View source for Snakebite

{{short description|Injury caused by bite from snakes}}
{{other uses}}
{{cs1 config|name-list-style=vanc}}
{{Use dmy dates|date=January 2014}}
{{Infobox medical condition (new)
| name          = Snakebite
| image         = Cobra bite in Thailand (image, 2023).jpg
| caption       = A [[cobra]] bite on the foot of a girl in [[Thailand]]
| field         = [[Emergency medicine]]
| symptoms      = Two [[puncture wound]]s, [[redness]], [[Edema|swelling]], severe pain at the area<ref name=CDC2012/><ref name=Gold2002/>
| complications = [[hemorrhage|Bleeding]], [[kidney failure]], [[anaphylaxis|severe allergic reaction]], [[necrosis|tissue death]] around the bite, breathing problems, [[amputation]], [[envenomation]]<ref name=CDC2012/><ref name=WHO2015/>
| onset         =
| duration      =
| types         =
| causes        = [[Snakes]]<ref name=CDC2012/>
| risks         = Working outside with one's hands ([[farming]], [[forestry]], construction);<ref name=CDC2012/><ref name=WHO2015/> harassment;<ref>{{cite web|url=http://www.fs.usda.gov/r05/eldorado|title=Eldorado - Outdoor Safety & Ethics}}</ref><ref>{{cite web | url=https://wildlife.utah.gov/news/utah-wildlife-news/1202-rattlesnake-encounter-what-to-do.html | title=What to do if you encounter a rattlesnake}}</ref> [[drunkenness]]<ref>{{cite web | url=https://reptilesmagazine.com/alcohol-and-snake-bites/ |title=Alcohol and Snake Bites – Reptiles Magazine | date=December 2011}}</ref>
| diagnosis     =
| differential  =
| prevention    = [[Protective footwear]], avoiding areas where snakes live, not handling snakes<ref name=CDC2012/>
| treatment     = Washing the wound with soap and water, [[antivenom]]<ref name=CDC2012/><ref name=WHONeg/>
| medication    =
| prognosis     = Depends on type of snake<ref name=Marx2010/>
| frequency     = Up to 5 million a year<ref name=WHO2015/>
| deaths        = 94,000–125,000 per year<ref name=WHO2015/>
}}
<!-- Definition and symptoms -->

A '''snakebite''' is an injury caused by the bite of a snake, especially a [[venomous snake]].<ref>{{cite web |title=Definition of Snakebite |url=https://www.merriam-webster.com/dictionary/snakebite |website=www.merriam-webster.com |access-date=17 June 2019 |language=en}}</ref> A common sign of a bite from a venomous snake is the presence of two [[puncture wound]]s from the animal's [[fang]]s.<ref name=CDC2012/> Sometimes [[envenomation|venom injection from the bite]] may occur.<ref name=WHO2015>{{cite web |title=Animal bites: Fact sheet N°373 |url=https://www.who.int/mediacentre/factsheets/fs373/en/ |publisher=[[World Health Organization]] |access-date=19 May 2015 |date=February 2015 |url-status=live |archive-url=https://web.archive.org/web/20150504100257/http://www.who.int/mediacentre/factsheets/fs373/en/ |archive-date=4 May 2015}}</ref> This may result in redness, swelling, and severe pain at the area, which may take up to an hour to appear.<ref name=CDC2012/><ref name=Gold2002/> [[Vomiting]], blurred vision, tingling of the limbs, and sweating may result.<ref name=CDC2012/><ref name=Gold2002/> Most bites are on the hands, arms, or legs.<ref name=Gold2002>{{cite journal | vauthors = Gold BS, Dart RC, Barish RA | title = Bites of venomous snakes | journal = The New England Journal of Medicine | volume = 347 | issue = 5 | pages = 347–356 | date = August 2002 | pmid = 12151473 | doi = 10.1056/NEJMra013477}}</ref><ref>{{cite journal | vauthors = Daley BJ, Torres J | title = Venomous snakebites | journal = Journal of Emergency Medical Services| volume = 39 | issue = 6 | pages = 58–62 | date = June 2014 | pmid = 25109149}}</ref> [[Fear]] following a bite is common with symptoms of a [[Tachycardia|racing heart]] and [[Dizziness|feeling faint]].<ref name=Gold2002/> The [[venom]] may cause [[hemorrhage|bleeding]], [[kidney failure]], a [[anaphylaxis|severe allergic reaction]], [[necrosis|tissue death]] around the bite, or breathing problems.<ref name=CDC2012>{{cite web|title=Venomous Snakes|url=https://www.cdc.gov/niosh/topics/snakes/|publisher=[[U.S. National Institute for Occupational Safety and Health]]|access-date=19 May 2015|date=24 February 2012|url-status=live|archive-url= https://web.archive.org/web/20150429051901/http://www.cdc.gov/niosh/topics/snakes/|archive-date=29 April 2015}}</ref><ref name=WHO2015/> Bites may result in the [[amputation|loss of a limb]] or other [[Chronic condition|chronic problems]] or even death.<ref name="Healthline Media UK Ltd">{{cite web |last1=Eske |first1=Jamie |last2=Biggers |first2=Alana |title=How to identify and treat snake bites |url=https://www.medicalnewstoday.com/articles/324007 |website=Medical News Today |publisher=Healthline Media UK Ltd |access-date=4 May 2022 |language=English |date=14 December 2018}}</ref><ref name=WHO2015/>

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.<ref name="Healthline Media UK Ltd"/><ref name=Marx2010>{{cite book| vauthors = Marx JA |title=Rosen's emergency medicine: concepts and clinical practice |date=2010 |publisher=Mosby/Elsevier |location=Philadelphia |isbn=978-0-323-05472-0|page=746|edition=7|url=https://books.google.com/books?id=u7TNcpCeqx8C&pg=PA746|url-status=live|archive-url= https://web.archive.org/web/20150521114649/https://books.google.com/books?id=u7TNcpCeqx8C&pg=PA746|archive-date=21 May 2015}}</ref> Problems are often more severe in children than adults, due to their smaller size.<ref name=WHO2015/><ref>{{cite book| vauthors = Peden MM |title=World Report on Child Injury Prevention|date=2008|publisher=[[World Health Organization]]|isbn=978-92-4-156357-4|page=128|url=https://books.google.com/books?id=UeXwoNh8sbwC&pg=PA128|language=en|url-status=live|archive-url=https://web.archive.org/web/20170202050637/https://books.google.com/books?id=UeXwoNh8sbwC&pg=PA128|archive-date=2 February 2017}}</ref><ref name=WHOantivenoms/> Allergic reactions to snake venom can further complicate outcomes and can include [[anaphylaxis]], requiring additional treatment and in some cases resulting in death.<ref name="Healthline Media UK Ltd"/>

<!-- Cause -->
Snakes bite both as a method of hunting and as a means of protection.<ref name=Kast2008/> [[Risk factor]]s for bites include working outside with one's hands such as in [[farming]], [[forestry]], and construction.<ref name="CDC2012" /><ref name="WHO2015" /> Snakes commonly involved in envenomations include [[elapid]]s (such as [[krait]]s, [[cobra]]s and [[mamba]]s), [[viper]]s, and [[sea snake]]s.<ref name=WHONeg>{{cite web|publisher=[[World Health Organization]] |title=Neglected tropical diseases: Snakebite|url=https://www.who.int/neglected_diseases/diseases/snakebites/en/|access-date=19 May 2015|archive-url=https://web.archive.org/web/20150930063057/http://www.who.int/neglected_diseases/diseases/snakebites/en/|archive-date=30 September 2015}}</ref> The majority of snake species do not have venom and kill their prey by [[constriction]] (squeezing them).<ref name=Gold2002/> Venomous snakes can be found on every continent except [[Antarctica]].<ref name=Kast2008/> Determining the type of snake that caused a bite is often not possible.<ref name=WHONeg/> The [[World Health Organization]] says snakebites are a "neglected [[public health issue]] in many tropical and subtropical countries",<ref name=WHOantivenoms>{{cite web |publisher=[[World Health Organization]] |title=Snake antivenoms: Fact sheet N°337 |url=https://www.who.int/mediacentre/factsheets/fs337/en/ |date=February 2015 |access-date=16 May 2017 |url-status=live |archive-url=https://web.archive.org/web/20170418105431/http://www.who.int/mediacentre/factsheets/fs337/en/ |archive-date=18 April 2017}}</ref> and in 2017, the WHO categorized snakebite envenomation as a [[Neglected tropical diseases|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.<ref name=Langley2020>{{cite journal |last1=Langley |first1=Ricky |last2=Haskell |first2=Marilyn Goss |last3=Hareza |first3=Dariusz |last4=King |first4=Katherine |title=Fatal and Nonfatal Snakebite Injuries Reported in the United States |journal=Southern Medical Journal |date=October 2020 |volume=113 |issue=10 |pages=514–519 |doi=10.14423/SMJ.0000000000001156|pmid=33005969 |s2cid=222070778}}</ref> Furthermore, the death toll from such an injury could range between 80,000 and 130,000 people per year.<ref>World Health Organization. Prevalence of snakebite envenoming. <nowiki>[https://web.archive.org/web/20170922113845/http://www.who.int/snakebites/epidemiology/en/ ]</nowiki>. Accessed April 15, 2019</ref><ref name=Langley2020/> The purpose was to encourage research, expand the accessibility of antivenoms, and improve snakebite management in "[[Developing country|developing countries]]".<ref>{{cite web|url=https://www.who.int/snakebites/resources/s40409-017-0127-6/en/|archive-url=https://web.archive.org/web/20170922115522/http://www.who.int/snakebites/resources/s40409-017-0127-6/en/|archive-date=22 September 2017|title=WHO &#124; Snakebite envenomation turns again into a neglected tropical disease!|website=WHO}}</ref>

<!-- Prevention and treatment -->
Prevention of snake bites can involve wearing protective footwear, avoiding areas where snakes live, and not handling snakes.<ref name=CDC2012/> Treatment partly depends on the type of snake.<ref name=CDC2012/> Washing the wound with soap and water and holding the limb still is recommended.<ref name=CDC2012/><ref name=WHONeg/> Trying to suck out the venom, cutting the wound with a knife, or using a [[tourniquet]] is not recommended.<ref name=CDC2012/> [[Antivenom]] is effective at preventing death from bites; however, antivenoms frequently have [[side effect]]s.<ref name=WHO2015/><ref name=Gutierrez2007/> The type of antivenom needed depends on the type of snake involved.<ref name=WHONeg/> When the type of snake is unknown, antivenom is often given based on the types known to be in the area.<ref name=WHONeg/> 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.<ref name=WHO2015/> An additional issue is the cost of these medications.<ref name=WHO2015/> Antivenom has little effect on the area around the bite itself.<ref name=WHONeg/> [[Mechanical ventilation|Supporting the person's breathing]] is sometimes also required.<ref name=WHONeg/>

