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The brown recluse is about 1/2 inch long. It is brown and bears a violin-shaped dorsal stripe on its cephalothorax.
Other Physical Features: ectothermic ; bilateral symmetry
Brown recluse spiders are often found around human habitations, outdoors under rocks and bark as well as indoors in houses, schools, sheds, and barns.
Terrestrial Biomes: desert or dune ; savanna or grassland ; chaparral ; forest
Eastern Texas to western Georgia and north to southern Illinois
Biogeographic Regions: nearctic (Native )
They feed largely on insects; they inject prey with venom that is hemolytic rather than neurotoxic. They normally eat at night.
They are our allies in the continuing battles with insects. They help to control many destructive and annoying insects and pests.
Their bites can be mild to serious and occasionally fatal. As of 1984, at least 5 deaths had been reported from their bites in the USA. Their hemolytic venom is dangerous. The toxins in the bite kill the cells surrounding the puncture, producing a black gangrenous spot. Often, the skin proceeds to peel away from the area around the wound, exposing the underlying tissues. In extreme cases, an area 6 inches across can be severely affected and, since the wounds are slow to heal, they leave a very unpleasant scar.
The brown recluse appears to be in great abundance.
A courtship usually preceeds the actual mating. A male relies mostly on the fine sensory hairs that cover his body and appendages to locate a female. Along with the sense of touch, a male also has the ability to distinguish various chemical substances. Through this combined chemotactic sense, the male finds his mate by a scent that she leaves on the threads of her web or on any substratum on which she may have moved. The female would be more than likely to view an advancing male as suitable prey if she was not made aware of his presence in some way. So the male must announce himself by certain maneuvers, in which the female may later engage when she has reached a certain pitch of excitement, that are part of the courtship ritual and which, if all goes well, eventually lead to the actual mating. These maneuvres consist of the male signalling his presence by tweaking the threads of the female's snare on her web and maybe by moving his palpi and abdomen in a sort of dance. The male may perform bizarre dances, wave his palpi or legs or both, display his ornaments, and strike peculiar attitudes. If the male is successful in lulling her normal instinct to view him as prey and in stimulating her to a point where sexual union is possible, she submits to his advances and mating takes place. In most cases the sexes separate peaceably. The male may even mate again with the same female or with some other female. The actual mating takes place when the male deposits a drop of sperm on a small web that he spins before mating, and then picks up the sperm and stores it in the special cavities of his pedipalps. He inserts the pedipalps into the female genital opening when he mates to store the sperm in her seminal receptacles. There is usually a courtship ritual before mating. The female lays her eggs in a silken cocoon, which she may carry about or attach to a web or plant. A cocoon may contain hundreds of eggs, which hatch in approximately two weeks. The young usually remain in the egg sac for a few weeks and molt once before leaving it. Several molts occur before adulthood.
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate)
At least by name, the Brown Recluse (Loxosceles reclusa) is one of the best known spiders among non-arachnologists. The Brown Recluse is a small, yellowish brown spider with a characteristic darker mark on the carapace, broader at the front and narrowed behind (to some observers, this mark resembles the shape of a violin). Length is around 9 mm for females and 10 mm for males (Kaston 1978). Although this spider is not hard to recognize for those familiar with it, inexperienced observers can easily find other small brown spiders with markings that could conceivably be described similarly. One additional character that is unambiguous is that Loxosceles (and other spiders in the family Sicariidae) have only six eyes (rather than the more common 8), which are arranged in a recurved row (i.e., median eyes farther forward than the laterals) of three pairs (Ubick 2005). Spiders without this distribution of eyes are not Brown Recluses.
Loxosceles spiders are widely known because their bites can cause significant skin necrosis (sometimes referred to as cutaneous loxoscelism) and other serious symptoms--although in the great majority of cases, no serious symptoms develop following a Brown Recluse bite. Loxosceles spiders were not documented in the literature as medically important until the mid-20th century. In North America, once they were determined to be a public health threat, there was great interest in defining the distribution of the Brown Recluse. This was followed by many reports of bites, both verified and unverified, in both the medical and popular literature. Most symptoms attributed by patients to "spider bites" in fact have some other cause. This misattribution of symptoms can have serious medical consequences if it results in delayed or inappropriate treatment. For example, methicillin-resistant Staphylococcus aureus (MRSA) bacterial infections are a potentially very serious cause of skin and soft tissue injury and are often presented by patients as spider bites. Suchard (2011) found that the great majority of patients seeking medical attention for a "spider bite" were actually suffering from skin and soft-tissue infections. Medical professionals also overdiagnose spider bites, with potentially serious consequences (such as failing to diagnose Lyme disease or other pathologies). More accurate diagnosis may sometimes be assisted by an ELISA immunoassay (Gomez et al. 2002; Stoecker et al. 2006).
Of the approximately 100 Loxosceles species, 51 are native to North and Central America and 33 to South America (one, L. rufipes, is shared between the two continents). The Brown Recluse is normally found only in the south-central United States, with several related species in the southwestern United States and southward. Although the general public and many physicians across the United States are quick to attribute mysterious skin lesions or other symptoms to Brown Recluse bites, Vetter (2005) could find no evidence that significant Brown Recluse populations exist outside the central and south-central United States (from southeastern Nebraska through the southernmost strip of Ohio and south into Texas to northern Georgia and western South Carolina), although reports of bites outside this region are not rare. Brown Recluses belong to a group of spiders that does not disperse by ballooning, which may partly explain why local infestations outside the primary range tend not to spread. Other studies have also found a pattern of Brown Recluse bite diagnoses inconsistent with the distribution and abundance of Brown Recluses (Vetter 2009a; Vetter et al. 2003, 2009). In many cases, the spider is never seen and diagnosis is based on poorly interpreted circumstantial evidence; in other cases, medical personnel, pest control operators, and other "authorities" have a specimen, but identify it incorrectly (Vetter 2009b).
Although symptoms from Loxosceles bites are usually mild, they can ulcerate or cause more severe, systemic reactions. These injuries mostly are due to sphingomyelinase D in the spider venom. There is no proven effective therapy for Loxosceles bites, although many therapies are reported in the literature. (Swanson and Vetter 2006) Vetter (2008) reviewed biological, medical, and (interestingly) psychological aspects of envenomation by Brown Recluse spiders and this key reference should be consulted by anyone interested in Brown Recluse (and other Loxosceles) spiders and, in particular, their interactions with humans. Medical aspects have also been reviewed by Swanson and Vetter (2006) and Vetter and Isbister (2008).
Although they do have the potential to be quite serious, bites are uncommon even where Brown Recluses are common. As their name implies, Brown Recluses are reclusive and have a predilection for crevices and other tight locations. In nature, they can be found under rocks and the loose bark of dead trees. In synanthropic environments (i.e. where they cohabit with humans), they are found in cardboard boxes (especially under folded flaps), in cupboards, behind bookcases and dressers, in trash, under broken concrete and asphalt, and (of particular medical concern) in shoes and clothes left out on the floor or stored in closets and garages.
These spiders can be found in very high density in synanthropic situations. A Kansas family collected 2,055 Brown Recluses in their home in the course of 6 months and a survey in Kansas showed that 22 of 25 homes sheltered Brown Recluses, with an average of 83.5 to 114.9 spiders per home (range 1 to 526). In an Oklahoma barn, a team of arachnologists collected 1,150 Brown Recluses over three consecutive nights with an essentially undiminished capture rate, although the size of the spiders decreased slightly as collecting progressed.
Brown Recluses are active hunters that do not make typical webs for prey capture. Instead, theyextend lines of silk from a retreat to opportunistically alert them to the presence of entangled prey. For more information about their biology, see Vetter (2008).
More information about Brown Recluse (and other) spiders is available from the University of California-Riverside Spiders Site.
(Vetter 2008 and references therein)
Despite ongoing claims by the general public, and in some cases medical practitioners, the brown recluse spider does not occur in California. Many years of searching for the spider, including public offerings of rewards, have failed to find the spider in the wild there.
A few specimens have been collected (about 40) in the 100+ years of scientific collecting in California, but they have ALL been associated with boxes or similar items that were recently shipped from locations where the spider occurs.
For additional places the spider does or does not occur, please see the maps associated with this taxon
Koutník jedovatý (Loxosceles reclusa) ve Spojených státech je známý také pod názvy brown recluse spider nebo violin spider podle tmavé skvrny ve tvaru houslí na hlavohrudi. Pavouci jsou velcí 6–20 mm. Žijí v oblasti jihovýchodu a jihu USA. Protože se rád zdržuje v domácnostech, je tento druh pavouka poměrně obávaný. Ačkoli není agresivní, může mít kousnutí vážné následky (dermonekrózu).
