Widow Spider Bite (Latrodectism)
Etiology
General Comments
There are approximately 30 different widow spider species found worldwide
Latrodectus Mactans (Black Widow Spider, Show-Button Spider)Seasonal Prevalence : most black widow bites occur between April-October in the United StatesGeography Found in USA and Canada (Black Widow is Most Abundant in Southeastern United States) Spider Resides in Dark Spaces, Such as Wood Piles, Rock Piles, Sheds, Garages, and Basements Female Spider (Which are Responsible for Most Significant Human Bites) In Contrast, Male Widow spiders Have Smaller Fangs, Less Venom, and Weaker Biting Muscles Black with 1 cm Body, 5 cm Legspan, and Red Hourglass Mark on Ventral Abdomen Spider is Aggressive and Bites on Slight Provocation: typically when trapped or web is disturbed
Latrodectus Bishopi (Red-Legged Widow Spider)
Other Latrodectus Species
Geography Found in Other Temperate and Subtropical Parts of the World
False Black Widow Spiders
Steatoda SpeciesFalse Black Widow Spider Bite )May Produce a Similar (But Milder) Presentation (Called “Steatodism”) to that of Widow Spider Bite
Physiology
Alpha Latrotoxin (Neurotoxin) in Venom<
Lack of Local Necrosis Binds Irreversibly to Nerves and Depletes Acetylcholine, Norepinephrine, Dopamine, Glutamate, and Enkephalin from Presynaptic Nerve Terminals Clinical Effects Autonomic Activation Diffuse Central and Peripheral Nervous System Excitation Neuropathy, Leading to Acute Hypoventilation Diagnosis
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Clinical Manifestations (Latrodectism)
Widow Spider Bite Site
General Comments History of Recent Activity (Within 8 hrs) Which May Have Led to Exposure to the Black Widow Spider : however, the time of onset of systemic symptoms is typically within 30-120 min after the biteChopping Wood Cleaning Out an Area Gardening Using Outdoor Furniture Approximately 75% of All Bites Occur on the (Usually Lower) Extremities Asymptomatic Bite Site : occurs in many casesSymptomatic Bite Site Fang Puncture Sites at Bite Site : uncommonMomentary Sharp Pain at Bite Site : however, this is often not prominent on examCardiovascular Manifestations
Hypotension (see Hypotension )Epidemiology : rarely occursSystolic Hypertension (see Hypertension )Physiology : due to vasoconstrictionTachycardia (see Sinus Tachycardia )Physiology : due to autonomic activationGastrointestinal Manifestations
Abdominal Pain with Rigidity (see Abdominal Pain )Physiology : due to muscle spasmsClinical :Abdomen is Usually Not Tender on Exam May Be Mistaken for an Abdominal Surgical Emergency (Such as Appendicitis, etc) Nausea/Vomiting (see Nausea and Vomiting )Hematologic Manifestations
Neurologic Manifestations
Anxiety (see Anxiety )Headache (see Headache )Hyperreflexia (see Hyperreflexia )Intracerebral Hemorrhage (Hemorrhagic Cerebrovascular Accident) (see Intracerebral Hemorrhage )Painful Muscle Cramps/Spasms of Extremities and Trunk Clinical : muscle cramping pain begins within 15-60 min after the biteParasthesias of Hands/Feet (see Peripheral Neuropathy )Twitching/Tremor/Fasciculations (see Tremor )Weakness Otolaryngologic Manifestations
Pulmonary Manifestations
Labored Respirations : due to respiratory muscle weaknessAcute Hypoventilation/Respiratory Failure (see Respiratory Failure )Renal Manifestations
Other Manifestations
Diaphoresis/Sweating (see Diaphoresis )Fever (see Fever )Uterine Contractions/Pre-Term Labor Treatment
Treatment of Pain at Bite Site
Spontaneous Resolution : pain at bite site usualy subsides within several hours (although recurrence over the next 2-3 days are common)Analgesics : may be requiredHot Bath : prompt, but temporary relief of painRICE Therapy R estI ceC ompressionE levationTreatment of Muscle Spasms
Spontaneous Resolution : painful spasms begin to subside within the first 12 hrs (but may recur for days-weeks before completely resolving)Calcium Gluconate (see Calcium Gluconate )Administration (10% Solution) : 10 mL IV, given over 10-20 minClinical Efficacy : transient cessation of muscle crampsBenzodiazepines : (see Benzodiazepines ) useful for muscle spasmsMethocarbamol (Robaxin) (see Methocarbamol )Administration : IVClinical Efficacy : may relieve muscle spasmsWidow Spider Antivenom
Administration : 1 vial in 50 mL of NS IV given over 15 minMay Need to Test for Hypersensitivity Before Use Effective within a Few Hours : may repeat PRNClinical Efficacy Controversial : indicated mainly for uncontrolled hypertension, pregnancy, seizures, or respiratory arrestSide Effects Tetanus Prophylaxis
Prognosis
Deaths : have been reported (mostly in children, elderly, and debilitated)References
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