Difference between revisions of "Spider bites"

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==Brown Recluse==
+
==Types==
===Background===
+
*[[Brown recluse spider bite]]
*Brown violin shape on cephalothorax (fiddleback)
+
*[[Black widow spider bite]]
*In Southern midwestern US
+
*[[Tarantula spider bite]]
  
===Mechanism===
+
<gallery mode="packed">
*Venom contains variety of cytotoxic enzymes causing necrotic wound
+
File:Tarantula640px-Brachypelma smithi 2009 G03.jpg|[[Tarantula]]
 +
File:Western Black Widow (Latrodectus hesperus).jpg|[[Black widow spider]]
 +
File:Brown Recluse.jpg|[[Brown recluse]]
 +
</gallery>
  
===Clinical Features===
+
==Differential Diagnosis==
#Bite is initially painless
+
{{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 ==
+
==History==  
===Background===
+
* Determine circumstances of bite to assess consistency with spider habitat and behavior   
*Red hourglass on otherwise black spider
+
** Indoors vs outdoors
===Mechanism===
+
** Day vs night 
Envenomation causes release of acetylcholine and norepinephrine from the nerve terminals causing muscle cramps, tachycardia and hypertension
+
** Geographic location (recent travel)
=== Clinical Features ===
+
* Appearance of the spider if seen
#Local
+
* 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 ===
+
==Clinically important spider genera by geographic region==  
#Pain and muscle spasms
+
* North America 
##Opiods and benzos
+
** Loxosceles
#Systemic illness
+
** Latrodectus
##Antivenin
+
** Tegenaria
###Consider for:
+
* South America
####Children
+
** Loxosceles
####Pregnant women
+
** Latrodectus
####Elderly
+
** Phoneutria
 +
* Africa
 +
** Loxosceles
 +
** Latrodectus
 +
* Europe
 +
** Loxosceles
 +
** Latrodectus
 +
* Australia
 +
** Atrax
 +
** Hadronyche
 +
** Latrodectus 
 +
* Asia
 +
** Latrodectus
  
=== Disposition ===
+
==Physical Exam==
#Consider admission for:
+
* No pathognomonic signs proving lesion is a spider bite
##Symptoms of moderate envenomation
+
* Assess both bite site and for systemic signs
##Pregnant women
+
* Bite Site
##Children
+
** Location
##Pts w/ preexisting cardiovascular disease or HTN
+
*** Spider bites more common when clothing is tight against skin
 
+
** Number of bites
==Tarantula==
+
*** Multiple bites suggest parasitic insect and not spider  
===Clinical Features===
+
** Appearance of bite
#Abdominal hairs may be flicked a short distance when threatened
+
*** Erythema, pallor, hemorrhage, induration, tenderness, paresthesia, vesicles
##Rarely penetrate human skin but can imbed deeply into conjunctiva and cornea
+
* Systemic findings
#Bites can be painful but systemic symptoms other than fever are unusual
+
** Abnormal vital signs ([[tachycardia]] possible with black widow)
 
+
** [[Altered mental status]]
===Management===
+
** [[Abdominal pain]]
#Red eye and pain after handling a tarantula necessitates an ocular exam
+
** Diaphoresis
##Hairs may be difficult to detect on slit lamp
+
** Generalized [[rash]]
#Treatment is surgical removal of hairs and topical steroids
+
** Muscle fasciculations, spasm, or tenderness
 
 
==Review Questions==
 
<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>
 
  
 +
==Treatment==
 +
* 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]]
  
 
==See Also==
 
==See Also==
[[Bites and Stings]]
+
*[[Bites and Stings]]
  
===Sources===
+
==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 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.