36 cases of bites by spiders, including the white-tailed spider, Lampona cylindrata

Pain-related toxins in scorpion and spider venoms: a face to face with ion channels

Pain is a common symptom induced during envenomation by spiders and scorpions. Toxins isolated from their venom have become essential tools for studying the functioning and physiopathological role of ion channels, as they modulate their activity. In particular, toxins that induce pain relief effects can serve as a molecular basis for the development of future analgesics in humans. This review provides a summary of the different scorpion and spider toxins that directly interact with pain-related ion channels, with inhibitory or stimulatory effects. Some of these toxins were shown to affect pain modalities in different animal models providing information on the role played by these channels in the pain process. The close interaction of certain gating-modifier toxins with membrane phospholipids close to ion channels is examined along with molecular approaches to improve selectivity, affinity or bioavailability in vivo for therapeutic purposes.

Arachnid toxinology in Australia: From clinical toxicology to potential applications

The unique geographic isolation of Australia has resulted in the evolution of a distinctive range of Australian arachnid fauna. Through the pioneering work of a number of Australian arachnologists, toxinologists, and clinicians, the taxonomy and distribution of new species, the effective clinical treatment of envenomation, and the isolation and characterisation of the many distinctive neurotoxins, has been achieved. In particular, work has focussed on several Australian arachnids, including red-back and funnel-web spiders, paralysis ticks, and buthid scorpions that contain neurotoxins capable of causing death or serious systemic envenomation. In the case of spiders, species-specific antivenoms have been developed to treat envenomed patients that show considerable cross-reactivity. Both in vitro and clinical case studies have shown they are particularly efficacious in the treatment of envenomation by spiders even from unrelated families. Despite their notorious reputation, the high selectivity and potency of a unique range of toxins from the venom of Australian arachnids will make them invaluable molecular tools for studies of neurotransmitter release and vesicle exocytosis as well as ion channel structure and function. The venoms of funnel-web spiders, and more recently Australian scorpions, have also provided a previously untapped rich source of insect-selective neurotoxins for the future development of biopesticides and the characterisation of previously unvalidated insecticide targets. This review provides a historical viewpoint of the work of many toxinologists to isolate and characterise just some of the toxins produced by such a unique group of arachnids and examines the potential applications of these novel peptides.

Funnel-web spider bite: a systematic review of recorded clinical cases

OBJECTIVE

To investigate species-specific envenoming rates and spectrum of severity of funnel-web spider bites, and the efficacy and adverse effects of funnel-web spider antivenom.

DATA SOURCES

Cases were identified from a prospective study of spider bite presenting to four major hospitals and three state poisons information centres (1999-2003); museum records of spider specimens since 1926; NSW Poisons Information Centre database; MEDLINE and EMBASE search; clinical toxinology textbooks; the media; and the manufacturer's reports of antivenom use.

DATA EXTRACTION

Patient age and sex, geographical location, month, expert identification of the spider, clinical effects and management; envenoming was classified as severe, mild-moderate or minor/local effects.

DATA SYNTHESIS

198 potential funnel-web spider bites were identified: 138 were definite (spider expertly identified to species or genus), and 77 produced severe envenoming. All species-identified severe cases were attributed to one of six species restricted to NSW and southern Queensland. Rates of severe envenoming were: Hadronyche cerberea (75%), H. formidabilis (63%), Atrax robustus (17%), Hadronyche sp. 14 (17%), H. infensa (14%) and H. versuta (11%). Antivenom was used in 75 patients, including 22 children (median dose, 3 ampoules; range, 1-17), with a complete response in 97% of expertly identified cases. Three adverse reactions were reported, all in adults: two early allergic reactions (one mild and one with severe systemic effects requiring adrenaline), and one case of serum sickness.

CONCLUSIONS

Severe funnel-web spider envenoming is confined to NSW and southern Queensland; tree-dwelling funnel webs (H. cerberea and H. formidabilis) have the highest envenoming rates. Funnel-web spider antivenom appears effective and safe; severe allergic reactions are uncommon.