Koutníci jsou jediní pavouci na světě, po jejichž kousnutí dochází k tomuto způsobu odumírání kůže. Jejich jed totiž obsahuje vzácný enzym sfingomyelináza D. Ten poškozuje tkáň kůže a posléze vede k její smrti. V případě, že není rychle podáno antidotum, umírají lidé v koncovém důsledku na selhání orgánů. Rány po kousnutí se hojí jen velmi obtížně, ne-li vůbec.[1]
Obrázky, zvuky či videa k tématu koutník jedovatý ve Wikimedia Commons
Koutník jedovatý (Loxosceles reclusa) ve Spojených státech je známý také pod názvy brown recluse spider nebo violin spider podle tmavé skvrny ve tvaru houslí na hlavohrudi. Pavouci jsou velcí 6–20 mm. Žijí v oblasti jihovýchodu a jihu USA. Protože se rád zdržuje v domácnostech, je tento druh pavouka poměrně obávaný. Ačkoli není agresivní, může mít kousnutí vážné následky (dermonekrózu).
Koutníci jsou jediní pavouci na světě, po jejichž kousnutí dochází k tomuto způsobu odumírání kůže. Jejich jed totiž obsahuje vzácný enzym sfingomyelináza D. Ten poškozuje tkáň kůže a posléze vede k její smrti. V případě, že není rychle podáno antidotum, umírají lidé v koncovém důsledku na selhání orgánů. Rány po kousnutí se hojí jen velmi obtížně, ne-li vůbec.
Loxosceles reclusa (deutsch meist: Braune Einsiedlerspinne) ist eine Art der Echten Webspinnen aus der Familie der Sechsäugigen Sandspinnen (Sicariidae). Die Giftspinne ist in den USA vom Mittleren Westen bis in den Süden verbreitet.
Loxosceles reclusa wird normalerweise zwischen 6 und 20 mm groß. Es gibt aber auch größere Exemplare. Sie ist braun, manchmal auch gelblich. Der Vorderkörper (Prosoma) ist vom Augenhügel bis zur Thoraxgrube dunkler und von der Thoraxgrube bis zum Hinterkörper (Opisthosoma) verläuft ein dunkler Strich. Diese dunkle Zeichnung hat eine violinenartige Form, die der Art im englischen Sprachraum den Trivialnamen „fiddleback spider“ oder auch „violin spider“ eingebracht hat.
Ansicht von vorne
Ansicht von oben, gut zu sehen sind hier die 3 Augenpaare
Wie alle Loxosceles-Arten bauen diese Spinnen ein unregelmäßiges Netz mit unregelmäßigen Fäden und einer Aufenthaltsnische. Die Netze werden häufig in Holzhaufen, Lagerhäusern, Toiletten, Garagen oder anderen Plätzen gebaut, wo es trocken ist und sie normalerweise lange Zeit ungestört sind. Weibchen verlassen ihren Zufluchtsort äußerst selten, nur die Männchen streifen umher auf der Suche nach einer Paarungspartnerin.
Das Verbreitungsgebiet von Loxosceles reclusa reicht vom mittleren Westen bis in den Süden der USA.[1] Die Nordwestgrenze des Areals verläuft auf einer Linie vom Südosten von Nebraska durch den Süden von Iowa, Illinois, und Indiana bis in den Südwesten von Ohio. Im Süden der USA kommt sie von Zentral-Texas bis in den Westen von Georgia vor.[2]
Die Spinne ist grundsätzlich nicht aggressiv und beißt nur zu, wenn sie Gefahr läuft, zerdrückt zu werden.[3] Dabei kommt es rund um die Bisswunde zu einer Nekrose und es kann eine Sepsis folgen.[4] Die nekrotische Erscheinung eines Bisses kann mit einer Staphylococcus-aureus-Infektion verwechselt werden. Diese kommen häufiger vor als Bisse von Loxosceles reclusa.
Der Biss ist weitgehend schmerzlos und wird meistens gar nicht wahrgenommen. Die Größe der betroffenen Hautfläche ist sehr klein. Im Laufe der Zeit (innerhalb 2 bis 8 Stunden danach) werden diese Wunden aber immer schmerzhafter. Innerhalb der nächsten 12 bis 36 Stunden werden die Schmerzen intensiver und die betroffene Fläche größer. Wenige Bisswunden werden in den nächsten Tagen (ca. eine Woche) nekrotisch.[5]
Weitere mögliche körperliche Symptome nach einem Biss sind: Kopfschmerzen, Übelkeit, Erbrechen, Krämpfe und Muskelschmerzen. Selten kommt es zu einer Sepsis. Auch Todesfälle kommen vor.[6]
Loxosceles reclusa (deutsch meist: Braune Einsiedlerspinne) ist eine Art der Echten Webspinnen aus der Familie der Sechsäugigen Sandspinnen (Sicariidae). Die Giftspinne ist in den USA vom Mittleren Westen bis in den Süden verbreitet.
The brown recluse (Loxosceles reclusa), Sicariidae (formerly placed in a family "Loxoscelidae") is a recluse spider with necrotic venom. Similar to those of other recluse spiders, their bites sometimes require medical attention. The brown recluse is one of three spiders in North America with medically significant venom, the others being the black widow and the Chilean recluse.
Brown recluse spiders are usually between 6 and 20 millimetres (0.24 and 0.79 in), but may grow larger. While typically light to medium brown, they range in color from whitish to dark brown or blackish gray. The cephalothorax and abdomen are not necessarily the same color. These spiders usually have markings on the dorsal side of their cephalothorax, with a black line coming from it that looks like a violin with the neck of the violin pointing to the rear of the spider, resulting in the nicknames fiddleback spider, brown fiddler, or violin spider.[2]
The violin pattern is not a definitive identifier, as other spiders can have similar markings (e.g. cellar spiders and pirate spiders). Instead, while most spiders have eight eyes, recluse spiders have six eyes arranged in pairs (dyads) with one median pair and two lateral pairs. Only a few other spiders have three pairs of eyes arranged in this way (e.g., scytodids). Recluses have no obvious coloration patterns on the abdomen or legs, and the legs lack spines.[3] The violin marking can vary in intensity depending on the age of the brown recluse spider, with mature spiders typically having dark violin shapes.[4][5]
The documented range of this species lies roughly south of a line from southeastern Nebraska through southern Iowa, Illinois, and Indiana to southwestern Ohio. In the southern states, it is native from central Texas to western Georgia and north to Kentucky.[6][7]
Despite rumors to the contrary, the brown recluse spider has not established itself in California or anywhere outside its native range.[8] There are other species of the genus Loxosceles native to the southwestern part of the United States, including California, which may resemble the brown recluse, but interactions between humans and the recluse species in California and the region are rare because those species native ranges lie outside of dense human populations.[8] The number of "false positive" reports based on misidentifications is considerable; in a nationwide study where people submitted spiders that they thought were brown recluses, of 581 from California only 1 was a brown recluse—submitted by a family that moved from Missouri and brought it with them (compared to specimens submitted from Missouri, Kansas, and Oklahoma, where between 75% and 90% were recluses).[9] From this study, the most common spider submitted from California as a brown recluse was in the genus Titiotus, whose bite is deemed harmless. A similar study documented that various arachnids were routinely misidentified by physicians, pest control operators, and other non-expert authorities, who told their patients or clients that the spider they had was a brown recluse when in fact it was not.[10] Despite the absence of brown recluses from the Western U.S., physicians in the region commonly diagnose "brown recluse bites", leading to the popular misconception that the spiders inhabit those areas.[11]
Over the last century, spiders have occasionally been intercepted in locations where they have no known established populations; these spiders may be transported fairly easily, though the lack of established populations well outside the natural range also indicates that such movement has not led to the colonization of new areas, after decades of opportunities.[12][13] Note that the occurrence of brown recluses in a single building (such as a warehouse) outside of the native range is not considered as successful colonization; such single-building populations can occur (e.g., in several such cases in Florida),[14] but do not spread, and can be easily eradicated.[15] The spider has also received numerous sensationalized media reports of bites occurring where these spiders are absent (and no specimens were found), such as a 2014 report from Thailand, where a man was claimed to have died from a brown recluse bite.[16] Many misidentifications and erroneous geographic records stem from the similarity between L. reclusa and a related introduced species, the Mediterranean recluse (Loxosceles rufescens), which is found worldwide, including numerous sightings throughout the United States; the two species are superficially almost indistinguishable, and misidentifications are common, making it difficult to distinguish which reports of recluses refer to which species.[17]
Adult brown recluse spiders often live about one to two years. Each female produces several egg sacs over a period of two to three months, from May to July, with approximately fifty eggs in each sac. The eggs hatch in about one month. The spiderlings take about one year to grow to adulthood. The brown recluse spider is resilient and can tolerate up to six months of extreme drought and scarcity or absence of food. On one occasion, a brown recluse survived in controlled captivity for over five seasons without any food at all.[18]
As part of the haplogynae, brown recluse do not balloon, which limits its ability to widely disperse geographically.[19] The brown recluse will, though not habitually, cannibalize another if food becomes scarce; especially during its typical mating season from June to September or when an unreceptive female encounters an aggressive male.[20]
A brown recluse's stance on a flat surface is usually with all legs radially extended. When alarmed it may lower its body, withdraw the forward two legs straight rearward into a defensive position, withdraw the rearmost pair of legs into a position for lunging forward, and stand motionless with pedipalps raised. The pedipalps in mature specimens are dark and quite prominent and are normally held horizontally forward. When threatened it usually flees, seemingly to avoid a conflict, and if detained may further avoid contact with quick horizontal rotating movements or even resort to assuming a lifeless pose (playing dead). The spider does not usually jump unless touched brusquely, and even then its avoidance movement is more of a horizontal lunge rather than a vaulting of itself entirely off the surface. When running, the brown recluse does not leave a silk line behind, which would make it more easily tracked when it is being pursued. Movement at virtually any speed is an evenly paced gait with legs extended.