<!-- Epidemiology -->
The number of venomous snakebites that occur each year may be as high as five million.<ref name=WHO2015 /> They result in about 2.5 million envenomations and 20,000 to 125,000 deaths.<ref name=WHO2015/><ref name=Kast2008/> The frequency and severity of bites vary greatly among different parts of the world.<ref name=Kast2008>{{cite journal | vauthors = Kasturiratne A, Wickremasinghe AR, de Silva N, Gunawardena NK, Pathmeswaran A, Premaratna R, Savioli L, Lalloo DG, de Silva HJ | display-authors = 6 | title = The global burden of snakebite: a literature analysis and modelling based on regional estimates of envenoming and deaths | journal = PLOS Medicine | volume = 5 | issue = 11 | pages = e218 | date = November 2008 | pmid = 18986210 | pmc = 2577696 | doi = 10.1371/journal.pmed.0050218 | doi-access = free}}</ref> They occur most commonly in [[Africa]], [[Asia]], and [[Latin America]],<ref name=WHO2015/> with rural areas more greatly affected.<ref name=WHO2015/><ref name=WHOantivenoms/> Deaths are relatively rare in [[Australia]], [[Europe]] and [[North America]].<ref name=Kast2008/><ref name=Gutierrez2007>{{cite journal | vauthors = Gutiérrez JM, Lomonte B, León G, Rucavado A, Chaves F, Angulo Y | title = Trends in snakebite envenomation therapy: scientific, technological and public health considerations | journal = Current Pharmaceutical Design | volume = 13 | issue = 28 | pages = 2935–2950 | year = 2007 | pmid = 17979738 | doi = 10.2174/138161207782023784| hdl = 10669/29338 | hdl-access = free }}</ref><ref name=Chippaux1998>{{cite journal | vauthors = Chippaux JP | title = Snake-bites: appraisal of the global situation | journal = Bulletin of the World Health Organization | volume = 76 | issue = 5 | pages = 515–524 | year = 1998 | pmid = 9868843 | pmc = 2305789}}</ref> 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).<ref name=CDC2012 />
{{TOC limit|3}}

== Signs and symptoms ==
[[File:Snake bite symptoms.png|thumb|upright=1.4|The most common symptoms of any kind of snake envenomation.<ref name=MedlinePlus/><ref>[http://www.health-care-clinic.org/diseases/snakebite.html Health-care-clinic.org – Snake Bite First Aid – Snakebite] {{webarchive|url=https://web.archive.org/web/20160116034305/http://www.health-care-clinic.org/diseases/snakebite.html |date=16 January 2016}} Retrieved on 21 mars, 2009</ref><ref>Snake bite image example at [http://www.mdconsult.com/das/patient/body/127551351-2/0/10041/8928_en.jpg MDconsult – Patient Education – Wounds, Cuts and Punctures, First Aid for] {{webarchive|url=https://web.archive.org/web/20160107214703/http://www.mdconsult.com/das/patient/body/127551351-2/0/10041/8928_en.jpg |date=7 January 2016}}</ref> However, there is vast variation in symptoms between bites from different types of snakes.<ref name="MedlinePlus">[https://www.nlm.nih.gov/MEDLINEPLUS/ency/article/000031.htm MedlinePlus – Snake bites] {{webarchive|url=https://web.archive.org/web/20101204102457/http://www.nlm.nih.gov/medlineplus/ency/article/000031.htm |date=4 December 2010}} From Tintinalli JE, Kelen GD, Stapcynski JS, eds. Emergency Medicine: A Comprehensive Study Guide. 6th ed. New York, NY: McGraw Hill; 2004. Update date: 27 February 2008. Updated by: Stephen C. Acosta, MD, Department of Emergency Medicine, Portland VA Medical Center, Portland, OR. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc. Retrieved on 19 mars, 2009</ref>]]

The most common first symptom of all snakebites is an overwhelming fear, which may contribute to other symptoms,  and may include [[nausea]] and [[vomiting]], [[diarrhea]], [[vertigo (medical)|vertigo]], [[fainting]], [[tachycardia]], and cold, clammy skin.<ref name="Gold2002" /><ref name="Kitchens1987">{{cite journal | vauthors = Kitchens CS, Van Mierop LH | title = Envenomation by the Eastern coral snake (Micrurus fulvius fulvius). A study of 39 victims | journal = JAMA | volume = 258 | issue = 12 | pages = 1615–1618 | date = September 1987 | pmid = 3625968 | doi = 10.1001/jama.258.12.1615}}</ref> Snake bites can have a variety of different signs and symptoms depending on their species.<ref name="Healthline Media UK Ltd" />

[[Dry bite|Dry snakebites]] and those inflicted by a non-venomous species may still cause severe injury. The bite may become infected from the snake's saliva. The fangs sometimes harbor pathogenic microbial organisms, including ''[[Clostridium tetani]]'', and may require an updated tetanus immunization.<ref>Otten E, Blomkalns A. Venomous animal injuries. In: Marx J, Hockberger R, Walls R, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. St Louis: Mosby; 2002</ref><ref name=Langley2020 />

Most snakebites, from either a venomous or a non-venomous snake, will have some type of local effect.<ref name="Online Khabar">{{cite web | vauthors = Lamsal S |title=Snakebites in Nepal are a medical emergency. Here are things you should know about them |url=https://english.onlinekhabar.com/snakebites-in-nepal-know-everything.html |date=3 June 2023 |website=[[Online Khabar]] |access-date=21 June 2023}}</ref> Minor pain and [[Erythema|redness]] occur in over 90 percent of cases, although this varies depending on the site.<ref name="Gold2002" /> Bites by [[Viper (animal)|vipers]] and some [[cobra]]s may be extremely painful, with the local tissue sometimes becoming tender and severely [[Edema|swollen]] within five minutes.<ref name=Gutierrez2007/> This area may also bleed and blister and may lead to tissue [[necrosis]]. Other common initial symptoms of [[pit viper]] and [[Viper (animal)|viper]] bites include lethargy, bleeding, weakness, nausea, and vomiting.<ref name="Gold2002" /><ref name=Gutierrez2007/> Symptoms may become more life-threatening over time, developing into [[hypotension]], [[tachypnea]], severe tachycardia, severe internal bleeding, altered [[sensorium]], [[kidney failure]], and [[respiratory failure]].<ref name="Gold2002" /><ref name=Gutierrez2007/>

Bites by some snakes, such as the [[kraits]], [[coral snake]], [[Mojave rattlesnake]], and the [[Crotalus mitchellii|speckled rattlesnake]], may cause little or no pain, despite their serious and potentially life-threatening venom.<ref name="Gold2002" /> Some people report experiencing a "rubbery", "minty", or "metallic" taste after being bitten by certain species of rattlesnake.<ref name="Gold2002" /> [[Spitting cobra]]s and [[rinkhals]]es can spit venom in a person's eyes. This results in immediate pain, [[ophthalmoparesis]], and sometimes [[blindness]].<ref name="Warrell1976">{{cite journal | vauthors = Warrell DA, Ormerod LD | title = Snake venom ophthalmia and blindness caused by the spitting cobra (Naja nigricollis) in Nigeria | journal = The American Journal of Tropical Medicine and Hygiene | volume = 25 | issue = 3 | pages = 525–529 | date = May 1976 | pmid = 1084700 | doi = 10.4269/ajtmh.1976.25.525}}</ref><ref name="Ismail1993">{{cite journal | vauthors = Ismail M, al-Bekairi AM, el-Bedaiwy AM, Abd-el Salam MA | title = The ocular effects of spitting cobras: I. The ringhals cobra (Hemachatus haemachatus) venom-induced corneal opacification syndrome | journal = Journal of Toxicology. Clinical Toxicology | volume = 31 | issue = 1 | pages = 31–41 | year = 1993 | pmid = 8433414 | doi = 10.3109/15563659309000372}}</ref>
[[File:Tissue necrosis following bite from Bothrops asper PLoS Medicine.jpg|thumb|left|upright|Severe [[tissue necrosis]] following ''[[Bothrops asper]]'' envenomation that required [[amputation]] above the knee. The person was an 11-year-old boy, bitten two weeks earlier in [[Ecuador]], but treated only with [[antibiotic]]s.<ref name="Gutierrez2006">{{cite journal | vauthors = Gutiérrez JM, Theakston RD, Warrell DA | title = Confronting the neglected problem of snake bite envenoming: the need for a global partnership | journal = PLOS Medicine | volume = 3 | issue = 6 | pages = e150 | date = June 2006 | pmid = 16729843 | pmc = 1472552 | doi = 10.1371/journal.pmed.0030150 | doi-access = free}}</ref>]]
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.<ref name="Gutierrez2007" /> Internal organs may bleed, including the brain and intestines,<ref name="Cunha2021">{{cite web | url = https://www.emedicinehealth.com/snakebite/symptom.htm | title = Symptoms and Signs of Snakebite (Snake Bite) | last = Cuhna | first = John P. | publisher = [[WebMD]] | date= August 6, 2021 | website = [[eMedicine]]Health | access-date = July 26, 2022}}</ref> and [[ecchymosis]] (bruising) of the skin is often seen.<ref name="SmallAnimalToxicology">{{cite journal | last1 = Peterson | first1 = Michael E. | last2 = Talcott | first2 = Patricia A. | year = 2013 | title = Snake Bite: North American Pit Vipers | url = https://www.sciencedirect.com/science/article/pii/B9781455707171000752 | journal = Small Animal Toxicology | edition = 3rd | pages = 783–797 | doi = 10.1016/B978-1-4557-0717-1.00075-2 | isbn = 978-1-4557-0717-1| url-access = subscription }}</ref>

The venom of elapids, including [[sea snakes]], [[Bungarus|kraits]], [[Naja|cobras]], [[Ophiophagus hannah|king cobra]], [[Dendroaspis|mambas]], and many Australian species, contains toxins which attack the nervous system, causing [[neurotoxicity]].<ref name="Gold2002" /><ref name=Gutierrez2007/><ref name="Phillips2002">{{cite journal | vauthors = Phillips CM |year=2002 |title=Sea snake envenomation |journal=Dermatologic Therapy |volume=15 |issue=1 |pages=58–61(4) |doi=10.1046/j.1529-8019.2002.01504.x |s2cid=73275266 |url=http://www.kingsnake.com/aho/pdf/menu6/phillips2002.pdf |access-date=24 July 2009 |url-status=live |archive-url=https://web.archive.org/web/20110428095839/http://www.kingsnake.com/aho/pdf/menu6/phillips2002.pdf |archive-date=28 April 2011}}</ref> 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.<ref name="Gold2002" /> 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]].<ref name="ManagementofRespiratoryFailure">{{cite journal |last1 = Sabirin |first1 = Mira R |last2 = Sudjud |first2 = Reza W |last3 = Suwarman |first3 = Suwarman |last4 = Pradian |first4 = Erwin |date = August 18, 2020 |title = Management of Respiratory Failure Following Snake Bite |journal = Journal of Health and Medical Sciences |volume = 3 |issue = 3 |pages = 338–349 |doi = 10.31014/aior.1994.03.03.129 |s2cid = 224885423 |url = https://ssrn.com/abstract=3676254 |issn = 2622-7258 |access-date=July 27, 2022 |url-status = live |archive-url = https://web.archive.org/web/20220727124831/https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3676254 |archive-date = July 27, 2022}}</ref>

Venom emitted from some types of cobras, almost all vipers, and some sea snakes cause [[necrosis]] of muscle tissue.<ref name="Gutierrez2007" /> 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 kidney injury]], and, if left untreated, eventually death.<ref name="Gutierrez2007" />

Snakebite is also known to cause depression and post-traumatic stress disorder in a high proportion of people who survive.<ref>{{cite journal | vauthors = Bhaumik S, Kallakuri S, Kaur A, Devarapalli S, Daniel M | title = Mental health conditions after snakebite: a scoping review | journal = BMJ Global Health | volume = 5 | issue = 11 | pages = e004131 | date = November 2020 | pmid = 33257419 | pmc = 7705584 | doi = 10.1136/bmjgh-2020-004131}}</ref>

