Insect and arthropod bites

Treatment for insect sting

• 1.

  Be prepared to treat a severe allergic reaction (see page 78). If the victim develops hives, shortness of breath, and profound weakness, and appears to be deteriorating, immediately administer epinephrine. Anyone known to have insect allergies who travels in the wilderness should carry epinephrine. Epinephrine (adrenaline) is injected intramuscularly (see page 469 and 484) as an aqueous solution of 1:1000 concentration in a dose of 0.3 to 0.5 mL for an adult and 0.01 mL/kg of body weight for a child (not to exceed 0.3 mL). For weight estimation, 1 kg equals 2.2 lb. It should be injected into the lateral thigh. If the thigh is obese, whether in an adult or a child, such that the needle might not reach into muscle, then inject into the lower thigh. If obesity is extreme, consider injecting into the mid-calf. The only reason to administer the drug subcutaneously is if the equipment is not available for an intramuscular injection. The drug is available in preloaded syringes in certain allergy kits, which include the EpiPen autoinjector (0.3 mg) and EpiPen Jr. autoinjector (0.15 mg), Auvi-Q autoinjectors, Adrenaclick autoinjectors, and SYMJEPI pre-filled (with epinephrine) syringes. FDA-approved generic products are sometimes less expensive. Other devices worldwide are the Jext, Emerade, Allerject, and Anapen. Instructions for use accompany the kits. For dosing purposes, a 0.3-mg autoinjector should be used for adults and children over 66 lb (30 kg) in weight. Children 66 lb and under should be injected with a 0.15-mg autoinjector. According to manufacturers, epinephrine should be stored between 68 ^o C to 77 ^o F (20 ^o C to 25 ^o C) with brief excursions permitted to 59 ^o F to 86 ^o F (15 ^o C to 30 ^o C). When injecting into a child’s leg, be sure to hold the leg firmly so that it does not move in order to prevent creating a cut. Never re-insert an autoinjector needle (See page 484).

  • Take particular care to handle preloaded syringes properly, to avoid inadvertent injection into an unintended location, such as a finger or toe. Do not intentionally inject epinephrine into the buttocks or a vein. Epinephrine should not be exposed to heat or sun, but does not need to be kept refrigerated. If clear (liquid) epinephrine turns cloudy or discolored, it should be discarded. When administering an injection, never share needles between people.

• 2.

  Administer diphenhydramine (Benadryl) by mouth, 50 to 100 mg for an adult and 1 mg/kg of body weight for a child. This antihistamine drug can be used by itself for a milder allergic reaction. Topical antihistamine lotions or creams might be beneficial.

• 3.

  Stingers or pieces of stingers left in the skin should be removed as soon as possible ( Fig. 233 ). It used to be taught that pulling the stinger out with fingers or forceps squeezed more venom into the victim, but this is currently not believed to be true. So, it is better to flick or pull a stinger and venom sac out of the skin of the victim using tweezers or your fingers than to waste precious time searching for a straight-edged object, such as a knife or credit card, to scrape away the stinger. Furthermore, crude scraping runs the risk of breaking off the stinger and leaving it embedded in the skin. An alternative is to try to pull out the stinger, then apply the Extractor device ( Fig. 234 ), if it is available, immediately after the sting has occurred.

  
  

• 4.

  Apply ice packs to the site of the sting.

• 5.

  Home topical remedies, such as crushed aspirin, a 20% aluminum salt-containing preparation (including many household antiperspirants) or paste of baking soda or papain-containing meat tenderizer (such as Adolph’s unseasoned meat tenderizer) and water applied directly to the wound (for no more than 15 minutes), are of unproven value. Do not apply mud. The commercial product After Bite (Tender Corporation), a mixture containing ammonia 3.5%, is moderately effective for relief of pain and itching following insect bites but will not abort an allergic reaction. StingEze liquid (Wisconsin Pharmacal) is a mixture of camphor, phenol, benzocaine, and propylene glycol. StingEze MAX ² contains twice the benzocaine. StingEze products are good to control itching and mild pain following any insect bite. Lidocaine 4% applied topically might help diminish discomfort.

• 6.

