Snakebite

Snakebite
A cobra bite on the foot of a girl in Thailand
Specialty	Emergency medicine
Symptoms	Two puncture wounds, redness, swelling, severe pain at the area[1][2]
Complications	Bleeding, kidney failure, severe allergic reaction, tissue death around the bite, breathing problems, amputation, envenomation[1][3]
Causes	Snakes[1]
Risk factors	Working outside with one's hands (farming, forestry, construction);[1][3] harassment;[4][5] drunkenness[6]
Prevention	Protective footwear, avoiding areas where snakes live, not handling snakes[1]
Treatment	Washing the wound with soap and water, antivenom[1][7]
Prognosis	Depends on type of snake[8]
Frequency	Up to 5 million a year[3]
Deaths	94,000–125,000 per year[3]

A snakebite is an injury caused by the bite of a snake, especially a venomous snake.^[9] A common sign of a bite from a venomous snake is the presence of two puncture wounds from the animal's fangs.^[1] Sometimes venom injection from the bite may occur.^[3] This may result in redness, swelling, and severe pain at the area, which may take up to an hour to appear.^[1][2] Vomiting, blurred vision, tingling of the limbs, and sweating may result.^[1][2] Most bites are on the hands, arms, or legs.^[2][10] Fear following a bite is common with symptoms of a racing heart and feeling faint.^[2] The venom may cause bleeding, kidney failure, a severe allergic reaction, tissue death around the bite, or breathing problems.^[1][3] Bites may result in the loss of a limb or other chronic problems or even death.^[11][3]

The outcome depends on the type of snake, the area of the body bitten, the amount of snake venom injected, the general health of the person bitten and whether or not anti-venom serum has been administered by a doctor in a timely manner.^[11][8] Problems are often more severe in children than adults, due to their smaller size.^[3][12][13] Allergic reactions to snake venom can further complicate outcomes and can include anaphylaxis, requiring additional treatment and in some cases resulting in death.^[11]

Snakes bite both as a method of hunting, and as a means of protection.^[14] Risk factors for bites include working outside with one's hands such as in farming, forestry, and construction.^[1][3] Snakes commonly involved in envenomations include elapids (such as kraits, cobras and mambas), vipers, and sea snakes.^[7] The majority of snake species do not have venom and kill their prey by constriction (squeezing them).^[2] Venomous snakes can be found on every continent except Antarctica.^[14] Determining the type of snake that caused a bite is often not possible.^[7] The World Health Organization says snakebites are a "neglected public health issue in many tropical and subtropical countries",^[13] and in 2017, the WHO categorized snakebite envenomation as a Neglected Tropical Disease (Category A). The WHO also estimates that between 4.5 and 5.4 million people are bitten each year, and of those figures 40–50% develop some kind of clinical illness as a result.^[15] Furthermore, the death toll of such an injury could range between 80,000 and 130,000 people per year.^[16][15] The purpose was to encourage research, expand accessibility of antivenoms, and improve snakebite management in "developing countries".^[17]

Prevention of snake bites can involve wearing protective footwear, avoiding areas where snakes live, and not handling snakes.^[1] Treatment partly depends on the type of snake.^[1] Washing the wound with soap and water and holding the limb still is recommended.^[1][7] Trying to suck out the venom, cutting the wound with a knife, or using a tourniquet is not recommended.^[1] Antivenom is effective at preventing death from bites; however, antivenoms frequently have side effects.^[3][18] The type of antivenom needed depends on the type of snake involved.^[7] When the type of snake is unknown, antivenom is often given based on the types known to be in the area.^[7] 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.^[3] An additional issue is the cost of these medications.^[3] Antivenom has little effect on the area around the bite itself.^[7] Supporting the person's breathing is sometimes also required.^[7]

The number of venomous snakebites that occur each year may be as high as five million.^[3] They result in about 2.5 million envenomations and 20,000 to 125,000 deaths.^[3][14] The frequency and severity of bites vary greatly among different parts of the world.^[14] They occur most commonly in Africa, Asia, and Latin America,^[3] with rural areas more greatly affected.^[3][13] Deaths are relatively rare in Australia, Europe and North America.^[14][18][19] For example, in the United States, about seven to eight thousand people per year are bitten by venomous snakes (about one in 40 thousand people) and about five people die (about one death per 65 million people).^[1]