Ferri – Bites and Stings, Arachnids

Mar 13, 2020 admin CƠ XƯƠNG KHỚP 0

Bites and Stings, Arachnids

  • Gail M. O’brien, M.D.

 Basic Information

Definition

There are two major classes of arthropods: insects and Arachnida. This chapter focuses on the class Arachnida. Arachnid bites consist of bites caused by:

  1. Spiders

  2. Scorpions

  3. Ticks

ICD-10CM CODES
T63.301 Toxic effect of unspecified spider venom, accidental (unintentional), initial encounter
T63.2 Toxic effect of venom of scorpion, accidental (unintentional), initial encounter
E906 Bite of nonvenomous arthropod; insect bite NOS

Epidemiology & Demographics

  1. Spiders—ubiquitous; only three types potentially significantly harmful:

    1. Sydney funnel web spider—Australia

    2. Black widow (Fig. E1)—worldwide (excluding Alaska)

FIG.E1 

Black widow spider (Latrodectus hesperus).
Courtesy Sean Bush, MD.

    1. Brown recluse (Fig. E2)—most common (South Central U.S.)

FIG.E2 

Loxosceles sp. (brown recluse spider).
Courtesy Katia C. Barbaro, Sao Paulo, Brazil.

  1. Scorpions—various warm climates: Africa, Central South America, Middle East, India; Texas, New Mexico, California, and Nevada in the U.S.

  2. Ticks—woodlands

Physical Findings & Clinical Presentation

Spiders:

  1. Sydney funnel web—atracotoxin toxin

    1. Piloerection, muscle spasms leading to tachycardia, hypertension, increased intracranial pressure, coma

  2. Black widow—females toxic

    1. Initial reaction: local swelling, redness (two fang marks) leading to local piloerection, edema, urticaria, diaphoresis, lymphangitis

    2. Pain in limb leading to rest of body (chest pain, abdominal pain), compartment syndrome

  3. Brown recluse

    1. Minor sting or burn.

    2. Wound may become pruritic and red with a blanched center with vesicle (Fig. E3). Can necrose, especially in fatty areas (Fig. E4). Leaves eschar, which sloughs and leaves ulcer; can take months to heal.

FIG.E3 

Brown recluse spider bite after 24 hours, with central ischemia and rapidly advancing cellulitis.
From Ignatavicius DD, Workman LM: Medical surgical nursing, ed 6, Philadelphia, 2010, Elsevier, pp 147.
FIG.E4 

Brown recluse spider bite after 48 hours of treatment.
From Hill MJ: Skin disorders—Mosby’s clinical nursing series, St. Louis, 1994, Mosby. Courtesy Dr. William N. New, Dallas.

    1. Systemic symptoms: headache, fever, chills, gastrointestinal upset, hemolysis, renal tubular necrosis, disseminated intravascular coagulation possible.

Scorpions:

  1. Sting leading to sympathetic and parasympathetic stimulation: hypertension, bradycardia, vasoconstriction, pulmonary edema, reduced coronary blood flow, priapism, inhibition of insulin.

  2. Also possible: tachycardia, arrhythmia, vasodilation, bronchial relaxation, excessive salivation, vomiting, sweating, bronchoconstriction, pancreatitis.

  3. Clinically significant scorpion envenomation by Centruroides sculpturatus produces a severe neuromotor syndrome and respiratory insufficiency that often requires ICU admission.

Ticks: U.S., Europe, Asia

  1. Very small (<1 mm). Must be attached >36 hr to transmit disease.

  2. Lyme disease—most common (see “Lyme Disease”). Caused by the bacterium Borrelia burgdorferi and is transmitted to humans through the Ixodes scapularis tick.

    1. Early: erythema migrans in 60% to 80% of cases

    2. 7 to 10 days: mild to moderate constitutional symptoms; disseminated—secondary skin lesions, fever, adenopathy, constitutional symptoms, facial palsy, peripheral neuropathy, lymphocytic meningitis, meningoencephalitis, cardiac manifestations (heart block)

    3. Late: chronic arthritis, dermatitis, neuropathy, keratitis

  3. Babesiosis (see “Babesiosis”)

  4. Ehrlichiosis/anaplasmosis (see “Ehrlichiosis and Anaplasmosis”)

Diagnosis

Differential Diagnosis

  1. Cellulitis

  2. Urticaria

Other tick-borne illnesses:

  1. Babesiosis

  2. Tick-borne relapsing fever/Borrelia miyamotoi

  3. Tularemia

  4. Rocky Mountain spotted fever

  5. Ehrlichiosis/anaplasmosis

  6. Colorado tick fever

  7. Tick paralysis, Powassan disease

  8. Community-acquired cutaneous methicillin-resistant Staphylococcus aureus

Workup

Physical examination: thorough skin examination may reveal fang marks, attached ticks, black eschar.

Treatment

Acute General Rx

Spiders:

  1. Sydney funnel web

    1. Pressure, immediate immobilization, supportive care, antivenin.

  2. Black widow

    1. Treatment based on severity of symptoms; bite is rarely fatal.

    2. All should receive oxygen, IV, cardiac monitor, tetanus prophylaxis.

    3. Symptomatic/supportive therapy.

    4. 10% calcium gluconate for muscle cramps (controversial).

    5. Antivenin only for more severe reactions; it carries a risk of anaphylaxis.

      1. Dose: one vial in 100 ml 0.9% saline over 20 to 30 min.

      2. Skin test before use.

      3. Give antihistamines with use.

  3. Brown recluse

    1. Pain management, tetanus, supportive treatment.

    2. No consensus regarding best treatment; some evidence for hyperbaric oxygen.

Scorpions:

  1. Fluids, supportive care, species-specific antivenin (equine based, risk of serum sickness) is controversial.

  2. IV administration of scorpion-specific F(ab’)2 antivenin has been reported effective in resolving the clinical syndrome within 4 hours and reducing the need for concomitant sedation with midazolam and reducing the levels of circulating unbound venom.

Ticks:

  1. Prophylactic: tick >36 hr: single dose of doxycycline 200 mg

  2. Early localized disease

    1. Duration of antibiotics: 10 to 21 days.

    2. Doxycycline preferred in patients with possible concurrent ehrlichiosis.

    3. Treatment of choice in children: amoxicillin for 14 days.

  3. Early disseminated: treatment depends on manifestation.

  4. Late disease: may require longer-term or IV therapy; controversial for neurologic disease (see “Lyme Disease”).

Disposition

  1. For patients with systemic reactions, send home with emergency epinephrine kit.

  2. If severe or anaphylactic reaction, admit and observe for 48 hr for cardiac, renal, or neurologic problems.

Referral

For patients with systemic reactions, refer to allergist for immunotherapy; 95% to 98% effective in preventing anaphylaxis.

Pearls & Considerations

Actual spider bites rare; need witnessed bite. Patient should bring spider if possible for confirmation. Bites usually occur in settings of unusually close contact with spider. Bedbugs becoming more prevalent, repeated exposure increases severity of reaction.

Suggested Readings

  • E. Choi, N.J. Pyzocha, D.M. Maurer: Tick-borne illnesses. Curr Sports Med Rep. 15 (2):98–104 2016 26963018

  • J.H. Diaz, K.E. LeBlanc: Common spider bites. Am Fam Physician. 75:869–873 2007 17390599

  • G.K. Isbister, H.S. Bawaskar: Scorpion envenomation. N Engl J Med. 371:457–463 2014 25075837

Related Content

  1. Bites and Stings (Patient Information)

  2. Bites and Stings, Insect (Related Key Topic)

 

BÀI LIÊN QUAN