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Sunday, January 21, 2007

Bites and Stings – Spider

Black Widow Spider

The black widow is a spider with a shiny black body, thin legs and an hourglass shaped red/white mark on its abdomen. Only the female bites, and it has a neurotoxic venom.The female is much larger than the male and is one of the largest spiders in the United States. Males generally do not bite. Females bite only when hungry, agitated or protecting the egg sac. The black widow is not aggressive. They are usually found in dry, secluded, dimly lit areas. More than 80 percent of all bite victims are adult men.

Black widow spider bites are the leading cause of death from spider bites in the United States. The venom is 14 times more toxic than rattlesnake venom. It is a neurotoxin that causes little local reaction but does cause pain and spasms in the larger muscle groups of the body within 30 minutes to three hours. The pain gradually spreads over the entire body and settles in the abdomen and legs. Abdominal cramps and progressive nausea, vomiting, and a rash may occur. Weakness, tremors, sweating, and salivation may occur. Anaphylactic reactions can occur. Symptoms begin to regress after several hours and are usually gone in a few days. Threat for shock. Be ready to perform CPR. Clean and dress the bite area to reduce the risk of infection. An antivenin is available. Severe bites can cause respiratory failure, coma and death.

Those at the highest risk are children under age 16, the elderly, people with chronic illness and people with high blood pressure. The symptoms usually happen in last 24 to 48 hours.

Signs and symptoms of a black widow spider bite:

  1. A pinprick sensation at the bite site, becoming a dull ache within 30 to 40 minutes
  2. Pain and spasms in the shoulders, back, chest, and abdominal muscles within 30 minutes to three hours
  3. Rigid, boardlike abdomen
  4. Restlessness and anxiety
  5. Fever
  6. Rash
  7. Headache
  8. Vomiting and nausea
  9. Flushing
  10. Sweating
  11. Grimacing

Treatment:

  1. Treat for shock
  2. Apply a cold compress but do not apply ice
  3. Transport to hospital as quickly as possible

The funnelweb spider is a large brown or gray spider found in Australia. The symptoms and the treatment for its bite are as for the black widow spider.

Brown House Spider

There are two types of brown house spiders or brown recluse spiders in Arizona. They often are called violin spiders because of the characteristic "violin-shaped" marking on the upper back. They are generally brown but can range in color from yellow to dark brown. They are timid with webs in dry undisturbed areas. The Arizona species is not the same as the brown recluse spider in the Midwest.

There is no pain, or so little pain, that usually a victim is not aware of the bite. The bite is nonhealing and causes tissue death. Sometimes surgery is necessary. The bite causes only a mild stinging sensation if any at all. Within a few hours a painful red area with a mottled cyanotic center appears. Necrosis does not occur in all bites, but usually in 3 to 4 days, a star-shaped, firm area of deep purple discoloration appears at the bite site. The area turns dark and mummified in a week or two. The margins separate and the scab falls off, leaving an open ulcer. Secondary infection and regional swollen lymph glands usually become visible at this stage. The outstanding characteristic of the brown recluse bite is an ulcer that does not heal but persists for weeks or months. In addition to the ulcer, there is often a systemic reaction that is serious and may lead to death. The target lesion will enlarge over the next few days and produce extensive tissue death. There is no antivenom. The lesion will have to be soaked in antispetic and possibly antibiotics. Surgery may be necessary to cut out the dead tissue.

Symptoms

Several hours after the bite, the following signs and symptoms begin to result:

  1. A small white area appears surrounded by a margin of redness which may produce a mild itching pain.
  2. A blister appears surrounded by mild swelling and redness.
  3. A "bulls-eye" or "target" lesion develops
  4. There may be fever, chills, hives, nausea, joint pain, vomiting, and a generalized rash in the joints over the next few days.

Tarantula

Tarantulas are large, hairy spiders found mainly in the tropics. Most do not inject venom, but some South American species do. They have large fangs. If bitten, pain and bleeding are certain, and infection is likely. Treat a tarantula bite as for any open wound, and try to prevent infection. If symptoms of poisoning appear, treat as for the bite of the black widow spider.

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