Elsevier

Clinics in Dermatology

Volume 24, Issue 3, May–June 2006, Pages 213-221
Clinics in Dermatology

Loxoscelism

https://doi.org/10.1016/j.clindermatol.2005.11.006Get rights and content

Abstract

Loxoscelism (bites by spiders of the genus Loxosceles) is the only proven arachnological cause of dermonecrosis. Although Loxosceles spiders can be found worldwide, their distribution is heavily concentrated in the Western Hemisphere, particularly the tropical urban regions of South America. Although Loxosceles bites are usually mild, they may ulcerate or cause more severe, systemic reactions. These injuries mostly are due to sphingomyelinase D in the spider venom. There is no proven effective therapy for Loxosceles bites, although many therapies are reported in the literature.

Section snippets

Loxoscelism

A small percentage of the spider species in the world are medically important with the majority causing systemic injury. Spiders of the genus Loxosceles cause necrotic dermatologic injury through a unique enzyme, sphingomyelinase D, found only in one other spider genus and several bacteria.1 The first inklings of association of spiders in general with dermonecrosis were made in the late 19th century in the Western Hemisphere.2, 3 In the early 20th century, suspected association specifically to

Distribution of Loxosceles

There are 11 native and two nonnative species of Loxosceles spiders in North America.6, 7 The brown recluse spider, Loxosceles reclusa, (Fig. 1) is the best known and is responsible for most American envenomations. In subtropical North America, the brown recluse can be found from Texas to northern Georgia. The anecdotal opinion of southeastern American arachnologists, which was corroborated by a recent distribution study,8 is that as one gets closer to the Gulf of Mexico, Loxosceles specimens

Identification of Loxosceles spiders

Many medical publications definitively state that Loxosceles spiders can easily be identified by a violin or fiddle pattern on the dorsal surface of the cephalothorax. Although this is true in principle, lack of expertise causes nonarachnologists (including physicians) to mistake many varied darkened forms on spider bodies as violin patterns.8, 17 Although several Loxosceles species can indeed be readily identified by a violin, using this overly simplified diagnostic identifier will lead to

Other spiders purported to cause necrosis

Over several decades, many additional spiders from a diverse number of spider genera have been implicated in dermonecrosis including orbweavers, wolf spiders, funnel-weaving spiders, etc. Much of this has occurred by the simple implication of spiders by patients presenting with dermonecrosis, but while lacking the definitive proof of a spider caught in the act of biting and properly identified. Many of these events have been reported under the blanket term of necrotic arachnidism, and,

Loxosceles toxin

Loxosceles bites can cause necrosis in humans, guinea pigs, and rabbits,28 but not in mice and rats,29 thereby showing differential mammalian toxicity due to unknown reason. Research has recently characterized the nature and composition of the toxins causing the necrosis. The toxins are the same in constituency in male and female Loxosceles, but the females have more concentrated venom—as much as two times the concentration of that of the male spider.30 Fifteen micrograms of venom will produce

Pathophysiology

In milder cases, Loxosceles bites may simply cause a very mild urticarial reaction.51 In the more severe cases, the initial bite is painless,13 but this is followed over 2 to 8 hours by sharp, penetrating pain that progressively changes into a burning sensation.3, 13 There may be two small puncta at the bite site (Fig. 4).13 The bite area pales52 and the area immediately surrounding the bite becomes red and edematous, with mild to severe pain secondary to vasospasm and ischemia.13 A blister may

Diagnosis

The standard for diagnosis of spider bites is collecting and properly identifying the biting spider responsible for the cutaneous findings.

Other diseases are frequently misdiagnosed as loxoscelism.65 These include staphylococcal or streptococcal infection, herpes simplex, herpes zoster, diabetic ulcer, fungal infection, pyoderma gangrenosum, lymphomatoid papulosis, chemical burn, Toxicodendron dermatitis, squamous cell carcinoma, neoplasia, localized vasculitis, syphilis, Stevens-Johnson

Laboratory diagnosis

The diagnosis of loxoscelism remains a clinical judgment dependent on proof of a Loxosceles spider bite. There is at least one potential venom test that has been developed and tested experimentally, using an ELISA.52 The authors detected venom from rabbit test subjects up to 7 days after injection. Venom was recoverable from plucked hair and skin aspirates, but the greatest yield was with biopsy specimens. There is currently no commercially available assay for humans.

Therapy

The proper treatment of loxoscelism remains controversial. Reported therapies include hyperbaric oxygen, dapsone,52 antihistamines including cyproheptadine,52 antibiotics, dextran, glucocorticosteroids,73 vasodilators,74 heparin, nitroglycerin, electric shock, curettage, surgical excision, and antivenin.52 It seems reasonable at minimum to provide routine first aid: elevation, immobilization, application of ice, local wound care, and tetanus prophylaxis.

Dapsone has been recommended for over two

Conclusions

Loxosceles spiders are the only important cause of skin necrosis from spider bites. Loxosceles spiders are common in much of the tropical and temperate world. Considering how prevalent they are, human bites from Loxosceles spiders are uncommon. When bites occur, they are usually mild, but they can occasionally cause ulceration and rarely systemic symptoms. Other more common diseases mimic spider bites, and, therefore, unless the culprit Loxosceles spider is caught in the act, practitioners must

References (94)

  • R.B. da Silveira et al.

    Identification of proteases in the extract of venom glands from brown spiders

    Toxicon

    (2002)
  • E. Kalapothakis et al.

    Molecular cloning, expression and immunological properties of LiD1, a protein from the dermonecrotic family of Loxosceles intermedia spider venom

    Toxicon

    (2002)
  • P. Guilherme et al.