  If a person suffers an extensive skin and soft tissue reaction (swelling, itching, blisters), they might benefit from administration of a corticosteroid, such as prednisone (60 mg by mouth day 1, tapered by 10 mg per day over the next 5 days) or methylprednisolone (24 mg by mouth day 1, tapered over the next 5 days).

• 7.

  If a person stung by an insect develops more than a mild to moderate local reaction, transport them to a hospital. If a person stung by a bee, hornet, wasp, etc. develops a severe allergic reaction (anaphylaxis) they should be referred to an allergy specialist after treating anaphylaxis for possible venom immunotherapy.

• 8.

  A bee sting in general does not pose a large risk for tetanus infection, unless there is concern for significant soil contamination simultaneously (see tetanus prophylaxis on page 183).

• 9.

  Fire ant pseudo-pustules should be kept clean and not be unroofed or otherwise disturbed, in order to avoid infection.

Avoidance of stinging insects

• 1.

  Store garbage, particularly fruit, at a distance from the campsite.

• 2.

  Remove (carefully) beehives and wasp nests from children’s play areas.

• 3.

  Wear light-colored clothing. Dark- and bright-colored clothing is attractive to insects and might evoke a defensive (sting or bite) response. Keep shirt sleeves closed and tuck pants into boots. Wear light-colored socks. Be aware of nests near or on the ground.

• 4.

  Avoid wearing sweet fragrances that make you smell like a flower. Avoid carrying sweet-smelling soft drinks and fruit juices.

• 5.

  Avoid orchards in bloom, fields of clover, and areas with lots of flowers.

• 6.

  Do not anger bees or wasps. If confronted by a swarm, cover your face (eyes, nose, and mouth) and move rapidly from the area. If necessary, throw a blanket or towel over your head. Run if you must. Maneuver through bushes or weeds to confuse the bees. Do not jump into a pool—the bees might wait for you and a severe allergic reaction from a sting while in the water might be extremely dangerous. Do not poke sticks or throw rocks into bee holes.

• 7.

  Avoid rapid or jerky movements near bees. Do not swat at them. Remain calm.

Black widow spider

In the United States, the female black widow spider (Latrodectus mactans) is about ⅝ inch (15 mm) in body length, black or brown, and with a characteristic red (or orange or yellow) hourglass marking on the underside of the abdomen ( Fig. 235 ). The top side of the spider is shiny and features a fat abdomen that resembles a large black grape. The longest legs are directed toward the front. This species and other Latrodectus species are found scattered in rural regions, in barns, within harvested crops, and around outdoor stone walls. Some are arboreal.

The bite of the black widow spider is rarely very painful (usually more like a pinprick) and often causes little swelling or redness, although there can be a warm and reddened area around the bite. If much venom has been deposited, the victim develops a typical reaction within an hour, largely due to latrotoxin. Symptoms include muscle cramps, particularly of the abdomen and back; muscle pain; muscle twitching; numbness and tingling of the palms of the hands and bottoms of the feet; headache; droopy eyelids; facial swelling; drooling; sweating; restlessness and anxiety; vomiting; chest muscle spasms that cause difficulty breathing; fever; and high blood pressure. A man might develop a persistent penile erection (priapism). A small child might cry persistently. A pregnant woman might develop uterine contractions and premature labor.

Untreated, most people recover without help over the course of 8 hours to 2 days. However, very small children and elderly victims might suffer greatly, with possible death. There is antivenom available to medical practitioners for treating the bite of the black widow spider. It is used to treat moderate to severe symptoms.

Treatment for a black widow spider bite

• 1.

  Apply ice packs to the bite.

• 2.

  Immediately transport the victim to a medical facility.

• 3.

  Once the victim is in the hospital, the doctor will have several therapies to use, which include intravenous calcium solutions and muscle relaxant medicines for muscle spasm; antihypertensive drugs for elevated blood pressure; pain medicine; and, in very severe cases, antivenom.

• 4.

