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SPIDER-LATRODECTUS SPECIES

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Classification   |    Detailed evidence-based information

Substances Included Synonyms

Therapeutic Toxic Class

    A) Widow or hour glass spiders are of the species Latrodectus and the phylum Arthropoda. The name "widow spider" is derived from the female's practice of destroying the male after insemination. Red-back spiders are also in the Latrodectus species, with a characteristic "hourglass" marking. Envenomations cause neurotransmitter release at synaptic junctions, until the neurotransmitters are depleted.
    B) Widow spiders belong to the genus Latrodectus and are the largest of the cobweb weavers (Theridiidae - "widow" family). All members of this family are poisonous. Venom is neurotoxic.
    C) The venom causes an unremitting cramping pain in the extremities, thorax, back, abdomen, and groin that can last for 24 to 36 hours. Pain may be accompanied by hypertension, diaphoresis, nausea, or respiratory compromise. Weakness and paresthesias may last for days to weeks in patients not treated with antivenin. The clinical picture of poisoning is termed "latrodectism."

Specific Substances

    1) BLACK WIDOW (Latrodectus mactans)
    2) EUROPEAN BLACK WIDOW (MALMIGNATTE) (Latrodectus mactans tredecimguttatus)
    3) WESTERN BLACK WIDOW (Latrodectus hesperus)
    4) NORTHERN WIDOW (Latrodectus variolus)
    5) RED WIDOW (Latrodectus bishopi)
    6) BROWN WIDOW (Latrodectus geometricus)
    7) RED-BACK (Latrodectus hasselti)
    8) ARANEA MACTANS (ALTERNATE ZOOLOGIC NAME FOR LACTRODECTUS MACTANS)
    9) BLACK WIDOW SPIDER (COMMON NAME FOR LATRODECTUS MACTANS)
    10) HOUR-GLASS SPIDER (COMMON NAME FOR LATRODECTUS MACTANS)
    11) LACTRODECTUS (MISSPELLING OF LATRODECTUS)
    12) LATRODECTUS ALBOMACLATUS (ALTERNATE ZOOLOGIC NAME FOR LATRODECTUS MACTANS)
    13) LATRODECTUS CURARIENSIS (ZOOLOGICAL NAME)
    14) LATRODECTUS FORMIDABILIS (ALTERNATE ZOOLOGIC NAME FOR LATRODECTUS MACTANS)
    15) LATRODECTUS INSULAIIS (ALTERNATE ZOOLOGIC NAME FOR LATRODECTUS MACTANS)
    16) LATRODECTUS INTERSECTOR (ALTERNATE ZOOLOGIC NAME FOR LATRODECTUS MACTANS)
    17) LATRODECTUS MACTANS (ZOOLOGIC NAME)
    18) LATRODECTUS PERIDUS (ALTERNATE ZOOLOGIC NAME FOR LATRODECTUS MACTANS)
    19) LATRODECTUS SAGITTIFER (ALTERNATE ZOOLOGIC NAME FOR LATRODECTUS MACTANS)
    20) SPIDER (WIDOW)
    21) SPIDER, BLACK WIDOW (COMMON NAME FOR LATRODECTUS MACTANS)
    22) SPIDER, HOUR-GLASS (COMMON NAME FOR LATRODECTUS MACTANS)
    23) SPIDER-WIDOW OR HOUR-GLASS
    24) SPIDERS (WIDOW)
    25) TETRAGNATHA ZORILLA (ALTERNATE ZOOLOGIC NAME FOR LATRODECTUS MACTANS)
    26) THERIDION LINEAMENTUM (ALTERNATE ZOOLOGIC NAME FOR LATRODECTUS MACTANS)
    27) THERIDION LINEATUM (ALTERNATE ZOOLOGIC NAME FOR LATRODECTUS MACTANS)
    28) THERIDION VERECUNDUM (ALTERNATE ZOOLOGIC NAME FOR LATRODECTUS MACTANS)
    29) WIDOW SPIDER, BLACK (COMMON NAME FOR LATRODECTUS MACTANS)

Overview

Life Support

    A) This overview assumes that basic life support measures have been instituted.