    Neutralization of dermonecrotic and lethal activities and differences among 32-35 kDa toxins of medically important Loxosceles spider venoms in Brazil revealed by monoclonal antibodies

    Toxicon

    (2001)
  • B.R. Norment et al.

    Separation and characterization of venom components in Loxosceles reclusa-III. Hydrolytic enzyme activity

    Toxicon

    (1979)
  • L.J. Forrester et al.

    Red blood cell lysis induced by the venom of the brown recluse spider: The role of sphingomyelinase D

    Arch Biochem Biophys

    (1978)
  • F.E. Russell

    Phosphodiesterase of some snake and arthropod venoms

    Toxicon

    (1966)
  • Y.S. Jong et al.

    Separation and characterization of venom components in Loxosceles reclusa-II. Protease enzyme activity

    Toxicon

    (1979)
  • L. Feitosa et al.

    Detection and characterization of metalloproteinases with gelatinolytic, fibronectinolytic and fibrinogenolytic activities in brown spider (Loxosceles intermedia) venom

    Toxicon

    (1998)
  • S.S. Veiga et al.

    Identification of high molecular weight serine-proteases in Loxosceles intermedia (brown spider) venom

    Toxicon

    (2000)
  • D.V. Tambourgi et al.

    Loxosceles intermedia spider envenomation induces activation of an endogenous metalloproteinase, resulting in cleavage of glycophorins from the erythrocyte surface and facilitating complement-mediated lysis

    Blood

    (2000)
  • M.J. Foradori et al.

    An examination of the potential role of spider digestive proteases as a causative factor in spider bite necrosis

    Comp Biochem Physiol C

    (2001)
  • C.L. Monteiro et al.

    Isolation and identification of Clostridium perfringens in the venom and fangs of Loxosceles intermedia (brown spider): enhancement of the dermonecrotic lesion in loxoscelism

    Toxicon

    (2002)
  • H.F. Gomez et al.

    A new assay for the detection of Loxosceles species (brown recluse) spider venom

    Ann Emerg Med

    (2002)
  • P.C. Anderson

    Loxoscelism threatening pregnancy: five cases

    Am J Obstet Gynecol

    (1991)
  • S.S. Veiga et al.

    In vivo and in vitro cytotoxicity of brown spider venom for blood vessel endothelial cells

    Thromb Res

    (2001)
  • D.V. Tambourgi et al.

    Loxosceles sphingomyelinase induces complement-dependent dermonecrosis, neutrophil infiltration, and endogenous gelatinase expression

    J Invest Dermatol

    (2005)
  • C.A. Gates et al.

    Serum amyloid P component: its role in platelet activation stimulated by sphingomyelinase D purified from the venom of the brown recluse spider (Loxosceles reclusa)

    Toxicon

    (1990)
  • R.S. Vetter et al.

    Diagnoses of brown recluse spider bites (loxoscelism) greatly outnumber actual verifications of the spider in four western American states

    Toxicon

    (2003)
  • F.E. Russell et al.

    Letter to the editor

    Toxicon

    (1983)
  • K.C. Osterhoudt et al.

    Lyme disease masquerading as brown recluse spider bite

    Ann Emerg Med

    (2002)
  • U. Paniker et al.

    Dapsone and sulfapyridine

    Dermatol Clin

    (2001)
  • S.M. Barrett et al.

    Dapsone or electric shock therapy of brown recluse spider envenomation?

    Ann Emerg Med

    (1994)
  • S. Phillips et al.

    Therapy of brown spider envenomation: a controlled trial of hyperbaric oxygen, dapsone, and cyproheptadine

    Ann Emerg Med

    (1995)
  • S.M. Bryant et al.

    Dapsone use in Loxosceles reclusa envenomation: is there an indication?

    Am J Emerg Med

    (2003)
  • R.H. Guderian et al.

    High voltage shock treatment for snake bite

    Lancet

    (1986)
  • K.C. Barbaro et al.

    Enzymatic characterization, antigenic cross-reactivity and neutralization of dermonecrotic activity of five Loxosceles spider venoms of medical importance in the Americas

    Toxicon

    (2005)
  • R. Rees et al.

    The diagnosis and treatment of brown recluse spider bites

    Ann Emerg Med

    (1987)
  • S.C. Araujo et al.

    Protection against dermonecrotic and lethal activities of Loxosceles intermedia spider venom by immunization with a fused recombinant protein

    Toxicon

    (2003)
  • W.A. Caveness

    Insect bite, complicated with fever

    Nashville J Med Surg

    (1872)
  • A. Macchiavello

    Cutaneous arachnidism or gangrenous spot of Chile

    P R J Public Health Trop Med

    (1947)
  • L.F. Schmaus

    Case of arachnidism (spider bite)

    JAMA

    (1929)
  • J.A. Atkins et al.

    Probable cause of necrotic spider bite in the Midwest

    Science

    (1957)
  • N.I. Platnick

    The World Spider Catalogue, Version 6.0

  • W.J. Gertsch et al.

    The spider genus Loxosceles in North America, Central America and the West Indies (Araneae Loxoscelidae)

    Bull Am Mus Nat Hist

    (1983)
  • R.S. Vetter

    Arachnids submitted as suspected brown recluse spiders (Araneae: Sicariidae): Loxosceles spiders are virtually restricted to their known distributions but are perceived to exist throughout the United States

    J Med Entomol

    (2005)
  • R.S. Vetter et al.

    Reports of envenomation by brown recluse spiders (Araneae: Sicariidae) outnumber verifications of Loxosceles spiders in Florida

    J Med Entomol

    (2004)
  • J. White et al.

    Clinical toxicology of spider bites. Ch. 20

  • Cited by (0)

    View full text