pathophysiology of spider bites
{{Short description|Reactions to venom of spider bites}}
The pathophysiology of a spider bite is due to the effect of its venom. A spider envenomation occurs whenever a spider injects venom into the skin. Not all spider bites inject venom – a dry bite, and the amount of venom injected can vary based on the type of spider and the circumstances of the encounter. The mechanical injury from a spider bite is not a serious concern for humans. Some spider bites do leave a large enough wound that infection may be a concern. However, it is generally the toxicity of spider venom that poses the most risk to human beings; several spiders are known to have venom that can cause injury to humans in the amounts that a spider will typically inject when biting.
Only a small percentage of species have bites that pose a danger to people. Many spiders do not have mouthparts capable of penetrating human skin. While venoms are by definition toxic substances, most spiders do not have venom that is toxic to humans (in the quantities delivered) to require medical attention. Of those that do, fatal outcomes are rare.{{cite journal |last1=Tavares |first1=Aluska Vieira |last2=Araújo |first2=Kalianny Adja Medeiros de |last3=Marques |first3=Michael Radan de Vasconcelos |last4=Leite |first4=Renner |title=Epidemiology of the injury with venomous animals in the state of Rio Grande do Norte, Northeast of Brazil |journal=Ciência & Saúde Coletiva |date=8 May 2020 |volume=25 |pages=1967–1978 |doi=10.1590/1413-81232020255.16572018 |url=https://www.scielosp.org/article/csc/2020.v25n5/1967-1978/ |language=en |issn=1413-8123 |quote=Most of the cases progressed to cure (91.8%) and 34 to death, of which 16 were caused by scorpions, 13 by snakes, 3 by honey bees, 1 by spiders|doi-access=free }}{{cite journal |last1=Forrester |first1=Jared A. |last2=Weiser |first2=Thomas G. |last3=Forrester |first3=Joseph D. |title=An Update on Fatalities Due to Venomous and Nonvenomous Animals in the United States (2008–2015) |journal=Wilderness & Environmental Medicine |date=March 2018 |volume=29 |issue=1 |pages=36–44 |doi=10.1016/j.wem.2017.10.004 |url=https://journals.sagepub.com/doi/full/10.1016/j.wem.2017.10.004 |language=en |issn=1080-6032|url-access=subscription }}
Spider venoms work on one of two fundamental principles; they are either neurotoxic (impairing the nervous system) or necrotic (dissolving tissues surrounding the bite). In some cases, the venom targets vital organs and systems.
Neurotoxic venom
Spiders paralyze prey with neurotoxic venom of some sort. A few have a venom that cross reacts with mammalian nervous system, though the specific manner in which the nervous system is attacked varies from spider to spider.{{cite journal |vauthors=Escoubas P, Rash L |title=Tarantulas: eight-legged pharmacists and combinatorial chemists |journal=Toxicon |volume=43 |issue=5 |pages=555–74 |date=April 2004 |pmid=15066413 |doi=10.1016/j.toxicon.2004.02.007 }}{{cite journal |author=Escoubas P |title=Molecular diversification in spider venoms: a web of combinatorial peptide libraries |journal=Molecular Diversity |volume=10 |issue=4 |pages=545–54 |date=November 2006 |pmid=17096075 |doi=10.1007/s11030-006-9050-4 |s2cid=32835420 }}{{cite journal |vauthors=Jiang L, Peng L, Chen J, Zhang Y, Xiong X, Liang S |title=Molecular diversification based on analysis of expressed sequence tags from the venom glands of the Chinese bird spider Ornithoctonus huwena |journal=Toxicon |volume=51 |issue=8 |pages=1479–89 |date=June 2008 |pmid=18482741 |doi=10.1016/j.toxicon.2008.03.024 }}
- Widow spider venom contains components known as latrotoxins, which cause the massive release of the neurotransmitters causing muscle contractions, sweating, and gooseflesh. This can affect the body in several ways, including causing painful abdominal cramps{{cite journal|author=Diaz, James H|title=The global epidemiology, syndromic classification, management, and prevention of spider bites|journal=American Journal of Tropical Medicine and Hygiene|volume=71|issue=2|date= August 1, 2004 |url=http://www.ajtmh.org/cgi/content/full/71/2/239|pages=239–250|pmid=15306718|doi=10.4269/ajtmh.2004.71.2.0700239|doi-access=free}}
- The atracotoxins of Australian funnel-web spiders work by opening sodium channels, causing excessive neural activity including strange sensations (paresthesias), muscle contractions, unstable blood pressure (hypertension or hypotension). The venom may cause fluid to accumulate in the lungs (pulmonary edema) that can be fatal.