== Cause ==
{{See also|List of dangerous snakes}}
In the developing world most snakebites occur in those who work outside such as farmers, hunters, and fishermen.<!-- <ref name=Brut2013/> --> They often happen when a person steps on the snake or approaches it too closely.<!-- <ref name=Brut2013/> --> In the United States and Europe snakebites most commonly occur in those who keep them as pets.<ref name=Brut2013>{{cite book | veditors = Garcia HH, Tanowitz HB, Del Brutto OH |title=Neuroparasitology and tropical neurology|date=2013|isbn=978-0-444-53499-6|page=351|url=https://books.google.com/books?id=bJx3g30aDhIC&pg=PA351|url-status=live|archive-url=https://web.archive.org/web/20170908174306/https://books.google.com/books?id=bJx3g30aDhIC&pg=PA351|archive-date=8 September 2017|last1=Garcia|first1=Hector H.|last2=Tanowitz|first2=Herbert|last3=Del Brutto|first3=Oscar H.|publisher=Newnes}}</ref>

The type of snake that most often delivers serious bites depends on the region of the world.<!-- <ref name=Brut2013/> --> In Africa, it is [[mamba]]s, [[Egyptian cobra]]s, [[Bitis arietans|puff adders]], and [[carpet viper]]s.<!-- <ref name=Brut2013/> --> In the Middle East, it is carpet vipers and [[elapid]]s.<!-- <ref name=Brut2013/> --> In [[Latin America]], it is snakes of the ''[[Bothrops]]'' and ''[[Crotalus]]'' types,<!-- <ref name=Brut2013/> --> the latter including [[rattlesnake]]s.<ref name=Brut2013/> In North America, rattlesnakes are the primary concern, and up to 95% of all snakebite-related deaths in the United States are attributed to the [[Crotalus atrox|western]] and [[Crotalus adamanteus|eastern diamondback]] rattlesnakes.<ref name="Gold2002"/><!-- Bothrops aren't in North America. Copperheads and water moccasins are less venomous (and mostly found only in Southeastern U.S.), and bites from coral snakes are rare. --> The greatest number of bites are inflicted on the hands.{{Citation needed|date=April 2024}} People get bitten by handling snakes or in the outdoors by putting their hands on the wrong places. The next largest number of bites occur on the ankles, as snakes are often hidden or camouflaged extremely well to fend off predators. Most bite victims are bitten by surprise, and it is a comfortable fiction that rattlesnakes always forewarn their bite victims - often the bite is the first indication a snake is near. Since most venomous snakes move about during the dawn dusk or night, one may expect more encounters during the early morning or late afternoon, though many species such as the Western Diamondback may be encountered at any time of day and in fact most bites occur during the month of April when both snakes and humans are out and about and encounter one another hiking, in yards, or on pathways.  Children playing within short distances of their homes crawl under porches, jump into bushes, pull boards of wood from a pile and are bitten. Most however occur when people handle rattlesnakes.<ref>{{cite book|last1=Campbell|first1=Sheldon|last2=Shaw|first2=Charles E.|title=Snakes of The American West|year=1974|publisher=[[Alfred A. Knopf]]|location=New York|isbn=978-0-394-48882-0}}</ref> In South Asia, it was previously believed that [[Indian cobra]]s, [[common krait]]s, [[Russell's viper]], and carpet vipers were the most dangerous;<!-- <ref name=Brut2013/> --> other snakes, however, may also cause significant problems in this area of the world.<ref name=Brut2013/>

== Pathophysiology ==
Since [[envenomation]] is completely voluntary, all venomous snakes are capable of biting without injecting venom into a person. Snakes may deliver such a "[[dry bite]]" rather than waste their venom on a creature too large for them to eat, a behaviour called [[venom metering]].<ref name="Young2002">{{cite journal | vauthors = Young BA, Lee CE, Daley KM |year=2002 |title=Do Snakes Meter Venom? |journal=BioScience |volume=52 |issue=12 |pages=1121–26 |doi=10.1641/0006-3568(2002)052[1121:DSMV]2.0.CO;2 |quote=The second major assumption that underlies venom metering is the snake's ability to accurately assess the target |doi-access=free}}</ref> However, the percentage of dry bites varies among species: 80 percent of bites inflicted by [[sea snakes]], which are normally timid, do not result in envenomation,<ref name="Phillips2002" /> whereas for [[pit viper]] bites the number is closer to 25 percent.<ref name="Gold2002" /> Furthermore, some snake [[genera]], such as [[rattlesnake]]s, can internally regulate the amount of venom they inject.<ref name="Young2001">{{cite journal | vauthors = Young BA, Zahn K | title = Venom flow in rattlesnakes: mechanics and metering | journal = The Journal of Experimental Biology | volume = 204 | issue = Pt 24 | pages = 4345–4351 | date = December 2001 | pmid = 11815658 | doi = 10.1242/jeb.204.24.4345 | bibcode = 2001JExpB.204.4345Y | url = http://jeb.biologists.org/cgi/reprint/204/24/4345.pdf | url-status = live | quote = With the species and size of target held constant, the duration of venom flow, maximum venom flow rate and total venom volume were all significantly lower in predatory than in defensive strikes | archive-url = https://web.archive.org/web/20090109013518/http://jeb.biologists.org/cgi/reprint/204/24/4345.pdf | archive-date = 9 January 2009}}</ref> There is a wide variance in the composition of venoms from one species of venomous snake to another. Some venoms may have their greatest effect on a victim's respiration or circulatory system. Others may damage or destroy tissues. This variance has imparted to the venom of each species a distinct chemistry. Sometimes antivenins have to be developed for individual species. For this reason, standard therapeutic measures will not work in all cases.

Some dry bites may also be the result of imprecise timing on the snake's part, as venom may be prematurely released before the fangs have penetrated the person.<ref name="Young2002" /> Even without venom, some snakes, particularly large constrictors such as those belonging to the [[Boidae]] and [[Pythonidae]] families, can deliver damaging bites; large specimens often cause severe [[laceration]]s, or the snake itself pulls away, causing the flesh to be torn by the needle-sharp recurved teeth embedded in the person. While not as life-threatening as a bite from a venomous species, the bite can be at least temporarily debilitating and could lead to dangerous infections if improperly dealt with.{{citation needed|date=May 2021}}

While most snakes must open their mouths before biting, African and Middle Eastern snakes belonging to the family [[Atractaspididae]] can fold their fangs to the side of their head without opening their mouth and jab a person.<ref name="Deufel2003">{{cite journal | vauthors = Deufel A, Cundall D | title = Feeding in Atractaspis (Serpentes: Atractaspididae): a study in conflicting functional constraints | journal = Zoology | volume = 106 | issue = 1 | pages = 43–61 | year = 2003 | pmid = 16351890 | doi = 10.1078/0944-2006-00088 | bibcode = 2003Zool..106...43D | url = https://www.academia.edu/7083466 | access-date = 19 May 2014 | url-status = live | archive-url = https://web.archive.org/web/20160107214703/http://www.academia.edu/7083466/Feeding_in_Atractaspis_-_for_analysis | archive-date = 7 January 2016}}</ref>

=== Snake venom ===
{{Main|Snake venom|Venom-induced consumption coagulopathy}}
It has been suggested that snakes evolved the mechanisms necessary for venom formation and delivery sometime during the [[Miocene]] epoch.<ref name="Jackson2003">{{cite journal | vauthors = Jackson K |year=2003 |title=The evolution of venom-delivery systems in snakes |journal=[[Zoological Journal of the Linnean Society]] |volume=137 |issue=3 |pages=337–354 |doi=10.1046/j.1096-3642.2003.00052.x |url=http://www.kingsnake.com/aho/pdf/menu2/jackson2002.pdf |access-date=25 July 2009 |url-status=live |archive-url=https://web.archive.org/web/20121010135351/http://www.kingsnake.com/aho/pdf/menu2/jackson2002.pdf |archive-date=10 October 2012 |doi-access=free}}</ref> During the mid-[[Tertiary period|Tertiary]], most snakes were large [[ambush predator]]s belonging to the superfamily [[Henophidia]], which use constriction to kill their prey. As open grasslands replaced forested areas in parts of the world, some snake families evolved to become smaller and thus more agile. However, subduing and killing prey became more difficult for the smaller snakes, leading to the evolution of snake venom. The most likely hypothesis holds that venom glands evolved from specialized salivary glands. The venom itself evolved through the process of natural selection; it retained and emphasized the qualities that made it useful in killing or subduing prey. Today we can find various snake species in stages of this hypothesized development. There are the highly efficient envenoming machines - like the rattlesnakes - with large capacity venom storage, hollow fangs that swing into position immediately before the snake bites, and spare fangs ready to replace those damaged or lost.<ref>{{cite book|last1=Campbell|first1=Sheldon|last2=Shaw|first2=Charles E.|title=Snakes of The American West|year=1974|page=181|publisher=[[Alfred A. Knopf]]|location=New York|isbn=978-0-394-48882-0}}</ref><ref name="Jackson2003" /> Other research on [[Toxicofera]], a hypothetical [[clade]] thought to be ancestral to most living reptiles, suggests an earlier time frame for the evolution of snake venom, possibly to the order of tens of millions of years, during the [[Late Cretaceous]].<ref name="Fry2006">{{cite journal | vauthors = Fry BG, Vidal N, Norman JA, Vonk FJ, Scheib H, Ramjan SF, Kuruppu S, Fung K, Hedges SB, Richardson MK, Hodgson WC, Ignjatovic V, Summerhayes R, Kochva E | display-authors = 6 | title = Early evolution of the venom system in lizards and snakes | journal = Nature | volume = 439 | issue = 7076 | pages = 584–588 | date = February 2006 | pmid = 16292255 | doi = 10.1038/nature04328 | url = http://www.venomdoc.com/downloads/2005_BGF_Nature_squamate_venom.pdf | access-date = 18 September 2009 | s2cid = 4386245 | bibcode = 2006Natur.439..584F | archive-url = https://web.archive.org/web/20090530032125/http://www.venomdoc.com/downloads/2005_BGF_Nature_squamate_venom.pdf | archive-date = 30 May 2009}}</ref>

Snake venom is produced in modified [[parotid gland]]s normally responsible for secreting saliva. It is stored in structures called [[wikt:alveolus|alveoli]] behind the animal's eyes and ejected voluntarily through its hollow tubular [[fangs]].{{citation needed|date=March 2023}}

