Transcript Slide 1

The Creepy and Crawling:
Bites and Stings in North
America
Dr. Rebecca C. Bowers FACEP
Assistant Professor
Department of Emergency Medicine
University of Kentucky
Learning Objectives
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Discuss scope of problem in the US and worldwide
Recognize the major groups of animals that pose an
envenomation threat
Gain an understanding of the prehospital and hospital
management of North American snake envenomations
Gain an understanding of the prehospital and hospital
management of North American arachnid envenomation
Gain an understanding of prehospital and hospital
management of Hymenoptera envenomation
Discuss the disposition of envenomation victims
Hymenoptera
Envenomation
North American Offenders
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Bees and Wasps
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Bees: Honeybees, bumblebees, and africanized
honeybees
Wasps: true wasps, yellow jackets, hornets
Found throughout USA. AHBs found in Southwest
Ants
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Imported red fire ant
Imported from South America. Found from Virginia to
Texas
Native ant species
Epidemiology
Scope of the Problem
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In 2005 AAPCC reported 10,792 bee and wasp
exposures
1200 required a hospital visit with only 1 death
Very underreported
2100 fire ant exposures with 250 requiring a
hospital visit and no deaths
AAAI survey 20,750 fire ant exposures
annually
Venom Pathophysiology
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Bees and Wasps
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Bees: Melittin, hyaluronidase, mast-cell
degranulation protein
Wasps: very similar with addition of Ach and
serotonin
Red fire ants
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Piperidine alkaloid causing histamine release and
skin necrosis
Cytotoxic and hemotoxic properties
Taken from WebMD.com
Clinical Syndromes
Bees and Wasps
 Small, local pruritic skin lesion. Larger local
reactions >5cm do occur and may last longer.
 Occasionally a mild systemic reaction occurs with
n/v, diarrhea, diffuse urticarial skin lesions.
 Very rarely, a victim will present with full blown
anaphylaxis
 Massive envenomation >50 stings CV collapse
 Delayed systemic toxicity: This includes hemolysis,
thrombocytopenia, liver dysfunction, and
rhabdomyolysis with subsequent renal failure
Red fire ants
 Multiple stings rule rather than exception
 Hundreds of pustules at bite sites
 Burning pain at each lesion
 25% of population in endemic areas has
hypersensitivity
 Resultant anaphylactic reaction possible
 Systemic venom toxicity after mass envenomation
Treatment
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Prehospital:
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Airway management, nebulizers, epinephrine,
fluids
Note number and location of stings, progression
Hospital:
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Same with addition of steroids and H1 and H2
blockers, pressors as needed for CV support,
tetanus
Massive envenomation requires monitoring for
rhabdo, hemolysis, ARF, and liver failure
Disposition
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Local: discharge after symptomatic care
Mild allergic reaction: discharge after 6 hours
with 3 days of oral antihistamines and oral
steroids
Moderate to anaphylaxis: admission, Epi-pen,
allergist referral, medic-alert bracelet
Mass envenomation: admission even if
asymptomatic due to delayed systemic toxicity
Reptilian
Envenomation
North American Offenders
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Crotalidae or Pit Vipers
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Elapidae
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Rattlesnake
Cottonmouth
Copperhead
Coral Snake
Multiple species of each located all over the
USA except Maine, Alaska and Hawaii
Epidemiology
Scope of the Problem
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In 2005 AAPCC reported 2900 pit viper bites
with 1875 being evaluated at a hospital and 6
deaths. 171 considered life-threatening. Not all
reported. 25% of bites are “dry bites”
Reported 58 coral snake bites with 6 lifethreatening and no deaths
Morbidity fairly high with lost productivity
due to pain and reduced function
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Worldwide a much bigger problem
Best estimates are as high as 1.8 million bites
per year with 94,000 deaths
Biggest problem in southern Asia and SubSaharan Africa due to lack of antivenin, rural
locales, and much higher incidence of lethal
species
Venom Pathophysiology
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Hemotoxic venom (Pit Vipers)
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One of most complex venoms
Thrombin-like enzymes: coagulopathy
Phospholipases: platelet dysfunction
Metalloproteinases:leaky vasculature with edema
and ecchymosis
Bradykinin: hypotension, N/V/D, pain
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Neurotoxic venom (Coral Snake and Mojave
Rattlesnake)
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Disrupts neuromuscular transmission by blocking
Ach receptors with resultant weakness,
paresthesias, and respiratory paralysis
Taken from emedicine article published by University of Tennessee
Pediatric Emergency Medicine Practice
May 2007 Vol. 4 No. 5
Pit Viper Treatment
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Prehospital
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ABCs
Assess for systemic symptoms
Note bite site, bite time and snake type
Mark initial area with time and follow progression
Elevate to level of heart
Compression dressing or pressure-immobilization
Transport immediately to facility with antivenin
Do Not…..
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Perform
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Cryotherapy (the old ice bucket)
Electrotherapy (jumper cables…I’m not kidding)
Cut and suck method
Sawyer extractor
Tourniquets
Treatment
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Hospital
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ABCs
Note progression
Labs
Grade envenomation
Determine need for CroFab (see next slide)
Tetanus update
Weant KA, Johnson PN, Bowers RC, Armitstead JA; Evidence-Based, Multidisciplinary Approach to the Development of a
Crotalidae Polyvalent Antivenin (CroFab) Protocol at a University Hospital. The Annals of Pharmacotherapy 2010;
44:xxxx.
Weant KA, Johnson PN, Bowers RC, Armitstead JA; Evidence-Based, Multidisciplinary Approach to the Development of a
Crotalidae Polyvalent Antivenin (CroFab) Protocol at a University Hospital. The Annals of Pharmacotherapy 2010;
44:xxxx.