- The venom of Brazilian wandering spiders is also a potent neurotoxin, which attacks multiple types of ion channels.{{cite journal|last1=Gomez|first1=Marcus V.|last2=Kalapothakis|first2=Evanguedes|last3=Guatimosim|first3=Cristina|last4=Prado|first4=Marco A. M.|title=Phoneutria nigriventer Venom: A Cocktail of Toxins That Affect Ion Channels|journal=Cellular and Molecular Neurobiology|volume=22|issue=5/6|year=2002|pages=579–588|issn=0272-4340|doi=10.1023/A:1021836403433|pmid=12585681|s2cid=19872450 |pmc=11533758}} Principally generating severe pain that travels up the limb, autonomic effects, including painful erections, occur with moderate envenomation. With severe envenomation heart and lung failure can result in death. In addition, the venom contains high levels of serotonin, making an envenomation by this species particularly painful.
Necrotic venom
Spiders known to have necrotic venom occur most notoriously in the family Sicariidae, which includes both the recluse spiders and the six-eyed sand spiders in the genus Hexophthalma and Sicarius. Spiders in this family possess a known dermonecrotic agent sphingomyelinase D,{{cite journal |vauthors=Senff-Ribeiro A, Henrique da Silva P, Chaim OM, Gremski LH, Paludo KS, Bertoni da Silveira R, Gremski W, Mangili OC, Veiga SS |title=Biotechnological applications of brown spider (Loxosceles genus) venom toxins |journal=Biotechnology Advances |volume=26 |issue=3 |pages=210–8 |year=2008 |pmid=18207690 |doi=10.1016/j.biotechadv.2007.12.003 }}{{cite journal |vauthors=Binford GJ, Bodner MR, Cordes MH, Baldwin KL, Rynerson MR, Burns SN, Zobel-Thropp PA |title=Molecular Evolution, Functional Variation, and Proposed Nomenclature of the Gene Family That Includes Sphingomyelinase D in Sicariid Spider Venoms |journal=Molecular Biology and Evolution |volume=26 |issue=3 |pages=547–66 |date=March 2009 |pmid=19042943 |doi=10.1093/molbev/msn274 |pmc=2767091}} which is otherwise found only in a few pathogenic bacteria.{{cite journal |vauthors=Binford GJ, Cordes MH, Wells MA |title=Sphingomyelinase D from venoms of Loxosceles spiders: evolutionary insights from cDNA sequences and gene structure |journal=Toxicon |volume=45 |issue=5 |pages=547–60 |date=April 2005 |pmid=15777950 |doi=10.1016/j.toxicon.2004.11.011 }}{{cite journal |vauthors=Cordes MH, Binford GJ |title=Lateral gene transfer of a dermonecrotic toxin between spiders and bacteria |journal=Bioinformatics |volume=22 |issue=3 |pages=264–8 |date=February 2006 |pmid=16332712 |doi=10.1093/bioinformatics/bti811 |doi-access=free }} Bites by spiders in this family can produce symptoms ranging from minor localized effects, to severe dermonecrotic lesions, up to and including severe systemic reactions including renal failure, and in some cases, death.{{cite journal
|author1=Schenone H |author2=Saavedra T |author3=Rojas A |author4=Villarroel F. | title=Loxoscelism in Chile. Epidemiologic, clinical and experimental studies
| journal=Revista do Instituto de Medicina Tropical de São Paulo
| volume=31
| year=1989
|issue=6 | pages=403–415
|doi=10.1590/S0036-46651989000600007 |pmid=2577020 | url=http://bases.bireme.br/cgi-bin/wxislind.exe/iah/online/?IsisScript=iah/iah.xis&nextAction=lnk&base=MEDLINE_1966-1995&exprSearch=2577020&indexSearch=UI&lang=i