The brown recluse spider displays autotomy as a defense mechanism against physical, predatory attack to a leg as well as to prevent predatory, venom injections from spreading to the rest of the body.[21] "Once a leg is lost, a recluse spider does not regenerate a new one with subsequent molts", unlike the huntsman spider that does regenerate autotomized legs.[21] With each time that a leg is autotomized, the recluse "changes its gait to compensate for the loss."[21]
Brown recluse spiders build asymmetrical (irregular) webs that frequently include a shelter consisting of disorderly threads. They frequently build their webs in woodpiles and sheds, closets, garages, plenum spaces, cellars, and other places that are dry and generally undisturbed. When dwelling in human residences they seem to favor cardboard, possibly because it mimics the rotting tree bark which they inhabit naturally.[22] Human-recluse contact often occurs when such isolated spaces are disturbed and the spider feels threatened. Unlike most web weavers, they leave these lairs at night to hunt. Males move around more when hunting than the females, which tend to remain nearer to their webs.
Loxosceles reclusa (as with all of the Loxosceles genus) can deliver, through envenomation via uncate chelicerae-type fangs, a potentially dermonecrotic[23] loxoscelism[24] due to the presence of sphingomyelinase D[23] toxin in its venom.[25] Most bites are minor with no dermonecrosis. However, a small number of brown recluse bites do produce dermonecrotic loxoscelism; an even smaller number produce severe cutaneous (skin) or viscerocutaneous (systemic) symptoms. In one study of clinically diagnosed brown recluse bites, skin necrosis occurred 37% of the time, while systemic illness occurred 14% of the time.[26] In these cases, the bites produced a range of symptoms common to many members of the genus Loxosceles known as loxoscelism, which may be cutaneous and viscerocutaneous. In very rare cases, bites can even cause hemolysis—the bursting of red blood cells.[27]
As suggested by its specific name reclusa (recluse), the brown recluse spider is rarely aggressive, and bites from the species are uncommon. In 2001, more than 2,000 brown recluse spiders were removed from a heavily infested home in Kansas, yet the four residents who had lived there for years were never harmed by the spiders, despite many encounters with them.[28][29] The spider usually bites only when pressed against the skin, such as when tangled within clothes, shoes, towels, bedding, inside work gloves, etc. Many human victims report having been bitten after putting on clothes or shoes that had not been worn recently or had been left for many days undisturbed on the floor. The fangs of the brown recluse are not large enough to penetrate most fabric.[30]
When both types of loxoscelism do result, systemic effects may occur before necrosis, as the venom spreads throughout the body in minutes. Children, the elderly, and the debilitatingly ill may be more susceptible to systemic loxoscelism. The systemic symptoms most commonly experienced include nausea, vomiting, fever, rashes, and muscle and joint pain. Rarely, such bites can result in hemolysis, low platelet levels, blood clots throughout the body, organ damage, and even death.[31] Most fatalities are in children under the age of seven[32] or those with a weak immune system.
While the majority of brown recluse spider bites do not result in any symptoms, cutaneous symptoms occur more frequently than systemic symptoms. In such instances, the bite forms a necrotizing ulcer as the result of soft tissue destruction and may take months to heal, leaving deep scars. These bites usually become painful and itchy within 2 to 8 hours. Pain and other local effects worsen 12 to 36 hours after the bite, and the necrosis develops over the next few days.[33] Over time, the wound may grow to as large as 25 cm (10 inches). The damaged tissue becomes gangrenous and eventually sloughs away. L. reclusa can produce slightly more than 0.1 microliters of venom, though the average yield is less.[34]
There is an ELISA-based test for brown recluse venom that can determine whether a wound is a brown recluse bite, although it is not commercially available and not in routine clinical use. Clinical diagnoses often use Occam's razor principle in diagnosing bites based on what spiders the patient likely encountered and previous similar diagnoses.[7][26][35]
A mnemonic device, "NOT RECLUSE", has been suggested as a tool to help laymen and medical professionals more objectively screen and diagnose potential cases of loxoscelism.[36]
There are numerous documented infectious and noninfectious conditions that produce wounds that have been initially misdiagnosed as recluse bites by medical professionals, including:
Many of these conditions are far more common and more likely to be the source of necrotic wounds, even in areas where brown recluse spiders actually occur.[7] The most important of these is methicillin-resistant Staphylococcus aureus (MRSA), a bacterium whose necrotic lesions are very similar to those induced by recluse bites, and which can be lethal if left untreated.[38] Misdiagnosis of MRSA as spider bites is extremely common (nearly 30% of patients with MRSA reported that they initially suspected a spider bite), and can have fatal consequences.[39]
Reported cases of brown recluse bites occur primarily in Arkansas, Colorado, Kansas, Missouri, Nebraska, Oklahoma, and Texas. There have been many reports of brown recluse bites in California—though a few related species may be found there, none of these are known to bite humans.[8] To date, the reports of bites from areas outside of the spider's native range have been either unverified or, if verified, the spiders have been moved to those locations by travelers or commerce. Many arachnologists believe that a large number of bites attributed to the brown recluse in the West Coast are either from other spider species or not spider bites at all. For example, the venom of the hobo spider, a common European species established in the northwestern United States and southern British Columbia, has been reported to produce similar symptoms as the brown recluse bite when injected into laboratory rabbits. However, the toxicity of hobo spider venom has been called into question as actual bites have not been shown to cause necrosis, and no such occurrences have ever been reported where the spider is native.[40]
Numerous other spiders have been associated with necrotic bites in the medical literature. Other recluse species, such as the desert recluse (found in the deserts of southwestern United States), are reported to have caused necrotic bite wounds, though only rarely.[41] The hobo spider and the yellow sac spider have also been reported to cause necrotic bites. However, the bites from these spiders are not known to produce the severe symptoms that can follow from a recluse spider bite, and the level of danger posed by these has been called into question.[42][43] So far, no known necrotoxins have been isolated from the venom of any of these spiders, and some arachnologists have disputed the accuracy of spider identifications carried out by bite victims, family members, medical responders, and other non-experts in arachnology. There have been several studies questioning the danger posed by some of these spiders. In these studies, scientists examined case studies of bites in which the spider in question was identified by an expert, and found that the incidence of necrotic injury diminished significantly when "questionable" identifications were excluded from the sample set.[44][45] (For a comparison of the toxicity of several kinds of spider bites, see the list of spiders having medically significant venom.)
First aid involves the application of an ice pack to control inflammation and prompt medical care. If it can be easily captured, the spider should be brought with the patient in a clear, tightly closed container so it may be identified.
Routine treatment should include immobilization of the affected limb, application of ice, local wound care, and tetanus prophylaxis. Many other therapies have been used with varying degrees of success, including hyperbaric oxygen, dapsone, antihistamines (e.g., cyproheptadine), antibiotics, dextran, glucocorticoids, vasodilators, heparin, nitroglycerin, electric shock, curettage, surgical excision, and antivenom.[46][47] In almost all cases, bites are self-limited and typically heal without any medical intervention.[7]
Outpatient palliative care following discharge often consists of a weak or moderate strength opioid (e.g. codeine or tramadol, respectively) depending on pain scores, an anti-inflammatory agent (e.g. naproxen, cortisone), and an antispasmodic (e.g. cyclobenzaprine, diazepam), for a few days to a week. If the pain or spasms have not resolved by this time, a second medical evaluation is generally advised, and differential diagnoses may be considered.
