II. Types: Recluse Spider scientific names

  1. Loxosceles arizonica
  2. Loxosceles deserta
  3. Loxosceles devia
  4. Loxosceles laeta
  5. Loxosceles rufescens
  6. Loxosceles reclusa

III. Epidemiology

  1. Spiders are most abundant and active on warm nights
  2. Bites are most common in early morning hours (Brown recluse is nocturnal)
  3. Brown Recluse Spiders distribution
    1. South America
    2. Southern United States (South of I-80)
      1. Southern half of Iowa, Ilinois and Ohio
      2. East through Kentucky, Tennessee and Georgia
      3. West through Kansas, Oklahoma, and Texas

IV. Mechanism

  1. Autoimmune response from cytokines, Neutrophil activation and Lymphocytes
  2. Venom induced cytotoxicity
    1. Contains phospholipase enzyme (Sphingomyelinase D)
    2. Results in local and sometimes systemic reaction

V. Pathophysiology

  1. Brown Recluse Spider identification
    1. Males are non-descript brown Spiders
    2. Three pair of eyes (most Spiders have 4 pair of eyes)
    3. Females are more distinctive
      1. Larger leg spans (20 to 30 mm)
      2. Darker brown on the dorsal body
      3. Dorsal pattern on thorax resembles a fiddle (or inverted violin)
  2. Circumstances
    1. Spiders hide indoors in dark areas (e.g. piles of clothing, behind furniture)
    2. Bed linens or bedclothes squeeze Spider against skin
    3. Most common bite sites
      1. Axilla
      2. Waist
      3. Foot and ankles (under socks)

VI. Signs: Local bite site (Loxoscelism)

  1. Initial
    1. Minimally painful bite
  2. Next
    1. Tender, red, violaceous or hemorrhagic halo forms around bite site
  3. Next
    1. Central necrosis (40% of cases, Necrotic Arachnidism)
  4. Next
    1. Scarring (13% of cases)

VII. Signs: Systemic reactions

  1. Mild Hemolysis
    1. Mild Hemolysis
    2. Mild coagulopathy
  2. Severe Hemolysis
    1. Viscerocutaneous Loxoscelism
    2. Severe intravascular hemolytic syndrome
    3. Fever to 39-40 degrees Celsius
    4. Chills, Vomiting, and Joint Pain
    5. Hematuria
    6. Petechiae
    7. Measles-like toxic erythema rash

VIII. Differential Diagnosis

  1. Brown Recluse Spider Bites are overdiagnosed
    1. Consider other causes of necrotic wounds
    2. Vetter (2002) Ann Emerg Med 39:544-6 [PubMed]

X. Management

  1. Initial symptomatic relief
    1. Ice packs
    2. Analgesics
    3. Elevate extremity with bite site
  2. Additional wound care measures
    1. Basic wound care and cleansing of site
    2. Debride necrotic tissue
    3. Antibiotics if signs of Cellulitis
      1. Consider wound culture
    4. Tetanus prophylaxis
  3. Specific Local Therapies
    1. No specific therapy has been shown to be beneficial
    2. Antitoxin is not available outside of South America
    3. Avoid ineffective or unsupported treatments
      1. Avoid Leukocyte inhibitors (Colchicine)
      2. Avoid hyperbaric oxygen
      3. Dapsone use is controversial, but may considered as low risk intervention in severe cases
        1. Dose: 50-100 mg twice daily for 10 days
        2. Postulated to decrease Neutrophil degranulation and necrosis
        3. Do not use if G6PD positive (test first)
    4. Avoid early local procedures (spreads necrosis)
      1. Avoid early local Corticosteroid Injection
      2. Avoid early lesion excision
        1. Consider later with grafting if scarring present
  4. Severe hemolytic systemic reaction
    1. Systemic Corticosteroids
    2. Organ specific supportive therapies

XI. Course

  1. Anticipate healing over 1-8 weeks
  2. Major scarring at wound site occurs in 10-15% of cases

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Ontology: brown recluse spider bite (C0241820)

Concepts Injury or Poisoning (T037)
English bites brown recluse spider, brown recluse spider bite, bite brown recluse spider, spider bite brown recluse, Brown Recluse Spider Bites

Ontology: Brown Recluse Spider (C0323754)

Definition (MSH) A spider of the genus Loxosceles, found in the midwestern and other parts of the United States, which carries a hemolytic venom that produces local necrosis or ulceration.
Concepts Eukaryote (T204)
MSH D063287
SnomedCT 23312003
English Loxosceles reclusa Gertsch & Mulaik, 1940, brown recluse spider, recluse brown spider, spider brown recluse, brown recluse spiders, brown spiders, loxoceles reclusa, brown spider, Recluse Spider, Brown, Recluse Spiders, Brown, Spiders, Brown Recluse, Spiders, Brown Violin, Violin Spiders, Brown Violin Spiders, Violin Spider, Brown Recluse Spiders, Spider, Brown Violin, Violin Spider, Brown, Spider, Violin, Spiders, Violin, Spider, Brown Recluse, Loxosceles reclusa, Violin Spiders, Brown, Brown Violin Spider, Brown Recluse Spider, Brown recluse spider, Loxosceles reclusus, Violin spider, Loxosceles reclusus (organism)
Czech Loxosceles reclusa, koutník jedovatý
French Araignée violon, Recluse brune, Araignée violoniste, Araignée recluse brune, Loxosceles reclusa
German Loxosceles reclusa, Violinenspinne, Amerikanische Braunspinne, Einsiedlerspinne
Italian Ragno eremita marrone
Spanish Araña Reclusa Parda, Loxosceles reclusus (organismo), araña de violín, pardo recluse araña, Loxosceles reclusus
Polish Pustelnik brunatny
Portuguese Aranha Marrom Reclusa

Ontology: Poisoning due to brown recluse spider venom (C2711013)

Concepts Injury or Poisoning (T037)
SnomedCT 40119006, 217667008
English Poisoning due to brown spider venom, Poisoning-brown spider venom, Poisoning by brown recluse spider bite, Poisoning due to brown recluse spider venom (disorder), Poisoning by brown recluse spider bite (disorder), Poisoning due to brown recluse spider venom, Poisoning due to brown spider venom (disorder), Poisoning by Loxosceles bite, Poisoning due to brown spider venom (finding)
Spanish envenenamiento por picadura de araña marrón (hallazgo), envenenamiento por veneno de araña reclusa parda (trastorno), envenenamiento por veneno de araña reclusa parda, envenenamiento por picadura de la araña de los cuadros (trastorno), envenenamiento por picadura de la araña de los cuadros, envenenamiento por picadura de araña marrón, envenenamiento por picadura de araña marrón (trastorno), envenenamiento por picadura de Loxosceles