|doi-access=free }} Even in the absence of systemic effects, serious bites from sicariid spiders may form a necrotising ulcer that destroys soft tissue and may take months and very rarely years to heal, leaving deep scars. The damaged tissue may become gangrenous and eventually slough away. Initially there may be no pain from a bite, but over time the wound may grow to 10 inches (25 cm) in extreme cases. Bites usually become painful and itchy within two to eight hours, pain and other local effects worsen 12 to 36 hours after the bite, and then necrosis will develop over the next few days.{{cite journal |vauthors=Wasserman G, Anderson P | title = Loxoscelism and necrotic arachnidism | journal = J Toxicol Clin Toxicol | volume = 21 | issue = 4–5 | pages = 451–72 | year =1983–1984 | pmid = 6381752 | doi = 10.3109/15563658308990434}}
Systemic effects are unusual but include mild nausea, vomiting, fever, rashes, and muscle and joint pain. Rarely, more severe symptoms occur including red blood cell destruction (hemolysis), low platelets (thrombocytopenia), and loss of clotting factors (disseminated intravascular coagulation).{{cite journal | author = Wasserman G | title = Bites of the brown recluse spider | journal = N Engl J Med | volume = 352 | issue = 19 | pages = 2029–30; author reply 2029–30 | year = 2005 | pmid = 15892198 | doi = 10.1056/NEJM200505123521922}} Children may be more susceptible to systemic loxoscelism effects. Deaths have been reported for both the brown recluse and the related South American species Loxosceles laeta and Loxosceles intermedia related to hemolysis and the injury that results to the kidney. Deaths attributed to brown recluse where no brown recluse live, highlight misdiagnosis and misconception{{cite news|vauthors = Lundquist L|url=http://www.bozemandailychronicle.com/news/montana_state_university/msu-expert-hopes-to-counter-brown-recluse-spider-fears/article_66ce44e2-53fb-11e4-a74b-3744663ed9ca.html|title=MSU expert hopes to counter brown recluse spider fears|date= 14 October 2014}}
Numerous other spiders have been associated with necrotic bites. The white tailed spider (Lampona spp.) had been suspected in necrotic lesions for decades only to be exonerated by the first extensive review.{{cite journal|last1=Isbister|first1=GK|last2=Gray|first2=MR|title=White-tail spider bite: a prospective study of 130 definite bites by Lampona species.|journal=The Medical Journal of Australia|date=18 August 2003|volume=179|issue=4|pages=199–202|pmid=12914510|doi=10.5694/j.1326-5377.2003.tb05499.x|s2cid=46155627 }} An early report Sac spider causing necrosis has been frequently referenced.{{cite journal|last1=FURMAN|first1=DP|last2=REEVES|first2=WC|title=Toxic bite of a spider, Cheiracanthium inclusum Hentz.|journal=California Medicine|date=August 1957|volume=87|issue=2|pages=114|pmid=13446759|pmc=1512058}} Recent surveys doubt the incidence of necrosis.{{cite journal|last1=Vetter|first1=RS|last2=Isbister|first2=GK|last3=Bush|first3=SP|last4=Boutin|first4=LJ|title=Verified bites by yellow sac spiders (genus Cheiracanthium) in the United States and Australia: where is the necrosis?|journal=The American Journal of Tropical Medicine and Hygiene|date=June 2006|volume=74|issue=6|pages=1043–8|pmid=16760517|doi=10.4269/ajtmh.2006.74.1043|doi-access=free}} Necrosis from Hobo spider, a member grass spider family Agelenidae, bite is under the same debate and doubt.{{cite journal
|author1=Bennett, R. G. |author2=R. S. Vetter.