Idiopathic necrotizing dermatitis: current management

OBJECTIVES

To identify and demonstrate necrotizing dermatitis in infancy; an uncommon, puzzling syndrome, in which anecdotal reporting and personal experience indicates that one third of cases may require skin grafting. Much informed discussion about the pathogenesis of this distressing syndrome centres on the role of spider envenomation; and in particular on the speculative role of the Australian White-tailed spider, Lampona cylindrata.

METHODS

We present here six cases of necrotizing dermatitis treated surgically at the Royal Children's Hospital and Mater Children's Hospital in Brisbane over the period from 1991 to 1999. Clinical history, surgical details and pathological investigations were reviewed in each case. Microbiological investigation of necrotic ulcers included standard aerobic and anaerobic culture.

RESULT

Nocardia and Staphylococcus were cultured in two cases, but no positive bites were witnessed and no spiders were identified by either the children or their parents. All cases were treated with silver sulphadiazine creme. Two of the infants required general anaesthesia, excision debridement and split skin grafting. The White-tailed spider, Lampona cylindrata, does not occur in Queensland, but Lampona murina does; neither species has necrotizing components in its venom. Circumstantial evidence is consistent with this syndrome being due to invertebrate envenomation, possibly following arachnid bites.

CONCLUSION

In our experience there is insufficient evidence to impute a specific genus as the cause, at this stage of scientific knowledge. If the offending creature is a spider, we calculate that the syndrome of necrotizing dermatitis occurs in less than 1 in 5000 spider bites.

Australian wolf spider bites (Lycosidae): clinical effects and influence of species on bite circumstances

BACKGROUND

Necrotic arachnidism continues to be attributed to wolf spider bites. This study investigates the clinical effects of bites by wolf spiders in Australia (family Lycosidae).

METHODS

Subjects were recruited prospectively from February 1999 to April 2001 from participating emergency departments or state poison information centers. Subjects were included if they had a definite bite by a wolf spider and had collected the spider, which was later identified by an arachnologist. Spiders were identified to the lowest taxonomic level possible and cephalothorax width was measured to correlate bite effects and spider size.

RESULTS

There were 45 definite wolf spider bites (23 male and 22 female patients; age range 1 to 69 years, median age 28 years). Species level identifications (14 species) were possible for 31 of 43 spiders belonging to seven different generic groupings. Most bites were by spiders from four generic groupings, Tasmanicosa (including 'Lycosa') (15), Venatrix (8), Venator (10), and Hogna (7). Bites occurred more commonly in south-eastern Australia and occurred throughout the year, with 7 bites (16%) in late autumn or winter. In 7 cases (16%) the person was swimming in or cleaning a pool. Seventy-two percent of bites occurred on distal parts of limbs. Pain occurred in all bites and was severe in 11 cases (24%), with a median duration of 10 min (IQR: 2-60 min). Other effects included puncture marks/bleeding (33%), swelling (20%), redness (67%), and itchiness (13%). Minor systemic effects occurred in three patients (7%): nausea (two), headache (one) and malaise (one). There were no cases of necrotic ulcers [0%; 97.5% CI 0-8%]. Tasmanicosa spider bites caused significantly more itchiness and redness, and large spiders (>5 mm) more often caused severe pain and left fang marks.

CONCLUSION

Wolf spider bites cause minor effects, no more severe than most other spiders, and do not appear to cause necrotic ulcers. The effects are likely to be due to mechanical injury, although minor local envenomation occurs with Tasmanicosa bites.