Clinical Effects

    0.2.1) SUMMARY OF EXPOSURE
    A) BACKGROUND: Latrodectus species are found throughout the world. Females cause serious envenomation because their bites pierce human skin. They are approximately 1-2 cm in length, and usually are shiny black with a red hourglass shape on the ventral abdomen; however, they can have variation in color and markings. Latrodectus are commonly found in dark environments like outhouses and garages.
    B) TOXICOLOGY: Black widow venom contains alpha-latrotoxin, a neurotoxin which causes opening of nonspecific cation channels, leading to an increased influx of calcium, resulting in release of neurotransmitters like acetylcholine and norepinephrine. Most clinical effects are secondary to acetylcholine causing muscle spasm and norepinephrine causing hypertension and tachycardia.
    C) EPIDEMIOLOGY: Black widow spider envenomations are common and may result in severe symptoms. Envenomations are more common when weather transitions from warm to cool.
    D) WITH POISONING/EXPOSURE
    1) LOCAL SIGNS: Local effects are common. Findings range from mild erythema to a target lesion with a central punctate site, central blanching, and an outer erythematous ring. Piloerection and local diaphoresis may also occur at the bite site.
    2) PAIN: Bites almost always become painful within 30 to 120 minutes. By 3 to 4 hours, painful cramping and muscle fasciculations can occur in the involved extremity, which progress centripetally toward the chest, back, or abdomen, and can produce board-like rigidity, weakness, dyspnea, and paresthesias.
    3) COMMON SYSTEMIC EFFECTS: Headache, hypertension, regional diaphoresis, nausea, vomiting, and tachycardia.
    4) LESS COMMON: Leukocytosis, fever, delirium, priapism, latrodectus facies (facial swelling and lid droop), and dysrhythmias. Rarely, untreated patients may feel unwell for up to a week.
    5) MILD TO MODERATE ENVENOMATION: In minor envenomation syndromes, patients develop local pain at the site of envenomation. In moderate envenomation, the muscle pain may spread to contiguous areas (buttocks or abdomen, if bitten on the leg; chest, if bitten on the arm). There may be localized diaphoresis at the bite site. Vital signs remain normal.
    6) SEVERE ENVENOMATION: Manifestations include severe muscle pain and spasm, usually involving the back, abdomen, chest and/or buttocks, as well as, the bitten extremity. Headache, nausea and vomiting, fasciculations, and abnormal vital signs (typically tachycardia and hypertension) may also develop.
    0.2.5) CARDIOVASCULAR
    A) WITH POISONING/EXPOSURE
    1) Mild tachycardia and hypertension are common. Chest pain and ECG changes have been reported in severe envenomations. Cardiac manifestations after a black widow bite are rare.
    0.2.6) RESPIRATORY
    A) WITH POISONING/EXPOSURE
    1) Dyspnea may develop; respiratory failure and pulmonary edema are rare complications of severe envenomation.
    0.2.7) NEUROLOGIC
    A) WITH POISONING/EXPOSURE
    1) Weakness, hyperreflexia, headache, and paresthesias are common. Patients are often restless and anxious; children may be irritable or drowsy.
    2) Severe cramping pain is most the common symptom and normally starts at the bite site and spreads proximally to involve large muscles in the thigh, buttock, and abdomen following a lower extremity bite or the chest after an upper extremity bite to involve the entire body. Pain generally peaks at 2 to 3 hours after the bite.
    0.2.8) GASTROINTESTINAL
    A) WITH POISONING/EXPOSURE
    1) Nausea, vomiting, excessive salivation, and abdominal pain are common.
    0.2.10) GENITOURINARY
    A) WITH POISONING/EXPOSURE
    1) Priapism, urinary retention, pyuria, proteinuria, microscopic hematuria, and testicular pain have been reported.
    0.2.14) DERMATOLOGIC
    A) WITH POISONING/EXPOSURE
    1) Local effects may include tiny puncture wounds, erythema, induration and diaphoresis, or the skin may appear perfectly normal. One case of toxic epidermal necrolysis has been reported.
    0.2.15) MUSCULOSKELETAL
    A) WITH POISONING/EXPOSURE
    1) Stiffness, pain, and spasms usually involving large muscle groups may develop within 30 to 120 minutes. Mild rhabdomyolysis has been reported.
    0.2.20) REPRODUCTIVE
    A) No evidence of fetal distress or premature labor were seen in several instances of Latrodectus bites. Healthy infants were delivered.

Laboratory Monitoring

    A) Laboratory testing may be required for an alternative diagnosis, but no specific diagnostic tests are required for most patients.
    B) Patients receiving antivenom therapy should be on an ECG monitor, continuous oxygen and an intravenous line should be placed.

Treatment Overview

    0.4.2) ORAL/PARENTERAL EXPOSURE
    A) One case report describes the ingestion of a live Latrodectus causing signs and symptoms of systemic envenomation. Treatment should include recommendations listed in the BITES/STINGS section when appropriate.
    0.4.4) EYE EXPOSURE
    A) Signs and symptoms of systemic envenomation have been reported after ocular exposure to crushed Latrodectus parts. Treatment should include recommendations listed in the BITES/STINGS section when appropriate.
    0.4.6) PARENTERAL EXPOSURE
    A) There has been a case report of a patient injecting a crushed black widow spider who developed symptoms consistent with black widow spider envenomation. Treatment should include recommendations listed in the BITES/STINGS section when appropriate.
    0.4.7) BITES/STINGS
    A) MANAGEMENT OF MILD TO MODERATE TOXICITY
    1) Monitor victims for at least 6 to 8 hours. Symptoms will typically wax and wane. Perform wound cleaning and apply cool compresses. Evaluate for appropriate tetanus prophylaxis. Treat patients with opioids and benzodiazepines for pain and muscle spasm control, though benzodiazepines are opioid sparing and may add to clinical central nervous system depression.
    B) MANAGEMENT OF SEVERE TOXICITY
    1) For patients requiring large amounts of pain medications consider antivenom therapy.
    C) AIRWAY MANAGEMENT
    1) Maintain open airway and assist ventilation (rarely required).
    D) ANTIVENOM
    1) INDICATIONS: Latrodectus mactans antivenin is used to treat patients with symptoms due to bites by Latrodectus or widow spiders. Red back spider antivenom is used to treat patients who exhibit manifestations of systemic envenoming after a bite by a red back spider (Latrodectus hasselti).
    a) In theory, black widow spider envenomation may cause abdominal spasm severe enough to threaten spontaneous abortion or early onset of labor in a pregnant patient; however, there is no human data to support this concern. Antivenom should be administered in the pregnant patient if there is intractable pain or clinical concern for premature labor or spontaneous abortion.
    2) PREGNANCY: FDA Class C
    3) CONTRAINDICATIONS: Hypersensitivity to horse serum, and severe reactive airway disease.
    4) ADVERSE EFFECT: Immediate hypersensitivity, and delayed onset serum sickness.
    5) US ANTIVENOM: DOSE: The manufacturer recommends that either dermal or conjunctival sensitivity testing should be done prior to administration of latrodectus antivenin. Administer contents of 1 vial diluted in 50 mL NS over 15 minutes. The antivenin may be administered undiluted (approximately 2.5 mL) IM, preferably into anterolateral thigh, but this route should be avoided in children under 12 years and patients with severe envenomation. One vial generally gives prompt relief; a second dose may be necessary in some cases. If there is no response to 2 vials, the diagnosis of Latrodectus envenomation should be reconsidered.
    6) CAUTION: Antivenom should only be administered in a setting with careful hemodynamic and respiratory monitoring, and where resuscitation can be readily performed. Fatal anaphylaxis has occurred after black widow antivenom administration.
    7) AUSTRALIAN ANTIVENOM: One vial (500 units) given IM. IN SEVERE CASES, use IV route, first diluting the antivenom 1:10 in Hartmann's solution; may be repeated in 2 hours. If no improvement was observed after 3 vials, consider bites from other species.
    E) OTHER THERAPIES
    1) Opioids and benzodiazepines should be utilized for pain control or muscle spasm. IV Benzodiazepines (Diazepam Adult: 5 to 10 mg IV, Child: 0.2 to 1 mg IV) and Opioids (Morphine: Adult: 1 to 5 mg IV, Child: 0.1 to 0.2 mg/kg IV).
    2) IV calcium, dantrolene, and methocarbamol are not well studied in this scenario, but are generally ineffective for treatment.
    F) ACUTE ALLERGIC REACTION
    1) MILD/MODERATE: Antihistamines with or without inhaled beta agonists, corticosteroids or epinephrine. SEVERE: Oxygen, aggressive airway management, antihistamines, epinephrine, corticosteroids, ECG monitoring, and IV fluids.
    G) PATIENT DISPOSITION
    1) HOME CRITERIA: Patients with only mild pain may be observed at home.
    2) OBSERVATION CRITERIA: Patients with severe pain should be referred in for evaluation and observed until symptoms resolve or improve.
    3) ADMISSION CRITERIA: Patients should be admitted if their symptoms do not improve with treatment or if they need ongoing pain management.
    4) CONSULT CRITERIA: A toxicologist should be involved if a patient’s symptoms are not responsive to general measures including pain and muscle spasm control and one is considering the use of the equine-derived Latrodectus mactans antivenom. Also, consider early toxicology involvement in critically ill, elderly, pregnant, or young patients.
    H) PITFALLS
    1) Common errors occur in misdiagnosis or overuse of narcotics and benzodiazepines in treating the patient's symptoms.
    2) Young patients given narcotics and then treated with antivenom may develop signs of opioid toxicity and should be observed closely after the administration of the antivenom.
    3) Avoid antivenom use in patients with a history of severe atopy, asthma or an equine allergy.
    I) TOXICOKINETICS
    1) Pain usually develops within 30 to 120 minutes, with severe manifestations developing in 3 to 4 hours. Most symptoms resolve in a few days, though some patients may be symptomatic for a longer period.
    J) PREDISPOSING CONDITIONS
    1) Pregnancy; elderly; young children; chronically or critically ill
    K) DIFFERENTIAL DIAGNOSIS
    1) Acute surgical abdomen; acute myocardial infarction. Steatoda grossa or S. capensis (the grey house spider) has been mistaken for the red back spider, it may cause similar systemic effects but the patient will fail to respond to red back spider antivenom.

