Derm

Insect Bite

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Insect Bite, Stinging Insect, Arthropod Bite, Arthopod, Arachnid, Insect, Arthropod Dermatosis, Bug Bite

  • Pathophysiology
  • Arthropod types
  1. Arachnids (8 legs)
    1. Spiders
      1. See Spider Bite
      2. Black Widow Spider (Lactodectus mactans)
      3. Brown Recluse Spider (Loxosceles reclusa)
      4. Precautions
        1. "Spider Bites" are typically not due to Spiders, but rather other causes (e.g. MRSA Cellulitis)
        2. Most Spider Bites are benign (not black widow or brown recluse)
          1. Need only minimal local therapy (Wound Cleansing, cold therapy)
    2. Mites
    3. Ticks
      1. See Tick Bite
      2. See Vector Borne Disease
  2. Insects (6 legs) - Hexpoda subphylum
    1. Diptera (2-winged Insects)
      1. Mosquito
      2. Gnats
      3. Flies
      4. Midges
  • Signs
  1. Most "Spider Bites" are due to some other cause
  2. Pruritic, Red Papules
    1. Typical Insect Bite (e.g. Mosquito Bite or biting midge such as no-see-ums, Sand Fly)
  3. Pruritic welts along constrictive clothing lines (waist band or sock line)
    1. Chigger Bite
  4. Clustered or linear Papules at the ankles
    1. Flea Bite
  • Complications
  1. Anaphylaxis or other serious Allergic Reaction
  2. Papular Urticaria
  3. Vector Borne Disease
  4. Cellulitis
    1. Inflammation out of proportion to Insect Bite
    2. Regional Lymphadenopathy
    3. Ascending lymphangitis
  • Management
  • General
  1. Remove Stinger with forceps (avoid pinching the Stinger gland)
  2. Apply ice pack for 10-20 minutes per hour for 3 hours
    1. Contraindicated in Tarantula Bite
  3. Treat itch symptomatically
    1. Benadryl for nighttime itch, Zyrtec for daytime itch
    2. Cool compresses
    3. Anti-irritant agents (e.g. sarna)
    4. Protective agents (e.g. calamine)
    5. Topical Corticosteroids (low potency, brief use) may be considered
  1. See Anaphylaxis
  2. Prescribe Epi-Pen for emergency use for those with Anaphylaxis history
  1. See Cellulitis for antibiotic selection
  2. Tetanus prophylaxis
  • Prevention
  1. See Prevention of Vector-borne Infection
  2. Check clothes for Insects before donning
  3. Avoid habitats
    1. Woodpiles
    2. Crawl spaces
    3. Corners of buildings
  4. Dress for working outdoors
    1. Keep skin covered by clothing
      1. Wear gloves
      2. Shirt tucked into pants
      3. Pants tucked into socks
      4. Wear a hat and high collar
      5. Avoid loose clothing
    2. Avoid Insect attractants
      1. Bright colors
      2. Perfumes
  5. Insect Repellants
    1. DEET (<30% is safe in young children)
      1. Mosquitoes
      2. Fleas
      3. Gnats
      4. Chiggers
    2. Permethrin (Elimite, Nix) on clothes
      1. Ticks