Clinical consequences of spider bites: recent advances in our understanding

Spider bite continues to be a controversial subject worldwide and attribution of clinical effects to different spiders is problematic because of poor case definition and paucity of clinical evidence. The effects of medically important spiders are sometimes underestimated and simultaneously there is misattribution of effects to harmless spider groups. The majority of suspected spider bites present as skin lesions or necrotic ulcers where the history of a spider bite must be confirmed. To be a definite spider bite, the patient must immediately observe the spider and there be evidence of the bite, such as pain. Important groups of spiders worldwide include the widow spiders (latrodectism), recluse spiders (loxoscelism) and some mygalomorph spiders including the Australian Funnel web spider. Most spiders only cause minor effects, including a large number of groups that have been implicated in necrotic arachnidism.

Black house spiders are unlikely culprits in necrotic arachnidism: a prospective study

Twenty-five patients with definite bites by Badumna spp. spiders were recruited prospectively. Bites occurred across Australia, 92% from October to March, and most during daylight. Pain occurred in all cases, was severe in seven cases, with a median duration of 5 min. Other effects included: puncture marks (24%), swelling (12%) and erythema (68%). Minor systemic effects occurred in 4 bites. No patient had a necrotic ulcer (0%; 97.5% confidence interval 0-14%). Black house spiders (Badumna spp.) are unlikely to cause necrosis, contrary to reports of suspected bites. Patients can be reassured and do not require any further investigation or treatment.

Bites by Australian mygalomorph spiders (Araneae, Mygalomorphae), including funnel-web spiders (Atracinae) and mouse spiders (Actinopodidae: Missulena spp)

A number of mygalomorph spiders cause bites in Australia, including the funnel-web spiders (Hexathelidae, Atracinae: Hadronyche and Atrax) and mouse spiders (Actinopodidae: Missulena). There is ongoing debate about the significance of bites by mouse spiders and the frequency of severe envenoming by funnel-web spiders. We conducted a prospective cohort study of definite spider bites with expert spider identification and include the analysis of mygalomorph spiders here. Subjects were recruited prospectively from February 1999 to April 2003 from patients presenting to participating hospitals or contacting a state poison information centre. Forty-nine cases of bites by mygalomorph spiders were included: 16 were by funnel-web spiders, 13 by mouse spiders and 20 by other trapdoor spiders (Families Idiopidae and Nemesiidae). Of the 49 bites, 45 (92%) occurred on distal limbs (hands and feet). Local effects included severe pain (53%), puncture marks (61%) and bleeding (27%), local redness (33%). Itchiness did not occur. The following were highly statistically associated with mygalomorph spider bites compared to all other spiders (p<0.0001) circumstances (gardening at the time (likelihood ratio (LR) 7.9) and distal limb bites (LR 2.0)) and early clinical features (presence of puncture marks OR bleeding (2.3), or severe pain (2.0)). Of 16 funnel-web spider bites, there were 10 cases with minor local effects, four with moderate envenoming (non-specific systemic or local neurotoxicity) and two with severe envenoming requiring antivenom. In addition to local effects, mouse spider bites caused local paraesthesia in three cases, local diaphoresis in one case and non-specific systemic effects in five cases, but not severe envenoming. True trapdoor spider bites caused only minor effects. The data from a mixed species sample of funnel-web spiders confirms previous observations suggesting that only a small proportion of funnel-web bites cause severe effects. Mouse spider bites are unlikely to cause major envenoming but the clinical effects are consistent with neurotoxic venom and are more severe than the trapdoor spiders.

Effects of Envenoming by Comb‐Footed Spiders of the GeneraSteatodaandAchaearanea(Family Theridiidae: Araneae) in Australia

BACKGROUND

The family Theridiidae (comb-footed spiders) contains the well-known and medically important widow spider group (Latrodectus spp.). Little is known about the effects of envenoming by other common members of this family.

OBJECTIVE

The objective of this study was to determine the clinical effects of bites by common theridiid spiders of the genera Steatoda and Achaearanea.

METHODS

This was a prospective cohort study of calls to Australian poison information centers and presentations to emergency departments. Twenty-eight persons with a definite bite by a spider of the family Theridiidae, excluding Latrodectus spp., were included where the spider was immediately collected and expertly identified from February 1999 to April 2002.

