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Introduction: Spider bites are often overestimated because there are no specific clinical or histopathological aspects that characterize them, and skin lesions that resemble a spider bite are often wrongly considered to be a "true spider bite". However, even in case of a true spider bite, it is almost impossible to confirm the biting species, since very often neither physicians nor patients are trained in spider identification., Objective: The aim of this report is to provide clinicians with a rapid and simple recognition of the few Italian medically relevant spiders, in order to take relative medical measures in case of spider bites., Materials and Methods: We defined spiders of considerable medical relevance the ones that cause local symptoms with possible systemic involvement, while we defined spiders with mild medical relevance the ones whose bite is not a medical emergency but is particularly painful or can cause lasting symptoms. We focused on the identification of the four spider taxa of major clinical interest through a brief descriptive, photographic and graphic guide, in association to dermatological manifestations., Results: Spiders of considerable medical relevance are Loxosceles rufescens and Latrodectus tredecimguttatus, while spiders of less severe medical relevance are Steatoda paykulliana, S. nobilis, S. grossa, Cheiracanthium punctorium, Amblyocarenum spp. and Macrothele calpeiana (the presence of the latter in Italy is only accidental and very sporadic). The only species capable of causing necrosis is Loxo-sceles rufescens, while Latrodectus tredecimguttatus can cause more systemic symptoms., Discussion and Conclusion: With the aim of promoting a first and rapid recognition of the species, we performed a morphological usable aspect for an initial and quick recognition according to an identification key.

Spider bites represent an unusual and potentially over-represented clinical diagnosis. Despite a common fear of spiders, known as arachnophobia, current knowledge suggests that only a small number of families within the order Araneae are medically relevant. Moreover, most cutaneous spider reactions, including both evenomations and physical trauma, produce mild, local symptoms which may be managed with supportive care alone. The differential diagnosis for spider bites may be broad, especially if the offending arachnid is not seen or found. We describe a series of spiders relevant to the dermatologist in the United States.

Loxoscelism is caused by envenomation by spiders from Loxosceles genus. Clinical symptoms only appear a few hours after envenomation and can evolve in local reactions, such as dermonecrosis, and systemic reactions, such as intravascular haemolysis, intravascular coagulation and renal failure. Current therapies are not effective, often not based in scientific research and can be even detrimental. A lack of understanding of the mechanism of action of the venom of the Loxosceles spider had thus far prevented development of effective therapies. In this review we aim to give an overview of our contributions to the understanding of the mechanism of action of the Loxosceles venom and propose targets and therapeutics for medical intervention., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Bites by the woodlouse spider, Dysdera crocata, are virtually innocuous. The main symptom is minor pain, typically lasting less than 1h, 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.

LIMITED RISKS: Although most species of spiders are venomous, only ten or so are able to induce human envenomations. From a systematic point of view, it is possible to distinguish the araneomorph spiders - or "true" spiders - from the mygalomorph spiders. Dangerous species for humans can be found in both groups. Regarding "true' spiders, two kinds of envenomation are frequent, ubiquitous and potentially severe: latrodectism (neurotoxic symptomatology) due to the Widow spiders of the Latrodectus species,and loxoscelism (viscero-cutaneous symptomatology). Regarding the mygalomorph spiders, the Australian species responsible for atraxism (neurotoxic symptomatology) are considered as the most dangerous. Most of the other mygalomorph spiders, when they bite, only provoke benign loco regional problems. A supplementary defensive weapon exists in certain South-American species: urticating hairs which may induce severe ocular damage.

Despite the great number of spiders in the world, only a small group of them is capable of producing death in humans. In Argentina, there are only three of the four genera of spiders considered of high risk to humans: Latrodectus is present in rural areas, Phoneutria is restricted to small regions while Loxosceles is distributed throughout the country. Accidents by Loxosceles represent around 4% of the total number produced by venomous animals in Argentina. The bite is accidental and may produce considerable local necrosis with scar formation and ulcers of slow and difficult healing that may require surgical repair. Some bitten people may suffer from intravascular hemolysis, disseminated coagulation and acute renal insufficiency leading to death. Despite the great number of studies performed on Loxosceles venoms, at present, the physiopathological course of poisoning is not clear and there is not common criteria for its treatment. In this review, biological and epidemiological data of this spider are described as well as the venom composition and the possible participation of its components in the poisoning. These data provide biological and biochemical tools to understand the course of poisoning and to have better criteria for the treatment and prevention of these accidents and their complications.