Range Of Toxicity

    A) TOXICITY: A single latrodectus bite can cause severe envenomation.

Clinical Effects

Summary Of Exposure

    A) BACKGROUND: Latrodectus species are found throughout the world. Females cause serious envenomation because their bites pierce human skin. They are approximately 1-2 cm in length, and usually are shiny black with a red hourglass shape on the ventral abdomen; however, they can have variation in color and markings. Latrodectus are commonly found in dark environments like outhouses and garages.
    B) TOXICOLOGY: Black widow venom contains alpha-latrotoxin, a neurotoxin which causes opening of nonspecific cation channels, leading to an increased influx of calcium, resulting in release of neurotransmitters like acetylcholine and norepinephrine. Most clinical effects are secondary to acetylcholine causing muscle spasm and norepinephrine causing hypertension and tachycardia.
    C) EPIDEMIOLOGY: Black widow spider envenomations are common and may result in severe symptoms. Envenomations are more common when weather transitions from warm to cool.
    D) WITH POISONING/EXPOSURE
    1) LOCAL SIGNS: Local effects are common. Findings range from mild erythema to a target lesion with a central punctate site, central blanching, and an outer erythematous ring. Piloerection and local diaphoresis may also occur at the bite site.
    2) PAIN: Bites almost always become painful within 30 to 120 minutes. By 3 to 4 hours, painful cramping and muscle fasciculations can occur in the involved extremity, which progress centripetally toward the chest, back, or abdomen, and can produce board-like rigidity, weakness, dyspnea, and paresthesias.
    3) COMMON SYSTEMIC EFFECTS: Headache, hypertension, regional diaphoresis, nausea, vomiting, and tachycardia.
    4) LESS COMMON: Leukocytosis, fever, delirium, priapism, latrodectus facies (facial swelling and lid droop), and dysrhythmias. Rarely, untreated patients may feel unwell for up to a week.
    5) MILD TO MODERATE ENVENOMATION: In minor envenomation syndromes, patients develop local pain at the site of envenomation. In moderate envenomation, the muscle pain may spread to contiguous areas (buttocks or abdomen, if bitten on the leg; chest, if bitten on the arm). There may be localized diaphoresis at the bite site. Vital signs remain normal.
    6) SEVERE ENVENOMATION: Manifestations include severe muscle pain and spasm, usually involving the back, abdomen, chest and/or buttocks, as well as, the bitten extremity. Headache, nausea and vomiting, fasciculations, and abnormal vital signs (typically tachycardia and hypertension) may also develop.

