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Basics ⬇

Author: Steven A.Greer, MD, CAQ, FAAFP

Arthropods inoculate poison or invading tissue and transmit diseases. Inoculation of poison may occur as either a bite or a sting. This discussion is limited to the irritative, poisonous, allergic effects of these pests.

Description

  • Harmful arthropods of the United States include (1):
    • Ants: fire ants, harvester ants
    • Bees: bumblebees, sweat bees, honeybees, Africanized (killer) bees
    • Bugs: kissing, bed, wheel
    • Caterpillars: puss, browntail, buck, moth saddleback
    • Centipedes
    • Fleas: human, cat, dog
    • Flies: deer, horse, black, stable, and biting midges
    • Lice: body, head, pubic
    • Mites: itch mite (scabies), red bugs (chiggers)
    • Mosquitoes
    • Scorpions
    • Spiders: brown recluse, black widow, hobo
    • Ticks: deer, lone star
    • Wasps: hornets, wasps
  • Characteristic reactions include:
    • Local tissue irritation, inflammation, and destruction.
    • Systemic effects related to inoculated poisons.
    • Allergic reactions: immediate or delayed.
  • System(s) affected: skin/exocrine

Epidemiology

  • Affects all ages with 0- to 4-yr-olds and 20- to 24-yr-olds at highest risk for nonfatal bites/stings (2)
  • Males = females

Incidence

  • Common, with ~1 million nonfatal and 50 fatal cases per year (3,4)
  • Anaphylaxis is estimated at 3% in adults and 0.4–0.8% in children.
  • Individual stings from Africanized (killer) bees are no more potent than other bees; the danger lies in their predilection to swarm, causing death by multiple stings.

Prevalence

Ubiquitous, varies by region and season (2)

Etiology and Pathophysiology

  • Local tissue inflammation and destruction from poison (5)
  • Allergic reaction from previous sensitization (0.4–3%)
  • Toxic reaction from large inoculation of poison

Genetics

No genetic predilection

Risk-Factors

  • Living environment (3,5)
  • Climate
  • Season
  • Clothing
  • Lack of protective measures
  • Perfumes, colognes
  • Previous sensitization
  • Young or elderly at more risk for morbidity/mortality

General Prevention

Prevention/avoidance (3,4,5):

  • Avoid reexposure in known hypersensitive individuals.
  • Prescribe anaphylactic (ANA kit) or self-administered epinephrine (EpiPen), if indicated.
  • Educate on risks of increasing anamnestic responses in the future.
  • Consider desensitization with immunotherapy in severe cases.
  • Cover as much skin as possible.
  • Use repellants on uncovered areas.
  • Apply sunscreen first, then repellant.
  • N-Diethyl-meta-toluamide (DEET), picaridin, or other proven insect repellants
  • Oil of lemon eucalyptus, p-menthane-3,8-diol (PMD), and IR3535 are considered biopesticides by the Environmental Protection Agency (EPA), but be sure to use EPA-approved products because many versions have not been tested.
  • Permethrin applied to clothes is effective through multiple washings.
  • Permethrin-infused clothing is commercially available and effective.
  • Consider immunization/prophylaxis for travel to endemic areas.

Diagnosis ⬆ ⬇

Physical Exam

Differential Diagnosis

  • Local reaction: infection, cellulitis, dermatoses, punctures, foreign bodies
  • Toxic reaction: chemical exposure/ingestion, medications, intravenous (IV) drug abuse, environmental, plants
  • Allergic reaction: medications, illicit drugs, foods, topical products, environmental, plants, chemicals

Diagnostic Tests & Interpretation

  • Lab: Leukocytosis, thrombocytopenia, hypofibrinogenemia, abnormal coagulation, disseminated intravascular coagulation, proteinuria, hemoglobinemia, hemoglobinuria, myoglobinemia, myoglobinuria, and azotemia are uncommon but possible manifestations in severe reactions.
  • Pathologic findings: inflammation, ulceration, vesiculation, pustulation, rupture, eschar, swelling (1,5)

Treatment ⬆ ⬇

  • Long-term treatment (5):
    • Recommended for those with hypersensitivity reaction but may be considered for individuals with large local reactions
    • Self-administered epinephrine device
    • Hypersensitivity identification
    • Venom immunotherapy for 3 to 5 yr is 80–90% effective even after cessation of treatment.
  • Acute treatment (1,5,6):
    • Outpatient or inpatient, depending on individual response to injury
    • Hospitalize for severe systemic reactions with threatened airway obstruction, bronchospasm, hypotension, severe angiodermatitis, or pain.

General Measures

  • First aid measures, local treatment, activate emergency services in severe reactions. If history of allergy or large envenomations, don’t wait to seek emergency care (1,3,5).
  • Use ANA kit and over-the-counter antihistamines, if available and required.
  • Local (depending on severity):
    • Remove stinger (scrape it out—don’t squeeze with tweezer).
    • Cleanse wound.
    • Ice packs to bite or sting site (alternate 10 min on or 10 min off)
    • Elevation of affected part
    • Débride ulcers.
    • Drain abscesses.
  • Systemic (depending on severity and type of reaction): home use—EpiPen:
    • Adequate airway (intubation, tracheostomy): if needed to bypass obstruction
    • Oxygen (4 to 6 L/min): if needed for respiratory distress
    • Hospitalize and observe 24 to 48 hr.

