Difference between revisions of "Spider bites"

(Brown Recluse)
(Physical Exam)
 
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==Brown Recluse==
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==Types==
===Background===
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*[[Brown recluse spider bite]]
*Brown violin shape on cephalothorax (fiddleback)
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*[[Black widow spider bite]]
*In Southern midwestern US
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*[[Tarantula spider bite]]
  
===Mechanism===
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<gallery mode="packed">
*Venom contains variety of cytotoxic enzymes causing necrotic wound
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File:Tarantula640px-Brachypelma smithi 2009 G03.jpg|[[Tarantula]]
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File:Western Black Widow (Latrodectus hesperus).jpg|[[Black widow spider]]
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File:Brown Recluse.jpg|[[Brown recluse]]
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</gallery>
  
===Clinical Features===
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==Differential Diagnosis==
#Bite is initially painless
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{{Bites and stings DDX}}
#Mild reaction
 
##Most common
 
##Mild erythematous lesion that later becomes firm and heals without scar
 
#Severe reaction
 
##Begins w/ mild-severe pain several hrs after bite accompanied by erythema and swelling
 
##Hemorrhagic blister then forms surrounded by vasoconstriction-induced blanched skin
 
##By day 3 or 4 hemorrhagic area may become ecchymotic
 
###Leads to "red, white, and blue" sign (erythema, blanching, ecchymosis)
 
##By end of first week ecchymotic area may become necrotic w/ eschar formation
 
#Systemic effects
 
##Rare
 
##Occur predominantly in children 24-72hr after the bite
 
###Include nausea/vomiting, fever, arthralgias, thrombocytopenia, rhabdo, renal failure
 
===Treatment===
 
#Local wound care
 
#Abx are indicated only if signs of infection exist; secondary infections are uncommon
 
#Although some texts recommend Dapsone, it has been shown to be of limited benefit and is associated with hemolysis in G6PD patients and als methemoglobinemia
 
  
== Black Widow ==
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==History==  
===Background===
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* Determine circumstances of bite to assess consistency with spider habitat and behavior   
*Red hourglass on otherwise black spider
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** Indoors vs outdoors
===Mechanism===
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** Day vs night 
Envenomation causes release of acetylcholine and norepinephrine from the nerve terminals causing muscle cramps, tachycardia and hypertension
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** Geographic location (recent travel)
=== Clinical Features ===
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* Appearance of the spider if seen
#Local
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* Dead spiders can be preserved in 70% EtOH and later identified by arachnologists or entomologist
##Pinprick sensation; then increasing local pain that may spread to entire extremity
 
##Erythema appears 20-60 min after the bite  
 
##Pain begins to abate after several hours and disappears by 2-3d
 
#Systemic
 
##Muscle cramp-like spasms in large muscle groups (although exam rarely reveals rigidity)  
 
##Pain becomes generalized
 
###Severe abdominal wall musculature pain and cramping
 
##HA, n/v, diaphoresis, photophobia, dyspnea
 
##A-fib, myocarditis, priapism, and death are rare
 
  
=== Treatment ===
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==Clinically important spider genera by geographic region==  
#Pain and muscle spasms
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* North America 
##Opiods and benzos
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** Loxosceles
#Systemic illness
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** Latrodectus
##Antivenin
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** Tegenaria
###Consider for:
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* South America
####Children
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** Loxosceles
####Pregnant women
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** Latrodectus
####Elderly
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** Phoneutria
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* Africa
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** Loxosceles
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** Latrodectus
 +
* Europe
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** Loxosceles
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** Latrodectus
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* Australia
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** Atrax
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** Hadronyche
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** Latrodectus 
 +
* Asia
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** Latrodectus
  
=== Disposition ===
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==Physical Exam==
#Consider admission for:
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* No pathognomonic signs proving lesion is a spider bite
##Symptoms of moderate envenomation
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* Assess both bite site and for systemic signs
##Pregnant women
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* Bite Site
##Children
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** Location
##Pts w/ preexisting cardiovascular disease or HTN
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*** Spider bites more common when clothing is tight against skin
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** Number of bites
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*** Multiple bites suggest parasitic insect and not spider
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** Appearance of bite
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*** Erythema, pallor, hemorrhage, induration, tenderness, paresthesia, vesicles
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* Systemic findings
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** Abnormal vital signs ([[tachycardia]] possible with black widow)
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** [[Altered mental status]]
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** [[Abdominal pain]]
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** Diaphoresis
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** Generalized [[rash]]
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** Muscle fasciculations, spasm, or tenderness
  
==Tarantula==
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==Treatment==
===Clinical Features===
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* Clean area of bite
#Abdominal hairs may be flicked a short distance when threatened
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* [[Tetanus prophylaxis]]
##Rarely penetrate human skin but can imbed deeply into conjunctiva and cornea
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* [[analgesia|Analgesics]]
#Bites can be painful but systemic symptoms other than fever are unusual
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* Hydration
 
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* Surgical follow up if indicated for debridement of necrotic area 
===Management===
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* [[Antivenin]] is indicated only for specific envenomation
#Red eye and pain after handling a tarantula necessitates an ocular exam
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* No proven benefit for [[corticosteroids]]
##Hairs may be difficult to detect on slit lamp
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* No indication for antibiotics unless concern for [[cellulitis]]
#Treatment is surgical removal of hairs and topical steroids
 
  
 
==See Also==
 
==See Also==
[[Bites and Stings]]
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*[[Bites and Stings]]
  
==Source==
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==References==
*Tintinalli
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<references/>
*Rosen's
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* Boyer LV, Binford GJ, Degan JA. Spider Bites. In Auerbach PS, Cushing TA, Harris NS. Auerbach’s Wilderness Medicine. 7th ed. Philadelphia, PA: Elsevier; 2017: 993-1016.
  
[[Category:Environ]]
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[[Category:Environmental]]
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[[Category:Toxicology]]

Latest revision as of 21:59, 28 September 2019

Types

Differential Diagnosis

Envenomations, bites and stings

History

  • Determine circumstances of bite to assess consistency with spider habitat and behavior
    • Indoors vs outdoors
    • Day vs night
    • Geographic location (recent travel)
  • Appearance of the spider if seen
  • Dead spiders can be preserved in 70% EtOH and later identified by arachnologists or entomologist

Clinically important spider genera by geographic region

  • North America
    • Loxosceles
    • Latrodectus
    • Tegenaria
  • South America
    • Loxosceles
    • Latrodectus
    • Phoneutria
  • Africa
    • Loxosceles
    • Latrodectus
  • Europe
    • Loxosceles
    • Latrodectus
  • Australia
    • Atrax
    • Hadronyche
    • Latrodectus
  • Asia
    • Latrodectus

Physical Exam

  • No pathognomonic signs proving lesion is a spider bite
  • Assess both bite site and for systemic signs
  • Bite Site
    • Location
      • Spider bites more common when clothing is tight against skin
    • Number of bites
      • Multiple bites suggest parasitic insect and not spider
    • Appearance of bite
      • Erythema, pallor, hemorrhage, induration, tenderness, paresthesia, vesicles
  • Systemic findings

Treatment

See Also

References

  • Boyer LV, Binford GJ, Degan JA. Spider Bites. In Auerbach PS, Cushing TA, Harris NS. Auerbach’s Wilderness Medicine. 7th ed. Philadelphia, PA: Elsevier; 2017: 993-1016.