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Hyperbaric oxygen effects on brown recluse spider (Loxosceles reclusa) envenomation in rabbits. Toxicon29, 989–996, 1991.—Human loxoscelism was modeled in albino rabbits by injection of brown recluse spider (Loxosceles reclusa) venom, and the effects of daily or twice-daily hyperbaric oxygen treatment on wound healing were investigated. Lesions similar to those seen in humans were produced in rabbits by intradermal injection of 200 μl of a venom extract (0.21 μg protein per μl), including edema and erythema, ischemia and cyanosis in the first 12 hr, extensive purpura by 24 hr, and crateriform ulcer formation by day four, with induration and eschar formation. Hyperbaric oxygen treatments, consisting of two atmospheres absolute (2 ATA) for 60 min, were applied daily (n = 8) or twice daily (n = 8), while control animals (n = 8) received no treatment. Treatments were initiated 72 hr after venom injection (day 3) to duplicate typical clinical treatment delays, and were administered for seven consecutive days. No significant effects of hyperbaric oxygen treatment on lesion healing were seen as measured by lesion area. However, histologic evaluation of wound tissue collected at euthanasia on day 24 showed clear differences between rabbits receiving twice-daily treatments and those receiving daily or no treatment. The former showed complete re-epithelization or slight ulceration, while the latter usually had necrotic cavities extending into the dermis, with myonecrosis and inflammatory cell accumulation. Thus, no superficial differences were seen between groups, but twice-daily treatments resulted in enhanced recovery at the histologic level.

Extensive chemical analyses of spider venoms from many species have revealed complex mixtures of biologically active compounds, of which several have provided important leads for drug development. We have recently shown that NMR spectroscopy can be used advantageously for a direct structural characterization of the small-molecule content of such complex mixtures. Here, we report the application of this strategy to a larger-scale analysis of a collection of spider venoms representing >70 species, which, in combination with mass spectrometric analyses, allowed the identification of a wide range of known, and several previously undescribed, small molecules. These include polyamines, common neurotransmitters, and amino acid derivatives as well as two additional members of a recently discovered family of natural products, the sulfated nucleosides. In the case of the well studied brown recluse spider, Loxosceles reclusa , sulfated guanosine derivatives were found to comprise the major small-molecule components of the venom.

Many stings and bites can be prevented if an individual has some knowledge of insect behavior. However, persons known to be allergic to insect stings should carry an epinephrine injection kit to use as a first aid measure. Those who travel far from medical facilities should additionally carry prednisone and oral antihistamines. The bite of a brown recluse spider may cause a minor reaction or it may evolve into extensive soft-tissue necrosis with a potentially fatal outcome. If necrosis occurs, a course of oral dapsone is recommended.

Loxoscelism or necrotic arachnidism are the terms used to describe the effects of the brown recluse spider bite. Over recent years, there has been a steady increase in the number of reported brown recluse spider bites. It is not clear whether this represents an expanded range of the spider's habitat or greater physician awareness. Although most commonly found in the warm, south central region of the United States, Loxosceles reclusa can be a cause of necrotic arachnidism in northern urban settings. Therefore, the diagnosis should also be considered in these areas. This article discusses three cases of suspected brown recluse spider bites referred to a Chicago-based poison control center and briefly reviews the literature regarding the diagnosis, clinical presentation and treatment of loxoscelism.

Brown recluse spider bites may result in extensive soft tissue injury, causing months of disability. We have described a patient who had a series of extensive surgical debridements after envenomation. Despite skin grafting, persistent cutaneous lesions and extensive satellitosis progressed to involve the entire lower extremity. A recent biopsy showed pseudoepitheliomatous hyperplasia and pyoderma gangrenosum complicating the original injury. Although the role of early surgical excision and newer forms of medical treatment including dapsone and antivenom are still in evolution, recent reports suggest that the majority of patients will respond to medical therapy and may not require any surgical intervention.