RESULTS

There were 23 bites by Steatoda spp. and five bites by Achaearanea spp. Steatoda bites occurred across Australia, throughout the year, and the majority during waking hours. Seventy-eight percent of bites occurred indoors and 48% while dressing indoors. Pain was universal and was severe in six (26%). Increasing pain in the first hour occurred in 30%, and the median duration of pain was 6 hr (interquartile range: 1-12 hr). Local or regional diaphoresis did not occur. Systemic effects occurred in 30% and included nausea, headache, lethargy, and malaise. The majority received no treatment: seven patients presented to a hospital (two patients received opiates for analgesia) and 1 patient inadvertently received intravenous redback spider (RBS) antivenom because the spider was initially misidentified as a RBS (Latrodectus). The pain and symptoms responded over 1 hr following antivenom administration. Bites by Achaeranea spp. caused moderate to severe persistent pain, but no systemic effects.

CONCLUSIONS

Steatoda spp. bites or "steatodism" may cause prolonged pain and systemic effects similar to Latrodectus bites, but less severe. In severe cases, the clinical effects were almost indistinguishable from Latrodectus, except diaphoresis was absent, and the spiders were often mistaken for Latrodectus. Intravenous RBS antivenom appears to be an effective treatment in isolated severe cases, consistent with in vitro work. Achaearanea bites caused pain similar to Latrodectus bites.

White-tail spider bite: a prospective study of 130 definite bites by Lampona species

OBJECTIVE

To investigate the circumstances and clinical effects of bites by white-tail spiders, including the two species Lampona cylindrata and L. murina commonly encountered by humans, and the incidence of necrotic lesions.

DESIGN

Prospective cohort study of definite white-tail spider bites. Cases were only included if there was a clear history of bite, the spider was caught and was identified by an expert.

SETTING

Calls to Australian poisons information centres and emergency departments.

PATIENTS

130 patients with a definite bite by a white-tail spider from February 1999 to April 2002.

RESULTS

There were 79 bites by L. cylindrata and 51 by L. murina. Bites occurred in warmer months, 95% indoors and 75% between 16: 00 and 08: 00. The activity at the time of the bite was characteristic and the spider was encountered between bedclothes, towels or clothing. 25% of bites occurred on distal limbs. Pain/discomfort occurred in all cases, and was severe in 27%. Other effects included puncture marks (17%), redness/red mark (83%) and itchiness (44%). Systemic effects occurred in 9%. There were no cases of necrotic ulcers (97.5% CI, 0-2.8%) or confirmed infections. Median duration of effects was 24 hours (interquartile range, 1-168 hours). There were three distinct clinical patterns: pain only (21%), pain and red mark for < 24 hours (35%), and a persistent painful or irritating red lesion (44%).

CONCLUSIONS

Bites by Lampona spp. cause minor effects in most cases, or a persistent painful red lesion in almost half the cases. White-tail spider bites are very unlikely to cause necrotic ulcers, and other diagnoses must be sought.

A prospective study of definite bites by spiders of the family Sparassidae (huntsmen spiders) with identification to species level

