Redback Spider Research Articles

Antivenom treatment in arachnidism.

Envenomation by arachnids causes significant medical illness worldwide. Scorpion sting is the most important arachnid envenomation causing adult morbidity and pediatric mortality. Important groups of spiders include the widow spiders (Latrodectus spp.), the recluse spiders (Loxosceles spp.), and two spiders confined to single countries: the Australian funnel web spider (Atrax and Hadronyche spp.) and the armed spider (Phoneutria spp.) from Brazil. There are four widow spider antivenoms available, including the Australian redback spider antivenom and the American black widow antivenom. Despite good in vitro animal work demonstrating effective neutralization with these antivenoms, and cross-reactivity between many species, there continues to be a reluctance to use them in some countries. They are both associated with a relatively low rate of allergic reactions. Redback antivenom is routinely used by the intramuscular route, which may not be as effective as intravenous use based on clinical experience and animal studies. Antivenoms are available for Loxosceles spp., but there is little evidence to support their effectiveness, particularly against local effects. The Australian funnel web spider causes severe neurotoxic envenomation, and antivenom appears to be effective in reported cases. An antivenom exists for the Brazilian armed spider, but is used in only a minority of cases. Many scorpion antivenoms exist worldwide, but there remains significant controversy regarding their efficacy. Animal and human venom level studies demonstrate neutralization of circulating venom in systemic envenomation. Clinical experience in countries where antivenom has been introduced suggests it has reduced pediatric mortality. However, three controlled trials demonstrated that antivenom was not effective, but these included few severe cases. Until controlled trials of antivenom in systemically envenomated patients are undertaken, antivenom use appears justified in severe envenomation. Although envenomation from arthropods is common, no antivenoms exist for these, excepting Lonomia caterpillars in South America, and Ixodes paralysis ticks in Australia.

A18 GIS による地理的分布パターンから推測されるセアカゴケグモの拡散について

A18 GIS による地理的分布パターンから推測されるセアカゴケグモの拡散について

A prospective study of 750 definite spider bites, with expert spider identification.

Spider bite is a subject of much medical mythology with prevalent fears that spiders cause severe envenoming, with neurotoxic effects or necrotic ulcers. Clinical experience and small studies suggest otherwise, but this has not been confirmed by prospective studies of bites by identified spiders. To describe the clinical effects of bites by accurately identified spiders, and determine whether early clinical features and circumstances can predict spider type. Prospective follow-up study. Patients were recruited from admissions to two emergency departments (n=48) and referrals from three state poison information centres (n=1426), over 27 months. Overall, there were 750 people with definite spider bites where the spiders were immediately collected and expertly identified. Significant effects occurred in 44 bites (6%), including 37 (of 56) redback spider bites (Latrodectus hasselti) with significant pain lasting >24 h. Of these, only 6 (11%) received antivenom. One severe neurotoxic envenoming by an Australian funnelweb spider required antivenom. No definite spider bites resulted in necrotic ulcers (0%, 99%CI 0-0.7%). There were no early allergic reactions and secondary infection occurred in seven cases (0.9%, 95%CI 0.4-1.9%). Circumstances and early clinical effects were strongly associated with taxonomic spider identification, with positive predictive values >0.95 for common groups of spiders. Australian spider bite caused minor effects in most cases and is unlikely to cause necrotic ulcers, allergic reactions or infection. Redback spider bite (widow spider) caused prolonged pain, and antivenom could have been used more frequently. The circumstances and early clinical features of spider bites may allow early appropriate advice and treatment of spider bite without taxonomic identification.

Value of male remating and functional sterility in redback spiders

In the Australian redback spider, Latrodectus hasselti, males typically use their paired copulatory organs (palps) to copulate twice with a single female then sacrifice themselves to their cannibalistic mates in a strategy that increases their paternity in that one mating, but leads to death. This type of terminal investment in one mating is predicted only if the expected value of future matings is low for males relative to the value of repeated mating with the same female. In this laboratory study, we quantified the reproductive value of mating more than once with the same female (repeated mating) and mating with more than one female (multiple mating) for male redback spiders. We tested two natural selection hypotheses for repeated mating, sperm limitation and reproductive insurance, but found no support for either hypothesis. We show that, in the absence of sperm competition or cannibalism, male lifetime reproductive output is the same whether a male copulates once, twice, or several times with a given female. Repeated mating does not increase the probability of successful fertilization, nor does it increase the number of offspring produced in successful matings. Although male repeated mating is not favoured because of increased fertility of mates, other studies suggest it may be important in sperm competition. Here we show that the relative reproductive value of the first two copulations is very high for redback males because they are functionally sterile after each palp has been used once; nonvirgin males are unable to father offspring. Functional sterility and repeated mating by male redbacks may be favoured by the same factors that lead to male sacrifice behaviour: ecological constraints on multiple mating combined with competitive benefits of maximal investment in the first mating. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.

