Brown recluse spider envenomation of the eyelid: an animal model

The authors developed a rabbit model of the brown recluse (BR) spider envenomation of the human eyelid. The spider bite causes cutaneous necrosis and systemic toxicity in human eyelids, possibly leading to disseminated intravascular coagulation, hemolysis, and death. The treatment has been controversial. The animal model evaluated the effects of single- and combined-agent therapy in four phases: venom dose response, time course, therapeutic effectiveness (steroid vs. dapsone vs. antivenom), and optimal therapy (steroid and dapsone; steroid and antivenom; and dapsone and antivenom combination groups). The combination dapsone and antivenom treatment group was the optimal animal regimen, although not completely effective in eliminating microscopic necrosis. The authors also report dramatic clinical improvement in human inflammatory response with dapsone therapy and recommend immediate dapsone therapy combined with specific BR venom, if available, in humans.

[Retrospective study on Latrodectus stings in Bahia, Brazil]

This work is a retrospective study of latrodectism in the State of Bahia, Brazil, from August 1980 to July 1990. The data concerning the accidents were obtained from file cards at the Antivenom Information Center of Bahia (AVICB). Latrodectus curacavienis was the ethiologic agent identified in 28% of the arachnid accidents. The major incidence was registered in urban area (57%) affecting men (70%) more than women, with 10 to 29 year-old age group (58%). Local pain (56%), erythematous papula (29%) and light oedema (17%) were the principal local symptoms. Pain in the limbs (29%), tremor and rigidities (29%), sweating (28%), limbs and arms paresthesia (21%) and abdominal pain (17%) were systemic ones. The treatment was mainly symptomatic (67%) and antivenin serum was used in 21% of the cases. After serotherapy, 64% of the patients left the hospital within less than 24 hours.

Spider bites

BACKGROUND

This review provides the physician with a clinical approach to the diagnosis and management of spider bites. It examines the recent literature concerning management of bites causing dermonecrosis, secondary infection, neuromuscular damage, and allergic reactions.

METHODS

Using the key words "spider bites," "brown recluse spider bites," "necrotic arachnidism," "black widow spider bites," "latrodectism," and "Tegenaria agrestis (Hobo spider)," the MEDLINE files were researched for articles pertinent to the practicing physician. Texts related to spiders and spider bites were also consulted.

RESULTS AND CONCLUSIONS

At least 60 species of spiders have been implicated in human bites. Most cause bites of minimal medical importance, requiring little treatment. Some (brown recluse, Hobo spider) cause severe cutaneous and systemic reactions requiring intensive medical management. The black widow bite can cause severe neurologic problems requiring the use of antivenin. Spider bites are frequently difficult to diagnose because the spider is not seen at the time of the suspected bite. Such bites should be labeled arthropod bites, vector unknown.

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

STUDY OBJECTIVE

To determine whether hyperbaric oxygen (HBO), dapsone, or cyproheptadine decreases the severity of skin lesions resulting from experimental Loxosceles envenomation.

DESIGN

Randomized, blinded, controlled study.

SETTING

Animal care facility.

INTERVENTIONS

We used New Zealand white rabbits. All groups received 20 micrograms of pooled L deserta venom intradermally. Our control group received 4 ml of a 5% ethanol solution by oral gavage every 12 hours for 4 days. The HBO group received hyperbaric oxygen at 2.5 ATA for 65 minutes every 12 hours for 2 days, plus 5% ethanol solution for 4 days. The dapsone group received dapsone 1.1 mg/kg in 5% ethanol by gavage every 12 hours for 4 days. The cyproheptadine group received cyproheptadine .125 mg/kg in 5% ethanol by gavage every 12 hours for 4 days.

RESULTS

Total lesion size and ulcer size were followed for 10 days. The lesions were then excised, examined microscopically, and ranked by the severity of the histopathology. The groups did not differ significantly with respect to lesion size, ulcer size, or histopathologic ranking.

CONCLUSION

Given the negative result in this study with adequate power to detect meaningful treatment benefits, we cannot recommend hyperbaric oxygen, dapsone, or cyproheptadine in the treatment of Loxosceles envenomation.

Red-back spider envenomation in the red centre of Australia

OBJECTIVE

To examine the incidence, symptoms and treatment of red-back spider envenomation at a rural hospital.

METHODS

A retrospective review of all patients admitted to the intensive care unit of Alice Springs Hospital with red-back spider envenomation from 1 January 1991 until 31 December 1992.

RESULTS

Thirty-two patients were identified, of whom 12 were Australian Aboriginals (35%). Mean time from bite to presentation was 21 hours. Twenty-six patients required antivenom. All patients responded well to therapy and adverse reactions to the antivenom were observed. Two antivenom recipients had had previous bites requiring treatment. Aboriginals received antivenom later than non-Aboriginals (27.0 h v. 16.5 h) and this delay was associated with more sweating and fever in Aboriginals.

CONCLUSION

Red-back spider envenomation is common in Central Australia. Aboriginals and non-Aboriginals are equally at risk but later presentation is more common in Aboriginals who thereby suffer greater systemic symptoms. Antivenom use is safe and effective.