C. A. Gates and R. S. Rees . 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 28, 1303–1315, 1990.—Serum amyloid P component or serum amyloid protein is a ubiquitous, highly conserved glycoprotein whose function is unknown. Although the related pentraxin, C-reactive protein, is an acute phase reactant in man, there is no direct evidence that human serum amyloid protein is involved in an inflammatory response. Here we show that serum amyloid protein is required by sphingomyelinase D, the principal necrotic agent of the venom of Loxosceles reclusa , for the in vitro-activation of human platelets. Furthermore, this platelet activation is dependent upon the presence of only serum amyloid protein; no other plasma components are necessary. Secretion of [ 3 H]-serotonin and aggregation of platelets are nearly maximal following incubation of the platelets with purified sphingomyelinase D (0.3 μg/ml) and 5 μg/ml pure serum amyloid protein in the presence of calcium. Since the platelets are no longer activated when this 10% physiologic amount of serum amyloid protein is omitted, serum amyloid protein is likely to have a role in the necrosis caused by brown recluse spider venom.

This is the first report of clinically significant bites by the grass spider (Agelenopsis aperta). Two cases of envenomation in southern California are presented. In the more serious case, a child exhibited several envenomation symptoms. Although this spider may be generally innocuous, it should be considered as a creature of occasional medical importance. Many skin lesions are attributed to spider bites despite insufficient incriminating evidence, and bites that are clinically significant may often erroneously be attributed to the brown recluse spider. Misidentification can lead to undue anxiety in a patient's family.

The toxic, biochemical, and immunological characteristics of L. boneti and L. reclusa venoms and its neutralization by anti-L. boneti and anti-L. reclusa antivenoms were studied. The electrophoretic profile showed very similar patterns and the toxic activities were very close. Immunological studies showed cross-reactivity among L. boneti and L. reclusa venoms, with L. boneti and L. reclusa experimental antivenoms, and anti-L. gaucho and anti-L. laeta antivenoms. The venom of L. laeta showed low immunological reactivity with the North American Loxosceles antivenoms. Experimental anti-North American Loxosceles antivenoms protected mice of the systemic toxicity and were able to prevent necrosis in rabbit skin after the injection of the venom. Both antivenoms displayed cross neutralization. The results showed that both Loxosceles venoms have very close toxic, biochemical, and immunological characteristics, and that either monospecific antivenoms or an antivenom raised with L. boneti and L. reclusa venoms as immunogens could be useful for treating bites by North American Loxosceles spiders.

Reports of spider bites appear throughout North America. Bites associated with the brown recluse spider (Loxosceles recluse) cause serious medical complications because the venom of this spider contains a powerful necrotising agent with the potential to cause severe cutaneous necrosis. Although not much is known regarding the application of negative pressure wound therapy (NPWT) to spider bites, this therapy has considerable literature support for its efficacy, cost‐effectiveness and ease of use in chronic, difficult‐to‐heal wounds. A case study using NPWT to successfully treat a non healing upper arm wound presumed due to a venomous spider bite is presented here. The patient was successfully treated with a new, less costly NPWT product called the Versatile 1(®) and a new combination drain plus dressing called the Miller DermiVex(®) drain, both manufactured by Blue Sky Medical (Carlsbad, CA).

PURPOSE: The purpose of this article was to provide a comprehensive epidemiological and clinical description of the brown recluse spider bite. DATA SOURCES: Review of evidenced-based scientific literature and practice guidelines. A specific descriptive case study is interwoven through the article to tie in the clinical presenting figure associated with this bite. CONCLUSIONS: The brown recluse lives in a circumscribed area of the United States (the south central Midwest) with a few less common recluse species living in the more sparsely populated southwest United States. In these areas, where spider populations may be dense, recluse spiders may be a cause of significant morbidity. IMPLICATIONS FOR PRACTICE: Most spider bites are asymptomatic but what makes this bite so devastating is the toxin injected by the brown recluse spider, which can cause considerable systemic symptoms as well as necrotic skin ulcers (necrotic arachnidism). The article presents process for diagnosis and stresses the importance of identifying the spider if at all possible. Language: en