| title=An approach to spider bites: erroneous attribution of dermonecrotic lesions to brown recluse and hobo spider bites in Canada
| journal=Canadian Family Physician
| year=2004
| volume=50
| pages=1098–1101
|pmid=15455808
|pmc=2214648
| author=James H. Diaz, MD
| title=Most necrotic ulcers are not spider bites
| journal=American Journal of Tropical Medicine and Hygiene
| volume=72
| issue=4
| date= April 1, 2005
| pages=364–367
| doi=10.4269/ajtmh.2005.72.364
| doi-access=free
}}
Differential diagnosis
The skin manifestations of recluse venom are thought to arise from Sphingomyelinase D. The enzyme acts on cell membranes. The action is therefore limited as the venom can only spread through a set area. The originally red swollen area becomes a dry black ulcer. Skin infections, in particular the widespread methicillin-resistant Staphylococcal aureus, remain swollen and red.{{cite journal|last1=Dominguez|first1=TJ|title=It's not a spider bite, it's community-acquired methicillin-resistant Staphylococcus aureus.|journal=The Journal of the American Board of Family Practice|date=May–June 2004|volume=17|issue=3|pages=220–26|pmid=15226288|doi=10.3122/jabfm.17.3.220|doi-access=free}} Pus forms and the lesion often drains. It can continue to spread and expand as the bacteria grow. Other skin lesions and infections are much more common than spider bites. Physicians have reported brown recluse spider bites where no brown recluse exist.{{cite journal|last1=Vetter|first1=RS|last2=Bush|first2=SP|title=Reports of presumptive brown recluse spider bites reinforce improbable diagnosis in regions of North America where the spider is not endemic.|journal=Clinical Infectious Diseases|date=15 August 2002|volume=35|issue=4|pages=442–45|pmid=12145729|doi=10.1086/341244|s2cid=8207786 |doi-access=free}} Ed: in 100 pictures retrieved online only 3 were consistent with Sphingomyelinase pathophysiology.
Incidence of severe envenomation
Despite public concern about spider bites, severe envenomation is rare. Few spiders have toxins in sufficient volume to harm people. Of those that do, some have limited habitats. Spider behavior may be caused by limited human interaction. Spider defense against predators include camouflage, and escape by falling or running.{{cite journal|last1=Pekár|first1=Stano|last2=Hardy|first2=Ian|title=Comparative analysis of passive defences in spiders (Araneae)|journal=Journal of Animal Ecology|date=July 2014|volume=83|issue=4|pages=779–790|doi=10.1111/1365-2656.12177|pmid=24205934|doi-access=free|bibcode=2014JAnEc..83..779P }} Biting is a last resort and the amount of venom injected varies greatly. Spider venom toxicity can be evaluated in experimental animals, or reported from accidental bites. Different experimental animals have different reactions to the same venom. The dose that is lethal to half of the animals poisoned is the LD50 and those values for mice is below. The LD50 of many poisons is known for humans but not that of spider venom.{{cn|date=January 2021}}
Serious bites develop symptoms quickly, within the hour. While a serious medical condition may result (see latrodectims and loxocelism) fatalities are exceedingly rare. Appropriate medical treatment can improve speed of recovery. The scenario given in movies such as Arachnophobia, where bite victims die within minutes, does not occur. Small children are considered an exception because the amount of venom dispersed throughout the body is many times the concentration in an adult. There is at least one recorded case of a small child dying within 15 minutes of a bite from a Sydney funnel-web spider; that death occurred before the development of an antivenom. Since the antivenom was developed there have been no fatalities due to this species.
