming fear, which contributes to other symptoms, including nausea and vomiting, diarrhea, vertigo, fainting, tachycardia, and cold, clammy skin.〔 Television, literature, and folklore are in part responsible for the hype surrounding snakebites, and people may have unwarranted thoughts of imminent death. Dry snakebites and those inflicted by a non-venomous species can still cause severe injury. There are several reasons for this: a snakebite may become infected, with the snake's saliva and fangs sometimes harboring pathogenic microbial organisms, including ''Clostridium tetani''. Infection is often reported with viper bites whose fangs are capable of deep puncture wounds. Bites may cause anaphylaxis in certain people. Most snakebites, whether by a venomous snake or not, will have some type of local effect. There is minor pain and redness in over 90 percent of cases, although this varies depending on the site.〔 Bites by vipers and some cobras may be extremely painful, with the local tissue sometimes becoming tender and severely swollen within five minutes.〔 This area may also bleed and blister and can eventually lead to tissue necrosis. Other common initial symptoms of pit viper and viper bites include lethargy, bleeding, weakness, nausea, and vomiting.〔〔 Symptoms may become more life-threatening over time, developing into hypotension, tachypnea, severe tachycardia, severe internal bleeding, altered sensorium, kidney failure, and respiratory failure.〔〔 Interestingly, bites caused by the Mojave rattlesnake, kraits, coral snake, and the speckled rattlesnake reportedly cause little or no pain despite being serious injuries.〔 Those bitten may also describe a "rubbery", "minty", or "metallic" taste if bitten by certain species of rattlesnake.〔 Spitting cobras and rinkhalses can spit venom in a person's eyes. This results in immediate pain, ophthalmoparesis, and sometimes blindness. Some Australian elapids and most viper envenomations will cause coagulopathy, sometimes so severe that a person may bleed spontaneously from the mouth, nose, and even old, seemingly healed wounds.〔 Internal organs may bleed, including the brain and intestines and will cause ecchymosis (bruising) of the skin. Venom emitted from elapids, including sea snakes, kraits, cobras, king cobra, mambas, and many Australian species, contain toxins which attack the nervous system, causing neurotoxicity.〔〔 The person may present with strange disturbances to their vision, including blurriness. Paresthesia throughout the body, as well as difficulty in speaking and breathing, may be reported.〔 Nervous system problems will cause a huge array of symptoms, and those provided here are not exhaustive. If not treated immediately they may die from respiratory failure. Venom emitted from some types of cobras, almost all vipers and some sea snakes causes necrosis of muscle tissue.〔 Muscle tissue will begin to die throughout the body, a condition known as rhabdomyolysis. Rhabdomyolysis can result in damage to the kidneys as a result of myoglobin accumulation in the renal tubules. This, coupled with hypotension, can lead to acute renal failure, and, if left untreated, eventually death.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「snakebite」の詳細全文を読む スポンサード リンク
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