The venom from spiders of the genus Loxosceles , the most famous being Loxosceles recluse (the most brown recluse spider) can cause serious poisoning. These spiders inhabit the south and south central states from Georgia through Texas and north to southern Wisconsin. They are commonly called violin spiders because of the violin-shaped marking on the dorsum of the cephalothorax. Many dermonecrotic lesions are incorrectly diagnosed as Brown recluse bites, as up to 50% of the diagnoses are in geographic regions of the country which do not have Loxosceles spiders. Sphingomyelinase D is the primary venom dermonecrotic factor. The toxin depletes serum hemolytic complement, prolongs the activated partial thromboplastin time and depletes clotting factors VIII, IX, XI, and XII. The venom induces rapid coagulation and occlusion of small capillaries, causing subsequent tissue necrosis. A classic "bulls eye" lesion develops, an erythematous area inside of which is a pale ischemic region that develops a dark necrotic center as the lesion matures. Healing is slow, and these ulcers may persist for months leaving a deep scar. Systemic signs occur less commonly but can be life threatening. The most prevalent sign is a hemolytic anemia with significant hemoglobinuria. There is no specific antidote. Dapsone a leukocyte inhibitor has been shown to be effective in treating dermal lesions in animal models. Conservative therapy includes several cleanings daily with Burrow's solution and hydrogen peroxide. Systemic signs of Loxosceles envenomation are potentially fatal and should be aggressively addressed. Hospitalization and intravenous fluid therapy may be needed to maintain adequate hydration and to protect renal function.

Background: The Loxosceles reclusa , commonly known as the brown recluse spider, is responsible for virtually all cases of spider bites leading to a significant necrosis. Case Report: We report the case of a 72-year-old man who presented to the Emergency Department complaining of back pain, weakness, and diarrhea. The patient stated that he sustained a bug bite 1 week before presenting to the hospital. His wound was necrotizing in nature and after an exhaustive work-up, the most likely etiology was found to be envenomation by a brown recluse spider, Loxosceles reclusa . Conclusion: This is an endemic cause of a necrotizing wound bite in areas of the Midwestern and Southern United States, but it is rarely reported in the Northeast.

Bites by the woodlouse spider, Dysdera crocata, are virtually innocuous. The main symptom is minor pain, typically lasting less than 1 h, probably due mostly to mechanical puncture of the skin. However, because the spider has a strong proclivity to bite, has large fangs which it bares when threatened and is commonly mistaken for the medically important brown recluse spider in the United States, documentation of the mild effects of its bites may prevent excessive, unwarranted and possibly harmful treatment. We present information on eight verified bites reported to us as well as eight additional bites recorded in the literature.

Brown recluse spider bite is a common diagnosis in almost every state in America. In fact, cases have been reported in areas where the spider has never been seen. A review of medical literature reveals that most current concepts regarding brown recluse spider envenomation are based on supposition. In this article, we attempt to review critically our present understanding of brown recluse bites with a focus on the published evidence.

Envenomation by the brown recluse spider (Loxosceles reclusa) is associated with shock, significant hemolysis, renal insufficiency, and disseminated intravascular coagulation (DIC). Shock has never been associated with envenomation by L arizonica, a related species indigenous to Arizona, southern California, and northwestern Mexico. We report the case of a 13-year-old girl, bitten by a specimen of L arizonica (the spider was identified by an entomologist), in whom shock and a typical cutaneous lesion developed. She did not experience renal insufficiency or disseminated intravascular coagulation. Infectious causes of shock were excluded. She recovered completely with supportive care.

A significant number of people are bitten by the brown recluse spider (BRS) each year. Medical treatment regimens are sometimes unsatisfactory and surgical intervention is often necessary to debride the necrotic wound. This case study reports the treatment given to a 19-year-old active duty United States Army soldier who suffered a BRS bite to the glans penis. This patient received immediate medical attention and was started on intravenously administered diphenhydramine, methylprednisolone, calcium gluconate, and famotidine. Oral dapsone treatment was begun in the emergency room. Within 24 hours after his injury, the patient received his first hyperbaric oxygen treatment, which was continued twice daily for 5 days. Skin necrosis was avoided, the patient did not require any surgical intervention, and he was discharged after 8 days without sequelae.

It has proven difficult to identify those spiders which cause necrotic lesions. In an effort to design a simple, inexpensive screening method for identifying spiders with necrotizing venoms, we have examined the venom gland homogenates of a variety of spider species for their ability to cause red blood cell lysis. Those venoms which were positive were further examined for the presence of sphingomyelinase D, and their ability to evoke necrotic lesions in the skin of rabbits. Sphingomyelinase D is known to be the causative agent of necrosis and red blood cell lysis in the venom of the brown recluse spider (Loxosceles reclusa), and our assumption was that this would be the same agent in other spider venoms as well. This did not prove to be the case. Of 45 species examined, only the venom of L. reclusa and Cheiracanthium mildei lysed sheep red blood cells. Unlike L. reclusa venom, however, C. mildei venom did not possess sphingomyelinase D nor did it cause necrotic lesions in the skin of rabbits. We present evidence suggesting that a phospholipase A2 is the hemolytic agent in C. mildei venom.