Venom in many snakes, such as pit vipers, affects virtually every organ system in the human body and can be a combination of many toxins, including [[cytotoxins]], [[hemotoxins]], [[neurotoxins]], and [[myotoxin]]s, allowing for an enormous variety of symptoms.<ref name="Gold2002" /><ref name="Russell1980a">{{cite journal | vauthors = Russell FE | title = Snake venom poisoning in the United States | journal = Annual Review of Medicine | volume = 31 | pages = 247–259 | year = 1980 | pmid = 6994610 | doi = 10.1146/annurev.me.31.020180.001335 | s2cid = 1322336}}</ref> Snake venom may cause [[cytotoxicity]] as various enzymes including [[hyaluronidase]]s, [[collagenase]]s, [[proteinase]]s and [[phospholipase]]s lead to breakdown (dermonecrosis) and injury of local tissue and inflammation which leads to pain, edema and blister formation.<ref name="Seifert">{{cite journal |last1=Seifert |first1=Steven A. |last2=Armitage |first2=James O. |last3=Sanchez |first3=Elda E. |title=Snake Envenomation |journal=New England Journal of Medicine |date=6 January 2022 |volume=386 |issue=1 |pages=68–78 |doi=10.1056/NEJMra2105228|pmid=34986287 |pmc=9854269 |s2cid=245771267}}</ref> [[Metalloproteinase]]s further lead to breakdown of the extracellular matrix (releasing inflammatory mediators) and cause microvascular damage, leading to hemorrhage, skeletal muscle damage (necrosis), blistering and further dermonecrosis.<ref name="Seifert" /> The metalloproteinase release of the inflammatory mediators leads to pain, swelling, and white blood cell ([[leukocyte]]) infiltration. The lymphatic system may be damaged by the various enzymes contained in the venom leading to edema; or the lymphatic system may also allow the venom to be carried systemically.<ref name="Seifert" /> Snake venom may cause muscle damage or [[myotoxin|myotoxicity]] via the enzyme [[phospholipase A2]] which disrupts the plasma membrane of muscle cells. This damage to muscle cells may cause [[rhabdomyolysis]], respiratory muscle compromise, or both.<ref name="Seifert" /> Other enzymes such as bradykinin potentiating peptides, natriuretic peptides, [[vascular endothelial growth factor]]s, [[proteases]] can also cause [[hypotension]] or low blood pressure.<ref name="Seifert" /> Toxins in snake venom can also cause kidney damage (nephrotoxicity) via the same inflammatory cytokines. The toxins cause direct damage to the [[Glomerulus (kidney)|glomeruli]] in the kidneys as well as causing protein deposits in [[Bowman's capsule]]. Or the kidneys may be indirectly damaged by envenomation due to shock, clearance of toxic substances such as immune complexes, blood degradation products, or products of muscle breakdown (rhabdomyolysis).<ref name="Seifert" />

In [[venom-induced consumption coagulopathy]], toxins in snake venom promote hemorrhage via activation, consumption, and subsequent depletion of clotting factors in the blood.<ref name="Seifert" /> These clotting factors normally work as part of the [[coagulation cascade]] in the blood to form blood clots and prevent hemorrhage. Toxins in snake venom (especially the venom of New World pit vipers (the family [[crotalina]]))  may also cause low platelets ([[thrombocytopenia]]) or altered platelet function also leading to bleeding.<ref name="Seifert" />

Snake venom is known to cause neuromuscular paralysis, usually as a flaccid paralysis that is descending; starting at the facial muscles, causing [[Ptosis (eyelid)|ptosis]] or drooping eyelids and [[dysarthria]] or poor articulation of speech, and descending to the respiratory muscles causing respiratory compromise.<ref name="Seifert" /> The neurotoxins can either bind to and block membrane receptors at the post-synaptic neurons or they can be taken up into the pre-synaptic neuron cells and impair neurotransmitter release.<ref name="Seifert" /> Venom toxins that are taken up intra-cellularly, into the cells of the pre-synaptic neurons are much more difficult to reverse using anti-venom as they are inaccessible to the anti-venom when they are intracellular.<ref name="Seifert" />

The strength of venom differs markedly between species and even more so between families, as measured by [[median lethal dose]] (LD<sub>50</sub>) in mice. Subcutaneous LD<sub>50</sub> varies by over 140-fold within elapids and by more than 100-fold in vipers. The amount of venom produced also differs among species, with the [[Gaboon viper]] able to potentially deliver from 450 to 600 milligrams of venom in a single bite, the most of any snake.<ref name="Spawls">{{cite book |title=The Dangerous Snakes of Africa | vauthors = Spawls S, Branch B |year=1997 |publisher=Southern Book Publishers |location=Johannesburg |isbn=978-1-86812-575-3 |page=192}}</ref> [[Opisthoglyphous]] colubrids have venom ranging from life-threatening (in the case of the [[boomslang]]) to barely noticeable (as in ''[[Tantilla]]'').{{citation needed|date=May 2021}}

== Prevention ==
[[File:RodriguezParkHoustonSnakes.JPG|thumb|right|Sign at Sylvan Rodriguez Park in [[Houston, Texas]], warning of the presence of snakes]]

Snakes are most likely to bite when they feel threatened, are startled, are provoked, or when they have been cornered. Snakes are likely to approach residential areas when attracted by prey, such as [[rodents]]. Regular [[pest control]] can reduce the threat of snakes considerably. It is beneficial to know the species of snake that are common in local areas, or while travelling or hiking. [[Africa]], [[Australia]], the [[Neotropics]], and [[South Asia]] in particular are populated by many dangerous species of snake. Being aware of—and ultimately avoiding—areas known to be heavily populated by dangerous snakes is strongly recommended.{{citation needed|date=July 2020}}

When in the wilderness, treading heavily creates ground vibrations and noise, which will often cause snakes to flee from the area. However, this generally only applies to vipers, as some larger and more aggressive snakes in other parts of the world, such as [[mamba]]s and [[cobra]]s,<ref name="Haji">{{cite web| vauthors = Haji R |title=Venomous snakes and snake bites|url=http://www.zoocheck.com/Reportpdfs/Venomous%20snakes.pdf|website=Zoocheck Canada|access-date=25 October 2013|archive-url=https://web.archive.org/web/20120425231856/http://www.zoocheck.com/Reportpdfs/Venomous%20snakes.pdf|archive-date=25 April 2012}}</ref> will respond more aggressively. If presented with a direct encounter, it is best to remain silent and motionless. If the snake has not yet fled, it is important to step away slowly and cautiously.{{citation needed|date=May 2021}}

The use of a flashlight when engaged in camping activities, such as gathering firewood at night, can be helpful. Snakes may also be unusually active during especially warm nights when ambient temperatures exceed {{convert|21|°C|°F|abbr=on}}. It is advised not to reach blindly into hollow logs, flip over large rocks, and enter old [[Log cabin|cabins]] or other potential snake hiding places. When [[climbing|rock climbing]], it is not safe to grab ledges or crevices without examining them first, as snakes are [[Ectotherm|cold-blooded]] and often sunbathe atop rock ledges.{{citation needed|date=May 2021}}

In the United States, more than 40 percent of people bitten by snakes intentionally put themselves in harm's way by attempting to capture wild snakes or by carelessly handling their dangerous pets—40 percent of that number had a [[blood alcohol level]] of 0.1 percent or more.<ref>{{cite journal | vauthors = Kurecki BA, Brownlee HJ | title = Venomous snakebites in the United States | journal = The Journal of Family Practice | volume = 25 | issue = 4 | pages = 386–392 | date = October 1987 | pmid = 3655676}}</ref>

It is also important to avoid snakes that [[apparent death|appear to be dead]], as some species will roll over on their backs and stick out their tongue to fool potential threats. A snake's detached head can immediately act by [[reflex action|reflex]] and potentially bite. The induced bite can be just as severe as that of a live snake.<ref name="Gold2002" /><ref>{{cite journal | vauthors = Gold BS, Barish RA | title = Venomous snakebites. Current concepts in diagnosis, treatment, and management | journal = Emergency Medicine Clinics of North America | volume = 10 | issue = 2 | pages = 249–267 | date = May 1992 | pmid = 1559468 | doi = 10.1016/S0733-8627(20)30712-4}}</ref>
As a dead snake is incapable of regulating the venom injected, a bite from a dead snake can often contain large amounts of venom.<ref name="Suchard1999">{{cite journal | vauthors = Suchard JR, LoVecchio F | title = Envenomations by rattlesnakes thought to be dead | journal = The New England Journal of Medicine | volume = 340 | issue = 24 | page = 1930 | date = June 1999 | pmid = 10375322 | doi = 10.1056/NEJM199906173402420 | doi-access = free}}</ref>

== Treatment ==
It may be difficult to determine if a bite by any species of snake is life-threatening. A bite by a North American [[Agkistrodon contortrix|copperhead]] on the ankle is usually a moderate injury to a healthy adult, but a bite to a child's abdomen or face by the same snake may be fatal. The outcome of all snakebites depends on a multitude of factors: the type of snake, the size, physical condition, and temperature of the snake, the age and physical condition of the person, the area and tissue bitten (e.g., foot, torso, vein or muscle), the amount of venom injected, the time it takes for the person to find treatment, and finally the quality of that treatment.<ref name="Gold2002" /><ref name="Gold1994" /> An overview of systematic reviews on different aspects of snakebite management found that the evidence base from majority of treatment modalities is low quality.<ref name="Interventions for the management of">{{cite journal | vauthors = Bhaumik S, Beri D, Lassi ZS, Jagnoor J | title = Interventions for the management of snakebite envenoming: An overview of systematic reviews | journal = PLOS Neglected Tropical Diseases | volume = 14 | issue = 10 | pages = e0008727 | date = October 2020 | pmid = 33048936 | pmc = 7584233 | doi = 10.1371/journal.pntd.0008727 | doi-access = free}}</ref> An analysis of World Health Organization guidelines found that they are of low quality, with inadequate stakeholder involvement and poor methodological rigour.<ref>{{cite journal | vauthors = Bhaumik S, Jagadesh S, Lassi Z | title = Quality of WHO guidelines on snakebite: the neglect continues | journal = BMJ Global Health | volume = 3 | issue = 2 | pages = e000783 | date = 2018-04-01 | pmid = 29662699 | pmc = 5898301 | doi = 10.1136/bmjgh-2018-000783}}</ref> In addition, access to effective treatment modalities is a major challenge in some regions, particularly in most African countries.<ref name=":0">{{Cite journal |last1=Berg |first1=Philipp |last2=Theart |first2=Francois |last3=van Driel |first3=Marcel |last4=Saaiman |first4=Esta L. |last5=Mavoungou |first5=Lise-Bethy |date=2024-11-06 |title=Snakebite envenoming in Africa remains widely neglected and demands multidisciplinary attention |journal=Nature Communications |language=en |volume=15 |issue=1 |pages=9598 |doi=10.1038/s41467-024-54070-y |pmid=39505859 |issn=2041-1723|pmc=11541957 |bibcode=2024NatCo..15.9598B }}</ref>

=== Snake identification ===
Identification of the snake is important in planning treatment in certain areas of the world but is not always possible. Ideally, the dead snake would be brought in with the person, but in areas where snake bite is more common, local knowledge may be sufficient to recognize the snake. However, in regions where polyvalent [[antivenom]]s are available, such as North America, identification of snakes is not a high-priority item. Attempting to catch or kill the offending snake also puts one at risk for re-envenomation or creating a second person bitten, and generally is not recommended.<ref name="auto">{{cite journal |last1=Knudsen |first1=Cecilie |last2=Jürgensen |first2=Jonas A. |last3=Føns |first3=Sofie |last4=Haack |first4=Aleksander M. |last5=Friis |first5=Rasmus U. W. |last6=Dam |first6=Søren H. |last7=Bush |first7=Sean P. |last8=White |first8=Julian |last9=Laustsen |first9=Andreas H. |date=2021 |title=Snakebite Envenoming Diagnosis and Diagnostics |journal=Frontiers in Immunology |volume=12 |page=661457 |doi=10.3389/fimmu.2021.661457 |pmid=33995385 |pmc=8113877 |issn=1664-3224|doi-access=free}}</ref>

The three types of venomous snakes that cause the majority of major clinical problems are [[Viper (animal)|vipers]], [[Bungarus|kraits]], and [[Naja|cobras]]. Knowledge of what species are present locally can be crucial, as is knowledge of typical signs and symptoms of envenomation by each type of snake. A scoring system can be used to try to determine the biting snake based on clinical features,<ref>{{cite journal | vauthors = Pathmeswaran A, Kasturiratne A, Fonseka M, Nandasena S, Lalloo DG, de Silva HJ | title = Identifying the biting species in snakebite by clinical features: an epidemiological tool for community surveys | journal = Transactions of the Royal Society of Tropical Medicine and Hygiene | volume = 100 | issue = 9 | pages = 874–878 | date = September 2006 | pmid = 16412486 | doi = 10.1016/j.trstmh.2005.10.003}}</ref> but these scoring systems are extremely specific to particular geographical areas and might be compromised by the presence of escaped or released non-native species.<ref name="auto"/>

