Editing Brown recluse spider (section)

===Misdiagnosis===
There is an [[ELISA]]-based test for brown recluse venom that can determine whether a wound is a brown recluse bite, although it is not commercially available and not in routine clinical use. Clinical diagnoses often use [[Occam's razor|Occam's razor principle]] in diagnosing bites based on what spiders the patient likely encountered and previous similar diagnoses.<ref name=NEJM2005-Vetter/><ref name=Leach/><ref>
{{cite journal
 | vauthors = Gomez H, Krywko D, Stoecker W
 | year = 2002
 | title = A new assay for the detection of ''Loxosceles'' species (brown recluse) spider venom
 | journal = [[Annals of Emergency Medicine]]
 | volume = 39 | issue = 5 | pages = 469–474
 | pmid = 11973553 | pmc = 3201721
 | doi = 10.1067/mem.2002.122914
}}
</ref>

{{harvp|Stoecker|Vetter|Dyer|2017}} suggested the [[mnemonic]] "NOT RECLUSE", shown below, as a memory device to help laymen and medical professionals more objectively screen and diagnose potential cases of loxoscelism.<ref name=Evans-2017-02-22>
{{cite news
 |first=John |last=Evans
 |date=22 February 2017
 |title=NOT RECLUSE – New mnemonic to prevent misdiagnosis of skin conditions as spider bites
 |website=derm.city
 |url=https://www.derm.city/post/2017/02/22/not-recluse-new-mnemonic-to-prevent-misdiagnosis-of-skin-conditions-as-spider-bites
}} — free access news article gives the full mnemonic
</ref><ref>
{{cite journal
 |last1=Stoecker |first1=William V.
 |last2=Vetter   |first2=Richard S.
 |last3=Dyer     |first3=Jonathan A.
 |year=2017
 |title=NOT RECLUSE – A mnemonic device to avoid false diagnoses of brown recluse spider bites
 |journal=JAMA Dermatology
 |volume=153 |issue=5 |pages=377–378
 |doi=10.1001/jamadermatol.2016.5665
 |pmid=28199453
}}
</ref>
:{| style="text-align:left;vertical-align:top;"
|+ '''NOT RECLUSE''' mnemonic<ref name=Evans-2017-02-22/>
|-
|colspan=2 align=center|''Note that these are '''contrary''' criteria: Any '''one''' being true indicates that the injury is '''not''' a brown recluse bite.''
|- style="vertical-align:top;"
| {{big|'''N'''}}umerous
| {{big|&nbsp;}}More than one wound.
|- style="vertical-align:top;"
| {{big|'''O'''}}ccurrence&nbsp;
| {{big|&nbsp;}}The injury did not occur in a place where brown recluses are likely to be found:<br/>{{big|&nbsp;}}Either outside of the spider's geographic territory ... or not in an enclosed space<br/>{{big|&nbsp;}}like a box, closet, or attic.{{big|&nbsp;}}
|- style="vertical-align:top;"
| {{big|'''T'''}}iming
| {{big|&nbsp;}}The wound arose sometime between November and March.
|- style="vertical-align:top;"
| {{big|'''R'''}}ed center
| {{big|&nbsp;}}The center of the wound is red.
|- style="vertical-align:top;"
| {{big|'''E'''}}levated
| {{big|&nbsp;}}The middle of the wound is elevated, not sunken.
|- style="vertical-align:top;"
| {{big|'''C'''}}hronic
| {{big|&nbsp;}}The wound has persisted for more than three months.
|- style="vertical-align:top;"
| {{big|'''L'''}}arge
| {{big|&nbsp;}}The wound is more than {{convert|10|cm|in|0|abbr=off}} wide.
|- style="vertical-align:top;"
| {{big|'''U'''}}lcerates<br/> too early
| {{big|&nbsp;}}The wound gets crusty within the first week.
|- style="vertical-align:top;"
| {{big|'''S'''}}wollen
| {{big|&nbsp;}}The wound swells up if it's below the neck.
|- style="vertical-align:top;"
| {{big|'''E'''}}xudative
| {{big|&nbsp;}}The wound is "wet" – oozing pus or clear fluid.
|}