Oral and maxillofacial surgeons must be prepared to manage a variety of maxillofacial infections, both odontogenic and non-odontogenic in nature. While odontogenic infections are quite common, non-odontogenic infections can present with diagnostic and therapeutic challenges. An uncommon non-odontogenic infection is the cellulitis secondary to a spider bite. Few spider species have the ability to bite through human skin. Most of these insults result in only a small, red nodule centered within a larger, erythematous plaque. Symptoms are usually limited to pruritus and perhaps mild tenderness. The brown recluse and the black widow are 2 types of spiders that inhabit the United States that can cause serious injury or major medical problems to their victim. The bite of the brown recluse spider (Loxosceles reclusa) results in an envenomation that can have deleterious effects on the patient. Within 6 hours after the bite, pain and erythema develop at the site. The area of erythema spreads during the first 24 hours and may turn bluish-purple. Necrosis of the skin often occurs 24 to 48 hours later. Signs include bullae formation, cyanosis, and hyperesthesia. Depending on their size, complete resolution of these lesions can take from weeks to months. Systemic symptoms include fever, chills, malaise, vomiting, and arthralgias. Less common but more severe reactions to the venom have resulted in hemolytic anemia, convulsions, renal failure, shock, disseminated intravascular coagulation, and rarely, death. Brown recluse spider bites usually occur on the extremities or the trunk, but bites to the face have been reported. Treatment of a brown recluse spider bite is controversial and ranges from conservative comfort measures including rest, ice compresses, and elevation, to drug therapy and surgical excision.

The brown recluse spider (Loxosceles reclusa) exists in significant populations mainly in the midwestern United States. Although bites can cause significant harm, envenomation is infrequent, and cases are usually clinically insignificant. Proper knowledge of the spider's habitat and lifestyle as well as the signs and symptoms of loxoscelism are needed to assess clinical cases adequately. Loxoscelism can masquerade as many serious pathologies, and vice versa, so it is important for the clinician to explore all possibilities in the differential diagnosis thoroughly. Treatments are controversial, and no conclusive test for envenomation is currently available. This review provides information to help physicians, especially in nonendemic areas, include or exclude brown recluse bite in the clinical diagnosis and provide proper care.

Study Objective: Dermal lesions from unrelated arthropod species and medical causes appear similar to Loxosceles species (brown recluse spider) bites. This may result in delayed diagnosis and treatment. We developed a sensitive Loxosceles species venom enzyme-linked immunosorbent assay (ELISA) and characterized the specificity of the assay by evaluating antigenic cross-reactivity from a variety of North American arthropod venoms. Methods: North American arthropod (14 spiders, 2 scorpions, and 1 bee) venoms were studied. Three venom amounts (diluted in 100 μL of ELISA buffer) were assayed: 16,000 ng, 2,000 ng, and 40 ng. The latter quantity was selected because this is the observed maximum amount of venom we detect when inoculating dermis with amounts likely to be deposited by a spider bite. The larger venom amounts are overwhelming quantities designed to test the limits of the assay for arthropod venom cross-reactivity. Similar amounts of Loxosceles species venom and bovine albumin served as positive and negative controls, respectively. Results: At the lowest amount of venom tested (40 ng), the ELISA detected only the Loxosceles species positive control. When 2,000 ng was assayed, only Scytodes fusca and Kukulcania hibernalis arachnid venoms (in addition to Loxosceles species) cross-reacted to the assay. Finally, at 16,000 ng, the ELISA assay modestly detected Diguetia canities , Heteropoda venatoria , Tegenaria agrestis , Plectreurys tristes , Dolomedes tenebrosus , and Hadrurus arizonensis arachnid venoms. Conclusion: Cross-reactivity was observed in 8 of 17 North American arthropod venoms when large venom amounts were assayed with a Loxosceles species ELISA. By using a relevant quantity of venom, 40 ng, the assay was specific for Loxosceles species venom. The venom specificity of the ELISA may allow clinical application in Loxosceles species endemic regions of North America. [Gomez HF, Krywko DM, Stoecker WV. A new assay for the detection of Loxosceles species (brown recluse) spider venom. Ann Emerg Med. May 2002;39:469-474.]