In presumed cases of recluse bites, dapsone is often used for the treatment of necrosis, but controlled clinical trials have yet to demonstrate efficacy.[48] However, dapsone may be effective in treating many "spider bites" because many such cases are actually misdiagnosed microbial infections.[49] There have been conflicting reports about its efficacy in treating brown recluse bites, and some have suggested it should no longer be used routinely, if at all.[50]
Wound infection is rare. Antibiotics are not recommended unless there is a credible diagnosis of infection.[51]
Studies have shown that surgical intervention is ineffective and may worsen outcomes. Excision may delay wound healing, cause abscesses, and lead to scarring.[52]
Purportedly application of nitroglycerin stopped necrosis.[53] However, one scientific animal study found no benefit in preventing necrosis, with the study's results showing it increased inflammation and caused symptoms of systemic envenoming. The authors concluded the results of the study did not support the use of topical nitroglycerin in brown recluse envenoming. [54]
Antivenom is available in South America for the venom of related species of recluse spiders. However, the bites, often being painless, usually do not present symptoms until 24 or more hours after the event, possibly limiting the effect of this intervention.[55]
Due to increased fear of these spiders prompted by greater public awareness of their presence in recent years, the extermination of domestic brown recluses is performed frequently in the lower midwestern United States. Brown recluse spiders possess a variety of adaptive abilities, including the ability to survive up to 10 months with no food or water.[56] Additionally, these spiders survive significantly longer in a relatively cool, thermally stable environment.[57]
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{{cite journal}}: CS1 maint: unfit URL (link) The brown recluse (Loxosceles reclusa), Sicariidae (formerly placed in a family "Loxoscelidae") is a recluse spider with necrotic venom. Similar to those of other recluse spiders, their bites sometimes require medical attention. The brown recluse is one of three spiders in North America with medically significant venom, the others being the black widow and the Chilean recluse.
Brown recluse spiders are usually between 6 and 20 millimetres (0.24 and 0.79 in), but may grow larger. While typically light to medium brown, they range in color from whitish to dark brown or blackish gray. The cephalothorax and abdomen are not necessarily the same color. These spiders usually have markings on the dorsal side of their cephalothorax, with a black line coming from it that looks like a violin with the neck of the violin pointing to the rear of the spider, resulting in the nicknames fiddleback spider, brown fiddler, or violin spider.
La araña ermitaña parda, araña violinista o araña reclusa marrón (Loxosceles reclusa) es una especie de araña que pertenece al género Loxosceles de la familia Sicariidae. Es una araña con un potente veneno necrótico y es una de las dos arañas (junto a la viuda negra) de importancia médica en América del Norte.
La distribución geográfica de Loxosceles reclusa es amplia en los Estados Unidos, compartiendo su distribución con México, Centro América hasta Panamá. Recientemente también se tiene constancia de que está bastante extendida por las Islas Baleares España. Habita entre piedras, cúmulos de maderas o leña.[1][2]
Tiene un color morado con café muy claro, y su aspecto es más bien pequeño, algo menor que la araña de los rincones (Loxosceles laeta), su prima sudamericana. Para su identificación definitiva es imprescindible examinar los ojos. Aunque la mayoría de las arañas tienen ocho ojos, las especies del género Loxosceles tienen seis ojos dispuestos en pares (díadas) con un par mediano y dos pares laterales. Sólo algunas otras especies de arañas tienen tres pares de ojos dispuestos de esta manera, como por ejemplo los escitódidos. Las reclusas Loxosceles no tienen patrones de coloración evidentes en el abdomen ni las patas, y las patas carecen de pelos.[3] El abdomen está cubierto de pelos cortos finos que, cuando se ve sin aumento, dan la apariencia de ser piel suave.
La reclusa parda tiene un ciclo de vida de uno a dos años. Cada hembra produce varios sacos de huevos en un período de dos a tres meses, de mayo a julio, con aproximadamente cincuenta huevos en cada saco. Los huevos eclosionan en aproximadamente un mes. Las arañas tienen alrededor de un año para crecer hasta la edad adulta. La reclusa parda es resistente y puede tolerar hasta seis meses de sequía extrema y escasez o ausencia de alimentos. En una ocasión se comprobó que un ejemplar sobrevivió en cautiverio controlado por más de cinco temporadas sin comida.[4]
El veneno de la araña violinista o reclusa parda produce una serie de síntomas (muy común en arañas del género Loxosceles) conocido como Loxoscelismo. Este es caracterizado por heridas necróticas a causa de las hemotoxinas encontradas en su veneno. El loxoscelismo puede tener dos variantes: el cutáneo (que afecta las células y tejidos de la piel), y el visceral o sistémico (que sucede cuando el veneno entra en el torrente sanguíneo y es transportado a diferentes órganos del cuerpo, causando síntomas a nivel general). El 49% de las mordeduras no producen ningún tipo de síntoma, mientras que un 37% si terminan en heridas necróticas. El 14% restante de las mordeduras terminan en daño a nivel sistémico. Los síntomas típicos del loxoscelismo visceral son náuseas, vómitos, fiebre, erupciones y dolor articular o muscular. En raras ocasiones también se pueden presentar síntomas como la destrucción de glóbulos rojos (hemólisis), trombocitopenia, coagulación intravascular diseminada, daños en los órganos e incluso la muerte. La mayoría de las muertes suceden en niños menores de 7 años y en personas con un sistema inmune débil. Aunque la mayoría de las mordeduras de la araña violinista no desarrollan ningún tipo de síntoma, los casos de loxoscelismo cutáneo son más frecuentes que los sistémicos. Si esto ocurre, la picadura se transforma en una úlcera necrótica que destruye los tejidos blandos y que puede llevar meses para curar, dejando una cicatriz profunda. La picadura se vuelve dolorosa y genera prurito alrededor de las 2 a 8 horas de haber sucedido. El dolor y otros síntomas locales empeoran a las 12 o 36 horas más tarde, y la necrosis se desarrolla los días siguientes. En ese lapso, la úlcera puede crecer hasta superar los 25 cm (10 pulgadas) de largo. A medida que pasa el tiempo, la herida se vuelve gangrenosa. En los casos más severos, el miembro afectado debe ser amputado.
Es importante no pisar a esta araña, ya que su veneno de alta toxicidad es capaz de dejar residuos que pueden permeabilizarse por la piel.
La Loxosceles reclusa, al igual que su prima Loxosceles laeta, no tiene un comportamiento agresivo hacia los seres humanos y morderá únicamente en el caso de sentirse amenazada. Es importante evitar al máximo el contacto con las manos. Lo más recomendable es, en el lugar donde sea hallada, colocar un vaso de vidrio boca abajo sobre ella, e ir en busca de un frasco para su cuidadosa captura. Posterior a esto, soltarla en un hábitat libre de la presencia humana o en caso de no disponer de un lugar así en las cercanías, llevarla a la unidad de salud más cercana para su posterior canalización a laboratorios de ordeña especializados.
|url= (ayuda) La araña ermitaña parda, araña violinista o araña reclusa marrón (Loxosceles reclusa) es una especie de araña que pertenece al género Loxosceles de la familia Sicariidae. Es una araña con un potente veneno necrótico y es una de las dos arañas (junto a la viuda negra) de importancia médica en América del Norte.
Loxosceles reclusa est une espèce d'araignées aranéomorphes de la famille des Sicariidae[1].
Elle est appelée « recluse brune » ou comme d'autres Loxosceles « araignée violoniste ».
Cette espèce se rencontre principalement aux États-Unis dans le Sud-Central américain, dans l'ouest du Sud profond, dans le sud du Midwest[2].
Contrairement à Loxosceles rufescens, autre araignée violoniste, la présence de Loxosceles reclusa n'est pas attestée en France[3].
Sur le continent américain elle a également été observée en Arizona, au Colorado, en Floride, en Ohio, au New Jersey, dans l'État de New York, au Maine ou en Oregon, au Canada dans le sud-est de l'Ontario et au Mexique au Tamaulipas.
Sa présence en Californie est considérée comme un mythe propagé par les médias[4].
Le mâle holotype mesure 8 mm et la femelle 9 mm[2].
Le nom anglais de cette araignée (« brown recluse spider ») vient de sa couleur (allant du jaune foncé au marron) et de ses habitudes de vie : elle préfère la solitude et ne se montre que très rarement.
Elle est désignée sous le nom d’« araignée violoniste » comme d'autres Loxosceles en raison de la forme de violon de son céphalothorax. Cette caractéristique est plus ou moins marquée suivant les espèces, particulièrement dans le sud-ouest des États-Unis.
La période de reproduction et de ponte de Loxosceles reclusa se situe entre mai et juillet. La femelle pond entre 40 et 50 œufs qu’elle enferme dans un cocon de soie. Chaque femelle peut ainsi produire plusieurs sacs d’œufs en plusieurs mois.
Les petits émergent des sacs après environ un mois d’incubation. Leur développement est long et est très influencé par les conditions climatiques et la nourriture disponible. Il faut compter environ un an pour obtenir un adulte qui vivra encore entre un et deux ans, et qui pourra parfois jeûner entre quatre et six mois. Sa taille adulte varie de 8 à 10 mm[5].