Spiders of the family Sparassidae occur on most continents in tropical and temperate regions of the world. They are large Araneomorphae (modern spiders) which are often feared. There are few reports of confirmed sparassid bites and some suggest that particular genera (Neosparassus) can cause severe effects. This study investigated the circumstances and clinical effects of bites by Australian sparassid spiders with correlation to taxonomic species level. Cases were recruited prospectively from calls to Australian poison information centres and two emergency departments. Patients were included if there was a clear history of bite and the spider was caught, and were followed up over a week. There were 173 patients with spider injuries and 168 with definite bites by sparassid spiders over a 27 month period. Ninety-five percent of bites were by spiders from four genera: Isopeda (32%), Isopedella (21%), Neosparassus (27%) and Heteropoda (14%); other genera included Delena and Holconia. The seasonal and diurnal distribution of bites differed between genera, although the majority occurred in warmer months in daylight hours. Seventy-six percent of bites occurred because the spider was interfered with (picked up, dressing or picked up an object with the spider) consistent with the behaviour of most of the family requiring provocation to bite. Ninety-five percent of bites occurred on limbs, 82% on distal limbs, again consistent with handling the spider. Pain/discomfort occurred in all cases, and was severe in 27%. The median duration of pain was 5 min which was significantly less than other spiders. Puncture marks (40%) or localised initial bleeding (35%) occurred in 54% of bites, and both occurred significantly more often in all sparassid bites compared to all other spider bites (p<0.0001). Swelling occurred in 16%, itchiness in 14% and redness/red mark in 57% of cases, the latter significantly less common than other spiders (p=0.0002). Systemic effects occurred in 4% of bites and were minor (nausea and/or headache). There were no cases of necrotic ulcers or allergic reactions. There were four cases with features consistent with local infection. Bites by sparassid spiders cause minor effects, characterised by immediate and transient pain, associated with bleeding, puncture marks and local redness. The mechanism of effects appeared to be trauma rather than envenoming. There were no major differences between genera, and Neosparassus spp. did not cause major effects.

Data collection in clinical toxinology: debunking myths and developing diagnostic algorithms

Clinical toxinology suffers from a long history of poor data collection. A 20-year review of MEDLINE illustrates the lack of randomized controlled trials and prospective studies in clinical toxinology. Mythology surrounds bites and stings, resulting from the general fear of many creatures such as spiders, which has not been disproved by appropriate well-designed studies. The current focus on necrotic arachnidism in many parts of the world is a good example. Previously, most studies have been retrospective, bites and stings have not been confirmed, and creatures have not been kept or have been incorrectly identified. Prospective observational studies of confirmed bites with correct identification of the creature are required in clinical toxinology. This requires a collaboration between those who can correctly identify the animals (biologists/taxonomists) and those involved in the clinical management (poison information services, emergency departments, and toxicology services). Prospective collection of data pertaining to the circumstances and effects of the bites is essential. Routine follow-up is required to identify delayed effects and the duration of immediate effects. Analysis of databases created from prospective studies will not only answer questions about the effects of different species, but will ultimately allow the development of evidence-based methods to identify animals based on the circumstances and effects of bites, rather than requiring formal identification of the culprit.

Pharmacology and biochemistry of spider venoms

Spider venoms represent an incredible source of biologically active substances which selectively target a variety of vital physiological functions in both insects and mammals. Many toxins isolated from spider venoms have been invaluable in helping to determine the role and diversity of neuronal ion channels and the process of exocytosis. In addition, there is enormous potential for the use of insect specific toxins from animal sources in agriculture. For these reasons, the past 15-20 years has seen a dramatic increase in studies on the venoms of many animals, particularly scorpions and spiders. This review covers the pharmacological and biochemical activities of spider venoms and the nature of the active components. In particular, it focuses on the wide variety of ion channel toxins, novel non-neurotoxic peptide toxins, enzymes and low molecular weight compounds that have been isolated. It also discusses the intraspecific sex differences in given species of spiders.

Comparison of enzymatic activity from three species of necrotising arachnids in Australia: Loxosceles rufescens, Badumna insignis and Lampona cylindrata

Necrotising arachnidism, or skin ulceration due to spider bite, is an unresolved clinical problem in Australia, with both the spiders responsible and disease pathogenesis remaining unclear. We have examined and compared enzymic activity from three species of Australian spiders capable of causing ulceration in humans; the recluse spider (Loxosceles rufescens), the black window spider (Badumna insignis) and the white-tailed spider (Lampona cylindrata). Enzymes which could contribute to skin ulceration, namely hyaluronidase and proteases, were detected in venom extracts of all the three spiders. Significant sphingomyelinase activity was detected in L. rufescens venom and in abdominal extracts from the three spider species, while significantly lower levels of sphingomyelinase activity were detected in abdominal extracts from the non-necrosing red-back spider (Latrodectus hasselti). These results suggest that both venom and gastric enzymes may contribute to the dermonecrotic effects of these spiders bites.