Objective: Our purpose was to review documented Loxosceles reclusa (brown recluse spider) envenomations and to describe the natural history. Methods: This article is a retrospective review of 19 documented cases seen in a university dermatology clinic. The study included the cases of 11 female and 8 male patients between the ages of 15 and 54 years with documented cases of brown recluse spider bite between 1987 and 1993. Rest, ice compresses, elevation, and prophylactic antibiotics were used in all cases. Fourteen patients received dapsone and 11 received nonsteroidal anti-inflammatory drugs. Two patients were hospitalized. A 3-point scale of cutaneous lesion severity was developed. Analysis of the association between maximum lesion severity (mild, moderate, severe) and time to complete healing or final evaluation was statistically significant ( P Results: All patients presented with localized erythema. Most bites were on the extremities (18/19; 95%). The most common presenting symptom was pain at the bite site (10/19; 53%). Eleven patients (58%) had skin necrosis; 32% of them had areas of necrosis larger than 1 cm 2 . Time to healing ranged from 5 days to more than 17 weeks (mean, 5.6 weeks). Average time to healing for grade 3 (severe) lesions was 74 days, for grade 2 (moderate) lesions 22 days, and for grade 1 (mild) lesions 8 days (in patients seen more than once). Conclusions: Brown recluse spider bites frequently induce necrotic, slowly healing lesions. Maximum lesion severity is a predictor of time to complete healing. (J Am Acad Dermatol 2001;44:603-8.)

Topical nitroglycerin has been reported to prevent skin necrosis from brown recluse spider bites, but this has never been scientifically tested. This study attempts to assess the effects of topical nitroglycerin on experimental Loxosceles reclusa envenomations.We performed a randomized, blinded, controlled study in an animal care facility. Twenty-four New Zealand white rabbits were experimentally envenomated by means of subcutaneous injection with 20 microg of brown recluse spider venom. Rabbits were randomized to 1 of 2 experimental groups. The treatment group received 1 in of 2% topical nitroglycerin ointment every 6 hours for 3 days applied directly to the envenomation site. The control group received the vehicle without nitroglycerin. Gross examination of the lesions and measurements of the areas of the lesions were made daily. Creatine phosphokinase (CPK), blood urea nitrogen, creatinine, hemoglobin, and hematocrit levels were measured on days 0, 5, and 10. Lesions were excised after 10 days and examined by a blinded pathologist, who measured the area of necrosis and quantified inflammation and edema using a standard wound-healing score. For all values, mean values plus SD were determined. All comparisons made over multiple time points were assessed for significance by using a repeated-measures analysis of variance followed by Fisher least significant difference and Scheffé post hoc comparisons. A P value of.05 or less was used to determine significance. The Student's t test was used to compare the means of single measures. Significance was determined by using 95% confidence intervals. Comparisons of total area of necrosis were made with the nonparametric Mann-Whitney U test because of the heavy positive skew of the data.Skin necrosis developed in all animals. Mean values of the lesion area were not significantly different over time between the 2 groups of animals. At day 10, the median area of necrosis was 22.3 cm2 for the treatment group and 15.4 cm2 for the control group (P =.12). The inflammation score was 3.33+/-0.78 for the treatment group and 2.79+/-1.29 for the control group (P.01). The edema score was 1.25+/-1.28 for the treatment group and 0.98+/-1.10 for the control group (not significantly different). CPK levels increased dramatically in both groups, with the greatest increase in the treatment group. In both groups hemoglobin and hematocrit levels decreased significantly, whereas WBC counts and platelet counts increased significantly, without significant differences between the 2 groups.At the dose used in this experiment, topical nitroglycerin did not prevent skin necrosis, increased inflammation score, and increased serum CPK levels. The results of this study do not support the use of topical nitroglycerin in the treatment of L reclusa envenomation and suggest that systemic toxicity could be increased.