Vital Signs

    3.3.2) RESPIRATIONS
    A) WITH POISONING/EXPOSURE
    1) CASE SERIES: TACHYPNEA was reported in 5 of 14 patients with L. mactans bites in one case series (Moss & Binder, 1987).
    3.3.3) TEMPERATURE
    A) WITH POISONING/EXPOSURE
    1) FEVER has been reported in 10% to 15% of patients (Maretic, 1983; Sutherland & Trinca, 1978; Mead & Jelinek, 1993; Mollison et al, 1994). This appears to be more common with L. hasselti (red-back spider) (Liew et al, 1994), L. indistinctus, and L. geometricus bites than other species. Fever has been reported following the bite of a Mediterranean spider, L. tredecimguttatus (Vutchev, 2001).
    3.3.4) BLOOD PRESSURE
    A) WITH POISONING/EXPOSURE
    1) HYPERTENSION: Moderate hypertension is common, occurring in 20% to 60% of patients in most case series (Clark et al, 1992; Moss & Binder, 1987; Timms & Gibbons, 1986; Artaza et al, 1982; Mead & Jelinek, 1993).
    a) Severe hypertension is less common (Sutherland & Trinca, 1978; Istell et al, 1979) (Visser & Khusi, 1988); in high-risk individuals, it may lead to stroke, exacerbation of heart failure, or myocardial ischemia.
    3.3.5) PULSE
    A) WITH POISONING/EXPOSURE
    1) TACHYCARDIA is common, occurring in 10 to 50% of patients in most case series (Artaza et al, 1982; Clark et al, 1992; Moss & Binder, 1987) Muller, 1992). It is rarely hemodynamically significant.

Heent

    3.4.2) HEAD
    A) WITH POISONING/EXPOSURE
    1) PAIN
    a) Pain in the head, abdomen, and limbs is the most prominent complaint in patients with L. hasselti (red-back spider) bites (Bonnet, 1999).
    3.4.3) EYES
    A) WITH POISONING/EXPOSURE
    1) PTOSIS has been reported (Russell, 1962; Kobernick, 1984).
    2) PERIORBITAL EDEMA and conjunctivitis may occur (Hoover & Fortenberry, 2004; Kobernick, 1984; Sutherland & Trinca, 1978). This may be more common with L. indistinctus than with some other species, being reported in 10 of 30 patients in one case series (Muller, 1993).
    3) OCULAR ENVENOMATION: Periorbital edema and conjunctivitis followed by systemic effects (nausea, abdominal pain, and muscle cramps) developed in a 37-year-old woman who got small pieces of a crushed spider in the eye (Fuller, 1984).
    3.4.4) EARS
    A) WITH POISONING/EXPOSURE
    1) RED-BACK SPIDER BITE TO TYMPANIC MEMBRANE: A woman developed acute severe left ear pain after being bitten by a red-back spider. Twelve hours earlier she had been in a pool and felt as if she had gotten water in her ear which persisted overnight. After rubbing her ear she developed "unbearable" pain that radiated around the left side of her face along with peri-auricular diaphoresis and erythema. Upon otoscope exam, a live red-back spider (characteristic red stripe on its black abdomen) was found in the external auditory canal. Once the spider was removed, there was a hematoma and general erythema detected on the tympanic membrane. The patient was treated with oral analgesics and benzocaine/phenazone ear drops. Because there was no evidence of significant latrodectism, antivenin was not given. Pain improved within 48 hours. However, mild conductive hearing loss occurred in the ear, likely due to edema, and peaked at day 7 with symptoms resolving completely by day 21 (Lewis et al, 2015).
    a) CLINICAL FINDINGS: The findings reported in this case are the same symptoms described as the classic signs of red-back envenomation: localized diaphoresis, erythema, and piloerection at the bite site (Lewis et al, 2015).

Cardiovascular

    3.5.1) SUMMARY
    A) WITH POISONING/EXPOSURE
    1) Mild tachycardia and hypertension are common. Chest pain and ECG changes have been reported in severe envenomations. Cardiac manifestations after a black widow bite are rare.
    3.5.2) CLINICAL EFFECTS
    A) TACHYARRHYTHMIA
    1) WITH POISONING/EXPOSURE
    a) Tachycardia is common, occurring in 10 to 50% of patients in most case series (Artaza et al, 1982; Clark et al, 1992; Moss & Binder, 1987) Muller, 1992). It is usually not hemodynamically significant.
    b) Severe tachycardia (pulse of 200 beats/minute with clinical evidence of hemodynamic compromise) were reported in a 9-month-old child and a neonate (Byrne & Pemberton, 1983; Sutherland, 1992).
    B) HYPERTENSIVE EPISODE
    1) WITH POISONING/EXPOSURE
    a) Moderate hypertension is common, occurring in 20% to 60% of patients in most case series (Clark et al, 1992; Moss & Binder, 1987) (Muller, 1992) (Timms & Gibbons, 1986; Artaza et al, 1982; Mead & Jelinek, 1993). In a review, Gueron et al (2000) reported hypertension within the first few hours of a bite in 21% to 31% of victims(Gueron et al, 2000).
    b) In a retrospective series of 12 pediatric envenomation victims, 92% were reported to have asymptomatic hypertension (Woestman et al, 1996).
    c) Severe hypertension is less common (Sutherland & Trinca, 1978; Istell et al, 1979) (Visser & Khusi, 1988) (Karcioglu et al, 2001); in high-risk individuals, it may lead to stroke, exacerbation of heart failure, or myocardial ischemia.
    C) ELECTROCARDIOGRAM ABNORMAL
    1) WITH POISONING/EXPOSURE
    a) ECG abnormalities have been reported in a few victims, and have included slurring of the QRS with ST and T segments depression, prolonged QT interval and changes consistent with inferolateral ischemia. Mortality due to these changes is very unlikely (Gueron et al, 2000).
    b) CASE SERIES: In a retrospective series of 14 patients bitten by L. mactans, one had chest pain and ECG changes consistent with inferior lateral ischemia which resolved rapidly without evidence of myocardial injury (Moss & Binder, 1987).
    c) CASE SERIES: In a retrospective series of 163 patients with L. hesperus bites, one patient (with a history of coronary artery disease) developed a brief episode of chest pain and nonspecific ST-T wave changes but did not sustain a myocardial infarction (Clark et al, 1992).
    D) CONDUCTION DISORDER OF THE HEART
    1) WITH POISONING/EXPOSURE
    a) CASE REPORT: A 25-year-old man developed labile hypertension (as high as 240/140 mmHg) after an L. m. tredecimguttatus bite. Seventy-two hours later he developed atrial fibrillation with a ventricular response of 180 to 210 beats/minute and associated elevations of urinary vanillyl mandelic acid. Conversion to sinus rhythm followed administration of 2 mg of digitalis and 1 mg of oxprenolol intravenously; a follow-up ECG was normal (Weitzman et al, 1977).