Medication

First Line

  • Local (depending on severity):
    • Analgesics
    • Antihistamines: diphenhydramine (Benadryl) 25 to 50 mg QID.
    • Steroids topical or oral: Prednisone 20 to 40 mg/day is unproven but may be helpful for large local reactions.
    • Antibiotics only if there is a secondary infection
  • Systemic (depending on severity and reaction type):
    • Epinephrine (1:1,000) subcutaneous (SC): to combat urticaria, wheezing, angioedema—child: 0.01 mL/kg; adult 0.3 to 0.5 mL/kg
    • Diphenhydramine: 25 to 50 mg IV or intramuscular (IM) to combat urticaria, wheezing, angioedema
    • Albuterol 5 mg Inhalation and ipratropium bromide 0.5 mg Inhalation: bronchospasm
    • IV fluids (Ringer lactate): if needed for hypotension, hypovolemia
    • Dopamine: 200 mg in 250 mL at 5 μg/kg/min to correct vascular collapse
  • Titrate to maintain systemic blood pressure (BP) over 90 mm Hg:
  • Antivenins may be appropriate based on availability, identification of organism, and previous sensitivity.
  • Topical insecticides:
    • Lice: 1% permethrin (Nix, Elimite) is still considered first line despite up to 50% resistance. 0.5% malathion (Ovide) may be used as initial choice or for permethrin failure. 1% lindane (Kwell) or pyrethrin (Rid) is also effective.
    • Scabies: 5% permethrin is drug of choice, but 10% crotamiton (Eurax) and lindane are effective.
  • Contraindications: Refer to manufacturer’s literature.
  • Precautions:
    • Dosing appropriate to age
    • If severe reaction, don’t delay treatment.
    • Severe vascular collapse may require central pressure monitor.
  • Significant possible interactions: Refer to manufacturer’s literature.

Second Line

Surgery/Other Procedures

Optimal treatment of necrotic spider bites is not well defined. Surgical repair may be required for severe ulcerative lesions but not until primary necrotizing process is complete (1,3).

COMPLEMENTARY & ALTERNATIVE MEDICINE

  • Oil of lemon eucalyptus, PMD, and IR3535 are considered biopesticides by the EPA, but be sure to use EPA-approved products because essential oils have not been tested (3,7).
  • Turmeric may help inflammation. Animal studies show promise but no proof in humans and no dose data.

Ongoing Care ⬆ ⬇

Follow-up Recommendations

No activity restrictions

Patient Monitoring

Follow-up wound care

Diet

No special diet; nothing by mouth if severe systemic reaction

Patient Education

  • Protective measures, ANA kit/EpiPen use, risks (3,5)
  • Individuals with known sensitivity should wear medical identification (bracelet, tag) or carry a card.

Prognosis

Expected course (5):

  • Minor reactions—excellent
  • Severe reactions—excellent with early, appropriate treatment

Complications

  • Infection (5,6):
    • Bacterial
    • Arthropod-associated diseases with tick, fly, bug, and mosquito bites (e.g., Lyme borreliosis, rickettsial disease [Rocky Mountain spotted fever], arboviral encephalitis, malaria, leishmaniasis, trypanosomiasis, dengue)
  • Scarring
  • Drug reactions
  • Multisystem failure
  • Death
ALERT

Not a contraindication to appropriate management

References ⬆ ⬇

Centers for Disease Control and Prevention. Injury prevention & control. http://www.cdc.gov/injury/wisqars/index.html.

  1. Centers for Disease Control and Prevention. Necrotic arachnidism—Pacific Northwest, 1988-1996. MMWR Morb Mortal Wkly Rep. 1996;45(21):433–436.
  2. Centers for Disease Control and Prevention. CDC Health Information for International Travel 2016. New York, NY. Oxford University Press; 2015.
  3. Fradin MS. Mosquitoes and mosquito repellants: a clinician’s guide. Ann Intern Med. 1998;128(11):931–940.
  4. Moffitt JE, Golden DB, Reisman RE, et al. Stinging insect hypersensitivity: a practice parameter update. J Allergy Clin Immunol. 2004;114(4):869–886.
  5. Pickering L, ed. Red Book: 2009 Report of the Committee on Infectious Diseases. 28th ed. Itasca, IL: American Academy of Pediatrics; 2009.
  6. Jurenka JS. Anti-inflammatory properties of curcumin, a major constituent of Curcuma longa: a review of preclinical and clinical research. Altern Med Rev. 2009;14(2):141–153.

Clinical Pearls ⬆

  • Prevention is often more effective than treatment.
  • Vigilant observation for systemic reaction allows for early treatment and better recovery.
  • Allergic reactions worsen with each successive exposure.