Annals of Emergency Medicine
Volume 39, Issue 5 , Pages 544-546, May 2002

The diagnosis of brown recluse spider bite is overused for dermonecrotic wounds of uncertain etiology☆

Department of Entomology, University of California-Riverside, Riverside, CA

Department of Emergency Medicine, Loma Linda University School of Medicine, Loma Linda, CA

Article Outline

Abstract 

[Vetter RS, Bush SP. The diagnosis of brown recluse spider bite is overused for dermonecrotic wounds of uncertain etiology. Ann Emerg Med. May 2002;39:544-546.]

 

See related articles, p. 469, p. 475, and p. 558.

In this issue of Annals , Osterhoudt et al1 report the misdiagnosis of Lyme disease as brown recluse spider envenomation. Throughout the United States, dermonecrotic wounds of uncertain etiology are often attributed to the brown recluse spider, Loxosceles reclusa . Many such diagnoses occur in parts of the country where the spider is neither native nor are populations known. Necrotic wounds can be caused by many different etiologies. Misdiagnosing a necrotic wound as a brown recluse spider bite can lead to delays in appropriate care, adverse or even fatal outcomes, and increased medical-legal risk, particularly if there is specific treatment for the actual etiology.

The endemic range of the brown recluse spider is southeastern Nebraska through Texas, east to Georgia and southernmost Ohio. Ten additional Loxosceles species are native to the southwestern US deserts, 5 with significant distributions.2, 3 Two nonnative species are found in the United States but are extremely rare, sporadic, and circumscribed in distribution. The 6 widespread native species are common and abundant in their respective endemic ranges, and all species should be considered of potential medical significance.

The brown recluse is the most widespread, well-studied, and clinically important of the Loxosceles species in North America and is a common urban house spider in endemic areas. In contrast, many western recluse species are numerous in native desert habitats but are rarely found inside urban houses, except those surrounded by natural environment. Loxosceles spiders are shy creatures that are reticent to bite. Bites typically occur defensively only when the spider is accidentally trapped against human flesh while a person is dressing or sleeping. Gertsch4 mentions hand-collecting hundreds of recluses without receiving bites. In a Chilean survey of L laeta , the 5 most infested homes averaged 163 recluse spiders (range 106 to 222), yet no envenomations of the occupants occurred.5

If a recluse spider bite is suspected, recluse specimens should be readily collectable within the local community. Despite this logic, annual reports of brown recluse bites from nonendemic areas (eg, South Carolina, Pacific Northwest, Florida, California6, 7, 8, 9) far exceed the number of historically known specimens ever collected in those areas.2, 8, 9 One Colorado medical report states that brown recluse bite is a significant annual seasonal affliction there,10 despite the fact that recluse populations are unknown in Colorado, and there are only 5 historical verifications of Loxosceles spiders (P. Cushing, Curator of Entomology and Arachnology, Denver Museum of Nature and Science, written communication, August 2001). Deaths have been attributed to the brown recluse, although there are no proven US fatalities in which the spider was witnessed biting, was collected, and was identified by a qualified expert.11, 12 Published histories of fatal bites report that a recluse bite was “possible,” “presumed,” or “suspected” when the only available evidence was a dermonecrotic wound.13, 14 We need a better understanding of the role of Loxosceles spiders as the cause of various skin lesions and systemic illness in different geographic regions. To accomplish this, future studies and case reports must use more strict diagnostic criteria, such as a verified bite with proper spider identification.15 To do otherwise perpetuates myth, inappropriate public fear, and improper treatment. Additionally, a misdiagnosis of brown recluse spider bite may lead to unnecessary, expensive, or even harmful therapy (eg, hyperbaric oxygen, dapsone, surgical excision, electric shock), particularly because much of the literature regarding treatment is contradictory.

Often a diagnosis of brown recluse spider envenomation in nonendemic regions is based on the possibility that the spider was transported outside its range.16

Although possible, this happens much less often than could account for the many necrotic wounds of uncertain etiology that are seen in the average practice. Almost all recluse spiders outside their range are found in commerce or translocated possessions and are single itinerants that die without successfully reproducing or biting a human. In the rare occurrence in which a recluse population becomes established, the new range is often restricted to a very small area (eg, a few buildings)2, 8 and the infestation does not spread in epidemic proportions.

