The brown recluse spider or violin spider , Loxosceles reclusa , is a well-known member of the family Sicariidae (formerly placed in a family "Loxoscelidae").
Brown recluse spiders are usually between 6–20 mm (¼ in and ¾ in), but may grow larger. They may be brown, gray, or a deep yellow color and 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 .
Description
Since the violin pattern is not diagnostic, and other spiders may have similar markings (i.e. cellar spiders and pirate spiders), for purposes of identification it is far more important to examine the eyes. Differing from most spiders, which 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 3 pairs of eyes arranged in this way (e.g., scytodids), and recluses can be distinguished from these as there are no coloration patterns on the abdomen or legs, which lack spines. The abdomen is covered with fine short hairs. The leg joints may appear to be a slightly lighter color. Other identifying characteristics: Stance on a flat surface usually is with all legs well extended unless alarmed, when it may withdraw its forward two legs straight rearward into a defensive position , withdraw its rear pair of legs into a position for lunging forward, and raise the pedipalps . Movement at virtually any speed is an evenly paced gait with legs extended, stopping naturally when renewing its internal hydraulic blood pressure (that like most spiders is required to renew strength in the legs); it then continues at a steady pace until again it needs to renew its blood pressure. When threatened it usually flees, seemingly to avoid a conflict, and if detained may further avoid contact with fast horizontal rotating movements.
Habitat
Recluse spiders build irregular webs that frequently include a shelter consisting of disorderly threads. These spiders frequently build their webs in woodpiles and sheds, closets, beds, garages, plenum, cellars and other places that are dry and generally undisturbed. They seem to favor cardboard when dwelling in human residences, possibly because it mimics the rotting tree bark which they inhabit naturally. They also have been encountered in shoes, inside dressers, in bed sheets of infrequently used beds, in stacks or piles of clothes, behind baseboards and pictures, and near sources of warmth when ambient temperatures are lower than usual. Human-recluse contact often is when such isolated spaces are disturbed and the spider feels threatened. Unlike most web weavers, they leave these webs at night to hunt. Males will move around more when hunting, while the female spiders tend to remain nearer to their webs.
Distribution
The brown recluse spider is native to the United States from the southern Midwest south to the Gulf of Mexico. The native range 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 of Virginia. A related species, the brown violin spider ( Loxosceles rufescens ), is found in Hawaii. Despite many rumors to the contrary, the brown recluse spider has not established itself in California. There are other species of Loxosceles native to the southwestern part of the United States, including California, that may resemble the brown recluse, but these species have never been documented as medically significant.
Venomous bite
As indicated by its name, this spider is not aggressive. Actual brown recluse bites are rare. The spider usually bites only when pressed against the skin, such as when tangled up within clothes, bath towels, or in bedding. Many human victims of brown recluse bites report having been bitten after donning garments that have been left idle for some time, particularly in a secluded place. In fact, many wounds that are necrotic and diagnosed as brown recluse bites can actually be methicillin-resistant Staphylococcus aureus (MRSA) or simple staphylococcus infections. Other causes include skin cancer, Lyme disease, and other infected insect bites and skin lesions. Brown recluse bites may produce a range of symptoms known as loxoscelism. There are two types of loxoscelism: cutaneous (skin) and systemic (viscerocutaneous).
Most bites are minor with no necrosis. However, a small number of bites produce severe dermonecrotic lesions, and, sometimes, severe systemic symptoms. These symptoms can include organ damage, and occasionally even death; most fatalities are in children under 7 or those with a weaker than normal immune system. (For a comparison of the toxicity of several kinds of spider bites, see the list of spiders having medically significant venom.)
A minority of brown recluse spider bites form a necrotizing ulcer that destroys soft tissue and may take months to heal, leaving deep scars. The damaged tissue will become gangrenous and eventually slough away. The initial bite frequently cannot be felt and there may be no pain, but over time the wound may grow to as large as 25 cm (10 inches) in extreme cases. Bites usually become painful and itchy within 2 to 8 hours; pain and other local effects worsen 12 to 36 hours after the bite with the necrosis developing over the next few days.
Serious systemic effects may occur before this time, as the venom spreads throughout the body in minutes. Mild symptoms include nausea, vomiting, fever, rashes, and muscle and joint pain. Rarely more severe symptoms occur including hemolysis, thrombocytopenia, and disseminated intravascular coagulation. Debilitated patients, the elderly, and children may be more susceptible to systemic loxoscelism. Deaths have been reported for both the brown recluse and the related South American species L. laeta and L. intermedia. Other recluse species such as the desert recluse (found in the desert southwestern United States) are reported to have caused necrotic bite wounds, though only rarely.
Numerous other spiders have been associated with necrotic bites in the medical literature. A partial list includes the hobo spider and the yellow sac spiders. However, the bites from these spiders are not known to produce the severe symptoms that often follow from a recluse spider bite, and the level of danger posed by each has been called into question. So far, no known necrotoxins have been isolated from the venom of any of these spiders, and some arachnologists have disputed the accuracy of many spider identifications carried out by bite victims, family members, medical responders, and other non-experts in arachnology. There have been several studies questioning danger posed by some of these spiders. In these studies, scientists examined case studies of bites in which the spider in question was positively identified by an expert, and found that the incidence of necrotic injury diminished significantly when "questionable" identifications were excluded from the sample set.
Bite treatment
First aid involves the application of an ice pack to control inflammation, the application of aloe vera to soothe and help control the pain, 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.
There is no established treatment for necrosis. Routine treatment should include elevation and 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. None of these treatments have been subjected to randomized controlled trials to conclusively show benefit. In almost all cases, bites are self-limited and typically heal without any medical intervention.
It is important to seek medical treatment if a brown recluse bite is suspected, as in the rare cases of necrosis the effects can quickly spread, particularly when the venom reaches a blood vessel. Cases of brown recluse venom traveling along a limb through a vein or artery are rare, but the resulting mortification of the tissue can affect an area as large as several inches, to the extreme of requiring excising of the wound. If you have any anti bacterial wipes or anti bacterial products, apply that to the affected area to kill the bacteria so that infection is less likely.
Specific treatments
Dapsone is commonly used in the USA and Brazil for the treatment of necrosis. In presumed cases of recluse bites, dapsone is often used effectively, but controlled clinical trials do not demonstrate similar effectiveness; however, dapsone may be effective at treating many "spider bites" because many such cases are actually misdiagnose
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