Loxosceles reclusa tisse des toiles irrégulières, en forme de cône, qui lui servent de nid. Celui-ci lui sert de retraite pour la journée et est généralement construit dans un endroit calme où elle ne sera pas dérangée. Elle peut s’installer aussi bien en extérieur qu’en intérieur (caves, greniers, toilettes, placards, conduits d’air conditionné, boîtes de rangement, chaussures, etc.)[6].
Cette araignée sort la nuit à la recherche de proies. Des études récentes de l’université du Kansas ont montré que celle-ci est largement charognarde et préfère se nourrir d’insectes morts.
Loxosceles reclusa n’est généralement pas agressive, mais peut mordre lorsqu’elle est dérangée ou attaquée. Quelques personnes ont déjà été mordues dans leur lit en se roulant par inadvertance sur une araignée de ce type, d’autres en rangeant des aires de stockage de matériel[6].
La réaction physique après une morsure d’une Loxosceles reclusa dépend de la quantité de venin injectée et de la sensibilité de l’individu mordu. Certaines personnes n’ont aucune séquelle après ce genre de morsure, mais la plupart du temps, les morsures sont très douloureuses, surtout si elles ne sont pas traitées à temps (pour bien faire, le traitement doit intervenir au plus tard dans les deux jours qui suivent la morsure, idéalement dans les 24 heures).
Le venin détruit artères et veines[7]. Dans les cas les plus graves, sa morsure peut provoquer la nécrose des tissus touchés et des infections. Les lésions observées sont généralement de type « volcanique », c’est-à-dire caractérisées par un trou dans la chair dû aux tissus sous-cutanés gangrenés qui provoquent une éruption infectieuse. Six à huit semaines de guérison sont alors nécessaires selon la surface du corps touchée.
Dans de très rares cas, la douleur peut provoquer des vomissements, des nausées, de la fièvre, des paralysies partielles. Les victimes peuvent mourir d'une défaillance circulatoire ou d'une insuffisance rénale[7].
Dans d’autres cas, généralement pour les enfants ou les gens en mauvaise condition physique, une morsure peut entraîner des séquelles physiques graves.
En cas de morsure, il est très important de consulter au plus vite un médecin ou un service d'urgence médicale.
On estime qu’environ 80 % des morsures annoncées comme dues à Loxosceles reclusa sont en fait mal diagnostiquées[8]. Ces erreurs pourraient retarder l’application de traitements pour des maladies bien plus graves[9]. Bien que son utilisation ne soit pas encore systématique, il existe aujourd’hui un test ELISA fiable dans la détection du venin de Loxosceles reclusa[10],[9].
Les erreurs de diagnostic concernant la morsure de Loxosceles reclusa proviennent le plus souvent du fait que le symptôme principal est une nécrose cutanée[6],[11]. Ainsi de nombreux médecins ont diagnostiqué une morsure de la recluse dans des lieux pourtant éloignés de la zone endémique de la recluse, empêchant ainsi les soins des maux réels. De nombreuses pathologies peuvent déclencher une nécrose, qu’elles soient de type infectieux (staphylocoque, herpès…) ou non (Pyoderma gangrenosum, ulcère diabétique, brûlures chimiques…). Ces dernières causes sont en général plus probables qu’une morsure de recluse, même en zone endémique[9].
Un chapitre est consacré à l'araignée recluse dans Une année à la campagne (1983) de Sue Hubbell.
Elle apparaît dans le roman de Maxime Chattam, Maléfices, troisième et ultime épisode de La Trilogie du mal paru en 2004.
Elle est une des espèces élevées par un psychopathe, avec l'araignée Goliath, dans le roman Derniers Adieux (2008) de Lisa Gardner.
Elle est au cœur de l’enquête menée par le commissaire Adamsberg dans le roman Quand sort la recluse (2017) de Fred Vargas.
Loxosceles reclusa est une espèce d'araignées aranéomorphes de la famille des Sicariidae.
Elle est appelée « recluse brune » ou comme d'autres Loxosceles « araignée violoniste ».
Loxosceles reclusa Gertsch & Mulaik, 1940 (conosciuto come ragno eremita marrone o anche recluso bruno), è un ragno appartenente alla famiglia Sicariidae dell'Ordine Araneae della Classe Arachnida.
È noto per il veleno fortemente tossico che causa necrosi.
È mediamente lungo dai 6 ai 20 mm ma può crescere molto di più. Il colore è marrone chiaro, anche se le gradazioni possono variare dal marrone chiaro a quello più scuro fino al grigio nerastro. Il cefalotorace e l'addome a volte non hanno lo stesso colore. La parte dorsale del cefalotorace ha una tipica macchia longitudinale di colore nero a forma di un violino.
Al contrario della maggior parte dei ragni, possiede 3 paia di occhi invece di 4.
È diffuso nella parte sudorientale degli Stati Uniti e nel nord del Messico, ma ne sono stati segnalati esemplari in Inghilterra, in Israele e nel bacino del Mediterraneo come specie aliene.
Il morso è fortemente velenoso e causa una sintomatologia nota come loxoscelismo. La parte colpita va in necrosi e lascia profonde cicatrici. Il morso solo raramente risulta mortale.
Loxosceles reclusa Gertsch & Mulaik, 1940 (conosciuto come ragno eremita marrone o anche recluso bruno), è un ragno appartenente alla famiglia Sicariidae dell'Ordine Araneae della Classe Arachnida.
De vioolspin (Loxosceles reclusa) is een spin uit de familie vioolspinnen (Sicariidae).
De vioolspin is lichtbruin van kleur en wordt ongeveer 1,5 centimeter lang. De naam is te danken aan de donkere, viool-achtige vlek op het rugschild. De spin is berucht in de Verenigde Staten, waar de spin voorkomt. Het gif kan soms necrotische wonden veroorzaken, waarbij weefsel rond de beet afsterft. Net als de in Nederland en België voorkomende huisspin schuwt de vioolspin de mens niet: de spin komt in de gebieden waar zij voorkomt vaak voor in huizen en hoewel niet agressief, kan zij bijten als zij in het nauw komt.
Niettemin zijn beten van de 'brown recluse spider' zeldzaam, en leidt een beet zelden tot een wond. Arachnologen beweren dat wel 80% van de wonden die worden toegeschreven aan de vioolspin eigenlijk andere oorzaken hebben, zoals infecties met stafylokokken, streptokokken en pyoderma gangraenosum.[1] Beten worden bijvoorbeeld ook geregeld gemeld in gebieden waar de spin helemaal niet voorkomt.
In een huis in Kansas in de VS werden bij systematisch onderzoek meer dan 2000 vioolspinnen gevonden; in de jaren dat er mensen samen met de spinnen woonden was er nooit iemand gebeten.[2][3] Zelfs als er een spin is waargenomen is correcte identificatie daarvan niet iets dat aan een niet-arachnologisch geschoolde dokter kan worden overgelaten.[4][5]
Bij verreweg de meeste wonden die worden toegeschreven aan deze spin is de spin helemaal niet waargenomen en kan de oorzaak dus niet met zekerheid worden vastgesteld.[6][7]
De vioolspin (Loxosceles reclusa) is een spin uit de familie vioolspinnen (Sicariidae).
De vioolspin is lichtbruin van kleur en wordt ongeveer 1,5 centimeter lang. De naam is te danken aan de donkere, viool-achtige vlek op het rugschild. De spin is berucht in de Verenigde Staten, waar de spin voorkomt. Het gif kan soms necrotische wonden veroorzaken, waarbij weefsel rond de beet afsterft. Net als de in Nederland en België voorkomende huisspin schuwt de vioolspin de mens niet: de spin komt in de gebieden waar zij voorkomt vaak voor in huizen en hoewel niet agressief, kan zij bijten als zij in het nauw komt.
Niettemin zijn beten van de 'brown recluse spider' zeldzaam, en leidt een beet zelden tot een wond. Arachnologen beweren dat wel 80% van de wonden die worden toegeschreven aan de vioolspin eigenlijk andere oorzaken hebben, zoals infecties met stafylokokken, streptokokken en pyoderma gangraenosum. Beten worden bijvoorbeeld ook geregeld gemeld in gebieden waar de spin helemaal niet voorkomt.
In een huis in Kansas in de VS werden bij systematisch onderzoek meer dan 2000 vioolspinnen gevonden; in de jaren dat er mensen samen met de spinnen woonden was er nooit iemand gebeten. Zelfs als er een spin is waargenomen is correcte identificatie daarvan niet iets dat aan een niet-arachnologisch geschoolde dokter kan worden overgelaten.
Bij verreweg de meeste wonden die worden toegeschreven aan deze spin is de spin helemaal niet waargenomen en kan de oorzaak dus niet met zekerheid worden vastgesteld.
Multimedia w Wikimedia Commons Pustelnik brunatny (Loxosceles reclusa) – gatunek pająka z rodziny Sicariidae; średniej wielkości (6–20 mm) ciała. Ubarwiony na brązowo, nogi długie i porośnięte rzadką szczeciną. Na grzbiecie charakterystyczny czarny znak w kształcie skrzypiec. Inną cechą charakterystyczną są trzy pary oczu. Samice są dwukrotnie większe od samców.