Lymphatic flow rates and first-aid in simulated peripheral snake or spider envenomation

OBJECTIVES

To demonstrate and define normal lymphatic transit times by lymphoscintigraphy and to evaluate the efficacy of the currently recommended first-aid measures for the management of snake or spider envenomation.

SETTING

The nuclear medicine department of a major teaching hospital.

PARTICIPANTS AND DESIGN

Twenty-four subjects received either intradermal or subcutaneous injections of 99mtechnetium antimony sulfur colloid (0.1 mL) in both hands/forearms and feet/legs. This simulated a snake or spider bite. Fifteen of the subjects had first-aid in the form of firm bandages and splints applied to an upper and a lower limb immediately after injection.

MAIN OUTCOME MEASURES

The progress of the radiotracer was followed with a large field of view gamma camera. If no egress of radiotracer was seen in the bandaged limbs, the subject walked until radioactivity was detected.

RESULTS

The mean (+/- SEM) periphery-to-systemic circulation transit time after subcutaneous injection was 58 (+/- 7) minutes. The first-aid was found to be very effective when applied with bandage pressures ranging from 40 to 70 mmHg (5.3-9.3 kPa) in the upper limb and 55 to 70 mmHg (7.3-9.3 kPa) in the lower limb. Lower and higher bandage pressures were ineffective. However, despite first-aid measures, egress of radiotracer, even in the upper limbs, was seen in all subjects who walked for 10 minutes or more.

CONCLUSIONS

Firm pressure bandaging is an effective means of restricting the lymphatic flow of toxins after envenomation, provided the bandage is applied within the defined pressure range. Strict limb immobilisation is necessary to minimise lymphatic flow, and walking after upper or lower limb envenomation will inevitably result in systemic envenomation despite first-aid measures.

Scorpion sting-induced pulmonary oedema: evidence of increased alveolocapillary membrane permeability

A 16-year-old boy died with acute pulmonary oedema and shock after Tityus serrulatus scorpion sting. The patient showed evidence of cardiac dysfunction and damage, an increase in tracheobronchial aspirate/plasma protein concentration, light microscopic features of the lung compatible with the adult respiratory distress syndrome and electron microscopic findings compatible with acute lung injury and increased alveolocapillary membrane permeability.

Dapsone or electric shock therapy of brown recluse spider envenomation?

STUDY OBJECTIVES

We tested the null hypothesis that no outcome differences exist among the treatment groups of animals with brown recluse spider envenomations.

STUDY DESIGN

A prospective, placebo-controlled, experimental trial. Hartley guinea pigs were randomized into the following treatment groups: dapsone, Parali/azer stun gun, Guardian stun gun, and control.

INTERVENTIONS

Brown recluse spider skin lesions were induced with intradermal injections of 30 micrograms spider venom and were treated beginning 16 hours after inoculation. Shock regimens consisted of four cross shocks of 1-second duration on anesthetized animals. Oral dapsone treatment was 0.7 mg/kg twice daily for 3 days. Lesion areas were measured daily for 3 days.

RESULTS

The dapsone therapy group demonstrated significantly less induration and necrosis (P < .05) than that shown by the other three groups 72 hours after envenomation.

CONCLUSION

Dapsone therapy is more effective than either electric shock or no therapy for brown recluse spider envenomation in the guinea pig model.

[Latrodectism in southern France. A series of cases from the poisoning center of Marseille]

OBJECTIVES

Black widows, which belong to the genus Latrodectus, are particularly dangerous spiders. The clinical syndrome caused by their bite is known as latrodectism. In Provence and in Corsica, there is a locally-found species, Latrodectus mactans tredecimguttatus called "malmignate". A series of 30 cases were collected by the Marseille Poison centre between 1973 and 1993 inclusive.

RESULTS

The cases of poisoning involved patients bitten in the summer, mostly in Corsica (only 5 of the cases were from Provence) in rural areas. The symptoms were generally widespread pain and muscle contractions, sometimes associated with neurosomatic symptoms, such as increased sweating, or alterations in the blood pressure or body temperature. On the other hand, local signs remained benign or were absent, this sometimes causing confusion with the diagnosis: in 5 of the cases were surprisingly severe, the outcome of the poisoning was always favourable, using symptomatic treatment including infusions of calcium salts, which combat the effects of toxins (disturbance of presynaptic ion exchange).

Use of hyperbaric oxygen in toxicology

HBO has become recognized as a potential treatment for a variety of toxins. HBO is helpful because it provides an excess of dissolved oxygen, which not only can sustain life in the absence of hemoglobin, but in some cases can actually increase the clearance of toxins. In addition, it is now apparent that HBO serves more complex roles in toxicological injuries, such as modifying PMN-endothelial interactions and preventing oxidative tissue injury. The major drawback of HBO therapy is the lack of controlled clinical trials, partly due to the rarity of most of the toxins discussed. In fact, the field of hyperbaric medicine has come under increasing criticism for this failure. There is a physiologic basis for use of HBO in the toxins discussed. Unfortunately, only for CO is patient volume adequate for studies to document efficacy. Regarding the other toxins mentioned, the use of HBO should be reserved for carefully selected cases in which patients have failed routine care or are at risk for delayed effects.