=== First aid ===
Snakebite [[first aid]] recommendations vary, in part because different snakes have different types of venom. Some have little local effect, but life-threatening systemic effects, in which case containing the venom in the region of the bite by pressure immobilization is desirable. Other venoms instigate localized tissue damage around the bitten area, and immobilization may increase the severity of the damage in this area, but also reduce the total area affected; whether this trade-off is desirable remains a point of controversy. Because snakes vary from one country to another, first aid methods also vary.{{citation needed|date=March 2023}}

Many organizations, including the [[American Medical Association]] and [[American Red Cross]], recommend washing the bite with soap and water. Australian recommendations for snake bite treatment are against cleaning the wound. Traces of venom left on the skin/bandages from the strike can be used in combination with a snake bite identification kit to identify the species of snake. This speeds the determination of which antivenom to administer in the emergency room.<ref>{{cite web|url=http://www.usyd.edu.au/anaes/venom/snakebite.html |title=Treatment of Australian Snake Bites |author=Chris Thompson |website=Australian anaesthetists' website |archive-url=https://web.archive.org/web/20070323132545/http://www.usyd.edu.au/anaes/venom/snakebite.html |archive-date=23 March 2007}}</ref>

=== Pressure immobilization ===
{{Further|Pressure immobilization technique}}
[[File:Bundesarchiv Bild 135-KA-01-019, Tibetexpedition, Melken einer Schlange.jpg|thumb|right|A [[Russell's viper]] is being "milked". Laboratories use extracted snake venom to produce [[antivenom]], which is often the only effective treatment for potentially fatal snakebites.]]

As of 2008, clinical evidence for [[pressure immobilization]] via the use of an [[elastic bandage]] is limited.<ref name="Currie2008">{{cite journal | vauthors = Currie BJ, Canale E, Isbister GK | title = Effectiveness of pressure-immobilization first aid for snakebite requires further study | journal = Emergency Medicine Australasia | volume = 20 | issue = 3 | pages = 267–270 | date = June 2008 | pmid = 18549384 | doi = 10.1111/j.1742-6723.2008.01093.x | s2cid = 40768561}}</ref> It is recommended for snakebites that have occurred in Australia (due to [[elapids]] which are neurotoxic).<ref name="Walker2013">{{cite journal | vauthors = Patrick Walker J, Morrison R, Stewart R, Gore D | title = Venomous bites and stings | journal = Current Problems in Surgery | volume = 50 | issue = 1 | pages = 9–44 | date = January 2013 | pmid = 23244230 | doi = 10.1067/j.cpsurg.2012.09.003}}</ref> It is not recommended for bites from non-neurotoxic snakes such as those found in North America and other regions of the world.<ref name="Walker2013" /><ref name="ACM2011" /> The British military recommends pressure immobilization in all cases where the type of snake is unknown.<ref>{{cite journal | vauthors = Wall C | title = British Military snake-bite guidelines: pressure immobilisation | journal = Journal of the Royal Army Medical Corps | volume = 158 | issue = 3 | pages = 194–198 | date = September 2012 | pmid = 23472565 | doi = 10.1136/jramc-158-03-09 | s2cid = 22415445}}</ref>

The object of pressure immobilization is to contain venom within a bitten limb and prevent it from moving through the [[lymphatic system]] to the vital organs. This therapy has two components: pressure to prevent lymphatic drainage, and immobilization of the bitten limb to prevent the pumping action of the [[skeletal muscle]]s.{{citation needed|date=March 2023}}

=== Antivenom ===
Until the advent of [[antivenom]], bites from some species of snake were almost universally fatal.<ref name="INCHEM">{{cite web | vauthors = White J  |title=Oxyuranus microlepidotus |url=http://www.inchem.org/documents/pims/animal/taipan.htm |date=November 1991 |publisher=Chemical Safety Information from Intergovernmental Organizations |quote=Without appropriate antivenom treatment up to 75% of taipan bites will be fatal. Indeed, in the era before specific antivenom therapy, virtually no survivors of taipan bite were recorded. |access-date=24 July 2009 |url-status=live |archive-url=https://web.archive.org/web/20090803070213/http://www.inchem.org/documents/pims/animal/taipan.htm |archive-date=3 August 2009}}</ref> Despite huge advances in emergency therapy, antivenom is often still the only effective treatment for envenomation. The first antivenom was developed in 1895 by French physician [[Albert Calmette]] for the treatment of [[Indian cobra]] bites. Antivenom is made by injecting a small amount of venom into an animal (usually a horse or sheep) to initiate an immune system response. The resulting [[antibodies]] are then harvested from the animal's blood.{{citation needed|date=March 2023}}

Antivenom is injected into the person [[Intravenous therapy|intravenously]], and works by binding to and neutralizing venom enzymes. It cannot undo the damage already caused by venom, so antivenom treatment should be sought as soon as possible. Modern antivenoms are usually polyvalent, making them effective against the venom of numerous snake species. Pharmaceutical companies that produce antivenom target their products against the species native to a particular area. The availability of antivenom is a major concern in some areas, including most of Africa, due to economic reasons (antivenom crisis).<ref name=":0" /> In Sub-Saharan Africa, the efficacy of antivenom is often poorly characterised and some of the few available products have even been found to lack effectiveness.<ref>{{Cite journal |last1=Potet |first1=Julien |last2=Smith |first2=James |last3=McIver |first3=Lachlan |date=2019-06-24 |title=Reviewing evidence of the clinical effectiveness of commercially available antivenoms in sub-Saharan Africa identifies the need for a multi-centre, multi-antivenom clinical trial |journal=PLOS Neglected Tropical Diseases |language=en |volume=13 |issue=6 |pages=e0007551 |doi=10.1371/journal.pntd.0007551 |issn=1935-2735 |pmc=6615628 |pmid=31233536 |doi-access=free}}</ref>

Although some people may develop serious adverse reactions to antivenom, such as [[anaphylaxis]], in emergency situations this is usually treatable in a hospital setting and hence the benefit outweighs the potential consequences of not using antivenom. Giving [[adrenaline]] (epinephrine) to prevent adverse reactions to antivenom before they occur might be reasonable in cases where they occur commonly.<ref name="Nuch2000" /> Antihistamines do not appear to provide any benefit in preventing adverse reactions.<ref name="Nuch2000">{{cite journal | vauthors = Nuchpraryoon I, Garner P | title = Interventions for preventing reactions to snake antivenom | journal = The Cochrane Database of Systematic Reviews | issue = 2 | pages = CD002153 | year = 2000 | volume = 1999 | pmid = 10796682 | pmc = 7017854 | doi = 10.1002/14651858.CD002153}}</ref>

=== Chronic complications ===
Chronic health effects of snakebite include but are not limited to non-healing and chronic ulcers, musculoskeletal disorders, amputations, chronic kidney disease, and other neurological and endocrine complications.<ref>{{cite journal | vauthors = Kasturiratne A, Lalloo DG, Janaka de Silva H | title = Chronic health effects and cost of snakebite | journal = Toxicon | volume = 9-10 | page = 100074 | date = July 2021 | pmid = 34355162 | pmc = 8321925 | doi = 10.1016/j.toxcx.2021.100074| bibcode = 2021TxcnX...900074K }}</ref><ref>{{cite journal | vauthors = Bhaumik S, Gopalakrishnan M, Meena P | title = Mitigating the chronic burden of snakebite: turning the tide for survivors | journal = Lancet | volume = 398 | issue = 10309 | pages = 1389–1390 | date = October 2021 | pmid = 34537105 | doi = 10.1016/S0140-6736(21)01905-X | issn=0140-6736  | s2cid = 237541103}}</ref> The treatment of chronic complications of snakebite has not been well researched and there a systems approach consisting of a multi-component intervention.<ref>{{cite journal | vauthors = Bhaumik S, Gopalakrishnan M, Meena P | title = Mitigating the chronic burden of snakebite: turning the tide for survivors | journal = Lancet | volume = 398 | issue = 10309 | pages = 1389–1390 | date = October 2021 | pmid = 34537105 | doi = 10.1016/S0140-6736(21)01905-X| issn=0140-6736 | s2cid = 237541103}}</ref><ref name="Interventions for the management of" />