Respiratory

    3.6.1) SUMMARY
    A) WITH POISONING/EXPOSURE
    1) Dyspnea may develop; respiratory failure and pulmonary edema are rare complications of severe envenomation.
    3.6.2) CLINICAL EFFECTS
    A) DYSPNEA
    1) WITH POISONING/EXPOSURE
    a) Dyspnea has been reported in 2% to 20% of patients (Timms & Gibbons, 1986; Clark et al, 1992). Bronchospasm may occur (Woestman et al, 1996).
    b) CASE REPORT: An 8-year-old boy complained of shortness of breath approximately 3 hours after being bitten by a L. mactans. He was given 1 vial of latrodectus antivenom and his symptoms began to improve during the infusion. He was released to home about 1.5 hours after being seen in the Emergency Department with no further symptoms (Offerman et al, 2011).
    B) APNEA
    1) WITH POISONING/EXPOSURE
    a) Because of abdominal muscle spasm, respiration is largely thoracic and respiratory difficulty and failure may occur (Kobernick, 1984). Ventilatory assistance was required in 10 of 2144 patients with L. hasselti bites in one series (Sutherland & Trinca, 1978).
    C) ACUTE LUNG INJURY
    1) WITH POISONING/EXPOSURE
    a) Pulmonary edema has been observed in several victims, but is uncommon; the pathogenesis has not been studied (Gueron et al, 2000).
    b) CASE REPORT: A 24-year-old woman developed severe hypertension (200/140 mmHg) after an L. indistinctus bite. The blood pressure gradually normalized, but the patient developed pulmonary edema 36 hours after the bite (Visser & Khusi, 1989).
    c) CASE REPORT: A 15-year-old girl presented 36 hours after an L. indistinctus bite with respiratory distress, cyanosis, hemoptysis, and pulmonary edema. These resolved over a two hour period following antivenin therapy (La Grange MAC, 1990).

Neurologic

    3.7.1) SUMMARY
    A) WITH POISONING/EXPOSURE
    1) Weakness, hyperreflexia, headache, and paresthesias are common. Patients are often restless and anxious; children may be irritable or drowsy.
    2) Severe cramping pain is most the common symptom and normally starts at the bite site and spreads proximally to involve large muscles in the thigh, buttock, and abdomen following a lower extremity bite or the chest after an upper extremity bite to involve the entire body. Pain generally peaks at 2 to 3 hours after the bite.
    3.7.2) CLINICAL EFFECTS
    A) MUSCLE WEAKNESS
    1) WITH POISONING/EXPOSURE
    a) Weakness may also develop and make walking difficult. Lower extremity weakness has been reported in 50% of patients in some case series (Moss & Binder, 1987) (Muller, 1992) and in case reports (Vutchev, 2001).
    b) Neonates may exhibit difficulty in swallowing (Byrne & Pemberton, 1983).
    B) HYPERREFLEXIA
    1) WITH POISONING/EXPOSURE
    a) Hyperreflexia is common (Maretic, 1983), occurring in 15% to 30% of patients in some case series (Artaza et al, 1982) (Muller, 1992).
    C) PAIN
    1) WITH POISONING/EXPOSURE
    a) Severe cramping pain is most the common symptom. It normally starts at the bite site and may spread proximally to involve large muscles in the thigh, buttock, and abdomen following a lower extremity bite or the chest after an upper extremity bite to involve the entire body. Pain generally peaks at 2 to 3 hours after the bite (Kunkel, 1996; Koh, 1998; Vutchev, 2001).
    b) LACTRODECTUS MACTANS: In a series of 4 patients envenomated by a black widow spider, severe pain persisted for 2 days in a 3-year-old child who did not receive antivenom. Of the other 3 patients (2 adults and 1 child), all experienced a significant decrease in pain during or shortly after receiving antivenom (Offerman et al, 2011).
    D) HEADACHE
    1) WITH POISONING/EXPOSURE
    a) Headache is common, occurring in 5% to 25% of patients in most case series (Sutherland & Trinca, 1978; Timms & Gibbons, 1986; Moss & Binder, 1987; Clark et al, 1992; Mead & Jelinek, 1993). In rare cases, headaches may persist for several months (Kobernick, 1984).
    E) ALTERED MENTAL STATUS
    1) WITH POISONING/EXPOSURE
    a) Restlessness and anxiety are common (Moss & Binder, 1987) (Muller, 1992). Drowsiness and irritability may develop after L. hasselti (red-back spider) bites, particularly in children (Byrne & Pemberton, 1983; Mead & Jelinek, 1993; Mollison et al, 1994).
    b) Woestman et al (1996) reported that 8 of 12 children had signs of irritability and agitation following envenomation(Woestman et al, 1996).
    F) SPASMODIC MOVEMENT
    1) WITH POISONING/EXPOSURE
    a) Fasciculations and tremor occur occasionally (Rayner, 1987) (Muller, 1992).
    G) PARESTHESIA
    1) WITH POISONING/EXPOSURE
    a) Paresthesia is reported in less than 10% of patients in most case series (Sutherland & Trinca, 1978; Artaza et al, 1982; Clark et al, 1992).
    b) CASE SERIES: In a series of 32 patients with red-back spider envenomation, 8 (25%) developed local paresthesias and 6 (19%) developed generalized paresthesias (Mollison et al, 1994).
    H) SEIZURE
    1) WITH POISONING/EXPOSURE
    a) Seizures have been reported but are rare (Sutherland & Trinca, 1978).