1. Latrodectus hasseltii(セアカゴケグモ)の個体数動態とその生息域の節足動物種との関係(第56回日本衛生動物学会西日本支部大会講演要旨)

1. Latrodectus hasseltii(セアカゴケグモ)の個体数動態とその生息域の節足動物種との関係(第56回日本衛生動物学会西日本支部大会講演要旨)

B27 地理情報システムによる大阪府におけるセアカゴケグモの分布解析

B27 地理情報システムによる大阪府におけるセアカゴケグモの分布解析

Clinical and in vitro evidence for the efficacy of Australian red-back spider ( Latrodectus hasselti) antivenom in the treatment of envenomation by a Cupboard spider ( Steatoda grossa)

We report the case of a 22-year-old female who was bitten on the shoulder by a spider subsequently identified as a female Cupboard spider ( Steatoda grossa). She developed nausea, vomiting, and severe local and regional pain, similar to that seen in latrodectism. Symptoms were treated successfully with red-back spider antivenom (RBSAV). We also present in vitro data, which supports this clinical observation, and suggests that S. grossa venom is immunogenically reactive with both RBSAV and latrotoxin (LTx)-specific antibodies by Western blotting. Moreover, the effects of S. grossa venom on the isolated chick biventer cervicis nerve–muscle preparation are dose-dependent and similar to those seen with Latrodectus spp. venoms. S. grossa venom produced a sustained muscle contracture which could be prevented by pre-incubation of venom with RBSAV. Venom effects could also be reversed by the addition of antivenom after application of venom to the preparation. Although severe envenomation is uncommon following the bite of Steatoda spp. it may resemble latrodectism. These results indicate that RBSAV is likely to be effective in reversing symptoms of envenomation and should be considered in the treatment of patients with distressing or persisting symptoms.

Red-back spider (Latrodectus hasselti) antivenom prevents the toxicity of widow spider venoms

Study Objectives: Widow spiders of the genus Latrodectus are found worldwide and produce similar clinical envenomation syndromes. In Australia, red-back spider antivenom (RBS-AV) is effective therapy for Latrodectus hasselti envenomation and it has been reported to reverse envenomation by other widow spiders. This study assessed the efficacy of RBS-AV in preventing in vitro and in vivo toxicity of widow spider venoms of North America and Europe. Methods: The binding of RBS-AV to α-latrotoxin and Latrodectus venoms (Latrodectus spp mactans, hesperus, lugubris, tredecimguttatus, hasselti ) was assayed using Western blotting. Prevention of in vitro toxicity to α-latrotoxin and the same venoms was tested by pretreating an isolated chick biventer cervicis nerve-muscle preparation with RBS-AV. Prevention of in vivo toxicity was determined by a lethality study in male Balb/c mice (2.5 to 5× median lethal dose [LD50]) or α-latrotoxin (10× LD50) preincubated with antivenom or without RBS-AV (control). Results: In Western blots, RBS-AV bound to α-latrotoxin and similar widow spider proteins in all venoms tested, indicating antigenic similarity with proteins found in RBS venom. Antivenom prevented the typical in vitro muscle contracture and loss of twitch tension seen with α-latrotoxin and the venoms tested. Control mice rapidly developed signs of envenomation, but mice treated with RBS-AV remained free of signs of envenomation. Conclusion: RBS-AV prevented both in vitro and in vivo toxicity from Latrodectus venoms and α-latrotoxin in mice. These data suggest that RBS-AV may be clinically effective in the treatment of envenomation resulting from the bite of other widow spiders. [Graudins A, Padula M, Broady K, Nicholson GM. Red-back spider (Latrodectus hasselti) antivenom prevents the toxicity of widow spider venoms. Ann Emerg Med. February 2001;37:154-160.]

Historical ecology, responses to current ecological changes and conservation of Australian spiders

In response to geohistorical events from the Mesozoic through the Tertiary with contraction of mesic forest to southwestern and eastern montane and coastal regions, and expansion of woodlands and xeric shrublands, nobreak Australian spiders today comprise relict families and genera (confined to Gondwanan habitats and refuges) along with later evolved representatives which have adapted to changing environments. Tropical relicts also persist in refugia in the arid interior while some spiders (both mygalomorphs and araneomorphs) have adapted to arid conditions, mainly through specialized behaviours. Although fire has become increasingly a phenomenon of the Australian environment it is doubtful whether any spiders are adapted to fire per se. European settlement has impacted differentially on relictual and later evolved representatives; a few species, including the funnelweb (Atrax robustus) and redback spider (Latrodectus hasselti) have benefited through enhanced habitat opportunities and some species of Badumna and other genera have become synanthropic. It is suggested that conservation strategies need to consider the ecoevolutionary history of particular spiders and their natural vulnerability or resilience to environmental factors.