=== Outmoded ===
[[File:Snakebite kit.jpg|thumb|right|Old-style snake bite kit that should not be used]]
The following treatments, while once recommended, are considered of no use or harmful, including tourniquets, incisions, suction, application of cold, and application of electricity.<ref name="ACM2011">{{cite journal | title = Pressure immobilization after North American Crotalinae snake envenomation | journal = Journal of Medical Toxicology | volume = 7 | issue = 4 | pages = 322–323 | date = December 2011 | pmid = 22065370 | pmc = 3550191 | doi = 10.1007/s13181-011-0174-2 | author1 = American College of Medical Toxicology | author2 = American Academy of Clinical Toxicology | author3 = American Association of Poison Control Centers | author4 = European Association of Poison Control Centres | author5 = International Society of Toxinology | author6 = Asia Pacific Association of Medical Toxicology}}</ref> Cases in which these treatments appear to work may be the result of [[dry bite]]s.
* Application of a [[tourniquet]] to the bitten limb is generally not recommended. There is no convincing evidence that it is an effective first-aid tool as ordinarily applied.<ref name="theak">{{cite journal | vauthors = Theakston RD | title = An objective approach to antivenom therapy and assessment of first-aid measures in snake bite | journal = Annals of Tropical Medicine and Parasitology | volume = 91 | issue = 7 | pages = 857–865 | date = October 1997 | pmid = 9625943 | doi = 10.1080/00034989760626 | url = http://www.kingsnake.com/aho/pdf/menu6/theakston1997.pdf | url-status = live | archive-url = https://web.archive.org/web/20081230093058/http://www.kingsnake.com/aho/pdf/menu6/theakston1997.pdf | archive-date = 30 December 2008}}</ref> Tourniquets have been found to be completely ineffective in the treatment of ''[[Crotalus durissus]]'' bites,<ref>{{cite journal | vauthors = Amaral CF, Campolina D, Dias MB, Bueno CM, Rezende NA | title = Tourniquet ineffectiveness to reduce the severity of envenoming after Crotalus durissus snake bite in Belo Horizonte, Minas Gerais, Brazil | journal = Toxicon | volume = 36 | issue = 5 | pages = 805–808 | date = May 1998 | pmid = 9655642 | doi = 10.1016/S0041-0101(97)00132-3| bibcode = 1998Txcn...36..805A }}</ref> but some positive results have been seen with properly applied tourniquets for cobra venom in the [[Philippines]].<ref>{{cite journal | vauthors = Watt G, Padre L, Tuazon ML, Theakston RD, Laughlin LW | title = Tourniquet application after cobra bite: delay in the onset of neurotoxicity and the dangers of sudden release | journal = The American Journal of Tropical Medicine and Hygiene | volume = 38 | issue = 3 | pages = 618–622 | date = May 1988 | pmid = 3275141 | doi = 10.4269/ajtmh.1988.38.618 | s2cid = 29451180}}</ref> Uninformed tourniquet use is dangerous since reducing or cutting off circulation can lead to [[gangrene]], which can be fatal.<ref name="theak" /> The use of a compression bandage is generally as effective, and much safer.
* Cutting open the bitten area, an action often taken before suction, is not recommended since it causes further damage and increases the risk of infection; the subsequent cauterization of the area with fire or silver nitrate (also known as ''infernal stone'') is also potentially threatening.<ref name="peola">{{cite book | vauthors = Lupano G, Peola P |date=1915 |title=Corso di Scienze Naturali a uso delle Scuole Complementari |trans-title=A Course of Natural Sciences for the Complementary Institutes |language=it |publisher=G.B. Paravia |page=68}}</ref>
* Sucking out venom, either by mouth or with a pump, does not work and may harm the affected area directly.<ref name="pmid16781926">{{cite journal | vauthors = Holstege CP, Singletary EM | title = Images in emergency medicine. Skin damage following application of suction device for snakebite | journal = Annals of Emergency Medicine | volume = 48 | issue = 1 | pages = 105, 113 | date = July 2006 | pmid = 16781926 | doi = 10.1016/j.annemergmed.2005.12.019 | doi-access = free}}</ref> Suction started after three minutes removes a clinically insignificant quantity—less than one-thousandth of the venom injected—as shown in a human study.<ref>{{cite journal | vauthors = Alberts MB, Shalit M, LoGalbo F | title = Suction for venomous snakebite: a study of "mock venom" extraction in a human model | journal = Annals of Emergency Medicine | volume = 43 | issue = 2 | pages = 181–186 | date = February 2004 | pmid = 14747805 | doi = 10.1016/S0196-0644(03)00813-8}}</ref> In a study with pigs, suction not only caused no improvement but led to [[necrosis]] in the suctioned area.<ref name="pmid11055564">{{cite journal | vauthors = Bush SP, Hegewald KG, Green SM, Cardwell MD, Hayes WK | title = Effects of a negative pressure venom extraction device (Extractor) on local tissue injury after artificial rattlesnake envenomation in a porcine model | journal = Wilderness & Environmental Medicine | volume = 11 | issue = 3 | pages = 180–188 | year = 2000 | pmid = 11055564 | doi = 10.1580/1080-6032(2000)011[0180:EOANPV]2.3.CO;2 | doi-access = free}}</ref> Suctioning by mouth presents a risk of further poisoning through the mouth's [[oral mucosa|mucous tissues]].<ref>Riggs BS, Smilkstein MJ, Kulig KW, ''et al.'' Rattlesnake envenomation with massive oropharyngeal edema following incision and suction (Abstract). Presented at the AACT/AAPCC/ABMT/CAPCC Annual Scientific Meeting, Vancouver, Canada, September 27 October 2, 1987.</ref> The helper may also release bacteria into the person's wound, leading to infection.
* Immersion in warm water or sour milk, followed by the application of [[snake-stones]] (also known as ''la Pierre Noire''), which are believed to draw off the poison in much the way a sponge soaks up water.
* Application of a one-percent solution of [[potassium permanganate]] or [[chromic acid]] to the cut, exposed area.<ref name="peola"/> The latter substance is notably toxic and carcinogenic.
* Drinking abundant quantities of alcohol following the cauterization or disinfection of the wound area.<ref name="peola"/>
* Use of electroshock therapy in animal tests has shown this treatment to be useless and potentially dangerous.<ref>{{cite journal | vauthors = Russell FE | title = Another warning about electric shock for snakebite | journal = Postgraduate Medicine | volume = 82 | issue = 5 | page = 32 | date = October 1987 | pmid = 3671201 | doi = 10.1080/00325481.1987.11699990}}</ref><ref>{{cite journal | vauthors = Ryan AJ | title = Don't use electric shock for snakebite | journal = Postgraduate Medicine | volume = 82 | issue = 2 | page = 42 | date = August 1987 | pmid = 3497394 | doi = 10.1080/00325481.1987.11699922 | s2cid = 222260195}}</ref><ref>{{cite journal | vauthors = Howe NR, Meisenheimer JL | title = Electric shock does not save snakebitten rats | journal = Annals of Emergency Medicine | volume = 17 | issue = 3 | pages = 254–256 | date = March 1988 | pmid = 3257850 | doi = 10.1016/S0196-0644(88)80118-5}}</ref><ref>{{cite journal | vauthors = Johnson EK, Kardong KV, Mackessy SP | title = Electric shocks are ineffective in treatment of lethal effects of rattlesnake envenomation in mice | journal = Toxicon | volume = 25 | issue = 12 | pages = 1347–1349 | year = 1987 | pmid = 3438923 | doi = 10.1016/0041-0101(87)90013-4| bibcode = 1987Txcn...25.1347J }}</ref>

In extreme cases, in remote areas, all of these misguided attempts at treatment have resulted in injuries far worse than an otherwise mild to moderate snakebite. In worst-case scenarios, thoroughly constricting tourniquets have been applied to bitten limbs, completely shutting off blood flow to the area. By the time the person finally reached appropriate medical facilities, their limbs had to be [[amputated]].{{citation needed|date=March 2023}}

=== In development ===
Several new drugs and treatments are under development for snakebite. For instance, the metal chelator [[dimercaprol]] has recently been shown to potently antagonize the activity of Zn<sup>2+</sup>-dependent snake venom [[metalloproteinase]]s ''in vitro''.<ref>{{cite journal | vauthors = Albulescu LO, Hale MS, Ainsworth S, Alsolaiss J, Crittenden E, Calvete JJ, Evans C, Wilkinson MC, Harrison RA, Kool J, Casewell NR | display-authors = 6 | title = Preclinical validation of a repurposed metal chelator as an early-intervention therapeutic for hemotoxic snakebite | journal = Science Translational Medicine | volume = 12 | issue = 542 | pages = eaay8314 | date = May 2020 | pmid = 32376771 | pmc = 7116364 | doi = 10.1126/scitranslmed.aay8314}}</ref> New [[Monoclonal antibody|monoclonal antibodies]], polymer gels and a small molecule inhibitor called [[Varespladib]] are in development.<ref>{{cite web|title=The search for better antivenoms heats up as snakebites get renewed attention|url=https://cen.acs.org/biological-chemistry/biotechnology/search-better-antivenoms-heats-snakebites/97/i4|access-date=2020-10-15|website=Chemical & Engineering News|language=en}}</ref> A core outcome set (minimal list of consensus outcomes that should be used in future intervention research)  for snakebite in South Asia is being developed.<ref>{{cite journal |last1=Bhaumik |first1=Soumyadeep |last2=Beri |first2=Deepti |last3=Tyagi |first3=Jyoti |last4=Clarke |first4=Mike |last5=Sharma |first5=Sanjib Kumar |last6=Williamson |first6=Paula R. |last7=Jagnoor |first7=Jagnoor |date=2022-06-08 |title=Outcomes in intervention research on snakebite envenomation: a systematic review |journal=F1000Research |volume=11 |page=628 |doi=10.12688/f1000research.122116.1 |pmid=36300033 |pmc=9579743 |language=en |doi-access=free}}</ref>

== Epidemiology ==
{{Main|Epidemiology of snakebites}}
{{see also|List of fatal snake bites in the United States|List of fatal snake bites in Australia}}
{{multiple image
| direction         = vertical
| width             = 350
| align             = right
| image1            = World distribution of snakes.svg
| image2            = Number of snake envenomings (2007).svg
| caption1          = Map showing the approximate world distribution of snakes
| caption2          = Map showing the global distribution of snakebite morbidity
}}

Earlier estimates for snakebite vary from 1.2 to 5.5&nbsp;million, with 421,000 to 2.5&nbsp;million being envenomings, and causing 20,000 to 125,000 deaths.<ref name=WHO2015/><ref name=Kast2008/> More recent modelling estimates that in 2019, about 63,400 people died globally from snakebite, with 51,100 of these deaths happening in India.<ref>{{cite journal |last1=Roberts |first1=Nicholas L. S. |last2=Johnson |first2=Emily K. |last3=Zeng |first3=Scott M. |last4=Hamilton |first4=Erin B. |last5=Abdoli |first5=Amir |last6=Alahdab |first6=Fares |last7=Alipour |first7=Vahid |last8=Ancuceanu |first8=Robert |last9=Andrei |first9=Catalina Liliana |last10=Anvari |first10=Davood |last11=Arabloo |first11=Jalal |last12=Ausloos |first12=Marcel |last13=Awedew |first13=Atalel Fentahun |last14=Badiye |first14=Ashish D. |last15=Bakkannavar |first15=Shankar M. |date=2022-10-25 |title=Global mortality of snakebite envenoming between 1990 and 2019 |journal=Nature Communications |language=en |volume=13 |issue=1 |page=6160 |doi=10.1038/s41467-022-33627-9 |pmid=36284094 |pmc=9596405 |bibcode=2022NatCo..13.6160G |s2cid=253111038 |issn=2041-1723}}</ref>  Since reporting is not mandatory in much of the world, the data on the frequency of snakebites is not precise.<ref name=Kast2008/> Many people who survive bites have permanent tissue damage caused by venom, leading to disability.<ref name="Gutierrez2007" /> Most snake envenomings and fatalities occur in [[South Asia]], [[Southeast Asia]], and [[sub-Saharan Africa]], with [[India]] reporting the most snakebite deaths of any country.<ref name=Kast2008/> Available evidence on the effect of climate change on the epidemiology of snakebite is limited but it is expected that there will be a geographic shift in the risk of snakebite: northwards in North America and southwards in South America and Mozambique, and increase in the incidence of bite in Sri Lanka.<ref>{{cite journal |last1=Bhaumik |first1=Soumyadeep |last2=Beri |first2=Deepti |last3=Jagnoor |first3=Jagnoor |date=October 2022 |title=The impact of climate change on the burden of snakebite: Evidence synthesis and implications for primary healthcare |journal=Journal of Family Medicine and Primary Care |language=en-US |volume=11 |issue=10 |pages=6147–6158 |doi=10.4103/jfmpc.jfmpc_677_22 |pmid=36618235 |pmc=9810950 |s2cid=253452433 |issn=2249-4863 |doi-access=free}}</ref>

Most snakebites are caused by non-venomous snakes. Of the roughly 3,000 known species of snake found worldwide, only 15% are considered dangerous to humans.<ref name="Gold2002"/><ref name=Kast2008/> Snakes are found on every continent except [[Antarctica]].<ref name=Kast2008/> The most diverse and widely distributed snake family, the [[colubrid]]s, has approximately 700 venomous species,<ref name="Mackessy2002">{{cite journal | vauthors = Mackessy SP |s2cid=86568032 |year=2002 |title=Biochemistry and pharmacology of colubrid snake venoms |journal=Journal of Toxicology: Toxin Reviews |volume=21 |issue=1–2 |pages=43–83 |doi=10.1081/TXR-120004741 |url=http://www.unco.edu/nhs/biology/faculty_staff/mackessy/colubrid.pdf |access-date=26 September 2009 |quote=Estimates of the number of venomous colubrids approach 700 species. Most may not produce a venom capable of causing serious damage to humans, but at least five species (''Dispholidus typus'', ''Thelotornis capensis'', ''Rhabdophis tigrinus'', ''Philodryas olfersii'' and ''Tachymenis peruviana'') have caused human fatalities |archive-url=https://web.archive.org/web/20100602041516/http://www.unco.edu/nhs/biology/faculty_staff/mackessy/colubrid.pdf |archive-date=2 June 2010 |citeseerx=10.1.1.596.5081}}</ref> but only five [[genera]]—[[boomslang]]s, [[Thelotornis|twig snakes]], [[Rhabdophis|keelback snakes]], [[Philodryas|green snakes]], and [[Tachymenis|slender snakes]]—have caused human fatalities.<ref name="Mackessy2002" />

