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Suborder: Araneomorphae
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Family: Sicariidae
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Genus: Loxosceles
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Species: intermedia
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Region
South America
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Countries
Argentina, Brazil
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Taxonomy and Biology
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Size: Male : Total length about 5.3 mm. Legs I to IV with lengths about 24.5, 31.8, 20.4 and 23.6 mm respectively. Palp about 5.4 mm in length.
Female : Total length about 8.5 mm. Legs I to IV with lengths about 15.1, 16.0, 13.1 and 15.5 mm respectively. Palp about 3.8 mm in length.
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Description
Male : Total length about 5.3 mm. Legs I to IV with lengths about 24.5, 31.8, 20.4 and 23.6 mm respectively. Palp about 5.4 mm in length.
Female : Total length about 8.5 mm. Legs I to IV with lengths about 15.1, 16.0, 13.1 and 15.5 mm respectively. Palp about 3.8 mm in length.
Male : Carapace is dull yellow to orange brown and thickly covered with black hairs and suberect black setae. Pars cephalica is darker orange brown to reddish brown and U-shaped contrasting with the yellowish pars thoracica. There is no darker pattern on the lateral margins. Eye tubercles are blackish. Abdomen is uniform greyish to blackish, darker dorsally than ventrally.Terminal segments of legs are orange brown to reddish brown.
Female : Carapace is dull yellow to orange brown and thickly covered with black hairs and suberect black setae. There is no darker pattern on the lateral margins. Eye tubercles are blackish. Abdomen : Abdomen is uniform greyish to blackish, darker dorsally than ventrally.
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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
Clinical effects uncertain, but related to medically important species, therefore major envenoming cannot be excluded.
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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
Insufficient case reports to know, but related species cause initially trivial bite, progressing to local pain, erythema, discolouration, blistering, ulceration & necrosis.
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General: Local Necrosis
Insufficient case reports to know, but related species cause significant local necrosis.
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General: General Systemic Effects
Insufficient case reports to know, but related species, 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
Insufficient case reports to know, but related species, potential in severe cases for haemolysis, thrombocytopenia, DIC.
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General: Renal Damage
Insufficient case reports to know, but related species 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
Insufficient case reports to know, but related species 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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