The neurotoxic venoms of the Sydney funnel-web spider and the Brazilian wandering spider are both known to have lethal complications. For the Brazilian wandering spider only 1 out of 200 bites is serious,{{Cite journal|url=http://www.revistas.usp.br/rimtsp/article/view/30402|title=A clinico-epidemiological study of bites by spiders of the genus Phoneutria | BUCARETCHI | Revista do Instituto de Medicina Tropical de São Paulo|journal=Revista do Instituto de Medicina Tropical de São Paulo|volume=42|pages=17–21|access-date=14 February 2015|doi=10.1590/S0036-46652000000100003|year=2000|last1=Bucaretchi|first1=Fábio|last2=Deus Reinaldo|first2=Cláudia Regina de|last3=Hyslop|first3=Stephen|last4=Madureira|first4=Paulo Roberto|last5=De Capitani|first5=Eduardo Mello|last6=Vieira|first6=Ronan José|issue=1|pmid=10742722|doi-access=free}} in part because they appear to be capable of biting without injecting venom.Vital-Brazil, O.; Bernardo-Leite, G.B. & Fontana, M.D. (1988) Modo de ação da peçonha da aranha armadeira, Phoneutria nigriventer (Keiserling, 1891), nas aurículas isoladas de cobaia. Ciênc. Cult., 40: 181-185 Atrax robustus has a limited distribution and few bites are reported yearly.
The geographical range of the widow spiders is very great. As a result, far more people are exposed, worldwide, to widow bites than any other spider. Widow spiders bites are most often mild but may rarely cause serious complications in people. Fatalities had been reported as high as 5% of bites and as low as 0.2% of bites.{{cite journal | author = Bettini S | title = Epidemiology of Latrodectism | journal = Toxicon | volume = 2 | issue = 2| pages = 93–102 | year = 1964| pmid = 14301291|doi=10.1016/0041-0101(64)90009-1}}
Loxosceles live in areas of South America and the southern United States. There are populations of desert and Arizona recluse in the Western deserts of the United States,{{cite web|url=http://insects.about.com/od/spiders/tp/brown-recluse-lies.htm|title=5 Lies About the Brown Recluse Spider|access-date=16 June 2016}} but bites are rarely reported from these species. In established areas many spiders may populate the home. Even still the "reclusive" nature of the spider limits true bites.{{cite journal|last1=Vetter|first1=Richard S.|last2=Barger|first2=Diane K.|title=An Infestation of 2,055 Brown Recluse Spiders (Araneae: Sicariidae) and No Envenomations in a Kansas Home: Implications for Bite Diagnoses in Nonendemic Areas|journal=Journal of Medical Entomology|date=1 November 2002|volume=39|issue=6|pages=948–951|doi=10.1603/0022-2585-39.6.948|pmid=12495200|doi-access=free}} More bites had been reported in Florida than recluses ever found in the area.{{cite journal|last1=Vetter|first1=Richard S.|last2=Edwards|first2=G. B.|last3=James|first3=Louis F.|title=Reports of Envenomation by Brown Recluse Spiders (Araneae: Sicariidae) Outnumber Verifications of Loxosceles Spiders in Florida|journal=Journal of Medical Entomology|date=1 July 2004|volume=41|issue=4|pages=593–597|doi=10.1603/0022-2585-41.4.593|pmid=15311449|doi-access=free}}
=Clinical presentation=
| class="wikitable" |
| align="left" style="background-color: #cccccc;"
! Genus ! Species ! Common name ! Body length ! Venom amount ! LD-50 ! Alternate LD-50 ! Deaths reported |
| Atrax