In general, spider bites have been overdiagnosed as the cause of necrotic lesions.9, 17, 18 In the Pacific Northwest, the hobo spider, Tegenaria agrestis , was often blamed as the cause of necrotic wounds in the absence of Loxosceles species.7 However, many reported cases relied on inconclusive or circumstantial evidence.7, 19 Recent research is questioning whether hobo spider venom actually causes necrosis.20 In Brazil, a wolf spider was thought to cause necrotic wounds, and antivenin was used for decades; however, in 515 subsequent verified wolf spider envenomations, no victim expressed necrosis.18, 21 Unless a spider is seen biting a patient, “spider bite” is a speculative diagnosis.

Many necrotic wounds have been misdiagnosed as brown recluse spider bites, including those caused by infectious, neoplastic, and other processes.22, 23, 24, 25, 26, 27, 28, 29 Other conditions misdiagnosed as brown recluse spider envenomation, such as the Lyme disease case reported by Osterhoudt et al,1 require specific treatment. Of recent interest, a 7-month-old child in New York who contracted cutaneous anthrax was initially diagnosed as having a brown recluse spider bite.30 (The state of New York is outside the endemic range of the brown recluse and has no populations of the spider.) Relying so readily on “brown recluse spider bite,” physicians may miss difficult diagnoses, such as cutaneous anthrax infection. In perhaps the worst case scenario, misdiagnosing necrotizing fasciitis as a recluse spider bite could lead to loss of life or limb.

Considering the biology, distribution, and temperament of brown recluse spiders and related species, the chance of finding a recluse in a nonendemic region is very unlikely, and the chance of being bitten by one even less so. Physicians should consider the many causes of necrotic wounds, instead of simply assigning the diagnosis of brown recluse spider bite, especially in regions where the spider is not endemic and populations cannot be reliably collected. Appropriate diagnosis is the best way to initiate appropriate therapy. Corroborative evidence should be sought before attributing etiology to a spider or other arthropod bites. Although general wound care may be sufficient for most similar wounds, it will be ineffective for conditions, such as Lyme disease, cutaneous anthrax, neoplasia, and necrotizing fasciitis, in which a delay to treatment can have grave consequences.