Gastrointestinal

    3.8.1) SUMMARY
    A) WITH POISONING/EXPOSURE
    1) Nausea, vomiting, excessive salivation, and abdominal pain are common.
    3.8.2) CLINICAL EFFECTS
    A) NAUSEA AND VOMITING
    1) WITH POISONING/EXPOSURE
    a) Nausea and vomiting are common effects, occurring in 10% to 20% of patients in most case series (Sutherland & Trinca, 1978; Jelinek et al, 1989; Timms & Gibbons, 1986; Mead & Jelinek, 1993; Clark et al, 1992; Mollison et al, 1994) and in case reports (Vutchev, 2001; Karcioglu et al, 2001).
    B) ABDOMINAL PAIN
    1) WITH POISONING/EXPOSURE
    a) Abdominal pain and rigidity are common, occurring in 15% to 50% of patients in most case series (Moss & Binder, 1987; Timms & Gibbons, 1986; Jelinek et al, 1989; Clark et al, 1992; Mead & Jelinek, 1993; Mollison et al, 1994).
    b) Pain and rigidity may be severe enough to mimic an acute abdomen (White & Harbord, 1985).
    c) In a case report Bush (1999) reported a black widow bite to the toe followed 3 hours later by intense abdominal pain mimicking acute cholecystitis in a 71-year-old man. The misdiagnosis of cholecystitis was initially based on location and severity of pain, ultrasound findings, and elevated white count (Bush, 1999).
    d) In a case series of 12 pediatric patients with envenomations, all patients complained of abdominal pain (Woestman et al, 1996).
    e) Pain in the head, abdomen, and limbs is the most prominent complaint in patients with L. hasselti (red-back spider) bites (Bonnet, 1999).
    C) EXCESSIVE SALIVATION
    1) WITH POISONING/EXPOSURE
    a) Hypersalivation may occur (Maretic, 1983; Byrne & Pemberton, 1983).
    D) DYSPHAGIA
    1) WITH POISONING/EXPOSURE
    a) CASE REPORT: Difficulty swallowing and gagging during attempts to feed were reported in a neonate after L. hasselti (red-back spider) envenomation (Byrne & Pemberton, 1983).

Genitourinary

    3.10.1) SUMMARY
    A) WITH POISONING/EXPOSURE
    1) Priapism, urinary retention, pyuria, proteinuria, microscopic hematuria, and testicular pain have been reported.
    3.10.2) CLINICAL EFFECTS
    A) PRIAPISM
    1) WITH POISONING/EXPOSURE
    a) Priapism is an uncommon effect.
    b) CASE REPORT: Priapism developed in a child bitten by a black widow spider (Stiles, 1982).
    c) CASE SERIES: Priapism developed in 1 of 89 patients bitten by L. mactans in one case series (Aretaza et al, 1982)
    d) CASE REPORT: A 17-month child developed priapism after black widow envenomation. His priapism resolved within 2 hours of antivenom administration(Hoover & Fortenberry, 2004).
    B) DISORDER OF TESTIS
    1) WITH POISONING/EXPOSURE
    a) Testicular pain mimicking torsion may occur.
    C) RETENTION OF URINE
    1) WITH POISONING/EXPOSURE
    a) CASE SERIES: Urinary retention is an uncommon effect, developing in 2 of 89 patients bitten by L. mactans in one case series (Artaza et al, 1982).
    D) BLOOD IN URINE
    1) WITH POISONING/EXPOSURE
    a) Pyuria, proteinuria, and microscopic hematuria have been reported occasionally (Moss & Binder, 1987; Artaza et al, 1982).
    E) ACUTE RENAL FAILURE SYNDROME
    1) WITH POISONING/EXPOSURE
    a) Although uncommon, acute renal failure has been reported following envenomation. A case of oliguric renal failure due to a combination of prerenal and renal causes was reported in a 59-year-old man following latrodectism. Laboratory findings supported the diagnosis of acute tubular necrosis (BUN/creatinine ratio, urinary sodium concentration (120 mEq/L), FENa (greater than 2%) and urine sediment) (Karcioglu et al, 2001).

Hematologic

    3.13.2) CLINICAL EFFECTS
    A) LEUKOCYTOSIS
    1) WITH POISONING/EXPOSURE
    a) Leukocytosis is a common finding (Clark et al, 1992; Timms & Gibbons, 1986).

Dermatologic

    3.14.1) SUMMARY
    A) WITH POISONING/EXPOSURE
    1) Local effects may include tiny puncture wounds, erythema, induration and diaphoresis, or the skin may appear perfectly normal. One case of toxic epidermal necrolysis has been reported.
    3.14.2) CLINICAL EFFECTS
    A) BITE - WOUND
    1) WITH POISONING/EXPOSURE
    a) LOCAL EFFECTS: The bite site may have one or two small puncture wounds, 1 to 2 mm apart. The immediate bite area may be warm, minimally indurated, and somewhat reddened ("target lesion") (Kobernick, 1984; Rauber, 1984; Moss & Binder, 1987; Clark et al, 1992). Acute pain, itching erythema, and paresthesia at the bite site are common (Vutchev, 2001). Local paresthesia may persist for several weeks.
    b) In a case series of 12 pediatric envenomated patients, 75% were reported to have an obvious target lesion (Woestman et al, 1996).
    B) EXCESSIVE SWEATING
    1) WITH POISONING/EXPOSURE
    a) In moderately severe envenomations patients may experience local diaphoresis of bite site or involved extremity (Clark et al, 1992; Mead & Jelinek, 1993; Liew et al, 1994; Karcioglu et al, 2001).
    b) In severe envenomations, diaphoresis also occurs remote from envenomation site (Sutherland & Trinca, 1978; Artaza et al, 1982; Clark et al, 1992).
    C) EDEMA
    1) WITH POISONING/EXPOSURE
    a) Edema may develop in the bitten extremity. This effect appears to be more common with L. hasselti (red-back spider) bites, occurring in 25% of patients in 3 large case series (Sutherland & Trinca, 1978; Mead & Jelinek, 1993; Mollison et al, 1994).
    b) Edema around the eyelids also occurs (Hoover & Fortenberry, 2004).
    D) LYELL'S TOXIC EPIDERMAL NECROLYSIS, SUBEPIDERMAL TYPE
    1) WITH POISONING/EXPOSURE
    a) CASE REPORT: Toxic epidermal necrolysis involving 60% of the body surface area developed in a young adult bitten by L. mactans. The patient recovered without sequelae (Welch et al, 1991).
    E) ERUPTION
    1) WITH POISONING/EXPOSURE
    a) Generalized rash, sometimes urticarial, has occurred occasionally (Sutherland & Trinca, 1978).