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.

Bites and stings from venomous animals: a global overview.

Venomous and poisonous animals are a significant cause of global morbidity and mortality. This Seminar will cover selected aspects of these animals, their venoms/poisons, and their clinical impact on humankind, from a global perspective, but with a distinctive Australian flavor and a clinical emphasis. Venomous snakes are found throughout most of the world, including many oceans, and have evolved a variety of highly effective toxins and methods of delivery. Their impact on humans is considerable, most current data suggesting they cause in excess of 3 million bites per year with more than 150,000 deaths. Particularly in the rural tropics, snakebite morbidity and mortality has a significant human medical and economic toll. The major groups of snakes causing bites are the vipers, the elapids (cobra type), the sea snakes, the side-fanged vipers, and the back-fanged colubrids. Australian venomous snakes are nearly all elapids and have evolved some of the most toxic of all snake venoms. Their effects include potent procoagulants and anticoagulants, neurotoxins, myotoxins, and nephrotoxins, but a distinct absence of the major local necrotoxins found in some non-Australian elapids and many vipers. The effect of these toxins on humans is not limited to envenoming, for the toxins are proving invaluable as research tools and diagnostic agents, and may even have a future as precursors of therapeutic agents. Because of the high toxicity and diversity of Australian elapids, a variety of monovalent antivenoms have been developed. There is also a venom detection kit to determine the type of snake and allow targeted antivenom therapy. The kit has also increased information available on diagnostic patterns of envenoming for each species. Australia is also home to the world's most lethal spiders, the funnel webs of eastern Australia, as well as the red back spider, the single most common reason for antivenom treatment in Australia. The latter spiders have been accidently exported to Japan. Within the marine environment exist a vast array of toxic animals, both poisonous and venomous, which not only cause morbidity and mortality in humans, but offer an incredibly rich array of valuable toxins. Australian waters contain some of the most lethal and medically problematic species, presenting a diverse range of clinical problems.

The clinical effects of spider bites in southern Tasmania

Objectives: To analyse the clinical features and outcomes of patients with spider bites who presented to the Department of Emergency Medicine, Royal Hobart Hospital, Tasmania, Australia. Methods: A retrospective study of all patients with an emergency department discharge diagnosis of confirmed spider bite during a 5 year period was performed. Results: Twenty-two cases were identified, 15 of which involved unidentified spiders. Most victims were in the 15–34 years age group and were bitten in the home. Identified spiders included: redback (Latrodectus hasselti), white-tailed house (Lampona cylindrata), black house (Badumna insignis) and huntsman (Delena cancerides). Pain, swelling and erythema were the main presenting symptoms; main presenting signs were erythema, swelling, bite marks, local tenderness, lymphadenopathy and blistering. In 23% of cases, no clinical signs were detectable. Treatment consisted of antihistamines (36%) and antibiotics (32%). Four patients had signs consistent with necrotizing arachnidism; two of the four healed with hyperbaric oxygen after antibiotic treatment failed. Redback antivenom was administered to four patients. Three patients required in-patient treatment for local complications. Conclusions: Most spider bites presenting to Royal Hobart Hospital were uncomplicated; redback bites were uncommon. Treatment strategies were ill-defined and microbiological specimens were taken infrequently. Patients’ tetanus immunization status was poorly documented. There is a need for a national register of spider bites in Australia.

Caution regarding Bier's block technique for redback spider bite

Caution regarding Bier's block technique for redback spider bite

Spider Bites: Assessment and Management

Spider bite is common, but most species cause minimal or no effects. Patients may be misinformed regarding the nature and consequences of a bite. Understanding the current literature can assist the physician in the management of spider bite patients.This article reviews the current literature on spider bites and describes the clinical assessment and management of the medically important spider bites.Most spider bite is minor and causes nothing more than local irritation. Some spiders can cause significant morbidity and rarely, mortality. Lay identification of the spider has not been shown to be reliable. Latrodectism (red back spider envenomation) is characterised by pain (local, radiating, and regional); systemic symptoms occur less commonly. Funnel web spider bite is a medical emergency; a pressure immobilisation bandage should be applied and the patient transferred to a hospital with available antivenom and resuscitation facilities. Clinicians must consider spider bite in the differential diagnosis of unexplained autonomic and neurological dysfunction, particularly in children. In Australia, skin ulceration is more likely to be an infective, inflammatory or traumatic cause than a case of necrotising arachnidism.