Spiders, especially brown recluses (Loxosceles reclusa) (figure 1), are frequently incriminated as causative agents in idiopathic wounds, even though diagnoses are usually made solely on the basis of dermatologic symptoms. Rarely is a spider seen inflicting the wound or captured while biting, and it is difficult to either prove or disprove spider participation in the event. The biologic distribution of the brown recluse and related recluse species indicates that many diagnoses made on cases occurring in the western United States are incorrect.1 Figure 1 Dorsal view of the brown recluse spider, Loxosceles reclusa. The most consistent diagnostic feature for identification is the pattern of 6 eyes, grouped in pairs, with 1 anterior pair and 2 lateral pairs (most spiders have 8 eyes in 2 rows of 4). Although ... SOURCES OF INFORMATION Because of my research interests in spider identification and medically important spiders, I have been avidly studying recluse spiders and their occurrence in the western United States. My experience is greatest in California, but the information presented here is pertinent to northern and western states as well. In almost a decade of research, I have found verification of fewer than 10 brown recluse specimens in California in more than 40 years of records. Sources include medical and arachnologic literature and correspondence with scores of arachnologists, county entomologists, vector control personnel, and the California Department of Food and Agriculture, which handles all exotic pest identifications in the state. Most verified specimens were individuals intercepted from facilities receiving goods from out of state. There are no populations of brown recluses in California.

Histologic specimens from 41 rabbits were studied for changes resulting from the manual injection of brown recluse spider venom. Major findings included a mixed inflammatory cell infiltrate, coagulative tissue necrosis, and vasculitis. All specimens demonstrated a well-delineated zone of eosinophilic staining recognizable as "mummified" coagulative necrosis of the epidermis and dermis. A dense band of neutrophils bordered the zone of necrosis. Immediately adjacent to the neutrophilic band, small vessel vasculitis was a universal finding. Degranulated eosinophils and neutrophils and macrophages filled with eosinophilic granules were common. Inflammatory foci were often centered on groups of lipocytes within the dermis. Large vessel vasculitis resembling that seen in polyarteritis nodosa was present deep to 7 of the 40 eschars. Large vessel vasculitis may contribute to the large zones of necrosis seen after some brown recluse spider bites. Eosinophils may play a role in tissue damage after envenomation.

Bites from the brown recluse spider and other arachnids from the genus Loxosceles frequently induce necrotic skin lesions that can be recalcitrant to treatment and disfiguring. The authors used a rabbit model of dermonecrotic arachnidism to address the therapeutic efficacy of intradermal (id) polyclonal anti-Loxosceles Fab fragments (alphaLoxd Fab) raised against Loxosceles deserta spider venom.Fab fragments were prepared by papain digestion and affinity chromatography from the IgG fraction of L. deserta antivenom raised in rabbits. Eighteen inbred New Zealand white rabbits were assigned to six groups of three. The rabbits received L. deserta venom (3 microg, id) injections into each flank. Cohorts of rabbits received single id injections (at one venom site/rabbit) of 30 microg alphaLoxd Fab at different times (T = 0, 1, 2, 4, 8, and 12 hours) after venom injection. In each rabbit the opposite flank was left untreated. As an additional control, one group of rabbits (T = 0) received nonspecific Fab (30 microg, id) in the opposite flank. Dermal lesions were quantified as a function of time through the use of a series of digital photographs and imaging software. In addition, myeloperoxidase (MPO) activity, a measure ofneutrophil accumulation, was determined in lesion biopsies. Lesion areas and MPO activities were analyzed by repeated-measures analysis of variance (ANOVA).Lesion areas and MPO activity were markedly reduced when alphaLoxd Fab was administered very early after venom injections. As the interval between venom inoculation and antivenom treatment increased, the therapeutic benefit of alphaLoxd Fab decreased. The final time tested that demonstrated therapeutic efficacy of alphaLoxd Fab was T = 4 hours. Lesion attenuation was no longer apparent when alphaLoxd Fab was given 8 hours post inoculation.Intradermal administration of alphaLoxd Fab attenuates Loxosceles-induced dermonecrotic lesion formation when given up to 4 hours after venom inoculation in this rabbit model.

The brown recluse spider, Loxosceles reclusa, is often implicated as a cause of necrotic skin lesions.[1-3] Diagnoses are most commonly made by clinical appearance and infrequently is a spider seen, captured or identified at the time of the bite.[1, 2, 4-6] The brown recluse lives in a circumscribed area of the U.S. (the south central Midwest) with a few less common recluse species living in the more sparsely-populated southwest U.S.[7] In these areas, where spider populations may be dense, recluse spiders may be a cause of significant morbidity. However, outside the natural range of these recluse species, the conviction that they are the etiological agents behind necrotic lesions of unknown origin is widespread, and most often erroneous. In some states such as California, unsubstantiated reports concerning recluse spider bites have taken on the status of "urban legend" leading to overdiagnosis and, therefore, inappropriate treatment. Language: en