There are numerous documented infectious and noninfectious conditions that produce wounds that have been initially misdiagnosed as recluse spider bites by medical professionals, including:
{{div col|colwidth=15em}}
* ''[[Pyoderma gangrenosum]]''
* Infection by ''[[Staphylococcus]]''
* Infection by ''[[Streptococcus]]''
* Herpes
* Diabetic ulcers
* Fungal infection
* Chemical burns
* [[Urushiol-induced contact dermatitis|''Toxicodendron dermatitis'']]
* [[Squamous cell carcinoma]]
* Localized [[vasculitis]]
* [[Syphilis]]
* [[Toxic epidermal necrolysis]]
* [[Sporotrichosis]]
* [[Lyme disease]]<ref>
{{cite journal
 |vauthors=Osterhoudt KC, Zaoutis T, Zorc JJ
 |year=2002
 |title=Lyme disease masquerading as brown recluse spider bite
 |journal=[[Annals of Emergency Medicine]]
 |volume=39 |issue=5 |pages=558–561
 |pmid=11973566  |doi = 10.1067/mem.2002.119509
}}
</ref>
{{div col end}}

Many of these conditions are far more common and more likely to be the source of necrotic wounds, even in areas where brown recluse spiders actually occur.<ref name=NEJM2005-Vetter/> The most important of these is [[methicillin-resistant Staphylococcus aureus|methicillin-resistant ''Staphylococcus aureus'']] (MRSA), a bacterium whose necrotic lesions are very similar to those induced by recluse bites, and which can be lethal if left untreated.<ref>
{{cite news
 |url=http://www.ktla.com/news/landing/ktla-spider-bite-death,0,5285653.story
 |title=Spider bite: Coroner's office says Pomona teen died of staph infection, not spider bite
 |website=[[KTLA]].com <!-- Bot generated title -->
 |archive-url=https://web.archive.org/web/20120318102617/http://www.ktla.com/news/landing/ktla-spider-bite-death%2C0%2C5285653.story
 |archive-date=18 March 2012
}}
</ref> Misdiagnosis of MRSA as spider bites is extremely common (nearly 30% of patients with MRSA reported that they initially suspected a spider bite), and can have fatal consequences.<ref>
{{cite journal
 | last1 = Moran | first1 = G.J.
 | display-authors = etal
 | year = 2006
 | title = Methicillin-resistant ''S. aureus'' infections among patients in the emergency department
 | journal = [[New England Journal of Medicine]]
 | volume = 355 | issue = 7 | pages = 666–674
 | doi=10.1016/0304-3940(90)90780-d | doi-access = free
 | pmid = 1691470
}}
</ref>

Reported cases of brown recluse bites occur primarily in [[Arkansas]], [[Colorado]], [[Kansas]], [[Missouri]], [[Nebraska]], [[Oklahoma]], and [[Texas]].
There have been many reports of brown recluse bites in California – though a few related species of spiders may be found there, none of the related spiders in California is known to bite humans.<ref name=VetterMyth/>

To date, the reports of bites from areas outside of the spider's native range have been either unverified or, if verified, the spiders have been moved to those locations by travelers or commerce.

==== Other spiders ====
: ''For a comparison of the toxicity of several kinds of spider''
: ''bites, see the [[list of medically significant spider bites]]''

Many arachnologists believe that a large number of bites attributed to the brown recluse in the [[West Coast of the United States|U.S. West Coast]] are either from other spider species or not spider bites at all. Other spiders in western states that might possibly cause necrotic injuries are the [[hobo spider]], [[Loxosceles deserta|desert recluse spider]], and the [[yellow sac spider]].