Worldwide, snakebites occur most frequently in the summer season when snakes are active and humans are outdoors.<ref name=Kast2008/><ref name="WingertChan1988">{{cite journal | vauthors = Wingert WA, Chan L | title = Rattlesnake bites in southern California and rationale for recommended treatment | journal = The Western Journal of Medicine | volume = 148 | issue = 1 | pages = 37–44 | date = January 1988 | pmid = 3277335 | pmc = 1026007}}</ref> Agricultural and tropical regions report more snakebites than anywhere else.<ref name=Kast2008/><ref name="Gutierrez2006"/> In the United States, those bitten are typically male and between 17 and 27 years of age.<ref name="Gold2002" /><ref name="WingertChan1988" /><ref>{{cite journal | vauthors = Parrish HM | title = Incidence of treated snakebites in the United States | journal = Public Health Reports | volume = 81 | issue = 3 | pages = 269–276 | date = March 1966 | pmid = 4956000 | pmc = 1919692 | doi = 10.2307/4592691 | jstor = 4592691}}</ref> Children and the elderly are the most likely to die.<ref name="Gold2002" /><ref name="Gold1994">{{cite journal | vauthors = Gold BS, Wingert WA | title = Snake venom poisoning in the United States: a review of therapeutic practice | journal = Southern Medical Journal | volume = 87 | issue = 6 | pages = 579–589 | date = June 1994 | pmid = 8202764 | doi = 10.1097/00007611-199406000-00001 | s2cid = 37771848}}</ref>

== Mechanics ==
{{see also|Envenomation}}
[[File:Snake Venom Delivery System Diagram.jpg|thumb|Basic diagram of a snake's venom delivery system]]
When venomous snakes bite a target, they secrete [[venom]] through their venom delivery system. The venom delivery system generally consists of two venom glands, a compressor muscle, venom ducts, a fang sheath, and [[fang]]s. The primary and accessory venom glands store the venom quantities required during [[envenomation]]. The compressor muscle contracts during bites to increase the pressure throughout the venom delivery system. The pressurized venom travels through the primary venom duct to the secondary venom duct that leads down through the fang sheath and fang. The venom is then expelled through the exit [[Body orifice|orifice]] of the fang. The total volume and flow rate of venom administered into a target varies widely, sometimes as much as an order of magnitude. One of the largest factors is snake species and size, larger snakes have been shown to administer larger quantities of venom.<ref name="Hayes et al. 2002"/>

=== Predatory vs. defensive bites ===
Snake bites are classified as either predatory or defensive. During defensive strikes, the rate of venom expulsion and total volume of venom expelled is much greater than during predatory strikes. Defensive strikes can have 10 times as much venom volume expelled at 8.5 times the flow rate.<ref>{{cite journal | vauthors = Young BA, Zahn K | title = Venom flow in rattlesnakes: mechanics and metering | journal = The Journal of Experimental Biology | volume = 204 | issue = Pt 24 | pages = 4345–4351 | date = December 2001 | pmid = 11815658 | doi = 10.1242/jeb.204.24.4345| bibcode = 2001JExpB.204.4345Y }}</ref> This can be explained by the snake's need to quickly subdue a threat. While employing similar venom expulsion mechanics, predatory strikes are quite different from defensive strikes. Snakes usually release the prey shortly after the envenomation allowing the prey to run away and die. Releasing prey prevents retaliatory damage to the snake. The venom scent allows the snake to relocate the prey once it is deceased.<ref name="Hayes et al. 2002">{{cite book |chapter=Factors that influence venom expenditure in viperids and other snake species during predatory and defensive contexts | vauthors = Hayes WK, Herbert SS, Rehling GC, Gennaro JF |year=2002 |url= http://eaglemountainpublishing.s3.amazonaws.com/PDF/Biology%20of%20the%20Vipers/CH%2013_hayes_.pdf |title=Biology of the Vipers |pages=207–233 |publisher=Eagle Mountain Publishing}}</ref> The amount of venom injected has been shown to increase with the mass of the prey animal.<ref>{{cite journal | vauthors = Hayes WK |title=Venom metering by juvenile prairie rattlesnakes, ''Crotalus v. viridis'': effects of prey size and experience |journal=Animal Behaviour |date=1995 |volume=50 |issue=1 |pages=33–40 |doi=10.1006/anbe.1995.0218|s2cid=53160144}}</ref> Larger venom volumes allow snakes to effectively euthanize larger prey while remaining economical during strikes against smaller prey. This is an important skill as venom is a metabolically expensive resource.{{citation needed|date=May 2021}}

=== Venom metering ===
Venom metering is the ability of a snake to have neurological control over the amount of venom released into a target during a strike based on situational cues. This ability would prove useful as venom is a limited resource, larger animals are less susceptible to the effects of venom, and various situations require different levels of force. There is a lot of evidence to support the venom metering hypothesis. For example, snakes frequently use more venom during defensive strikes, administer more venom to larger prey, and are capable of dry biting. A dry bite is a bite from a venomous snake that results in very little or no venom expulsion, leaving the target asymptomatic.<ref>{{cite journal | vauthors = Naik BS | title = "Dry bite" in venomous snakes: A review | journal = Toxicon | volume = 133 | pages = 63–67 | date = July 2017 | pmid = 28456535 | doi = 10.1016/j.toxicon.2017.04.015 | bibcode = 2017Txcn..133...63N | s2cid = 36838996}}</ref> However, there is debate among many academics about venom metering in snakes. The alternative to venom metering is the pressure balance hypothesis.{{citation needed|date=March 2023}}

The pressure balance hypothesis cites the retraction of the fang sheath as the many mechanisms for producing outward venom flow from the venom delivery system. When isolated, fang sheath retraction has experimentally been shown to induce very high pressures in the venom delivery system.<ref>{{cite journal | vauthors = Young BA, Kardong KV | title = Mechanisms controlling venom expulsion in the western diamondback rattlesnake, Crotalus atrox | journal = Journal of Experimental Zoology Part A: Ecological Genetics and Physiology | volume = 307 | issue = 1 | pages = 18–27 | date = January 2007 | pmid = 17094108 | doi = 10.1002/jez.a.341 | doi-access = free | bibcode = 2007JEZA..307...18Y}}</ref> A similar method was used to stimulate the compressor musculature, the main muscle responsible for the contraction and squeezing of the venom gland, and then measuring the induced pressures. It was determined that the pressure created from the fang sheath retraction was at times an order of magnitude greater than those created by the compressor musculature. Snakes do not have direct neurological control of the fang sheath, it can only be retracted as the fangs enter a target and the target's skin and body provide substantial resistance to retract the sheath. For these reasons, the pressure balance hypothesis concludes that external factors, mainly the bite and physical mechanics, are responsible for the quantity of venom expelled.{{citation needed|date=March 2023}}

=== Venom spitting ===
Venom spitting is another venom delivery method that is unique to some Asiatic and African [[cobra]]s. In venom spitting, a stream of venom is propelled at very high pressures outwards up to 3 meters (300 centimeters). The venom stream is usually aimed at the eyes and face of the target as a deterrent for predators. There are non-spitting cobras that provide useful information on the unique mechanics behind venom spitting. Unlike the elongated oval shaped exit orifices of non-spitting cobras, spitting cobras have circular exit orifice at their fang tips.<ref>{{cite journal | vauthors = Bar-On B | title = On the form and bio-mechanics of venom-injection elements | journal = Acta Biomaterialia | volume = 85 | pages = 263–271 | date = February 2019 | pmid = 30583109 | doi = 10.1016/j.actbio.2018.12.030 | s2cid = 58587928}}</ref> This combined with the ability to partially retract their fang sheath by displacing the palato-maxillary arch and contracting the adductor mandibulae, allows the spitting cobras to create large pressures within the venom delivery system.<ref>{{cite journal | vauthors = Young BA, Dunlap K, Koenig K, Singer M | title = The buccal buckle: the functional morphology of venom spitting in cobras | journal = The Journal of Experimental Biology | volume = 207 | issue = Pt 20 | pages = 3483–3494 | date = September 2004 | pmid = 15339944 | doi = 10.1242/jeb.01170 | doi-access = free| bibcode = 2004JExpB.207.3483Y }}</ref> While venom spitting is a less common venom delivery system, the venom can still cause the effects if ingested.{{citation needed|date=May 2021}}

== Society and culture ==
{{See also|Serpent (symbolism)}}
[[File:Benczur-kleopatra.jpg|thumb|right|According to tradition, [[Cleopatra|Cleopatra VII]] famously committed suicide by snakebite to her left breast, as depicted in this 1911 painting by Hungarian artist [[Gyula Benczúr]].]]
Snakes were both [[Snake worship|revered and worshipped]] and [[Ophidiophobia|feared]] by early civilizations. The [[ancient Egyptians]] recorded prescribed treatments for snakebites as early as the [[Thirteenth dynasty of Egypt|Thirteenth Dynasty]] in the [[Brooklyn Papyrus]], which includes at least seven venomous species common to the region today, such as the [[Cerastes (genus)|horned vipers]].<ref name="Schneemann2004">{{cite journal | vauthors = Schneemann M, Cathomas R, Laidlaw ST, El Nahas AM, Theakston RD, Warrell DA | title = Life-threatening envenoming by the Saharan horned viper (Cerastes cerastes) causing micro-angiopathic haemolysis, coagulopathy and acute renal failure: clinical cases and review | journal = QJM | volume = 97 | issue = 11 | pages = 717–727 | date = November 2004 | pmid = 15496528 | doi = 10.1093/qjmed/hch118 | quote = This echoed the opinion of the Egyptian physicians who wrote the earliest known account of the treatment of snake bite, the Brooklyn Museum Papyri, dating perhaps from 2200 BC. They regarded bites by horned vipers 'fy' as non-lethal, as the victims could be saved. | doi-access = free}}</ref> In [[Judaism]], the [[Nehushtan]] was a pole with a snake made of copper fixed upon it. The object was regarded as a divinely empowered instrument of God that could bring healing to Jews bitten by venomous snakes while they were wandering in the desert after their [[exodus from Egypt]]. Healing was said to occur by merely looking at the object as it was held up by [[Moses]].{{citation needed|date=March 2023}}

Historically, snakebites were seen as a means of execution in some cultures.<ref>{{cite book |last=Wilcox |first=Christie |url=https://books.google.com/books?id=tUsBCwAAQBAJ&pg=PA32 |title=Venomous: How Earth's Deadliest Creatures Mastered Biochemistry |date=2016-08-09 |publisher=Farrar, Straus and Giroux |isbn=978-0-374-71221-1 |language=en}}</ref> Reportedly, in [[Southern Han]] during [[China]]'s [[Five Dynasties and Ten Kingdoms period]] and in [[India]] a form of capital punishment was to throw people into [[snake pit]]s, leaving people to die from multiple venomous bites.<ref name="Anil2004" /> According to popular belief, the Egyptian queen [[Cleopatra|Cleopatra VII]] committed suicide by letting herself be bitten by an [[Asp (reptile)|asp]]—likely an [[Egyptian cobra]]<ref name="Schneemann2004" /><ref name="Smithsonian">{{cite web | vauthors = Crawford A |title=Who Was Cleopatra? Mythology, propaganda, Liz Taylor and the real Queen of the Nile |url=http://www.smithsonianmag.com/history-archaeology/biography/cleopatra.html |date=1 April 2007 |website=[[Smithsonian (magazine)|Smithsonian]] |access-date=4 September 2009}}</ref>—after hearing of [[Mark Antony]]'s death, while some contemporary ancient authors rather assumed a direct application of poison.<ref>{{cite book |last=Grant |first=Michael |url=https://books.google.com/books?id=7nk5AgAAQBAJ&pg=PP179 |title=Cleopatra: Cleopatra |date=2011-07-14 |publisher=Orion |isbn=978-1-78022-114-4 |language=en}}</ref>