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References 

  1. Osterhoudt KC, Zaoutis T, Zorc JJ. Lyme disease masquerading as brown recluse spider bite. Ann Emerg Med. 2002;39:558–561
  2. Gertsch WJ, Ennik F. The spider genus Loxosceles in North America, Central America, and the West Indies (Araneae, Loxoscelidae ). Bull Am Mus Nat Hist. 1983;175:264–360
  3. Vetter RS. Brown recluse and other recluse spiders: integrated pest management in and around the home. University of California Pest Notes. Available at http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7468.htmlFebruary 28, 2002.; Accessed
  4. Gertsch WJ. The spider genus Loxosceles in South America (Araneae, Scytodidae ). Bull Am Mus Nat Hist. 1967;136:117–174
  5. Schenone H, Rojas A, Reyes H, et al.  Prevalence of Loxosceles laeta in houses in Central Chile. Am J Trop Med Hyg. 1970;19:564–567
  6. Schuman SH, Caldwell ST. 1990 South Carolina physician survey of tick, spider, and fire ant morbidity. J South Carolina Med Assoc. 1991;87:429–432
  7. Vest DK, Keene WE, Kaufman S. Necrotic arachnidism-Pacific Northwest, 1988-1996. MMWR Morb Mortal Wkly Rep. 1996;45:433–436
  8. Edwards GB. The present status and a review of the brown recluse and related spiders, Loxosceles (Araneae: Sicariidae ), in Florida. Bulletin of the Florida Department of Agriculture and Consumer Services, Plant Industry Division, Bureau of Entomology. No. 398. In press.
  9. Vetter RS. Myth: idiopathic wounds are often due to brown recluse or other spider bites throughout the United States. West J Med. 2000;173:357–358
  10. Mara JE, Myers BS. Brown spider bite. Rocky Mountain Med J. 1977;74:257–258
  11. Anderson PC. Missouri brown recluse spider: a review and update. Missouri Med. 1998;95:318–322
  12. Sams HH, King LE. Brown recluse spider bites. Dermatol Nurs. 1999;11:427–433
  13. Litovitz TL, Klein-Schwartz W, White S, et al.  1999 Annual report of the American Association of Poison Control Centers Toxic Exposure Surveillance System. Am J Emerg Med. 2000;18:517–574
  14. Litovitz TL, Klein-Schwartz W, Caravati EM, et al.  1998 Annual report of the American Association of Poison Control Centers Toxic Exposure Surveillance System. Am J Emerg Med. 1999;17:435–487
  15. Anderson PC. On proven brown recluse spider bites. [letter] Toxicon. 1982;20:533
  16. Greenberg MI. The home of the brown recluse spider. [letter] Emerg Med News. 1997;19:14
  17. Kemp DR. Inappropriate diagnosis of necrotizing arachnidism: watch out Miss Muffet-but don't get paranoid. Med J Aust. 1990;152:669–671
  18. Nishioka SA. Misdiagnosis of brown recluse spider bite. [letter] West J Med. 2001;174:240
  19. Akre RD, Myhre EA. Biology and medical importance of the aggressive house spider, Tegenaria agrestis , in the Pacific Northwest (Arachnida: Araneae: Agelenidae ). Melanderia. 1991;47:1–30
  20. Binford GJ. An analysis of geographic and intersexual chemical variation in venoms of the spider Tegenaria agrestis (Agelenidae ). Toxicon. 2001;39:955–968
  21. Ribeiro LA, Jorge MT, Piesco RV, et al.  Wolf spider bites in Sao Paulo, Brazil: a clinical and epidemiological study of 515 cases. Toxicon. 1990;28:715–717
  22. Russell FE. A confusion of spiders. Emerg Med. 1986;18:8–13
  23. Russell FE, Gertsch WJ. For those who treat spider or suspected spider bites. [letter] Toxicon. 1983;21:337–339
  24. Kunkel DB. The myth of the brown recluse spider. Emerg Med. 1985;17:124–128
  25. Vetter RS, Visscher PK. Bites and stings of medically important venomous arthropods. Int J Dermatol. 1998;37:481–496
  26. Rosenstein ED, Kramer N. Lyme disease misdiagnosed as a brown recluse bite. [letter] Ann Intern Med. 1987;107:782
  27. Nadelman RB, Wormser GP. Erythema migrans and early Lyme disease. Am J Med. 1995;98(Suppl 4A):15S–23S
  28. Moaven LD, Altman SA, Newnham AR. Sporotrichosis mimicking necrotising arachnidism. Med J Aust. 1999;171:865–868
  29. Vetter RS, Bush SP. Chemical burn misdiagnosed as brown recluse spider bite. Am J Emerg Med. 2002;20:68–69
  30. Roche KJ, Chang MW, Lazarus H. Cutaneous anthrax infection. N Engl J Med. 2001;345:1611

☆ Address for reprints: Richard S. Vetter, MS, Department of Entomology, University of California-Riverside, Riverside, CA 92521; 909-787-3550, fax 909-787-3086; E-mail vetter@citrus.ucr.edu.

PII: S0196-0644(02)25977-6

doi:10.1067/mem.2002.123594

Refers to article:

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

    Hernan F. Gomez, Diann M. Krywko, William V. Stoecker
    Annals of Emergency Medicine May 2002 (Vol. 39, Issue 5, Pages 469-474)

  • Detection of Loxosceles species venom in dermal lesions: A comparison of 4 venom recovery methods

    Diann M. Krywko, Hernan F. Gomez
    Annals of Emergency Medicine May 2002 (Vol. 39, Issue 5, Pages 475-480)

  • Lyme disease masquerading as brown recluse spider bite

    Kevin C. Osterhoudt, Theoklis Zaoutis, Joseph J. Zorc
    Annals of Emergency Medicine May 2002 (Vol. 39, Issue 5, Pages 558-561)

Annals of Emergency Medicine
Volume 39, Issue 5 , Pages 544-546, May 2002

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