Background Although Ixodes ticks are considered the chief vector for Borrelia burgdorferi in the USA, B. burgdorferi has also been identified in mosquitoes, horse flies, and deer flies. We examined the possibility of these organisms being harbored in two species of spider in central Arkansas. Methods Ten wolf spiders (Lycosa gulosa) and two brown recluse spiders (Loxosceles reclusa) were collected in central Arkansas during early summer and fixed in formalin. Paraffin-embedded sections of the spiders were examined for spirochetes using the modified Steiner spirochete staining method and examined for B. burgdorferi using immunohistochemistry. Results All 12 spiders from both species were found to be negative for all spirochetes including B. burgdorferi. Conclusions Spiders in our sample appeared not to harbor B. burgdorferi. Further studies utilizing larger sample sizes, more sensitive testing measures, or spiders from an area more endemic with B. burgdorferi may further prove or disprove that spiders are capable of harboring this organism.

Patients with brown recluse spider bites commonly suffer from pain, muscular aching, and a variety of local dysesthesias during the acute and resolution phases of toxin-induced injury. This is our first well-documented observation of persistent cutaneous anesthesia caused by a spider bite. The anesthetic area conformed to the distribution of a specific nerve, the transverse cervical cutaneous nerve. The identification of the spider as a brown recluse and the location of the bite over the nerve's usual pathway strongly suggest that the venom was responsible for this complication.

The dermatology and general medical literature is filled with articles that report skin disease caused by the brown recluse spider, Loxosceles reclusa. A large number of these articles contain inadequate documentation of Loxosceles bites; many come from areas that have no Loxosceles spiders. Authors submitting papers alleging loxoscelism should adhere to standards of evidence when writing case reports.

M. L. Merchant, J. F. Hinton and C. R. Geren. Sphingomyelinase D activity of brown recluse spider (Loxosceles reclusa) venom as studied by 31P-NMR: effects on the time-course of sphingomyelin hydrolysis. Toxicon 36, 537–545, 1998.—The time-course for the hydrolysis of the D linkage of chicken egg yolk sphingomyelin in a Triton X-100 mixed micelle and of lysophosphotidylcholine micelles, as catalyzed by brown recluse spider venom and brown recluse spider toxin, was followed by phosphorous-31 nuclear magnetic resonance spectroscopy. The overall rate of hydrolysis of sphingomyelin in mixed micelles was found to be an order of magnitude faster than the hydrolysis of lysophosphotidylcholine. Incorporation of lysophosphotidylcholine into mixed micelles with Triton X-100 inhibited the lipase activity of brown recluse spider venom and brown recluse spider venom toxin. The effects of increased rates of overall reaction were observed with increased temperature and also with decreased ionic strength. The presence of divalent calcium ions was found to be necessary for hydrolytic activity, but only in catalytic amounts (less than 1 mM).

Bites and stings from arthropods are largely inevitable because of the number of offending species and their distribution throughout our environment. Wasps, bees, ants, mosquitoes, gnats, chiggers, and fleas are found all across the United States. Thus far, Africanized honeybees are limited to southwestern states and fire ants to southern states. Brown recluse spiders are found most often in the Midwest and south central region, but the black widow spider is found in all 48 contiguous states. The dangerous Centruroides species of scorpion live mostly in southern states and California. Fortunately, in most people, bites and stings from arthropods produce only self-limited reactions, which can usually be managed with cold packs, analgesics, and topical agents. In the few encounters that produce serious reactions, prompt diagnosis and appropriate treatment result in a good outcome in nearly all cases. The number of stings and bites can be reduced with use of a few basic avoidance and protection measures.