Clinical effects of bites from formally identified spiders in tropical Northern Territory

OBJECTIVE

To determine the types of spiders causing bites and the clinical effects of their bites in tropical Northern Territory (north of the town of Katherine).

DESIGN

A prospective study of confirmed and suspected spider-bites and a retrospective analysis of data from a standardised, local database of spider- and snake-bites. Confirmed spider-bites were those in which there was a clear history of the bite, and the captured spider was identified by an arachnologist.

SETTING

Emergency department of a teaching hospital. SUBJECTS AND DATA SOURCE: All subjects with confirmed or suspected spider-bite presenting to the Emergency Department or referred from August 1999 to August 2000, or identified from the database.

RESULTS

Thirty-four subjects had a confirmed spider-bite from an identified spider: 25 in the prospective group and nine in the retrospective group. The spiders were Sparassidae (huntsman spider) (12 bites), Missulena pruinosa (northern mouse spider) (7), Latrodectus (widow spider) (4), Araneidae (orb-weaver) (4), Salticidae (jumping spider) (4), Nemesidae (trapdoor spider) (1), Conothele (1) and Selenocosmia (whistling spider) (1). Clinical effects were local pain in 97% (severe in 29%), redness in 47% and swelling in 24% of cases. Systemic effects occurred in three victims, two of whom were bitten by M. pruinosa. There were no cases of confirmed necrotic arachnidism.

CONCLUSIONS

None of the spider-bites resulted in severe effects. Compared with data from other parts of Australia, different species were involved and latrodectism was uncommon. Our study highlighted the importance of correctly identifying the spider species.

Sex differences in the pharmacological activity of venom from the white-tailed spider (Lampona cylindrata)

This study compared the pharmacological activity of venom from male and female white-tailed spiders (L. cylindrata). In guinea-pig ileum, male L. cylindrata venom (1-10 microg/ml) caused dose-dependent contractions. The response to venom (5 microg/ml) was significantly inhibited by mepyramine (0.5 microM). Venom (5-50 microg/ml) from female L. cylindrata had no contractile activity in this tissue. However, female L. cylindrata venom (50 microg/ml) inhibited electrically-evoked twitches of guinea-pig ileum. This inhibitory effect was attenuated by 8-phenyltheophylline (10 microM) or by prior exposure of venom to adenosine deaminase. In the rat vas deferens, male (5 microg/ml) and female (50 microg/ml) L. cylindrata venom inhibited electrically-evoked twitches. 8-Phenyltheophylline (20 microM) significantly attenuated the response to female L. cylindrata venom, while the histamine H(2)- and H(3)-receptor antagonists ranitidine (10 microM) and thioperamide (0.2 microM) significantly attenuated the response to male L. cylindrata venom. Male L. cylindrata venom (5-20 microg/ml) caused dose-dependent contractions in the epididymal segment of the rat vas deferens. The response to male L. cylindrata venom (10 microg/ml) was significantly inhibited by prazosin (0.3 microM) but was unaffected by depleting monoamine stores with reserpine. Male L. cylindrata venom (5-15 microg/ml) caused dose-dependent increases in rate and force of rat atria which were significantly inhibited by propranolol (5 microM) but not by reserpine. Female L. cylindrata venom (50 microg/ml) had no effect in atria. In the anaesthetised (pentobarbitone, 100 mg/kg, i.p.) rat, male L. cylindrata venom (10-300 microg/kg, i.v.) caused dose-dependent depressor responses while venom (up to 1 mg/kg, i.v.) from female L. cylindrata had no effect on arterial pressure. A histamine content of 5 and 0.01% (dry weight) was detected in venom from male and female L. cylindrata, respectively. Venom from male L. cylindrata was found to contain 56 pg noradrenaline/microg whereas venom from the female contained negligible noradrenaline. The results of this study show the presence of histamine and noradrenaline in venom from male L. cylindrata. Although devoid of significant quantities of these amines, female L. cylindrata venom has activity at adenosine receptors.