For example, the venom of the [[hobo spider]], a common European species now established in the northwestern United States and southern [[British Columbia]], has been reported to produce similar symptoms as the brown recluse bite when injected into laboratory rabbits. However, the toxicity of hobo spider venom has been called into question: Actual bites (rather than syringe injections) have not been shown to cause necrosis, and no necrotic hobo spider bites have ever been reported where it is native.<ref name=AnnEmergMed2004-Isbister>
{{cite journal
 | vauthors = Vetter R, Isbister G
 | year = 2004
 | title = Do hobo spider bites cause dermonecrotic injuries?
 | journal = [[Annals of Emergency Medicine]]
 | volume = 44 | issue = 6 | pages = 605–607
 | pmid = 15573036
 | doi = 10.1016/j.annemergmed.2004.03.016
}}
</ref>

Numerous other spiders have been associated with necrotic bites in the medical literature. Other recluse species, such as the [[Loxosceles deserta|desert recluse]] (found in the deserts of southwestern United States), are reported to have caused necrotic bite wounds, though only rarely.<ref name = Vetter2008>
{{cite journal
 | last = Vetter | first = R.S.
 | year = 2008
 | title = Spiders of the genus ''Loxosceles'' (Araneae, Sicariidae): A review of biological, medical, and psychological aspects regarding envenomations
 | journal = [[Journal of Arachnology]]
 | volume = 36 | pages = 150–163
 | s2cid = 7746032
 | doi = 10.1636/RSt08-06.1
 | url = https://www.biodiversitylibrary.org/part/229051
}}
</ref>
The hobo spider and the [[yellow sac spider]] have also been reported to cause necrotic bites. However, the bites from these spiders are not known to produce the severe symptoms that can follow from a recluse spider bite, and the level of danger posed by these has been called into question.<ref>
{{cite journal
 |vauthors=Bennett RG, Vetter RS
 |date=August 2004
 |title=An approach to spider bites. Erroneous attribution of dermonecrotic lesions to brown recluse or hobo spider bites in Canada
 |journal=Canadian Family Physician
 |volume=50  |issue=8  |pages=1098–1101
 |pmid=15455808 |pmc=2214648
 |url=http://www.cfp.ca/cgi/reprint/50/8/1098.pdf
}}
</ref><ref>
{{cite journal
 |first=James H. |last=Diaz
 |date=April 2005
 |title=Most necrotic ulcers are not spider bites
 |journal=American Journal of Tropical Medicine and Hygiene
 |volume=72 |issue=4 |pages=364–367
 |doi=10.4269/ajtmh.2005.72.364 |doi-access=free
}}
</ref>

So far, no known necrotoxins have been isolated from the venom of any of these spiders, and some arachnologists have disputed the accuracy of spider identifications carried out by bite victims, family members, medical responders, and other non-experts in arachnology.
There have been several studies questioning the danger posed by some of the other spiders mentioned: In these studies, scientists examined case studies of bites in which the spider in question was identified by an expert, and found that the incidence of necrotic injury diminished significantly when "questionable" identifications were excluded from the sample set.<ref name=WhiteTail>
{{cite journal
 |vauthors=Isbister GK, Gray MR
 |date=August 2003
 |title=White-tail spider bite: A prospective study of 130 definite bites by ''Lampona'' species
 |journal=The Medical Journal of Australia
 |volume=179 |issue=4 |pages=199–202
 |pmid=12914510 |s2cid=46155627
 |doi=10.5694/j.1326-5377.2003.tb05499.x
 |url=http://www.mja.com.au/public/issues/179_04_180803/isb10785_fm.html
|url-access=subscription
 }}
</ref><ref>
{{cite journal
 |vauthors=Isbister GK, Hirst D
 |date=August 2003
 |title=A prospective study of definite bites by spiders of the family Sparassidae (huntsmen spiders) with identification to species level
 |journal=Toxicon
 |volume=42 |issue=2 |pages=163–171
 |pmid=12906887
 |doi= 10.1016/S0041-0101(03)00129-6
|bibcode=2003Txcn...42..163I
 }}
</ref>