Pająk aktywny głównie nocą, polujący aktywnie; żywi się prawie wyłącznie innymi pająkami i owadami.
Dosyć pospolity w południowych i środkowych stanach USA: Missisipi, Teksas, Oklahoma, Kansas aż do Iowa. Występuje również na Bermudach i na Kubie.
Chociaż jad tych pająków może powodować rozległą martwicę tkanek, jego ukąszenie rzadko bywa śmiertelne[1][2].
Pustelnik brunatny (Loxosceles reclusa) – gatunek pająka z rodziny Sicariidae; średniej wielkości (6–20 mm) ciała. Ubarwiony na brązowo, nogi długie i porośnięte rzadką szczeciną. Na grzbiecie charakterystyczny czarny znak w kształcie skrzypiec. Inną cechą charakterystyczną są trzy pary oczu. Samice są dwukrotnie większe od samców.
Pająk aktywny głównie nocą, polujący aktywnie; żywi się prawie wyłącznie innymi pająkami i owadami.
Dosyć pospolity w południowych i środkowych stanach USA: Missisipi, Teksas, Oklahoma, Kansas aż do Iowa. Występuje również na Bermudach i na Kubie.
Chociaż jad tych pająków może powodować rozległą martwicę tkanek, jego ukąszenie rzadko bywa śmiertelne.
A Loxosceles reclusa, comummente conhecida como aranha-violinista[1] ou aranha-reclusa-castanha[2], é uma espécie de aranha araneomorfa da família Sicariidae, capaz de infligir mordeduras venenosas proteolíticas com consequências significativas para o ser humano.[3]
A espécie tem uma distribuição natural ampla na parte leste da América do Norte[4], desde o norte do México até à Nova Inglaterra, em habitats abrigados e húmidos, nomeadamente entre pedras, madeira ou lenhas deixadas no exterior ou em recantos húmidos e escuros de edifícios.[3]
Este aracnídeo pode apresentar entre 6–20 mm de comprimento, raramente maior, com coloração entre o castanho-claro e o bege, mas podendo apresentar tons de castanho mais escuros.[5] Pauta-se, ainda, pelas pernas finas e pela epónima mancha em forma de violino no cefalotórax.[6]
A aranha-reclusa-castanha é uma espécie insectívora, que se costuma alimentar à noite.[6] Ao contrário do que fazem outras espécies de aranhas, que se servem de venenos de acção neurotóxica, a aranha-reclusa-castanha injecta as presas com veneno de acção hemolítica.[6]
A Loxosceles reclusa, comummente conhecida como aranha-violinista ou aranha-reclusa-castanha, é uma espécie de aranha araneomorfa da família Sicariidae, capaz de infligir mordeduras venenosas proteolíticas com consequências significativas para o ser humano.
Păianjenul pustnic maro (lat. Loxosceles reclusa) este un bine cunoscut păianjen veninos din Statele Unite.
Lungimea corpului este cuprinsă îîntre 6 - 20 mm, femela este mai mare decât masculul. Având în vedere că păianjenul are marcaje similare nu numai cu reprezentanții aceluiaș gen, ci și cu cei din alte familii Pholcidae și Mimetidae, în scopul identificării este mult mai important să se examineze ochii. Numărul și dispoziția ochilor diferă foarte mult de ceilalți păianjeni, care au 8 ochi. Păianjenul pustnic maro are 6 ochi grupați în trei perechi, una median și câte două laterale. Chiar dacă și alții au o asemenea aranjare a ochilor (familia Scytodidae), dar se deosebește de aceștia prin modelul de colorație a corpului și prin lipsa spinilor, opistosma este acoperită cu perișori fin și scurți[1]. Articulațiile picioarelor poate avea o culoare ușor mai deschisă, decât restul corpului. Alte caracteristici de identificare este poziția păianjenului pe o suprafață plană, de obicei, picioarele sunt bine extinse cu excepția cazurilor de alarmare. Când este amenințat, întinde picioare posterioare într-o poziție defensivă, să retragă în spate și ridică pedipalpii. Păianjenul se mișcă cu o viteză uniformă, oprindu-se pentru restabilirea presiunii arteriale hidraulice din picioare, apoi continuă într-un ritm constant. Păianjenul pustnic maro evită situațile de conflict, preferând să fugă.
Ziua acest păianjen se ascunde printre pietre, prin crăpături în vizuinile altor animale sau își țese pânze în locuri retrase și uscate: grajduri, dulapuri, paturi, pivnițe. Pânzele sunt neregulate. În casele oamenilor el preferă cartonul, deoarece imite culoare scoarței copacilor pe care trăiește. El a fost găsit și în cutii deșarte, lenjerie, haine, încălțăminte etc. Spre deosebire de alțipăianjeni țesători de pânze, acesta părărsește pânza sa pe timp de noapte pentru a vâna. Masculul cea mai mare parte a timpului și-o petrece la vânătoare pe când femela pe pânză sau în apropierea ei. Se hrănesc cu diferite insecte. Păianjenul pustnic injectează în victimă venin cu acțiune hemolitică și necritică.
Această specie este rareori agresivă. Atacurile asupra oamenilor sunt, relativ, rare. Păianjenul mușcă, de obicei, doar atunci când este amenințat, presat pe piele când se găsește în haine, ștergar sau lenjeria de pat. Multe victime umane au fost mușcate după îmbrăcarea unei haine sau încălțăminte[2]. Uneori, multe răni necrotice diagnosticate ca mușcăturile păianjenului pustnic maro pot fi de fapt infecții cauzate de meticilino-rezistent Staphylococcus aureus (MRSA)[2]. În altele cazuri, poate fi cancerul cutaneu, boala Lyme, mușcături ale unor insecte veninoase sau leziuni chimice ale pielii. Mușcătura păianjenului pustnic maro produce o serie de simptome denumit ca loxoscelism. Există două tipuri de loxoscelism: cutaneu și viscerocutaneu.
Păianjenul pustnic maro se întâlnește în Statele Unite din Midwest până la Golful Mexic[3][4]. O specie înrudită (Loxosceles rufescens), se găsește în Hawaii[5]. Există alte specii de Loxosceles în sud-vestul Statelor Unite, inclusiv California[6], care pot semăna cu Păianjenul pustnic maro, dar aceste specii nu au fost niciodată documentate cu un efectiv important.
|url= lipsă sau vid (ajutor); |access-date= necesită |url= (ajutor)Mentenanță CS1: Pipe lipsă (link) 
Păianjenul pustnic maro (lat. Loxosceles reclusa) este un bine cunoscut păianjen veninos din Statele Unite.
Rjavi pajek samotar (znanstveno ime Loxosceles reclusa) je strupeni pajek iz družine Sicariidae, katerega ugriz lahko povzroči obsežno nekrozo tkiva v območju ugriza. Lahko so rjave, sive ali temno rumene barve, na hrbtni (dorzalni) strani glavoprsja pa navadno poteka črni pas v obliki violine, katere vrat je usmerjen proti zadku. Zaradi tega nosi pajek različne vzdevke, kot sta violinski pajek ali goslarski pajek. Prebiva na vzhodnem območju ZDA do Mehiškega zaliva.
Glede na to, da vzorec violine nemalokrat ni prisoten in da imajo lahko tudi drugi pajki podobne vzorce (kot npr. družini Pholcidae in Mimetidae), so za prepoznavo tega pajka pomembne oči. Slednje se od drugih pajkov razlikujejo po številu in organizaciji: rjavi pajek samotar in drugi pajki iz istega rodu imajo 6 oči, organiziranih v tri pare (diade), in sicer v enega sredinskega (medianega) in dva obstranska (lateralna), medtem ko imajo drugi pajki 8 oči, urejenih v dve vrsti. Podobno organizacijo oči imajo sicer tudi pajki iz družine Scytodidae, vendar se ti razlikujejo po tem, da imajo značilne vzorce na nogah in trebušni strani, poleg tega pa ima samotar na trebušni strani mehke dlačice, ki nimajo trdih konic.[1] Sklepi so obarvani svetlejše.
V umirjenem drži ima vse noge raztegnjene, v primeru ogroženosti pa potegne sprednji nogi navzad v obrambno držo, stranske noge potegne v pozicijo za hiter in nenaden premik, pedipalpa pa dvigne. Premika se s konstantno hitrostjo z iztegnjenimi nogami in se ustavi le, ko rabi obnoviti interni hidravlični pritisk (tj. ko rabi obnoviti »moč« v nogah). V primeru ogroženosti zbeži stran od nevarnosti, v skrajnem primeru (npr. v zaprtih prostorih) pa nevarnost hitro zaobide in s tem poskuša preprečiti neposreden stik.