Four cases of envenomation by green lynx spiders (Peucetia viridans) are reported. Despite the unusual appearance and occasional aggressive behavior of this spider, envenomation caused only local pain, pruritus, erythema, and induration. No local necrosis or systemic symptoms occurred. Treatment included tetanus immunization, wound care, and symptomatic therapy.

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.

The zoology and behaviour of Latrodectus hasselti, the Australian red back spider is described. The symptoms of envenomation are discussed; the most prominent symptom is pain of various types in the head, abdomen and limbs.

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.

Three types of poisonous spiders that inhabit the Iberian Peninsula are discussed. How to identify these spiders and the type of venom they inject are described. Symptoms and specific treatments, both in the field and in the hospital, are listed.

The only spiders of real medical importance to humans in the United States are the Loxosceles and Latrodectus species, primarily the brown recluse and the black window, respectively. These spiders bite humans only when trapped or crushed against the skin. Severe brown recluse spider bites produce dermonecrosis within 72-96 hours, which should be treated with rest, ice compresses, antibiotics, dapsone, and surgery delayed for several weeks. Using systemic corticosteroids may be helpful in treating the much rarer systemic loxoscelism, which has minimal skin changes but produces massive hemolysis. Black widow bites do not produce marked skin changes but primarily produce muscle cramping, pain, and other neuromuscular-related symptoms. Though a specific antivenin for black widow bites is available, pain control, muscle relaxants, and calcium gluconate are generally adequate treatment. Many other spiders inflict painful bites, but arachnids do not medically deserve the bad reputation that they generally have with the public.

Black widow spiders (Latrodectus species) are found worldwide. Envenomation of humans usually occurs as the result of chance intrusion into the spider's domain by the human. The venom is regarded as one of the most potent biologic toxins. The venom acts by destabilization of cell membranes and degranulation of nerve terminals resulting in the release of neurotransmitters. The clinical picture is characterized by painful muscle spasm and hypertension. The very young, the elderly or enfeebled, and those with cardiovascular disease are at greatest risk. While not always necessary, the most effective treatment is specific antiserum. Muscle relaxants, analgesics and intravenous calcium are useful adjuvant treatment.

A 19-year-old man was abruptly awakened during the night by the painful bite of a female sac spider, later identified as Chiracanthium mildei. An erythematous urticarial plaque formed immediately. Later, punctate macules appeared, and the bite site became indurated. The clinical response was similar to those reported following bites by Chiracanthium spiders in Japan, Australia, Europe, Massachusetts, Georgia, Indiana, California, and Hawaii. The necrotic lesions associated with some of those bites did not occur in this case. This is the first reported case of C. mildei bite in Connecticut.

Spiders of the genus Chiracanthium are very common in and about homes in southern Africa. The bite of this spider results in cutaneous necrosis. The clinical and histopathological features and the natural history and identification of these spiders are discussed briefly.

Medically important spiders in southern Africa are discussed in terms of their morphological features and distribution, the signs and symptoms of envenomation and the possible treatment thereof. A simple pictorial key is provided to enable the non-specialist to identify the neurotoxic and cytotoxic species. The following spiders are now known to be medically important in southern Africa: Latrodectus indistinctus (neurotoxic), Chiracanthium lawrencei (cytotoxic), Loxosceles sp. (cytotoxic) and Sicarius sp. (cytotoxic - haemotoxic).

The authors introduce their newest case of spider-bite. They demonstrate the consequences of two types of spider bite based on referencial datas.

Known and suspected medically important Southern African spiders are reviewed in terms of their distribution, identification, action of the venom and treatment of the bite. Simple diagnostic characteristics of each species are provided to assist the non-specialist in identifications.