Musculoskeletal

    3.15.1) SUMMARY
    A) WITH POISONING/EXPOSURE
    1) Stiffness, pain, and spasms usually involving large muscle groups may develop within 30 to 120 minutes. Mild rhabdomyolysis has been reported.
    3.15.2) CLINICAL EFFECTS
    A) PAIN
    1) WITH POISONING/EXPOSURE
    a) Pain from the bite site spreads from local muscle groups to larger regional muscle groups such as chest, back, abdomen, pelvis, and lower extremities (Offerman et al, 2011; Kobernick, 1984; Rauber, 1984; Moss & Binder, 1987; Miller, 1992; Vutchev, 2001).
    1) Pain in the head, abdomen, and limbs is the most prominent complaint in patients with L. hasselti (red-back spider) bites (Bonnet, 1999).
    b) LATRODECTUS MACTANS: In a series of 4 cases of L. mactans envenomations, severe pain was described by each patient; symptoms progressed and included the chest, back and abdomen (Offerman et al, 2011).
    c) Pain may descend into lower extremities, especially feet, where burning pain in soles may occur (Kobernick, 1984; Rauber, 1984; Moss & Binder, 1987; Miller, 1992).
    d) Pain peaks from 1 to 6 hours after onset and usually last for 12 to 72 hours (Kobernick, 1984; Rauber, 1984; Moss & Binder, 1987; Miller, 1992; Vutchev, 2001).
    B) INCREASED MUSCLE TONE
    1) WITH POISONING/EXPOSURE
    a) Muscle spasms may produce board-like rigidity of abdominal, shoulder, chest, thigh, and back muscles. Symptoms peak from 1 to 6 hours after onset and usually last for 12 to 72 hours (Kobernick, 1984; Miller, 1992) (O'Malley et al, 1999)(Vutchev, 2001). Severe spasms may interfere with the ability to breath or walk.
    C) RHABDOMYOLYSIS
    1) WITH POISONING/EXPOSURE
    a) Mild rhabdomyolysis with CPK levels less than 1,500 International Units/L has occasionally occurred (Clark et al, 1992; Sutherland, 1992; Cohen & Bush, 2005).
    D) JOINT PAIN
    1) WITH POISONING/EXPOSURE
    a) Arthralgia has been reported but occurs rarely (Sutherland & Trinca, 1978; Fischer, 1976; Mollison et al, 1994).
    E) COMPARTMENT SYNDROME
    1) WITH POISONING/EXPOSURE
    a) Compartment syndrome has only been reported in one case of envenomation from a Latrodectus hesperus spider (Cohen & Bush, 2005).
    b) CASE REPORT: A 55-year-old man presented to the ED with severe cramping pain of his left arm, from his shoulder to his fingertips, approximately three hours after envenomation from a spider believed to be Latrodectus hesperus (western black widow spider). His left forearm was markedly swollen and was tender to palpitation, and appeared to be more swollen on the volar aspect than on the dorsal. There was no visible bite mark or puncture wound. He had mild rhabdomyolysis (serum creatinine 1.9 mg/dL and creatinine kinase 999 International Units/L). Compartment pressures, measured twice in the volar compartment and once in the dorsal compartment of the left forearm, were 6 and 54 mmHg and 24 mmHg (normal range 0 to 8 mmHg), respectively.
    1) He was treated with one vial of Latrodectus mactans antivenin intravenously, and his symptoms improve immediately. Repeat measurements of compartment pressures showed a decrease (32 mmHg for the volar compartment and 21 mmHg for the dorsal compartment). Over the next three days, the patient continued to improve with supportive care, and was discharged without sequelae (Cohen & Bush, 2005).

Reproductive

    3.20.1) SUMMARY
    A) No evidence of fetal distress or premature labor were seen in several instances of Latrodectus bites. Healthy infants were delivered.
    3.20.3) EFFECTS IN PREGNANCY
    A) CASE REPORTS
    1) A 30-year-old woman at 30 weeks gestation developed abdominal cramps and thigh pain after suspected Latrodectus bite. There was no evidence of fetal distress or premature labor. Symptoms resolved over 48 hours. At 40 weeks gestation she delivered a healthy male infant (Scalzone & Wells, 1994).
    2) A 36-year-old woman at 22 weeks gestation developed restlessness, muscle pain and cramping, and chest tightness after a Latrodectus bite. There was no evidence of premature labor or fetal distress. After treatment with calcium gluconate, diazepam, and morphine, the symptoms resolved (Handel et al, 1994).
    3) A 30-year-old woman at 25 weeks gestation was bitten by a red-back spider. She was treated with antivenin, responded well, and delivered a normal baby at term (Sutherland, 1992).
    4) A 20-year-old pregnant woman at 16 weeks gestation developed hypertension, abdominal cramps and rigidity, and muscle fasciculation after being bitten by L. hesperus. There was no evidence of premature labor or fetal distress. Treatment with antivenin resolved the symptoms. At 34 weeks gestation she delivered a healthy male infant (Russell et al, 1979).
    5) Maretic & Lebez (1979) report that in three women in the second, fourth, and eighth months of pregnancy, Latrodectus envenomation produced severe cramps without spontaneous abortion or premature delivery.
    B) LACK OF EFFECT
    1) Despite historical reports of the use of venom as an abortifacient and fears that muscle spasms may involve the gravid uterus, no modern reports of spontaneous abortion following envenomation exist and reported outcomes in pregnant women have been good (Key, 1981; Russell et al, 1979; Dart, 1994).
    C) ANIMAL STUDIES
    1) Abortion did not occur in 12 rats after Latrodectus envenomation. Latrodectus envenomation did induce abortion in mice (Russell et al, 1979) and guinea pigs (Maretic Z & Lebez D, 1979).