Pajek prebiva v ZDA na območju, ki se razteza od južnega dela srednjega vzhoda do Mehiškega zaliva. Meja območja poteka od jugovzhoda Nebraske skozi južno Iowo, Illinois in Indiano do jugozahoda Ohia. V južnih državah poteka meja od osrednjega dela Teksasa, preko zahodne Georgie do zahoda Virginije.[2][3] V Kaliforniji se kljub domnevnim opažanjem ni naselil.[4] Sorodna vrsta, L. rufescens, prebiva na Havajih.[5]
Pajki gradijo nepravilne mreže (ki pogosto vključujejo zavetje) v skladiščih drv, hlevih, omarah, posteljah, garažah, kleteh in drugih prostorih, ki so suhi in kjer je človeška aktivnost relativno majhna. Prednost dajejo odpadni kartonasti embalaži, saj naj bi bila podobna gnilemu lubju, v katerem živijo v naravi. Odkriti so bili tudi v čevljih, v notrajnosti pisalnih strojev, za mizami in slikami, kupih nerabljenih oblek in blizu virov toplote (npr. radiator), ko je temperatura okolja nižja kot običajno. Do stika s človekom pogosto pride takrat, ko človek zaide v take predele in ko se pajek počuti ogroženo. V nasprotju z drugimi pajki, ki gradijo mreže, ponoči zapustijo svoje mreže in se odpravijo loviti. Pri tem se bolj gibljejo samci, medtem ko se samice zadržujejo v bližini mreže.
Že po samem imenu (samotar) se lahko sklepa, da je ta vrsta pajka redko agresivna, zato so dejanski ugrizi relativno redki. Pajek bo ugriznil človeka v primeru, če se ga bo dotaknil (zato so pogosti ugrizi na roki) ali kakorkoli drugače pritisnil del telesa, kot npr. pri oblačenju ali obuvanju.[6][7]
Večina ugrizov je nenevarnih brez nekroze. Resnost ugriza je odvisna predvsem od prejete količine toksina in zdravstvenega stanja človeka.[7] Navkljub temu manjše število ugrizov povzroči spekter simptomov, kolektivno znanih pod imenom loksoscelizem. Obstajata dve vrsti slednjega, in sicer kožni (kutani) ter sistemski (viscerokutani) loksoscelizem. Glede na to, da vključuje tudi morebitne poškodbe organov, lahko privede ugriz tudi do smrti; ogrožene skupine so otroci pod 7 let starosti, starejši ljudje in osebe z oslabljenim imunskim sistemom.[8]
Sam ugriz je navadno neboleč, vendar lahko skozi čas nastane rana premera od 5–30 cm. Mesto ugriza postane boleče in srbeče po 2-8 urah, po 12-36 urah pa se bolečina in drugi lokalni znaki še poslabšajo. Pri kožnem loksoscelizmu nastane po nekaj dnevih dermatonekrozna lezija, ki uniči mehko tkivo, celjenje rane pa lahko traja več mesecev in pusti globoke brazgotine. Poškodovano tkivo bo čez čas postalo gangrenozno in na koncu odpadlo stran od zdravega tkiva.[7][9]
Resni sistemski učinki se lahko pojavijo pred tem časom, saj se toksin razširi po telesu v nekaj minutah; lokalno razširjenje je odvisno od mnogih dejavnikov v samem toksinu, kot so hialuronidaza, kolagenaza, proteaze in fosfolipaze. Blažji simptomi vključujejo slabost, bruhanje, mrzlico, izpuščaje ter bolečine mišic in sklepov. Izpuščaji so na sredini rdeče-vijolični, okoli tega pa je prisoten bledi obroč, ki je zamejen z rdečo črto; takemu izgledu pravimo tudi »bikovo oko« (angleško bull′s eye). V hujših primerih lahko pride do hemolize, trombocitopenije (znižana koncentracija trombocitov v krvi), diseminirane intravaskularne koagulacije (DIK) in odpovedi ledvic, na koncu pa lahko nastopi tudi smrt. Za sistemske učinke so dovzetnejši starejši in otroci.[7][10]
Ocenjeno je, da je približno 80 % vseh diagnoz ugrizov rjavega pajka samotarja postavljenih napačno, kar je klinično pomembno, saj onemogoča pravilno zdravljenje resne bolezni.[3] Obstajajo različne okužbe in druge bolezni ter poškodbe, ki povzročajo podobne simptome, kot so okužbe s stafilokoki (npr. MRSA)[6] in streptokoki, kemične opekline, okužbe z glivami, določene vrste raka kože (npr. spinocelularni karcinom) in Lymska borelioza.[3] Obstaja ELISA test, s katerim se lahko dokaže nekrotoksin tega pajka, čeprav trenutno še ni komercialno na razpolago.[3][11] Poleg naštetega predstavljajo problem tudi drugi pajki (npr. rod Phidippus), katerih ugrizi prav tako povzročajo nekrozo.[7]
Prva pomoč vključuje aplikacijo ledu na mesto ugriza za zaviranje vnetja ter aloe vere za blaženje bolečine. Po možnosti je priporočljivo ujeti pajka in ga prinesti k zdravniku za natančno razpoznavo.
Trenutno ne obstaja nobeden standardni način zdravljenja tovrstne nekroze, vendar vključuje dvig in imobilizacijo poškodovanega uda, aplikacijo ledu, lokalno zdravljenje rane in preventivo proti morebitnemu pojavu tetanusa. Uporabljene so bile tudi druge terapije z različnimi rezultati, kot so hiperbarični kisik, antihistaminiki (npr. ciproheptadin), dekstran, glukokortikoidi, vazodilatatorji, heparin in električni šoki.[12][13]
Teoretično naj bi bili učinkoviti tudi dapson (zaradi zaviranja polimorfonuklearnih levkocitov in s tem vnetja)[7][14] ter nitroglicerin, ki je vazodilatator (širi krvne žile) in povzroči filtracijo toksina v krvni obtok ter dotok sveže krvi v rano.[15][16] V primeru sekundarne okužbe je potrebno dati antibiotike.[17] Kirurški poseg je neučinkovit (še posebej v začetni fazi) in lahko še poslabša simptome.[7][18] Protistrup (antidot) proti drugim vrstam pajkov iz istega rodu naj bi bil tudi obetaven, vendar je najbolj učinkovit v roku 24 ur. Praktična uporaba je v resnici zaradi nebolečega ugriza in relativno dolgega časovnega roka, po katerem se pokažejo simtpomi, zelo težavna.[19] Učinkoviti naj bi bil tudi hiperbarični kisik.[7]
Rjavi pajek samotar (znanstveno ime Loxosceles reclusa) je strupeni pajek iz družine Sicariidae, katerega ugriz lahko povzroči obsežno nekrozo tkiva v območju ugriza. Lahko so rjave, sive ali temno rumene barve, na hrbtni (dorzalni) strani glavoprsja pa navadno poteka črni pas v obliki violine, katere vrat je usmerjen proti zadku. Zaradi tega nosi pajek različne vzdevke, kot sta violinski pajek ali goslarski pajek. Prebiva na vzhodnem območju ZDA do Mehiškega zaliva.
Loxosceles reclusa là một loài nhện trong họ Sicariidae. Loài này trước kia được đặt trong họ Loxoscelidae) là một loài nhện với vết cắn có nọc độc. Nhện nâu ẩn dật có chiều dài thường giữa 6–20 mm, nhưng có thể phát triển lớn hơn. Trong khi thông thường có màu sáng đến màu nâu trung bình, chúng có màu sắc trong khoảng màu từ kem màu xám nâu hoặc đen tối.
Loài nhện này có nguồn gốc Hoa Kỳ từ miền nam Trung Tây phía nam đến Vịnh Mexico. Phạm vi bản địa nằm gần như cách phía nam của một đường từ phía đông nam Nebraska qua phía nam Iowa, Illinois, và Indiana tây nam Ohio. Ở các bang miền Nam, nó có nguồn gốc từ trung tâm Texas tây Gruzia và phía bắc Kentucky.
Loxosceles reclusa là một loài nhện trong họ Sicariidae. Loài này trước kia được đặt trong họ Loxoscelidae) là một loài nhện với vết cắn có nọc độc. Nhện nâu ẩn dật có chiều dài thường giữa 6–20 mm, nhưng có thể phát triển lớn hơn. Trong khi thông thường có màu sáng đến màu nâu trung bình, chúng có màu sắc trong khoảng màu từ kem màu xám nâu hoặc đen tối.
Укус паука очень часто остаётся незамеченным, однако в большинстве случаев ощущения схожи с ощущениями при уколе иголкой. Потом в течение 2-8 часов боль и зуд дают о себе знать. Далее ситуация развивается в зависимости от количества яда, попавшего в кровь.[6]
Укус коричневого паука-отшельника вызывает ряд симптомов, известный как локсосцелизм. Он характеризуется гангренным струпом на месте укуса, тошнотой, недомоганием, лихорадкой, гемолизом и тромбоцитопенией. В большинстве случаев укус паука незначителен и обходится без некроза, однако в больших дозах способен спровоцировать образование некротической язвы, уничтожающей мягкую ткань. В диаметре язва может достигать 25 см и более, а после заживления, которое занимает 3-6 месяцев, остается вдавленный рубец.