To cut or not to cut….
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Fasciotomy very rarely indicated
Mimics compartment syndrome
Usually subcutaneous edema
Antivenin will almost always reverse true
compartment syndrome
Only proceed to fasciotomy if elevated
pressure sustained and confirmed with
measurement
A word on CroFab….
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Only FDA approved Pit Viper antivenin
currently
Other good antivenins used in Central and
South America for pit vipers
Much less expensive
Do work on North American species
Used by local venom expert
Treatment
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Coral Snakes (Elapids)
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Respiratory support as needed
Return of muscular function can take weeks
requiring prolonged intubation
Antivenin is available in USA but whole IgG so no
longer produced
Other possibilities include mexican product and
Tiger snake antivenin from Australia
Disposition
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Pit Viper (Crotalid)
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Observe 8 hours. If no symptoms then may
discharge
No CroFab warranted but envenomated: Discharge
with lab and MD follow up 24-48 hours
CroFab given: admission to floor versus ICU
depending on clinical scenario
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Coral Snake (Elapid)
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Admission warranted even if asymptomatic
Some argue to give antivenin empirically given
severity of envenomation
Arachnid
Envenomation
North American Offender
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Centruroides exilicauda or the Bark Scorpion
Found in Southwestern USA mainly in Arizona
Few in Texas, Northern Mexico, and areas of
California
Epidemiology
Scope of the Problem
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In 2005 AAPCC reported 14,521 reports of
scorpion envenomation
20 victims felt to have life threatening
outcomes
No deaths reported that year
Almost all lethal envenomations are children
or occur outside the US
Venom Pathophysiology
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No cytotoxins
2 potent neurotoxins enhance membrane
depolarization and prolong action potential
Over stimulation of parasympathetic and
sympathetic nervous system with Ach and
catecholamine release
Clinical Syndrome
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+ tap test over sting site
Autonomic dysfunction
Fasciculations and roving eye movements
Uncontrolled limb movements
Increased secretions including bronchorrhea
Mild envenomation: adrenergic syndrome
Severe envenomation: cholinergic syndrome
Additional treatments
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Sympatholytic antihypertensive agents for
hypertension
Atropine may be used to control secretions
Antivenin
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Antivenin:
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Previous goat serum derived has expired
New drug Anascorp manufactured in Mexico is
being trialed in Arizona
Using since 2004 and over 1500 patients treated
Still pending FDA approval
Disposition
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Most adults require supportive treatment only
Children more likely to suffer with
neuromuscular dysfunction and require ICU
admission and antivenin
North American Offenders
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Only 2 medically significant spiders in the
USA
Loxosceles reclusa or the Brown Recluse
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Found mainly in central and southern US decreasing
towards the coast
Latrodectus or the Black Widow Spider
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Found throughout the US
Epidemiology
Scope of the Problem
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In 2005 the AAPCC reported 2236 recluse
bites with 14 being life-threatening. High
morbidity
Over last 20 years 40,000 Black Widow
envenomations have been reported to AAPCC.
Mortality highest in children
Venom Pathophysiology
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Black Widow (Latrodectus)
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No cytotoxins
Alpha-latrotoxin most important
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Decreases reuptake of acetylcholine at NMJ
Also epinephrine
Brown Recluse (Loxosceles)
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Many cytotoxic components and inflammatory
mediators
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Sphingomyelinase D as well prostaglandins,
leukotrienes, and thromboxanes
Pediatric Emergency Medicine Practice
May 2007 Vol. 4 No. 5
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Brown Recluse
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Local tissue destruction
Systemic loxoscelism
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24-72 hours flu-like illness
Hemolysis, DIC, ARF, shock, pulmonary edema
Verified Brown Recluse Bite
Bites of Brown Recluse Spiders and Suspected Necrotic Arachnidism
David L. Swanson, M.D., and Richard S. Vetter, M.S.
N Engl J Med 2005; 352:700-707February 17, 2005
Treatment of Brown Recluse
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Delayed surgical excision
No to Dapsone
No to Steroids
No to nitroglycerine
No to HBO
Systemic Loxoscelism requires supportive treatment
Antivenin
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Rabbit-derived Fab fragments
Must be administered within 4 hours
Typical delay makes this impractical
Pediatric Emergency Medicine Practice
May 2007 Vol. 4 No. 5
Pediatric Emergency Medicine Practice
May 2007 VOl.4 No. 5
Black Widow antivenin
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Whole IgG with high incidence of serum
sickness and hypersensitivity
Reserved for severe autonomic dysfunction
and pain
A Fab antivenin is being tested
Disposition
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Black Widow
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May discharge after 6 hours if asymptomatic
Admission otherwise for IV opiates and benzos
Brown Recluse
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Most can be discharged with follow-up for longterm wound care
ICU admission for systemic syndrome
Be careful out there!!!
??????
Questions
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Bites and Stings-Snakes, spiders, and scorpions in the United States.
Pediatric Emergency Medicine Practice May 2007 Vol. 4 No. 5
Hymenoptera envenomation: Bees, Wasps, and Ants. Pediatric
Emergency Medicine Practice June 2008 VOl. 5 No.6
Antivenom for Critically Ill Children with Neurotoxicity from Scorpion
Stings. NEJM 2009; 3360:2090-8.
Bites of Brown Recluse Spiders and Suspected Necrotic Arachnidism.
NEJM 2005; 352:700-7
The global burden of snakebite: a literature analysis and modeling based
on regional estimates of envenoming and deaths. PLoSMed. 2008 Nov
4;5(11):e218
Evidence-Based, Multidisciplinary Approach to the Development of a
Crotalidae Polyvalent Antivenin (CroFab) Protocol at a University
Hospital. The Annals of Pharmacotherapy March 2010 Vol. 44