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
* ''Loxosceles'' family


===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, DIC, rhabdo, renal failure


===Differential Diagnosis===
==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
** Abnormal vital signs ([[tachycardia]] possible with black widow)
** [[Altered mental status]]
** [[Abdominal pain]]
** Diaphoresis
** Generalized [[rash]]
** Muscle fasciculations, spasm, or tenderness
 
==Differential Diagnosis==
{{Bites and stings DDX}}
{{Bites and stings DDX}}


===Treatment===
==Evaluation==
#Local wound care
===Workup===
#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 ==
===Diagnosis===
===Background===
*Typically a clinical diagnosis
*Red hourglass on otherwise black spider
===Mechanism===
Envenomation causes release of acetylcholine and norepinephrine from the nerve terminals causing muscle cramps, tachycardia and hypertension
=== Clinical Features ===
#Local
##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 ===
==Management==
#Pain and muscle spasms
* Clean area of bite
##Opiods and benzos
* [[Tetanus prophylaxis]]
#Systemic illness
* [[analgesia|Analgesics]]
##Antivenin
* Hydration
###Consider for:
* Surgical follow up if indicated for debridement of necrotic area 
####Children
* [[Antivenin]] is indicated only for specific envenomation
####Pregnant women
* No proven benefit for [[corticosteroids]]
####Elderly
* No indication for antibiotics unless concern for [[cellulitis]]


=== Disposition ===
==Disposition==
#Consider admission for:
##Symptoms of moderate envenomation
##Pregnant women
##Children
##Pts w/ preexisting cardiovascular disease or HTN


==Tarantula==
===Clinical Features===
#Abdominal hairs may be flicked a short distance when threatened
##Rarely penetrate human skin but can imbed deeply into conjunctiva and cornea
#Bites can be painful but systemic symptoms other than fever are unusual


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


==Review Questions==
==External Links==
<quiz display=simple>
{Environmental emergencies question – Regarding black widow and brown recluse spider envenomations, which of the following is FALSE?
|type="()"}
-Black widow spiders (BWS) are found in the temperate regions of six continents and are widespread through North America, including the western United States (California included).
-Signs and symptoms associated with BWS (e.g. diffuse pain, muscle cramps, tachycardia, and hypertension) usually develop begin within 30 to 120 minutes of the envenomation.
-After antivenom for BWS is administered, symptoms typically resolve within 30 minutes, with complete relief within 2 hours.
+Brown recluse spider (BRS) envenomation is most common in west coast states, such as California.
||'''Harwood-Nuss – 1734-1739. Although BWS occur in Southern California, BRS are most common in the southern Midwestern states (but not California). Note that BRS have more local toxicity with eschar formation and necrosis, and these should not be debrided or excised. BRS may result in hemolysis and rhabdomyolysis. There is no antivenom available for BRS in the US, but there is one for BWS, which manifest severe life-threatening systemic signs.'''
-Most bites from BRS have a benign clinical course, but necrosis with induration and eschar formation may occur, and systemic effects, such as fever, chills, headache, malaise, arthralgia, and myalgias progress after more than 24 to 48 hours and resolve by 72 to 96 hours post bite.
</quiz>




==See Also==
==References==
[[Bites and Stings]]
<references/>
[[Envenomation]]
* 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.
 
===Sources===
*Tintinalli
*Rosen's


[[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.