Brown recluse spider bite= عضة العنكبوت الناسك البني Print

  

Brown recluse spider bite 

Most spiders are absolutely harmless to humans. In fact, of the 20,000 different species of spiders that inhabit the Americas, only 60 are capable of biting humans. Within that small group, only four are known to be dangerous to humans: the brown recluse, the black widow, the hobo or aggressive house spider, and the yellow sac spider. Within this select group, only the brown recluse and the black widow spider have ever been associated with significant disease and very rare reports of death.

  • Deaths from brown recluse spiders have been reported only in children younger than seven years. Brown recluse spiders are native to the Midwestern and Southeastern states. Documented populations of brown recluse spiders outside these areas are extremely rare. In recent years controversy has arisen over the appearance of brown recluse spiders in California and Florida. At this time most experts agree that the brown recluse is not endemic to these areas. With increasing travel, individual spiders and spider bites can be found in areas where the spider is not endemic, and health care practitioners should consider this when treating suspected bites.
  • Fewer than 10 individual spiders have ever been collected outside of these native states. Most false sightings are due to confusion with one of the 13 other species found in the same family.
  • The most common non-brown recluse spiders are the desert recluse found in Texas, Arizona, and California, and the Arizona recluse. No deaths have ever been reported from non-brown recluse spiders. Bites from these cousins produce mild to moderate local skin disease.

Features: Brown recluse spiders are notable for their characteristic violin pattern on the back of the cephalothorax, the body part to which the legs attach. The violin pattern is seen with the base of the violin at the head of the spider and the neck of the violin pointing to the rear. These small non-hairy spiders are yellowish-tan to dark brown in color with darker legs. They have legs about one inch in length. The name of the genus, Loxosceles, means six eyes. Most other spiders have eight eyes. Yet this unique feature of the brown recluse is lost on the casual observer because the eyes are too small to be seen with the naked eye.

Habits: These spiders are not aggressive and bite only when threatened, usually when pressed up against the victim's skin. They seek out dark, warm, dry environments such as attics, closets, porches, barns, basements, woodpiles, and old tires. Its small, haphazard web, found mostly in corners and crevices, is not used to capture prey. Most bites occur in the summer months

Brown Recluse Bite - Causes

The brown recluse venom is extremely poisonous, even more potent than that of a rattlesnake. Yet recluse venom causes less disease than a rattlesnake bite because of the small quantities injected into its victims. The venom of the brown recluse is toxic to cells and tissues.

  • This venom is a collection of enzymes. One of the specific enzymes, once released into the victim's skin, causes destruction of local cell membranes, which disrupts the integrity of tissues leading to local breakdown of skin, fat, and blood vessels. This process leads to eventual tissue death (necrosis) in areas immediately surrounding the bite site

  • The venom also induces in its victim an immune response. The victim's immune system releases inflammatory agents-histamines, cytokines, and interleukins-that recruit signal specific disease-fighting white blood cells to the area of injury. In severe cases, however, these same inflammatory agents can themselves cause injury. These secondary effects of the venom, although extremely rare, can produce these more significant side effects of the spider bite:
    • Destruction of red blood cells
    • Low platelet count
    • Blood clots in the capillaries and loss of ability to form clots where needed
    • Acute renal failure (kidney damage)
    • Coma
    • Death

Brown Recluse Bite Symptoms

Brown recluse spider bites often go unnoticed initially because they are usually painless bites. Occasionally, some minor burning that feels like a bee sting is noticed at the time of the bite. Symptoms usually develop two to eight hours after a bite. Keep in mind that most bites cause little tissue destruction.

  • Victims may experience these symptoms:
    • severe pain at bite site after about four hours,
    • severe itching,
    • nausea,
    • vomiting,
    • fever, and
    • myalgias (muscle pain).
  • Initially the bite site is mildly red and upon close inspection may reveal fang marks. Most commonly, the bite site will become firm and heal with little scaring over the next few days or weeks. Occasionally, the local reaction will be more severe with erythema and blistering, sometimes leading to a blue discoloration, and ultimately leading to a necrotic lesion and scarring. Signs that may be present include:
    • blistering (common),
    • necrosis (death) of skin and subcutaneous fat (less common), and
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      • Daily follow-up of wounds for the first 96 hours to assess the possibility or extent of necrosis of wound
      • Hospitalization for people with systemic disease
      • Continuation of antibiotics until secondary infections clear

    • Follow-up with a surgeon if necrosis of the wound is evident

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      • severe destructive necrotic lesions with deep wide borders (rare).

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    Self-Care at Home

    Home first aid care is simple. This self-care should not replace a visit to a doctor or emergency department.

    • After a spider bite:
      • Apply ice to decrease pain and swelling.
      • Elevate area if possible above the level of the heart.
      • Wash the area thoroughly with cool water and mild soap.
      • Avoid any strenuous activity because this can spread the spider's venom in the skin.
      • Use acetaminophen (Tylenol) for pain relief.
    • Do not perform any of the following techniques:
      • Do not apply any heat to the area. This will accelerate tissue destruction.
      • Do not apply any steroid creams to the area such as hydrocortisone cream.
      • Do not attempt to remove the spider venom with suction devices or cut out the affected tissue.
      • Do not apply electricity to the area. Anecdotal reports of high voltage electrotherapy from common stun guns have never been shown to be effective in any scientific studies. This can also cause secondary burns and deepen tissue destruction.
      • Do not apply a tourniquet to the extremity involved

    Medical Treatment

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      • After initial evaluation, the doctor may provide the following treatment:
        • Tetanus immunization
        • Pain medication
        • Antibiotics if signs of infection are present in the wound
        • Antihistamines such as diphenhydramine (Benadryl) for itch relief
    There is no antivenom available in the United States to counteract the poisonous venom of the brown recluse spider. Controversial therapies include steroids and the drug dapsone (Avlosulfon). These are often reserved for people with severe systemic

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      • disease (such as certain types of anemia, blood clotting problems, and kidney failure). The therapies have little proven benefit.
      • The patient will need to follow-up with a doctor because most wounds will need to be checked daily for at least three to four days. Necrotic lesions will need close follow-up. The doctor may carefully remove dead tissue in necrotic areas to reduce the chance of developing secondary bacterial infections.

    Follow-up

    After the initial evaluation by a doctor, the patient may expect this type of follow-up: