Spider Bites

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The brown recluse spider, scientifically known as Loxosceles reclusa, is known for its venomous bite. This spider is found in southern US states.

  1. Mechanism of Toxin: Sphingomyelinase D causes hemolysis and complement mediated erythrocyte destruction. There are multiple proteases that break down collagen, elastin, fibrinogen, etc and act synergistically with sphingomyelinase D to cause local tissue destruction

  2. Clinical Features of Bites:

    • Course of bite: The bite is often painless or with minimal pain. There will be two small puncture wounds. This will become pale with the edges becoming red. Over the next few days, this turns into a blister with a central ulcer, followed by skin sloughing. Can take weeks for wound to heal.

    • Early Symptoms (2-8 hours):

      • Redness and swelling around the bite site

      • Mild to moderate pain and itching

    • Delayed Symptoms (12-36 hours):

      • Necrotic (dead) tissue formation, leading to an ulcer

      • Systemic symptoms like fever, chills, malaise, headache, nausea

    • Worsening complications:

      • DIC

      • Rhabdo

      • Kidney Failure

  3. Evaluation: Lab tests should only be ordered in patients with systemic symptoms and fear of worsening complications. Should order CBC, CMP, CK, retic count, haptoglobin, LDH, PT/INR, D-dimer, fibrinogen.

  4. Medical Management:

    • Local Wound Care: Primary management is local wound care. Clean the site with soap and water, apply a cold compress to reduce swelling, and elevated the affected site. Sphingomyelinase D also has reduced activity in lower temp, so ice packs are important! Patient should also receive tetanus prophylaxis!

    • Pain Management: NSAIDs

    • Wound Care for Necrotic Tissue: If wound is severe enough, may require eval for debridement and potential skin grafting (this is usually weeks later). Hyperbaric oxygen therapy can also be considered for severe cases.

    • Antibiotics: Only if concern for local cellulitis.

    • Systemic Treatments: Weak evidence for use of dapsone. There is slightly more evidence behind the use of corticosteroids for reducing the risk of AKI and rhabdo.

It's crucial to note that brown recluse spider bites are rare, and most cases resolve with local wound care.

 

Black widow spiders, known as Lactrodectus spp, are venomous arachnids found in various regions around the world. The venom they produce contains neurotoxins, primarily alpha-latrotoxin, which affects the nervous system. These spiders classically have the “red hourglass” marking on them.

1.       Mechanism of Toxin: The primary toxin in black widow spider venom is alpha-latrotoxin. It works by binding presynaptic neurons, creating calcium permeable channels in the lipid layers, causing an influx of calcium into the presynaptic cells. This leads to an excessive release of neurotransmitters. Primarily concerned with release of acetylcholine.

 

2.       Clinical Features of Bites:

  • Course of bite: Bites are often initially characterized by severe local pain at the bite site. Very quickly patients will develop erythema and edema at site of bite

  • Systemic Symptoms: As the venom spreads, systemic symptoms may develop, including muscle pain and cramps, abdominal pain, weakness, sweating, and nausea. Patients may experience autonomic nervous system effects such as increased blood pressure and heart rate.

  • Worsening complications

    • Rhabdo

    • Myocarditis

    • A-fib

3.     Laboratory Tests: Lab values are generally nonspecific for black widow bites. Patients will tend to have elevated WBC, hematuria, and elevated liver enzymes. There are documented cases of rhabo and myocarditis from black widow bites, and there for kidney function and troponins can be checked if patients complain of systemic symptoms.

4.       Medical Management:

  • Local Wound Care: Clean the site with soap and water. Patient should also receive tetanus prophylaxis!

  • Pain Control: Analgesics, such as opioids or muscle relaxants, may be used to manage pain.

  • Antivenom: In severe cases or when systemic symptoms are significant, antivenom may be administered. This can rapidly reverse the effects of the venom. It is horse derived, and may cause anaphylaxis.

  • Observation: Patients may be observed for several hours to ensure symptoms do not worsen and to monitor for potential complications. Consider admission in children, patients with preexisting cardiac conditions, pregnant women, or for severe symptoms.

    It's important to note that while black widow spider bites can be painful and cause distressing symptoms, fatalities are rare.

     

    Anoka IA, Robb EL, Baker MB. Brown Recluse Spider Toxicity. [Updated 2023 Aug 7]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK537045/

    Williams M, Sehgal N, Nappe TM. Black Widow Spider Toxicity. [Updated 2023 Aug 7]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK499987/