Clinical features and management of Hadronyche envenomation in man

Using case reports and a review of the literature, the clinical features of envenomation by the genus of Australian funnel web spiders known as Hadronyche, are characterised. Five cases are reported here, including the first life-threatening envenomation by Hadronyche species 14 (the Port Macquarie funnel web). Two severe envenomations by Hadronyche cerberea (the Southern Tree funnel web) and one each by Hadronyche formidabilis (the Northern Tree funnel web) and Hadronyche infensa (the Darling Downs funnel web) are also described. The clinical experience of the authors' provided the five cases described in detail one of which has previously been reported in brief. Eight cases of Hadronyche envenomation from the literature (Medline 1966-1998 and Embase 1980-1998) were analysed in order to draw comparisons between this syndrome and the well described envenomation syndrome of Atrax robustus (the Sydney funnel web). Reports of funnel web spider antivenom use to Commonwealth Serum Laboratories (CSL) between 1995 and June 1998 were also examined. The biology of these dangerous spiders, their geographic distribution, venom characteristics and management issues are addressed. It is concluded that bites from at least six Hadronyche species have produced a life-threatening envenomation syndrome clinically indistinguishable from that of Atrax robustus. Atrax robustus derived antivenom is effective although antivenom requirements may be greater than for Atrax envenomation. Antivenom supplies are limited and sufficient stocks to treat a severe envenomation are unlikely to be found in any one institution. Pressure-immobilisation first aid is effective in delaying onset of envenomation, may enhance local inactivation of venom and early removal can result in rapid clinical deterioration.

Pharmacological action of Australian animal venoms

1. Australia has some of the most venomous fauna in the world. Although humans are not usually perceived as being predators against these animals they are often envenomated, accidentally or otherwise. This has led to the development of antivenoms against some of the potentially lethal venoms. However, further understanding of the mechanism(s) of action of these and other venoms is important, not only for developing new treatment strategies but also in the search for novel research tools. 2. The present review discusses the pharmacology of some of the components found in venoms and outlines the research undertaken on some of Australia's venomous animals, with the exception of snakes. 3. Biogenic amines, peptides and enzymes are common venom components and produce a wide range of effects in envenomated humans. For example, respiratory failure observed after envenomation by the box jellyfish (Chirnex fleckeri) and Sydney funnel-web spider (Atrax robustus) is most likely due to potent neurotoxins in the venoms. Stonefish (Synanceja trachynis) and platypus (Ornithorhynchus anatinus) venoms, although not considered lethal, cause severe pain. However, the components responsible for these effects have not been isolated. Venom components, as yet unidentified, may be responsible for the cutaneous necrotic lesions that have been reported after some spider bites (e.g. Lampona cylindrata). Other venoms, such as those of the jumper ant (Myrmecia pilosula) and bull ant (M. pyriformis), may produce only mild skin irritation to the majority of humans but a severe anaphylactic response in sensitized victims. 4. While there has been a renewed interest in toxinology, further research is required to fully elucidate the pharmacological action of many of these venoms.

Evidence against the involvement of Mycobacterium ulcerans in most cases of necrotic arachnidism

Cutaneous lesions caused by M. ulcerans were shown to bear only a superficial resemblance to those produced by certain spider species. M. ulcerans was not found in either the venoms or the midguts of several Australian spiders, and deliberate contamination by inoculation of the fangs and digestive system of the wolf spider, Lycosa godeffroyi, did not result in permanent colonization. M. ulcerans was successfully introduced into the skin of mice through a small trauma site similar to that caused by a spider bite. However, because M. ulcerans was shown to survive on exposed surfaces for only a short period, a successful inoculation is likely only if the skin is contaminated with this organism after, or at the same time as, the skin suffers damage. The claim by other workers that M. ulcerans produces cutaneous ulcers by release of an exotoxin could not be confirmed. The authors conclude that M. ulcerans is not involved in most cases of necrotic arachnidism and hence there is no justification for prescribing anti-mycobacterial antibiotics to resolve alleged spider bite lesions unless the presence of M. ulcerans has been demonstrated by appropriate laboratory tests.