| A. robustus | 0.25 mg (F) and 0.81 mg (M) {{cite web |author1=While, Julian |author2=Gray, Michael | title=Atrax Robustus | work=IPCS INCHEM | publisher=International Programme on Chemical Safety | url=http://www.inchem.org/documents/pims/animal/atrax.htm | year=1989 }} 2 mg {{cite journal |author1=Sutherland SK |author2=Duncan AW |author3=Tibballs J. | title=Local inactivation of funnel-web spider (Atrax robustus) venom by first-aid measures: potentially lifesaving part of treatment | journal=Medical Journal of Australia | volume=2 | issue=8 | date=1980-10-18 | pages=435–437 |doi=10.5694/j.1326-5377.1980.tb131912.x | pmid=7207322 |s2cid=10212346 }} | 0.16 mg/kg {{cite journal |vauthors=Sheumack DD, Baldo BA, Carroll PR, Hampson F, Howden ME, Skorulis A | title=A comparative study of properties and toxic constituents of funnel web spider (Atrax) venoms | journal=Comparative Biochemistry and Physiology | year=1984 | volume=78 | issue=1 | pages=55–68 | doi=10.1016/0742-8413(84)90048-3 | pmid=6146485 }} | unknown | 13 attributed deaths from 1927 to 1980Manson's tropical diseases By Gordon C. Cook, Patrick Manson, Alimuddin Zumla, p. 592 |
| Hadronyche
| H. formidabilis | Northern tree funnel-web spider | 23–45 mm. | | | | 1 death.{{cite web|url=http://www.csiro.au/Outcomes/Environment/Biodiversity/Funnelweb-Spider-Facts.aspx|title=Funnel-web spider|last=CSIRO|date=15 May 2012|work=CSIRO website|access-date=4 November 2013|archive-url=https://web.archive.org/web/20131106110207/http://www.csiro.au/Outcomes/Environment/Biodiversity/Funnelweb-Spider-Facts.aspx|archive-date=6 November 2013|url-status=dead}} High rates of severe envenoming.{{cite journal |author1=Vetter, Richard S. |author2=Isbister, Geoffrey K. |title=Medical Aspects of Spider Bites |journal=Annual Review of Entomology |volume=53 |pages=409–29 |year=2008 |pmid=17877450 |doi= 10.1146/annurev.ento.53.103106.093503}}{{cite journal |vauthors=Isbister G, Gray M, Balit C, Raven R, Stokes B, Porges K, Tankel A, Turner E, White J, Fisher M | title = Funnel-web spider bite: a systematic review of recorded clinical cases | journal = Med J Aust | volume = 182 | issue = 8 | pages = 407–11 | year = 2005 | pmid = 15850438|url=https://www.mja.com.au/journal/2005/182/8/funnel-web-spider-bite-systematic-review-recorded-clinical-cases?iframe=true | doi=10.5694/j.1326-5377.2005.tb06760.x| hdl = 2440/17349 | s2cid = 18066524 | hdl-access = free }} |
| Hadronyche
| H. cerberea | Southern tree funnel-web spider | | | | |
| Latrodectus
| L. mactans | Black widow | 0.02–.03 mg.{{Cite journal |author=Stewart, Charles |title=Beyond the Road: Environmental Emergencies for Emergency Service Providers |publisher=Charles Stewart and Associates |year=1998 |url=http://www.storysmith.net/Articles/Bites%20and%20stings.pdf |access-date=2015-02-14 |archive-url=https://web.archive.org/web/20070810231017/http://www.storysmith.net/Articles/Bites%20and%20stings.pdf |archive-date=2007-08-10 |url-status=dead | 0.9 mg/kg | 36 deaths recorded from 1965 to 1990 in the U.S. |
| Latrodectus
| L. tredecimguttatus | (approx. same) | (approx. same) | 0.68 μg/kg {{cite journal | author1=Ori, Masahisa | author2=Ikeda, Hiroyoshi | title=Spider Venoms and Spider Toxins | journal=Journal of Toxicology: Toxin Reviews | volume=17 | issue=3 | year=1998 | pages=405–426 | url=http://homepage3.nifty.com/~hispider/spidervenom.txt | doi=10.3109/15569549809040401 | access-date=2015-02-14 | archive-url=https://web.archive.org/web/20091222192002/http://homepage3.nifty.com/~hispider/spidervenom.txt | archive-date=2009-12-22 | url-status=dead | url-access=subscription }} | possibility of deaths in Southern Europe first attributed to the brown recluse, suggesting larger frequency of the bites. |
