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Loxosceles reclusa
General Details, Taxonomy and Biology, Venom, Clinical Effects, Treatment, First Aid , Antivenoms
Loxosceles reclusa ( Violin Spider )  [ Original photo copyright © Dr Julian White ]
Suborder: Araneomorphae
Family: Sicariidae
Genus: Loxosceles
Species: reclusa
Common Names
Violin Spider , Brown Recluse Spider
Region
North America + Central America
Countries
Mexico, United States of America
 
Taxonomy and Biology
Size: Total length of adult females varies between about 7 mm to 12 mm and total length of adult males varies between about 6 mm to 11 mm.

Male : Total length about 8.0 mm. Legs I to IV with lengths about 19.85, 24.40, 17.25 and 18.85 mm respectively. Palp about 3.79 mm in length.

Female : Total length about 9.0 mm. Legs I to IV with lengths about 16.70, 18.30, 15.00 and 17.20 mm respectively. Palp about 4.25 mm in length.
Description
Total length of adult females varies between about 7 mm to 12 mm and total length of adult males varies between about 6 mm to 11 mm.

Male : Total length about 8.0 mm. Legs I to IV with lengths about 19.85, 24.40, 17.25 and 18.85 mm respectively. Palp about 3.79 mm in length.

Female : Total length about 9.0 mm. Legs I to IV with lengths about 16.70, 18.30, 15.00 and 17.20 mm respectively. Palp about 4.25 mm in length.

Males and Females : Carapace dorsal colour is pale yellowish to dark orange brown or reddish brown. Pars cephalica is reddish brown, paler towards the centre with several dark and pale streaks and followed posteriorly by a narrow dark stripe along the median groove to form a violin shaped marking. Sides of pars cephalica with 3 darker, dusky spots, extending to the lateral margin. Abdomen is relatively uniform whitish to grey and sometimes dark grey.
Habitat
Widely distributed in southern central USA. In more southern areas it is most often found under rocks and ground litter in moist locations and inside buildings. In northern portions of its range it is most often found in domestic situations such as in gardens and houses and other buildings.
Species Map
Small (Approx 20k) version
 
Venom
General: Venom Neurotoxins
Possibly present but not clinically significant
General: Venom Myotoxins
Possibly present but not clinically significant
General: Venom Procoagulants
Possibly present but not clinically significant
General: Venom Anticoagulants
Not present
General: Venom Haemorrhagins
Not present
General: Venom Nephrotoxins
Not present
General: Venom Cardiotoxins
Not present
General: Venom Necrotoxins
Primary necrotoxins
General: Venom Other
Not present or not significant
 
Clinical Effects
General: Dangerousness
Severe envenoming possible, potentially lethal
General: Rate of Envenoming: Unknown but likely to be low
General: Untreated Lethality Rate: Unknown but lethal potential cannot be excluded
General: Local Effects
Initially trivial bite, progressing to local pain, erythema, discolouration, blistering, ulceration & necrosis.
General: Local Necrosis
Major effect of envenoming is progressive local necrosis.
General: General Systemic Effects
May develop 2-3 days of fever, malaise, rash.
General: Myotoxicity
Does not occur, based on current clinical evidence
General: Coagulopathy & Haemorrhages
Potential in severe cases (viscero-cutaneous loxoscelism) for haemolysis, thrombocytopenia, DIC.
General: Renal Damage
Can cause secondary renal failure (rare; viscero cutaneous loxoscelism only).
General: Cardiotoxicity
Does not occur, based on current clinical evidence
General: Other
Can cause shock (rare; viscero cutaneous loxoscelism only).
 
First Aid
Description: First aid for Recluse Spider Bites (includes fiddleback spiders)
Details
1. Most bites go unnoticed at the time, only becoming evident later, once local tissue injury commences, by which time first aid is useless.
2. If the bite is witnessed, capture the spider and take it with the victim to a hospital or doctor.
3. Most traditional, and many of the more recently fashionable, first aid measures are useless and potentially dangerous. These include local cauterization, incision, excision, amputation, suction by mouth, vacuum pump or syringe, combined incision and suction ("venom-ex" apparatus), injection or instillation of compounds such as potassium permanganate, phenol (carbolic soap) and trypsin, application of electric shocks or ice (cryotherapy), use of traditional herbal, folk and other remedies including the ingestion of emetic plant products and parts of the snake, multiple incisions, tattooing and so on.
 
Treatment
Treatment Summary
The treatment of loxoscelism is controversial. Except for Brazil, no antivenom is available and even in Brazil, its role is uncertain. Good wound care, targeted treatment of secondary infection, avoidance of early surgical intervention and pain relief are important. Hyperbaric oxygen therapy remains an unproven treatment, though some experts believe it can assist pain relief and healing. Patients should be aware that local skin necrosis may take many weeks or months to heal. Patients with viscerocutaneous loxoscelism require urgent medical attention and full supportive therapy.
Key Diagnostic Features
Bite usually minor or not noticed; progressive local erythema, pain, mottled haemorrhagic colour, blisters, eschar formation (5-7 days), systemically unwell.
General Approach to Management
While most cases will be minor, not requiring admission, some cases will be more severe, requiring admission and treatment, so assess carefully before early discharge.
Antivenom Therapy
The role of antivenom in treating loxoscelism is uncertain, but where available (eg parts of Sth America) it should be used.
Antivenoms
1. Antivenom Code: IAmIBB01
Antivenom Name: Soro antiarachnidico
Manufacturer: Instituto Butantan
Phone: +55-11-3726-7222
Address: Av. Vital Brasil, 1500 Butanta
05503-900
Sao Paulo - SP
Country: Brazil
2. Antivenom Code: IAmINP04
Antivenom Name: Suero Antiloxoscelico
Manufacturer: Instituto Nacional de Salud
Phone: ++51-1-467-4499
Address: Centro Nacional de Produccion de Biologicos
Av. Defensores del Morro 2268
Chorrillos
Lima 9
Country: Peru
3. Antivenom Code: IAmIBM07
Antivenom Name: Aracmyn
Manufacturer: Instituto Bioclon
Phone: ++56-65-41-11
Address: Calzada de Tlalpan No. 4687
Toriello Guerra
C.P. 14050
Mexico, D.F.,
Country: Mexico
Loxosceles reclusa ( Violin Spider ) [ Original photo copyright © Dr Julian White ]
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