Arthropod Bites and Stings

Descriptive text is not available for this image BASICS

DESCRIPTION

  • Arthropods are the largest division of the animal kingdom. Two classes, insects and arachnids, have the greatest impact on human health. Arthropods affect humans by inoculating venom, microorganisms, or irritative substances through a bite or sting; by invading tissue, or by contact allergy to their skin, hairs, or secretions.
  • Anaphylactic reactions and transmission of infectious microorganisms are the greatest concerns.
  • Sequelae of bites, stings, or contact include:
    • Local redness with itch, pain, and swelling: common, usually immediate and transient; large local reactions that increase over 24 to 48 hours; systemic reactions with anaphylaxis, neurotoxicity, organ damage, or other systemic toxin effects; tissue necrosis or secondary infection

EPIDEMIOLOGY

Incidence

Arthropod bites and stings account for up to 1 million emergency department visits annually in the United States.

Prevalence

Widespread, with regional and seasonal variations

ETIOLOGY AND PATHOPHYSIOLOGY

  • Arthropods: four medically important classes
    • Insects: Hymenoptera (bees, wasps, hornets, fire ants), mosquitoes, bed bugs, flies, lice, fleas, beetles, caterpillars, and moths
    • Arachnids: spiders, scorpions, mites, and ticks
    • Chilopods: centipedes
    • Diplopods: millipedes
  • Four general categories of pathophysiologic effects:
    • Toxic effects of venom: local (tissue inflammation or destruction) versus systemic (neurotoxic or organ damage)
    • Allergic: Antigens in saliva or venom may cause local inflammation, anaphylaxis, or serum sickness. Alpha-gal syndrome, an immunoglobulin E (IGE)-mediated hypersensitivity to mammalian red meat, is associated with bites from the lone star tick
    • Trauma: Mechanical injury from biting or stinging causes pain, swelling, and portal of entry for bacteria and secondary infection. Retention of arthropod parts can cause a granulomatous reaction.
    • Infection: Arthropods transmit bacterial, viral, and protozoal diseases.

Genetics

Family history of atopy may increase risk of more severe allergic reactions.

RISK FACTORS

Previous sensitization; although most arthropod contact is inadvertent, certain activities, occupations, and travel exposures increase risk; greater risk for adverse outcomes in young, elderly, immunocompromised, and those with cardiac or respiratory disease; increased risk of anaphylaxis, especially to Hymenoptera stings, in patients with mastocytosis

GENERAL PREVENTION

  • Avoid common arthropod habitats.
  • Insect repellents (effective for mosquitoes, ticks, and flies)
    • N,N-diethyl-meta-toluamide (DEET)
      • Broad spectrum of activity against biting arthropods (1)[A]
      • Concentrations of 20–35% offer approximately 5 hours of protection (1)[A]. Safe for children >2 months of age and pregnant and lactating women (1)[A]
    • Picaridin
      • 20% spray comparable to 20% DEET for mosquito and tick protection
    • p-Menthane-3,8-diol (PMD; lemon eucalyptus extract)
      • 30% concentrations give 4 to 5 hours of protection against mosquitoes and ticks. Not for use on children <3 years old
    • There are many other products but lack evidence regarding efficacy, duration of action, and safety.
  • Barrier methods: use of light-colored pants, long-sleeved shirts, and hats may reduce arthropod impact. Permethrin: synthetic insecticide derived from chrysanthemum plant. Permethrin-impregnated clothing provides good protection against arthropods. Permethrin should not be applied directly to skin. Mosquito nets: advised for travelers to disease-endemic areas. Permethrin-treated nets may offer additional protection.
  • Risk of tick-borne diseases decreased by removal of ticks within 24 hours of attachment.

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