Mygalomorph spider bites: a report on 91 cases in the state of São Paulo, Brazil

From 1966 to 1991 91 cases of bites due to mygalomorph spiders were recorded at the Hospital Vital Brazil, Instituto Butantan, São Paulo, Brazil, representing less than 1% of all spider bites. The diagnosis was confirmed by positive identification of the spider involved. Envenoming is generally mild, the main symptom is local pain, and there is minor oedema and erythema. The data confirm the assumption that these nonaggressive spiders pose no health problem.

A comparison of the toxicity of the venoms of twelve common Australian spider species on rodent vital organ systems

1. Venom samples from twelve different Australian spider species were compared for their toxic effects on the heart and respiratory systems of anaesthetized rats. 2. The first and most serious effect of all venoms was on breathing, cardiotoxicity mostly being secondary to respiratory failure. 3. Only Atrax infensus and Selenocosmia stirlingi venoms proved highly toxic to rats, and therefore potentially toxic to humans, when single doses were used. 4. The low potency of most of the other venoms tested showed that several simultaneous spider bites would be necessary to cause significant toxicity.

Neurotoxic envenoming by an immigrant spider (Steatoda nobilis) in southern England

A young woman was bitten on the shoulder by a female Steatoda nobilis spider, in Worthing on the south coast of England. She noticed intense radiating pain, local sweating (indicating parasympathetic stimulation) and feverishness. This immigrant species from the Canary Islands has established itself along the south coast of England in recent years. Like the related Mediterranean species S. paykulliana, S. nobilis may be of medical importance and deserves further study.

Studies of the necrotic actions of the venoms of several Australian spiders

1. Raw venoms from a number of Australian Araneomorph spiders were found to cause epidermal disruption in cultured skin from both mice and humans. 2. The more potent ones also caused loss of epidermal cell-cell adhesion of mouse skin in vivo. 3. Raw venoms from three Mygalomorph species did not have these actions. 4. Venom gland extracts from the Araneomorph species were also ineffective. 5. It was concluded that where spider venoms appear to possess necrogenic activity the most likely reason for this is contamination of the venoms with digestive tract secretions.

Inappropriate diagnosis of necrotizing arachnidism. Watch out Miss Muffet--but don't get paranoid

A 28-year-old man presented with painful progressive necrosis of the skin of his left leg which was associated with general toxicity and a high fever. A working diagnosis of necrotizing arachnidism was made, but no improvement followed two weeks of therapy with analgesics, antibiotics and antihistamines. His symptoms responded rapidly to prednisolone therapy, and a diagnosis of pyoderma gangrenosum was confirmed by biopsy. This subsequently proved to be associated with early acute myelomonocytic leukaemia.

A study of the necrotic actions of the venom of the wolf spider, Lycosa godeffroyi, on mouse skin

1. The venom of the wolf spider, Lycosa godeffroyi, caused cutaneous necrosis when injected into mice. 2. A strong inflammatory response and total loss of epidermal cellularity were features of this in vivo necrosis. 3. Mouse skin envenomated while in tissue culture showed epidermal detachment and reduced cellular adhesion. 4. Triprolidine and methysergide, used together, indomethacin, heparin and human and mouse sera all failed to inhibit the necrosis significantly. 5. The venom caused moderate haemolysis, complement consumption and inhibition of clotting, these apparently not being the main reasons for the necrosis. 6. Neither Atrax infensus venom nor hyaluronidase caused similar epithelial damage.