| Loxosceles
| L. reclusa | .13–.27 mg.{{cite journal |author1=M. F. Manzoli-Palma |author2=N. Gobbi |author3=M. S. Palma | title=Insects as biological models to assay spider and scorpion venom toxicity | journal=Journal of Venomous Animals and Toxins Including Tropical Diseases | volume=9 | issue=2 | year=2003 | doi=10.1590/S1678-91992003000200004 | pages=174–185 | doi-access=free | hdl=11449/212375 | hdl-access=free }} | | |
| Loxosceles
| L. intermedia | | | | 0.48 mg/kg {{cite journal |vauthors=Barbaro KC, Ferreira ML, Cardoso DF, Eickstedt VR, Mota I | title=Identification and neutralization of biological activities in the venoms of Loxosceles spiders | journal=Brazilian Journal of Med Biol Res | date=November 1996 | volume=29 | issue=11 | pages=1491–7 | pmid=9196551 }} 0.34 mg/kg (SC){{Cite web|title=Loxosceles intermedia ~ VenomZone page|url=https://venomzone.expasy.org/3596|access-date=2020-10-17|website=venomzone.expasy.org}} | | |
| Loxosceles
| L. laeta | | | |
| Loxosceles
| L. gaucho | | | | | |
| Phoneutria
| P. bahiensis | 30 mm | | cardiac failure reported in 5 out of 12 bitten |
| Phoneutria
| P. boliviensis | 30 mm | | |
| Phoneutria
| P. fera | | disputed effectiveness of the antivenin – 4 deaths out of 7 administered |
| Phoneutria
| P. nigriventer | 3–5 cm (1.25–2 in) {{cite web | author=Lelle Petterson | title=The genus Phoneutria, Perty 1833, wandering spiders | work=Minax tarantulas | url=http://www.minaxtarantulas.net/artiklar/phoneutria/phoneutria_e.html | access-date=2015-02-14 | archive-url=https://web.archive.org/web/20110927173910/http://www.minaxtarantulas.net/artiklar/phoneutria/phoneutria_e.html | archive-date=2011-09-27 | url-status=dead }} | 15.20 ng/mg. 00061–.00157 mg/kg | severe cardiac failure, signs of priapism and irreversible damage to the central nervous system recorded. |
| Phoneutria
| P. reidyi | 30 mm | | 0.3 mg/kg | |
| Hexophthalma
| spp. | Six-eyed sand spiders | 17 mm | | | | large necrotic lesions |
| Haplopelma
| H. schmidti (previously H. huwenum, Selenocosmia huwena) | Chinese bird spider | | 0.70 mg/kg {{cite journal |vauthors=Liang SP, Zhang DY, Pan X, Chen Q, Zhou PA | title=Properties and amino acid sequence of huwentoxin-I, a neurotoxin purified from the venom of the Chinese bird spider Selenocosmia huwena | journal=Toxicon | date=August 1993 | volume=31 | issue=8 | pages=969–78 | doi=10.1016/0041-0101(93)90256-I | pmid=8212049 }} | | 1 death reported of a 5-year-old child suffocated, possibly caused by allergens to the venom. |
| Poecilotheria
| P. ornata | Fringed ornamental tarantula | | | | | Instances of coma reported.http://www.spidertalk.net/SpiderTalk/post.php?action=reply&fid=1&tid=2165&repquote=16279 {{dead link|date=May 2013}}{{reliable source|date=May 2013}} |
| Poecilotheria
| P. fasciata | Sri Lankan ornamental tarantula | | | | | Instances of cardiac failure reported {{dead link|date=May 2013}}{{reliable source|date=May 2013}} |
| Cheiracanthium
| spp. | 6–10 mm | | | |
| Cheiracanthium
| C. japonicum | Japanese sac spider | 6–10 mm | | | | |
| Macrothele
| M. holsti, M. gigas, M. taiwanensis | Primitive burrowing spiders | | | | | No deaths reported in Taiwan.{{cite journal |author1=Hung, Shin-Wen |author2=Wong, Tzong-Leun | title=Arachnid Envenomation in Taiwan | journal=Ann. Disaster Med. | volume=3 |issue=Suppl. 1 | pages=S12–S17 | url=http://www.disaster.org.tw/chinese/annmed/Vol3supp1/3.pdf }} |
| Steatoda
| S. grossa | | | | | Mild widow-like symptoms reported, no severe consequences |