Spider bites: Difference between revisions
 
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==Brown Recluse==
==Background==
===Background===
*Standard [[abscess]] are not typically due to spider bites and should not be diagnosed as such
*Brown violin shape on cephalothorax (fiddleback)
*In Southern midwestern US


===Mechanism===
===Clinically important spider genera by geographic region===  
*Venom contains variety of cytotoxic enzymes causing necrotic wound
* North America 
** Loxosceles (e.g. [[brown recluse]])
** Latrodectus (e.g. [[black widow]])
** Tegenaria
* South America
** Loxosceles
** Latrodectus
** [[Phoneutria]] (e.g. [[armed spider]])
* Africa
** Loxosceles
** Latrodectus
* Europe
** Loxosceles
** Latrodectus
* Australia
** Atrax (e.g. [[funnel-web spider]])
** Hadronyche (e.g. [[funnel-web spider]])
** Latrodectus 
* Asia
** Latrodectus
*Other
**[[Tarantula spider bite]]


===Clinical Features===
===Visual Spider Identification===
#Bite is initially painless
<gallery mode="packed">
#Mild reaction
File:Tarantula640px-Brachypelma smithi 2009 G03.jpg|[[Tarantula]]
##Most common
File:Western Black Widow (Latrodectus hesperus).jpg|[[Black widow spider]]
##Mild erythematous lesion that later becomes firm and heals without scar
File:Brown Recluse.jpg|[[Brown recluse]]
#Severe reaction
File:p nigreventer.jpeg|[[Armed spider]] (''phoneutria nigreventer'')
##Begins w/ mild-severe pain several hrs after bite accompanied by erythema and swelling
File:Funnel Web Spider.png|[[Funnel-web spider]] (Hadronyche versuta)
##Hemorrhagic blister then forms surrounded by vasoconstriction-induced blanched skin
</gallery>
##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 ==
==Clinical Features==
===Background===
===History===  
*Red hourglass on otherwise black spider
* Determine circumstances of bite to assess consistency with spider habitat and behavior   
===Mechanism===
** Indoors vs outdoors
Envenomation causes release of acetylcholine and norepinephrine from the nerve terminals causing muscle cramps, tachycardia and hypertension
** Day vs night 
=== Clinical Features ===
** Geographic location (recent travel)
#Local
* Appearance of the spider if seen
##Pinprick sensation; then increasing local pain that may spread to entire extremity
* Dead spiders can be preserved in 70% EtOH and later identified by arachnologists or entomologist
##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 ===
===Physical Exam===
#Pain and muscle spasms
* No pathognomonic signs proving lesion is a spider bite
##Opiods and benzos
* Assess both bite site and for systemic signs
#Systemic illness
* Bite Site
##Antivenin
** Location
###Consider for:
*** Spider bites more common when clothing is tight against skin
####Children
** Number of bites
####Pregnant women
*** Multiple bites suggest parasitic insect and not spider
####Elderly
** Appearance of bite
*** Erythema, pallor, hemorrhage, induration, tenderness, paresthesia, vesicles
* Systemic findings
** Abnormal vital signs ([[tachycardia]] possible with black widow)
** [[Altered mental status]]
** [[Abdominal pain]]
** Diaphoresis
** Generalized [[rash]]
** Muscle fasciculations, spasm, or tenderness


=== Disposition ===
==Differential Diagnosis==
#Consider admission for:
{{Bites and stings DDX}}
##Symptoms of moderate envenomation
##Pregnant women
##Children
##Pts w/ preexisting cardiovascular disease or HTN


==Tarantula==
==Evaluation==
===Clinical Features===
===Workup===
#Abdominal hairs may be flicked a short distance when threatened
 
##Rarely penetrate human skin but can imbed deeply into conjunctiva and cornea
===Diagnosis===
#Bites can be painful but systemic symptoms other than fever are unusual
*Typically a clinical diagnosis
 
==Management==
* Clean area of bite
* [[Tetanus prophylaxis]]
* [[analgesia|Analgesics]]
* Hydration
* Surgical follow up if indicated for debridement of necrotic area 
* [[Antivenin]] is indicated only for specific envenomation
* No proven benefit for [[corticosteroids]]
* No indication for antibiotics unless concern for [[cellulitis]]
 
==Disposition==


===Management===
#Red eye and pain after handling a tarantula necessitates an ocular exam
##Hairs may be difficult to detect on slit lamp
#Treatment is surgical removal of hairs and topical steroids


==See Also==
==See Also==
[[Bites and Stings]]
*[[Bites and Stings]]
 
==External Links==
 


==Source==
==References==
*Tintinalli
<references/>
*Rosen's
* 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]]
[[Category:Environmental]]
[[Category:Toxicology]]

Latest revision as of 13:28, 29 May 2022

Background

  • Standard abscess are not typically due to spider bites and should not be diagnosed as such

Clinically important spider genera by geographic region

Visual Spider Identification

Clinical Features

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

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

Differential Diagnosis

Envenomations, bites and stings

Evaluation

Workup

Diagnosis

  • Typically a clinical diagnosis

Management

Disposition

See Also

External Links

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.
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