Snakebite as a surreptitious form of murder has been featured in stories such as Sir [[Arthur Conan Doyle]]'s ''[[The Adventure of the Speckled Band]]'', but actual occurrences are virtually unheard of, with only a few documented cases.<ref name="Anil2004">{{cite journal| vauthors = Anil A |year=2004 |title=Homicide with snakes: A distinct possibility and its medicolegal ramifications |journal=Anil Aggrawal's Internet Journal of Forensic Medicine and Toxicology |volume=4 |issue=2 |url=http://www.geradts.com/anil/ij/vol_004_no_002/others/pg001.html |archive-url=https://web.archive.org/web/20070718031431/http://www.geradts.com/anil/ij/vol_004_no_002/others/pg001.html |archive-date=18 July 2007}}</ref><ref name="Warrell2009">{{cite journal | vauthors = Warrell DA | title = Commissioned article: management of exotic snakebites | journal = QJM | volume = 102 | issue = 9 | pages = 593–601 | date = September 2009 | pmid = 19535618 | doi = 10.1093/qjmed/hcp075 | doi-access = free}}</ref><ref name="Straight1994">{{cite journal | vauthors = Straight RC, Glenn JL |year=1994 |title=Human fatalities caused by venomous animals in Utah, 1900–90 |journal=[[Great Basin Naturalist]] |volume=53 |issue=4 |pages=390–4 |url=https://ojs.lib.byu.edu/ojs/index.php/wnan/article/viewFile/545/1430 |access-date=4 September 2009 |quote=A third unusual death was a tragic fatality (1987), recorded as a homicide, which resulted when a large rattlesnake (''G. v. lutosus'') bit a 22-month-old girl after the snake had been placed around her neck (Washington County). The child died in approximately 5 h. |url-status=live |archive-url=https://web.archive.org/web/20111008073525/https://ojs.lib.byu.edu/ojs/index.php/wnan/article/viewFile/545/1430 |archive-date=8 October 2011 |doi=10.5962/bhl.part.16607 |doi-access=free}}</ref> It has been suggested that [[Boris III of Bulgaria]], who was allied to [[Nazi Germany]] during [[World War II]], may have been killed with snake venom,<ref name="Anil2004" /> although there is no definitive evidence. At least one attempted suicide by snakebite has been documented in medical literature involving a [[Bitis arietans|puff adder]] bite to the hand.<ref name="Strubel2008">{{cite journal | vauthors = Strubel T, Birkhofer A, Eyer F, Werber KD, Förstl H | title = [Attempted suicide by snake bite. Case report and literature survey] | language = de | journal = Der Nervenarzt | volume = 79 | issue = 5 | pages = 604–606 | date = May 2008 | pmid = 18365165 | doi = 10.1007/s00115-008-2431-4 | trans-title = Attempted suicide by snake bite: Case report and literature survey | quote = Ein etwa 20-jähriger Arbeiter wurde nach dem Biss seiner Puffotter (''Bitis arietans'') in die Hand auf die toxikologische Intensivstation aufgenommen. Zunächst berichtet der Patient, dass es beim "Melken" der Giftschlange zu dem Biss gekommen sei, erst im weiteren Verlauf räumt er einen Suizidversuch ein. Als Gründe werden Einsamkeit angeführt sowie unerträgliche Schmerzen im Penis. | s2cid = 21805895}}</ref>

In [[Jainism]], the goddess [[Padmavati (Jainism)|Padmāvatī]] has been associated with curing snakebites.<ref>Slouber, Michael. 2017. [https://www.google.com/books/edition/Early_Tantric_Medicine/tGl4DQAAQBAJ?hl=en&gbpv=1&dq=Tvarit%C4%81&pg=PA99&printsec=frontcover Early Tantric Medicine: Snakebite, Mantras, and Healing in the Garuda Tantras]. Page 99. [[Oxford University Press]].</ref>

==Research==
In 2018, the [[World Health Organization]] listed snakebite envenoming as a neglected tropical disease.<ref>{{cite journal | vauthors = Minghui R, Malecela MN, Cooke E, Abela-Ridder B | title = WHO's Snakebite Envenoming Strategy for prevention and control | journal = The Lancet. Global Health | volume = 7 | issue = 7 | pages = e837–e838 | date = July 2019 | pmid = 31129124 | doi = 10.1016/S2214-109X(19)30225-6 | doi-access = free}}</ref><ref>{{cite journal | vauthors = Schiermeier Q | title = Snakebite crisis gets US$100-million boost for better antivenoms | language = EN | journal = Nature | date = May 2019 | pmid = 32409762 | doi = 10.1038/d41586-019-01557-0 | s2cid = 189458866}}</ref> In 2019, they launched a strategy to prevent and control snakebite envenoming, which involved a program targeting affected communities and their health systems.<ref>{{cite web |title=Snakebite: WHO targets 50% reduction in deaths and disabilities |url=https://www.who.int/news-room/detail/06-05-2019-snakebite-who-targets-50-reduction-in-deaths-and-disabilities |website=[[World Health Organization]] |access-date=30 May 2019 |language=en}}</ref><ref>{{cite journal | vauthors = Williams DJ, Faiz MA, Abela-Ridder B, Ainsworth S, Bulfone TC, Nickerson AD, Habib AG, Junghanss T, Fan HW, Turner M, Harrison RA, Warrell DA | display-authors = 6 | title = Strategy for a globally coordinated response to a priority neglected tropical disease: Snakebite envenoming | journal = PLOS Neglected Tropical Diseases | volume = 13 | issue = 2 | pages = e0007059 | date = February 2019 | pmid = 30789906 | pmc = 6383867 | doi = 10.1371/journal.pntd.0007059 | doi-access = free}}</ref> A policy analysis however found that the placement of snakebite in the global health agenda of WHO is fragile due to reluctance to accept the disease in the neglected tropical disease community and the perceived colonial nature of the network driving the agenda.<ref>{{cite journal |last1=Bhaumik |first1=Soumyadeep |last2=Zwi |first2=Anthony B. |last3=Norton |first3=Robyn |last4=Jagnoor |first4=Jagnoor |date=2023-08-01 |title=How and why snakebite became a global health priority: a policy analysis |url=https://gh.bmj.com/content/8/8/e011923 |journal=BMJ Global Health |language=en |volume=8 |issue=8 |pages=e011923 |doi=10.1136/bmjgh-2023-011923 |issn=2059-7908 |pmid=37604596 |pmc=10445399}}</ref>

Key institutions conducting snakebite research on snakebite are the George Institute for Global Health, the Liverpool School of Tropical Medicine, and the Indian Institute of Science.

==Other animals==
Several animals acquired immunity against the venom of snakes that occur in the same habitat.<ref>{{cite web| vauthors = Bittel J |title=The Animals That Venom Can't Touch|url=https://www.smithsonianmag.com/science-nature/animals-venom-cant-touch-180960658/|website=[[Smithsonian (magazine)|Smithsonian]] |access-date=29 May 2018|language=en}}</ref> This has been documented in some humans as well.<ref>{{cite news| vauthors = Collins B |title=Poison pass: the man who became immune to snake venom|url=https://www.theguardian.com/environment/2018/feb/11/poison-pass-the-man-who-became-immune-to-snake-venom-steve-ludwin|access-date=29 May 2018|work=the Guardian|date=11 February 2018|language=en}}</ref>

{{Clear}}

== References ==
{{Reflist}}

;Bibliography
{{Refbegin}}
* {{cite book |title=Snakes: The Evolution of Mystery in Nature | vauthors = Greene HW |author-link=Harry W. Greene |year=1997 |publisher=University of California Press |location=Berkeley, CA |isbn=978-0-520-20014-2 |url=https://archive.org/details/snakesevolutiono00fogd}}
* {{cite book |title=Handbook of Venoms and Toxins of Reptiles | veditors = Mackessy SP |year=2010 |publisher=CRC Press |location=Boca Raton, FL |isbn=978-0-8493-9165-1 |edition=2nd}}
* {{cite book |title=Venomous Snakes: Envenoming, Therapy | vauthors = Valenta J |year=2010 |publisher=Nova Science Publishers |location=Hauppauge, NY |isbn=978-1-60876-618-5 |edition=2nd}}
{{Refend}}

== Further reading ==
{{Library resources box|onlinebooks=yes}}
{{Refbegin|30em}}
* {{cite book | vauthors = Campbell JA, Lamar WW | author-link1 = Jonathan A. Campbell | date = 2004 | title = The Venomous Reptiles of the Western Hemisphere | location = Ithaca, NY | publisher = Cornell University Press 978-0-8014-4141-7}}
* {{cite book | vauthors = Spawls S, Branch B | date = 1995 | title = The Dangerous Snakes of Africa: Natural History, Species Directory, Venoms and Snakebite | location = Sanibel Island, FL | publisher = Ralph Curtis Publishing | isbn = 978-0-88359-029-4}}
* {{cite journal | vauthors = Sullivan JB, Wingert WA, Norris Jr RL | date = 1995 | title = North American Venomous Reptile Bites. | journal = Wilderness Medicine: Management of Wilderness and Environmental Emergencies | volume = 3 | pages = 680–709}}
* {{cite book | vauthors = Thorpe RS, Wüster W, Malhotra A | author-link2 = Wolfgang Wüster | title = Venomous Snakes: Ecology, Evolution, and Snakebite | date = 14 May 1997 | location = Oxford, England | publisher = [[Oxford University Press]] | isbn = 978-0-19-854986-4}}
{{Refend}}

== External links ==
* [https://web.archive.org/web/20100506022208/http://apps.who.int/bloodproducts/snakeantivenoms/database/ WHO Snake Antivenoms Database]
* {{cite book |last1=Organization |title=Guidelines for the management of snakebites |date=2016 |publisher=Regional Office for South-East Asia, World Health Organization |isbn=978-92-9022-530-0 |language=en|hdl=10665/249547}}
{{Medical resources
|   DiseasesDB     = 29733
|   ICD10          = {{ICD10|T|63|0|t|51}}, T14.1, W59 (nonvenomous), X20 (venomous)
|   ICD9           = {{ICD9|989.5}}, {{ICD9|E905.0}}, {{ICD9|E906.2}}
|   ICDO           =
|   OMIM           =
|   MedlinePlus    = 000031
|   eMedicineSubj  = med
|   eMedicineTopic = 2143
|   MeshID         = D012909
|   Scholia        = Q68854
}}

{{General injuries}}
{{Poisoning and toxicity}}
{{Animal bites and stings}}
{{Reptiles in culture}}
{{Authority control}}

[[Category:Animal bites]]
[[Category:Snake attacks]]
[[Category:Medical emergencies]]
[[Category:Parasitic infestations, stings, and bites of the skin]]
[[Category:Venomous snakes]]
[[Category:Wilderness medical emergencies]]
[[Category:Tropical diseases]]
[[Category:Wikipedia medicine articles ready to translate]]
[[Category:Wikipedia emergency medicine articles ready to translate]]