![Loxosceles rufescens ( ) [ Original photo copyright © Dr Julian White ]](images/spiders/SPP001581.jpg)
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Suborder: Araneomorphae
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Family: Sicariidae
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Genus: Loxosceles
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Species: rufescens
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Region
Global-land only
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Countries
Albania, Algeria, Australia, Bosnia and Herzegovina, Brazil, Central African Republic, Chad, China, Democratic Republic of Congo, Republic of Congo, Croatia, Cuba, Cyprus, Dominican Republic, Egypt, Eritrea, Ethiopia, France, Greece, Haiti, Israel, Italy, Jamaica, Japan, Jordan, Lebanon, Libya, Macedonia, Madagascar, Mali, Mexico, Morocco, Myanmar, Niger, Paraguay, Portugal, Russia, Slovenia, Spain, Sudan, Turkey, Ukraine, United States of America, Yugoslavia, Mauritania, West Sahara
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Taxonomy and Biology
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Size: Male : Total length about 7.7 mm. Legs I to IV with lengths about 15.50, 16.85, 13.90 and 16.05 mm respectively. Palp about 3.50 mm in length.
Female : Total length about 7.0 mm. Legs I to IV with lengths about 20.15, 23.70, 18.15 and 20.20 mm respectively. Palp about 3.20 mm in length.
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Description
Male : Total length about 7.7 mm. Legs I to IV with lengths about 15.50, 16.85, 13.90 and 16.05 mm respectively. Palp about 3.50 mm in length.
Female : Total length about 7.0 mm. Legs I to IV with lengths about 20.15, 23.70, 18.15 and 20.20 mm respectively. Palp about 3.20 mm in length.
Males and Females : Carapace is dull to bright orange brown with or without dusky lateral lines on the pars cephalica and dusky spots or patches on lateral margins of pars thoracica. Abdomen is yellowish to greyish brown. Legs are yellowish to dusky orange.
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Venom
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General: Venom Neurotoxins
Possibly present but not clinically significant
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General: Venom Myotoxins
Possibly present but not clinically significant
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General: Venom Procoagulants
Possibly present but not clinically significant
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General: Venom Anticoagulants
Not present
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General: Venom Haemorrhagins
Not present
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General: Venom Nephrotoxins
Not present
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General: Venom Cardiotoxins
Not present
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General: Venom Necrotoxins
Primary necrotoxins
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General: Venom Other
Not present or not significant
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Clinical Effects
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General: Dangerousness
Severe envenoming possible, potentially lethal
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General: Rate of Envenoming: Unknown but likely to be low
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General: Untreated Lethality Rate: Unknown but lethal potential cannot be excluded
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General: Local Effects
Initially trivial bite, progressing to local pain, erythema, discolouration, blistering, ulceration & necrosis.
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General: Local Necrosis
Major effect of envenoming is progressive local necrosis.
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General: General Systemic Effects
May develop 2-3 days of fever, malaise, rash.
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General: Myotoxicity
Does not occur, based on current clinical evidence
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General: Coagulopathy & Haemorrhages
Potential in severe cases (viscero-cutaneous loxoscelism) for haemolysis, thrombocytopenia, DIC.
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General: Renal Damage
Can cause secondary renal failure (rare; viscero cutaneous loxoscelism only).
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General: Cardiotoxicity
Does not occur, based on current clinical evidence
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General: Other
Can cause shock (rare; viscero cutaneous loxoscelism only).
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First Aid
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Description: First aid for Recluse Spider Bites (includes fiddleback spiders)
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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.
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Treatment
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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.
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Key Diagnostic Features
Bite usually minor or not noticed; progressive local erythema, pain, mottled haemorrhagic colour, blisters, eschar formation (5-7 days), systemically unwell.
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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.
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Antivenom Therapy
The role of antivenom in treating loxoscelism is uncertain, but where available (eg parts of Sth America) it should be used.
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| 1. Antivenom Code: IAmIBB01
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Antivenom Name: Soro antiarachnidico
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Manufacturer: Instituto Butantan
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Phone: +55-11-3726-7222
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Address: Av. Vital Brasil, 1500 Butanta
05503-900
Sao Paulo - SP
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Country: Brazil
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| 2. Antivenom Code: IAmINP04
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Antivenom Name: Suero Antiloxoscelico
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Manufacturer: Instituto Nacional de Salud
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Phone: ++51-1-467-4499
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Address: Centro Nacional de Produccion de Biologicos
Av. Defensores del Morro 2268
Chorrillos
Lima 9
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Country: Peru
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| 3. Antivenom Code: IAmIBM07
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Antivenom Name: Aracmyn
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Manufacturer: Instituto Bioclon
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Phone: ++56-65-41-11
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Address: Calzada de Tlalpan No. 4687
Toriello Guerra
C.P. 14050
Mexico, D.F.,
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Country: Mexico
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