Study objective: To examine the clinical presentation and outcome of patients treated in the ED or toxicology clinic for suspected brown recluse spider bites. Methods: We assembled a retrospective case series of patients at a southeastern US university hospital. Our study group comprised 111 patients with suspected brown recluse spider bites treated during a 30-month period. Our main outcome measures were the need for skin grafting and the development of other complications. Results: The mean age of our subjects was 34±17 years. Thirteen patients (12%) brought the spider to the hospital, 22 (20%) saw a spider at the time of the bite, and an exclusively clinical diagnosis was made in the remaining 76 (68%). Most wounds (59%) involved the leg. At the time of presentation, 81% had central discoloration and 37% necrosis. Sixteen patients (14%) were systemically ill, and 6 (5%) were admitted to the hospital. Most (86%) were treated with antibiotics. Dapsone was infrequently used (9%) and had usually been prescribed before the patient's presentation to our ED. Only three patients (3%; 95% confidence interval, 1% to 8%) required skin grafting. Mild hemolytic anemia developed in one patient, and another had mild hemolysis and a mild coagulopathy; neither patient was taking dapsone. No deaths or serious complications occurred in our study group. Conclusion: In our series, long-term outcome after brown recluse spider bite was good. Serious complications were rare, as was the need for skin grafting. Because the vast majority of bites heal with supportive care alone, aggressive medical therapy does not appear warranted. [Wright SW, Wrenn KD, Murray L, Seger D: Clinical presentation and outcome of brown recluse spider bite. Ann Emerg Med July 1997;30:28-32.]

Objectives: Loxosceles reclusa (brown recluse) spider bites can produce severe skin lesions that may necessitate extensive surgical repair. This study delineated the effects of hyperbaric oxygen (HBO) therapy on these lesions by performing a prospective controlled animal study. Methods: After approval by the Institutional Animal Care and Use Committee, 41 New Zealand white rabbits received 64 intradermal injections of 73 μL of raw venom extract mixed with physiologic buffered saline (Dulbecco's solution). Control injections were made with buffer. The animals were divided into 5 groups: 1) venom and no HBO; 2) venom and 1 immediate HBO treatment (100% O2); 3) venom and immediate HBO with 10 treatments (100% O2); 4) venom and then delayed (48 hr) HBO therapy with 10 treatments (100% O2); and 5) venom and immediate hyperbaric treatment with normal inspired Po2 for 10 treatments (8.4% O2). Three animals in group 2 also received a control sodium citrate buffer injection. HBO treatments were at 2.5 atm absolute (ATA) for 90 minutes twice daily. Daily measurements were made of the lesion diameter, and skin blood flow using a laser Doppler probe. Results: There was no significant effect of HBO on blood flow at the wound center or 1–2 cm from the wound center. Standard HBO significantly decreased wound diameter at 10 days (p < 0.0001; ANOVA), whereas hyperbaric treatment with normoxic gas had no effect. Histologic preparations from 2 animals in each group revealed that there were more polymorphonuclear leukocytes in the dermis of all the HBO-treated animals when compared with the venom-alone and sodium-citrate controls. Conclusion: HBO treatment within 48 hours of a simulated bite from L. reclusa reduces skin necrosis and results in a significantly smaller wound in this model. The mechanism appears unrelated to augmented local blood flow between treatments.

3-year-old girl was admitted for sudden onset of 12 hours of high fever, vomiting, malaise, and skin rash the day prior to admission, with no history of trauma or drugs. The patient showed a petechial and morbilliform rash, swelling, redness and a dry dark blue-purple lesion on the right big toe (Figure). Blood tests showed thrombocytopenia (18 10 9 /L), high C-reactive protein, and no signs of disseminated intravascular coagulation. A presumptive diagnosis of loxoscelism was made, based on the clinical picture in an endemic area during the warm season. The patient was treated with antibiotics until blood and wound cultures appeared negative and prednisone for 5 days, and was discharged after 4 days with resolution of the systemic symptoms and laboratory improvement. The dermonecrosis underwent desquamation and healing within 3 weeks. Loxoscelism describes the reactions and lesions caused by bites from spiders of the genus Loxosceles. 1-3 In Israel, certified bites of L rufescens have been reported and many cases of loxoscelism have been described. 1,4 Most bites are benign, but local and/or systemic reactions can appear. The typical local manifestation is dermonecrosis. Systemic symptoms include morbilliform rash, fever, chills, nausea, vomiting, malaise, arthralgia, and myalgia; hemolytic anemia and leukocytosis; less frequent thrombocytopenia, disseminated intravascular coagulation, renal failure, multiorgan failure, and even death, more commonly in children than in adults. 1-3 Loxosceles venom contains enzymes (hyaluronidase, alkaline phosphatase, esterase, and sphingomyelinase D2) responsible for tissue destruction and cytotoxicity. 1-3 The diagnosis is rarely based on identification of the spider. A presumptive diagnosis is made clinically, based on