Прозрачный вязкий яд этого паука содержит эстеразу, щёлочную фосфатазу , протеазу и другие ферменты, вызывающие некроз тканей и гемолиз . Основная роль в развитии некроза принадлежит сфингомиелиназе D , которая связывается с клеточными мембранами и вызывает хемотаксис нейтрофилов, тромбоз сосудов и феномен Артюса. В случае некроза подкожной клетчатки заживление может растянуться на 3 года.[3]
В редких случаях характерны систематические симптомы:[7] повреждения внутренних органов и, в особо редких случаях, даже смерть; большинство смертельных исходов наблюдается у детей младше семи лет [8], людей со слабой иммунной системой и пожилых людей.[6] Причиной смерти могут стать гемолитическая анемия, гемоглобинурия и почечная недостаточность.[3]
В медицинской литературе числятся несколько пауков, укус которых приводит к некрозу. К таковым относятся, например, американский бродячий паук (лат. Tegenaria agrestis) и желтосумный колющий паук (лат. Cheiracanthium punctorium). Однако укусы этих пауков, в отличие от укуса коричневого паука-отшельника, не производят таких серьёзных симптомов[9][10].
При укусе необходимо, в первую очередь, сохранять спокойствие и вызвать врача. Затем необходимо любым способом замедлить распространение яда от места укуса. Для этого нужно приложить к месту укуса лёд. Следует иммобилизировать (обездвижить) пораженную конечность и в зависимости от того куда был произведён укус наложить жгут и выдавить яд либо иным образом воспрепятствовать распространению яда по венам к сердцу и его сосудам. Для обеззараживания раны стоит применить антисептики, а для снижения боли можно применить сок алоэ. Если возможно, стоит поймать паука в чистый и надёжный контейнер — это необходимо для идентификации паука экспертом.[11]
Существует множество вариантов лечения последствий укуса, действующих с различной степенью эффективности: гипербарическая оксигенация, дапсон, антигистаминные препараты (например, ципрогептадин), антибиотики, декстран, глюкокортикоиды, вазодилататоры, гепарин, нитроглицерин, электрический шок, кюретаж, хирургическое вмешательство и противоядие.[12][13] Ни один из этих вариантов не был подвергнут контрольным испытаниям для выявления эффективности. В большинстве случаев последствия укусов вылечиваются без какого-либо медицинского вмешательства.[14]
Во избежание укуса паука следует:
Санитария:
Другие меры:
Существует множество средств для контроля пауков. Некоторые из них предназначены для домашнего использования, в то время как другие — только для лицензированного применения. Если вы обнаружили коричневого паука-отшельника в вашем доме, то будет целесообразно обратиться к услугам профессиональных компаний по борьбе с вредителями.
Исследования показывают, что недавно разработанные пиретроиды (например цифлютрин, циперметрин и т. д.) в некоторой степени эффективны против коричневого паука-отшельника. Смачиваемые порошки и микроинкапсулированные формулы «медленного действия» обеспечивают долговременную активность и предпочтительны для использования в качестве эмульсионных спреев.
Обработку инсектицидами следует проводить так, чтобы химикат имел контакт с как можно большим числом пауков и их сетей. Аэрозоли следует применять к внешнему периметру дома (в том числе под карнизом, патио и досками; за оконными ставнями), плинтусам, углам и другим местам, где предположительно может поселиться паук. Порошки следует применять к щелям и другим труднодоступным местам, где может прятаться паук. Аэрозольные агенты, такие как пиретрин, хоть сами по себе и не очень эффективны, всё же способны заставить паука держаться ближе к обработанной поверхности.[11]
Вид паука снизу
Поражённая кожа ноги
|month= (справка) |year= (справка на английском) Укус паука очень часто остаётся незамеченным, однако в большинстве случаев ощущения схожи с ощущениями при уколе иголкой. Потом в течение 2-8 часов боль и зуд дают о себе знать. Далее ситуация развивается в зависимости от количества яда, попавшего в кровь.
Укус коричневого паука-отшельника вызывает ряд симптомов, известный как локсосцелизм. Он характеризуется гангренным струпом на месте укуса, тошнотой, недомоганием, лихорадкой, гемолизом и тромбоцитопенией. В большинстве случаев укус паука незначителен и обходится без некроза, однако в больших дозах способен спровоцировать образование некротической язвы, уничтожающей мягкую ткань. В диаметре язва может достигать 25 см и более, а после заживления, которое занимает 3-6 месяцев, остается вдавленный рубец.
Прозрачный вязкий яд этого паука содержит эстеразу, щёлочную фосфатазу , протеазу и другие ферменты, вызывающие некроз тканей и гемолиз . Основная роль в развитии некроза принадлежит сфингомиелиназе D , которая связывается с клеточными мембранами и вызывает хемотаксис нейтрофилов, тромбоз сосудов и феномен Артюса. В случае некроза подкожной клетчатки заживление может растянуться на 3 года.
В редких случаях характерны систематические симптомы: повреждения внутренних органов и, в особо редких случаях, даже смерть; большинство смертельных исходов наблюдается у детей младше семи лет , людей со слабой иммунной системой и пожилых людей. Причиной смерти могут стать гемолитическая анемия, гемоглобинурия и почечная недостаточность.
В медицинской литературе числятся несколько пауков, укус которых приводит к некрозу. К таковым относятся, например, американский бродячий паук (лат. Tegenaria agrestis) и желтосумный колющий паук (лат. Cheiracanthium punctorium). Однако укусы этих пауков, в отличие от укуса коричневого паука-отшельника, не производят таких серьёзных симптомов.
Первая помощь при укусеПри укусе необходимо, в первую очередь, сохранять спокойствие и вызвать врача. Затем необходимо любым способом замедлить распространение яда от места укуса. Для этого нужно приложить к месту укуса лёд. Следует иммобилизировать (обездвижить) пораженную конечность и в зависимости от того куда был произведён укус наложить жгут и выдавить яд либо иным образом воспрепятствовать распространению яда по венам к сердцу и его сосудам. Для обеззараживания раны стоит применить антисептики, а для снижения боли можно применить сок алоэ. Если возможно, стоит поймать паука в чистый и надёжный контейнер — это необходимо для идентификации паука экспертом.
Существует множество вариантов лечения последствий укуса, действующих с различной степенью эффективности: гипербарическая оксигенация, дапсон, антигистаминные препараты (например, ципрогептадин), антибиотики, декстран, глюкокортикоиды, вазодилататоры, гепарин, нитроглицерин, электрический шок, кюретаж, хирургическое вмешательство и противоядие. Ни один из этих вариантов не был подвергнут контрольным испытаниям для выявления эффективности. В большинстве случаев последствия укусов вылечиваются без какого-либо медицинского вмешательства.
棕色遁蛛（拉丁文學名：Loxosceles reclusa，英语：Brown recluse spider），也譯為褐色隱蛛、棕色隱遁蛛，提琴背蜘蛛（fiddleback spider），棕色提琴蜘蛛（brown fiddler），也能為提琴蜘蛛（violin spider），但提琴蜘蛛這稱號都可用於平甲蛛属(Loxosceles)的其他成員，屬於絲蛛科（Sicariidae），是一種著名的有毒蜘蛛，生活於北美洲南部，與紅頭平甲蛛、智利隱蛛同屬一個家族，都是有劇毒的蜘蛛。
身長約6-20公釐之間，但也有可能長得更大。毒性強，被咬傷者很快就會出現紅斑、潰爛、噁心的症狀，孩童被咬後的反應尤其激烈，2014年就曾有一名5歲的美國男童在被咬後的一天內死亡。
-top_01.png){kind=small}
这是一篇與蜘蛛相關的小作品。你可以通过编辑或修订扩充其内容。 
ドクイトグモ（学名：Loxosceles reclusa）は、クモ綱・クモ目・イトグモ科に分類されるクモの一種。
体長7-12mm[2]。頭胸部背面にバイオリンによく似た形の褐色の斑紋をもつ。
石や枝の下、人家、納屋に生息する。夜行性で、壁に網をつくり、昆虫を捕食する。その名のとおり、とても強い毒をもっている。
毒グモである本種に咬まれる被害が原産地では多発している。咬まれると周辺の組織が壊死したり死亡例もある[2]。
日本では、原産地からの物資に紛れ込んで侵入することが危惧されており、外来生物法にて特定外来生物に指定されている[2]。
ドクイトグモ（学名：Loxosceles reclusa）は、クモ綱・クモ目・イトグモ科に分類されるクモの一種。
