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Cutaneous Reactions to Arthropod Bites

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  • Arthropods are defined by an exoskeleton, segmented body, and jointed appendages. Four of 9 classes of arthropods cause local and systemic reactions associated with their bites: Arachnida, Chilopoda, Diplopoda, and Insecta.

  • Cutaneous reactions to arthropod bites are inflammatory and/or allergic reactions.

  • Characterized by an intensely pruritic eruption at the bite sites immediately to minutes to hours to days after the bite, persisting for days to weeks, manifested by solitary or grouped: Urticarial papules; papulovesicles; bullae. Persons are often unaware of having been bitten.

  • Systemic symptoms may occur, ranging from mild to severe, with death occurring from anaphylactic shock.

  • Arthropods are vectors of many systemic infections.

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Arthropods that Bite, Sting, or Infest

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Four of nine classes of arthropods cause local or systemic reactions.

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  1. Arachnida (four pairs of legs): mites, ticks, spiders, scorpions

    1. Acarina. (mites and ticks) Sarcoptes scabiei (scabies). Demodex folliculorum and D. brevis (demodicidosis). Environmental mites. Ticks (Fig. 28-1) that feed on humans and are vectors for disease include blacklegged or Ixodes tick, lone star tick, and dog tick.

    2. Araneae. (spiders) Loxosceles reclusa or brown recluse spider. Latrodectus or widow spiders. Tegenaria or hobo spiders cause necrotic arachnidism in Pacific Northwest of United States. Tarantula: Mild inflammatory response to bite and to shed hairs.

    3. Scorpionida. Venom contains a neurotoxin that can cause severe local and systemic reactions.

  2. Chilopoda or centipedes

  3. Diplopoda or millipedes

  4. Insecta (three pairs of legs)

    1. Anoplura. Phthirius pubis or crab lice. Pediculus capitis or head lice. Pediculus corporis or body lice.

    2. Coleoptera. Beetles. Blister beetles contain the chemical cantharidin, which produces a blister when the beetle is crushed on the skin.

    3. Diptera. Mosquitoes, black flies (bites produce local reactions as well as black fly fever with fever, headache, nausea, generalized lymphadenitis), midges (punkies, no-see-ums, sand flies), Tabanidae (horseflies, deerflies, clegs, breeze flies, greenheads, mango flies); botflies, Callitroga americana, Dermatobia hominis, phlebotomid sand flies, tsetse flies

    4. Hemiptera. Bedbugs, kissing bugs

    5. Hymenoptera. Ants, bees, wasps, hornets

    6. Lepidoptera. Caterpillars, butterflies, moths

    7. Siphonaptera. Fleas, chigoe or sand flea

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Figure 28-1.

Comparison of blacklegged, lone star, and dog ticks Blacklegged or Ixodes nymphal ticks transmit Borrelia burgdorferi (Lyme disease) and other infections. Lone star ticks or Amblyomma americanum is the vector for anaplasmosis, tularemia, and Southern tick-associated rash illness. Dog or wood ticks, Dermacentor variabilis, transmit Rocky Mountain spotted fever and tularemia.

Graphic Jump Location
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Arthropod-Borne Infections

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  • Lyme borreliosis, tularemia, bubonic plague

  • Scrub typhus, endemic (murine) typhus, spotted fever groups, Q fever

  • Human granulocytic anaplasmosis

  • Tick-borne meningoencephalitis

  • Leishmaniasis, trypanosomiasis (sleeping sickness, Chagas disease).

  • Malaria, babesiosis.

  • Filariasis, onchocerciasis (river blindness), loiasis

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Clinical Manifestation

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Erythematous macules
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occur at bite sites and are usually transient.

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Papular urticaria
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or urticarial ...

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