Laboratory Monitoring

Monitoring Parameters Levels

    4.1.1) SUMMARY
    A) Laboratory testing may be required for an alternative diagnosis, but no specific diagnostic tests are required for most patients.
    B) Patients receiving antivenom therapy should be on an ECG monitor, continuous oxygen and an intravenous line should be placed.
    4.1.2) SERUM/BLOOD
    A) HEMATOLOGIC
    1) There are no laboratory tests of diagnostic value or of specific assistance in making therapeutic decisions, but a CBC and urinalysis should be done to evaluate other diagnoses (eg, an acute surgical abdomen) and provide a baseline for any subsequent laboratory studies (Moss & Binder, 1987).
    B) BLOOD/SERUM CHEMISTRY
    1) Follow CPK in patients with severe muscle spasms.

Treatment

Life Support

    A) Support respiratory and cardiovascular function.

Patient Disposition

    6.3.6) DISPOSITION/BITE-STING EXPOSURE
    6.3.6.1) ADMISSION CRITERIA/BITE-STING
    A) Patients should be admitted if their symptoms do not improve with treatment or if they need ongoing pain management.
    B) Patients with severe or worsening symptoms that are unresponsive to treatment should be hospitalized as patients often return within several hours with more severe symptoms (Miller, 1992).
    C) Most patients with risk factors should be hospitalized, including young children, elderly patients, those with cardiovascular disease, and pregnant women (Anon, 1992).
    D) Patients who have urticarial or other even minor reactions to antivenom administration should be admitted to the hospital (Clark et al, 1992).
    E) Patients treated with antivenom rarely have recurrence of symptoms and may be discharged home (Clark et al, 1992).
    6.3.6.2) HOME CRITERIA/BITE-STING
    A) Patients with only mild pain may be observed at home.
    B) One study suggested that patients with only local symptoms following latrodectism be monitored at home, with follow-up calls at 1 and 2 hours (Alsop & Albertson, 2001).
    6.3.6.3) CONSULT CRITERIA/BITE-STING
    A) A toxicologist should be involved if a patient’s symptoms are not responsive to general measures including pain and muscle spasm control and one is considering use of the equine-derived Latrodectus mactans antivenom. Also, consider early toxicology involvement in critically ill, elderly, pregnant, or young patients.
    6.3.6.5) OBSERVATION CRITERIA/BITE-STING
    A) Patients with severe pain should be referred in for evaluation and observed until symptoms resolve or improve.

Monitoring

    A) Laboratory testing may be required for an alternative diagnosis, but no specific diagnostic tests are required for most patients.
    B) Patients receiving antivenom therapy should be on an ECG monitor, continuous oxygen and an intravenous line should be placed.

Oral Exposure

    6.5.3) TREATMENT
    A) SUPPORT
    1) Ingestion of a live Latrodectus spider has caused systemic envenomation (McDonald et al, 1995).
    2) Treatment should include recommendations listed in the BITES/STINGS section when appropriate.

Eye Exposure

    6.8.2) TREATMENT
    A) OCULAR ABSORPTION
    1) Systemic intoxication has resulted from ocular exposure to crushed spider parts (Fuller, 1984).
    B) SUPPORT
    1) Treatment should include recommendations listed in the BITES/STINGS section when appropriate.
    C) Treatment should include recommendations listed in the ORAL EXPOSURE section when appropriate.

Range Of Toxicity

Summary

    A) TOXICITY: A single latrodectus bite can cause severe envenomation.

Maximum Tolerated Exposure

    A) In a case series of 241 suspected black widow spider bites, an actual bite was reported in 79.7% of cases. Following a bite, 55.2% did not develop symptoms beyond the local bite site. In only one case was antivenom used, and that patient was admitted for 28 hours. The authors suggested that patients with only local symptoms be monitored at home, with follow-up calls at 1 and 2 hours (Alsop & Albertson, 2001).

Toxicity Information

    7.7.1) TOXICITY VALUES
    A) LATRODECTUS HESPERUS VENOM
    B) LATRODECTUS MACTANS VENOM
    C) LATRODECTUS TREDECIMGUTTATUS VENOM

Pharmacology Toxicology

Toxicologic Mechanism

    A) The venom of the Latrodectus (widow) spiders is a complex poison, consisting of at least five or six biologically active proteins; it also contains small amounts of proteolytic enzymes. Its principal action is on the nervous system; although the exact physiologic mechanism of action is incompletely understood (Rosenthal & Meldolesi, 1989).
    B) A whole extract of black widow spider venom glands increases the frequency of miniature end plate potentials, blocks neuromuscular transmission, causes a release of neurotransmitter from cholinergic nerve terminals in the brain, sympathetic ganglia and from some adrenergic terminals, and induces a depletion of synaptic vesicles at the neuromuscular junction (Frontalli et al, 1976).
    C) alpha-LATROTOXIN - The lethal fraction of the venom, alpha-latrotoxin, acts on the neuromuscular junction to cause massive release and depletion of acetylcholine (Pumplin & McClure, 1977; Grishin, 1998; Kunkel, 1996) and norepinephrine at the postganglionic sympathetic synaptic sites (Anon, 1992; Kunkel, 1996) followed by complete blockade of the neuromediator release. This toxin is a polypeptide consisting of about 1000 amino acids (Grishin, 1998).
    D) The venom impairs presynaptic neuronal uptake of amines (Rothlin et al, 1977).

References

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