Balancing sexual selection through opposing mate choice and male competition

Male–male competition and female mate choice act contemporaneously in the cockroach Nauphoeta cinerea and the social pheromone of males influences the outcome of both forms of sexual selection. We therefore examined the joint and separate effects of male–male competition and female mate choice to determine if the selective optima for the pheromone were the same or different. Dominant males in a newly established hierarchy mated more frequently, but not exclusively. Manipulations of the multi-component social pheromone produced by males of N. cinerea showed that both long- and close-range attraction of females by males were influenced by the quantity and composition of the pheromone. The most attractive composition, however, differed from that which was most likely to confer high status to males. Since the outcome of male–male competition can conflict with mating preferences exhibited by females, there is balancing sexual selection on the social pheromone of N. cinerea. Such balancing selection might act to maintain genetic variation in sexually selected traits. We suggest that the different forms of sexual selection conflict in N. cinerea because females prefer a blend different to that which is most effective in male–male competition in order to avoid mating with overly aggressive males.

Envenoming and antivenom use in Australia

Australia has a diverse and rich venomous fauna, both terrestrial and marine, including some of the most venomous species in each class. Antivenom is the principal therapy for the majority of medically significant envenomings and is currently supplied through a single source, CSL, Melbourne. Cases of envenoming reported to Australian poisons information centers (PICs) are dominated by spiderbite and insect stings, respectively accounting for 53.7% and 39.3% of all bite/sting calls. Marine animal bites/stings/poisonings account for only 4% of PIC calls in this category, while snakebites account for a mere 3% (still at least 400 calls/yr). Because most PIC calls are from the public, not doctors/hospitals, snakebite in particular is under-represented. The author has recently reviewed antivenom usage in Australia. Snakebite affects between 1,000 to 3,000 people per year, with an average annual mortality of about 2 cases. Brown snakes (genus Pseudonaja) cause the majority of deaths (and bites), with tiger snakes (genus Notechis) and taipans (genus Oxyuranus) accounting for nearly all other fatalities. Up to 500 cases require snake antivenoms each year, the majority of cases coming from rural areas of Queensland, Western Australia, New South Wales and Victoria, these being the most populated states. The wide availability of snake venom detection kits has allowed specific antivenom to be used more often, rather than polyvalent antivenom, but the latter is still used in nearly 30% of cases, suggesting underutilization of venom detection. The issue of premedication prior to antivenom remains unresolved. Antivenom usage and complication data for 1995 and 1996 will be presented. Red back spider antivenom is the most commonly used antivenom, with reports of usage being greater than for all other antivenoms combined. It is reported as being therapeutically efficacious in 94% of cases, with a single ampoule being used in 76% of cases, 2 ampoules in 18% of cases, and 3 or more ampoules in 6% of cases. Clinical experience suggests only 20% of red back spider bites require antivenom therapy. It is likely that between 5–10,000 bites occur annually.

我が国に分布する他 2 種のゴケグモ毒腺タンパク質に対するセアカゴケグモ抗毒血清の反応性

我が国に分布する他 2 種のゴケグモ毒腺タンパク質に対するセアカゴケグモ抗毒血清の反応性

Female hunger can explain variation in cannibalistic behavior despite male sacrifice in redback spiders

Male Australian redback spiders (Latrodtctus hasselti Thorell: Theriidae) place their abdomens directly over their mate's mouthparts during copulation, increasing the likelihood of sexual cannibalism. Male sacrifice may be adaptive because cannibalized males increase their paternity relative to those that are not eaten. Despite male sacrifice behavior, however, up to 50% of laboratory matings may end without sexual cannibalism. Here, I report a similar pattern in the field, where males were not cannibalized in 35% of observed matings (6/17). I examined variation in female cannibalistic behavior by evaluating the following three hypotheses for the occurrence of cannibalism from the female perspective: (1) the mistaken identity hypothesis proposes that females sometimes cannibalize males because they mistake them for prey, (2) the mate rejection hypothesis predicts that females cannibalize males who are unacceptable as mates, and (3) the feeding opportunism hypothesis predicts that hungry females are more likely to be cannibalistic Field observations refuted die first two hypotheses: females recognized males as potential mates (i.e., nonprey), and cannibalized and noncannibalized males were not phenotypically different. The feeding opportunism hypothesis was supported. In staged field matings, cannibalistic females were hungrier than their noncannibaUstic counter-parts. Moreover, a logistic regression analysis indicated that hunger was a significant predictor of cannibalism. Because redback males are below the typical prey size that females accept, well-fed females are less likely to consume their mates, despite the vulnerable mating posture. These results indicate that, although males facilitate sexual cannibalism, their fate may depend on the female's physical condition.

8 日本に上陸したセアカゴケグモについて (7) 耐寒性試験と冬期における生息状況

8 日本に上陸したセアカゴケグモについて (7) 耐寒性試験と冬期における生息状況

B20 ヤエヤマゴケグモ (仮称) の毒腺タンパク質と輸入抗毒血清との反応について

B20 ヤエヤマゴケグモ (仮称) の毒腺タンパク質と輸入抗毒血清との反応について