  If you will be unable to reach a hospital within a few hours and the victim is suffering severe muscle spasms, you can administer an oral dose of diazepam (Valium) or lorazepam (Ativan), if you happen to be carrying it. The starting dose of diazepam for an adult who does not regularly take the drug is 5 mg, which can be augmented in 2.5 mg increments every 30 minutes up to a total dose of 10 mg, so long as the victim remains alert and is capable of normal, purposeful swallowing. The starting dose for a child aged 2 to 5 years is 0.5 mg; for a child aged 6 to 12 years the starting dose is 2 mg. Total dose for a child should not exceed 5 mg; never leave a sedated child unattended. The starting adult dose of lorazepam for an adult is 1 mg, which can be augmented in 0.5 mg increments every 30 minutes up to a total dose of 2 mg.

Recluse spiders

At least 11 species of recluse spiders are found in the United States. The brown recluse spider (Loxosceles reclusa) is the best known and found most commonly in the South and southern Midwest. However, interstate commerce has created habitats in many other parts of the country for the brown recluse and related species. The spider is brown, with an average body length of just under ½ inch (10 mm). A characteristic dark violin-shaped marking (“fiddleback” or “violin” spider) is sometimes, but not always, found on the top of the upper section of the body ( Fig. 236 ). Recluse spiders have six equal-sized eyes arranged in three pairs. The brown recluse spider is found in dark, sheltered areas, such as under porches and in storage areas, in attics and woodpiles, and in crates of fruit. It is most active at night. It commonly bites when it is trapped but is not otherwise aggressive toward humans.

The bite of the brown recluse spider might cause very little pain at first, or a sharp sting might be felt. The stinging subsides over 6 to 8 hours and is replaced by aching and itching. Within 1 to 5 hours, a painful red or purplish blister sometimes appears, surrounded by a bull’s-eye of whitish-blue (pale) discoloration, with occasional slight swelling. The red margin might spread into an irregular fried-egg pattern, with gravitational influence, such that the original blister remains near the uppermost part of the lesion. The victim might develop chills, fever, weakness, and a generalized red skin rash. Severe allergic reactions within 30 minutes of the bite occur infrequently. Over 5 to 7 days, the venom causes a violet discoloration and breakdown of the surrounding tissue, leading to an open ulcer that might take months to heal. If the reaction has been severe, the tissue in the center of the wound becomes destroyed, blackens, and dies.

A rare reaction is “systemic loxoscelism,” in which the venom binds to red blood cells and induces severe symptoms within 24 to 72 hours. These include a flu-like presentation with fever, chills, headache, fatigue, weakness, nausea, vomiting, muscle and joint aches, blood in the urine, yellow skin discoloration (jaundice), kidney failure, and even shock, seizures, coma, and rarely death. This is more common in children and requires intensive medical therapy.

Treatment for a brown recluse spider bite

Because the bite of the brown recluse spider typically causes severe tissue destruction, the victim should see a physician, who will prescribe medicine or another therapy as soon as possible. In the meantime, apply cold packs to the wound for as long as is practical and administer an antibiotic (erythromycin, azithromycin, or cephalexin). Do not apply a heating pad or hot packs. Depending on the severity of the reaction, the doctor might advise taking medicines. There are therapies that have been reported, but not been proven, effective. These include surgical excision of the bite; dapsone (a drug used to inhibit certain cells that are part of the inflammatory response); topical application of nitroglycerin; and hyperbaric oxygen therapy.

Until you receive other advice, treat the wound with a thin layer of mupirocin or bacitracin ointment, or mupirocin cream, underneath daily dressing changes. Don’t apply topical steroids.

Other spiders

Other spiders that might produce painful bites and a small amount of local tissue breakdown (ulcers) include the tarantula, wolf spider, jumping spider, yellow sac spider, orb weaver, and hobo spider (Tegenaria agrestis). The bites should be treated with ice packs, pain medicine, and standard wound care.

Some tarantulas ( Fig. 237 ) carry hairs that can irritate the skin, eyes, and mucous membranes of humans. When the spider is threatened, it rubs its hind legs over its abdomen and flicks thousands of hairs at its foe. These hairs can penetrate human skin and cause swollen bumps, which can itch for weeks. If any hairs or hair fragments remain in the skin, they can be removed by applying and peeling off sticky tape. After that, treatment is with an oral antihistamine and topical medication such as StingEze liquid. A topical antihistamine or corticosteroid preparation might provide some relief.