bites and stings - ohsu.edu · arthropod bites in u.s. vaughn mg, holzer kj, carbone jt,...
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Bites and StingsJenna M. Wiley, MD
Wilderness Medicine Fellow
Oregon Health & Science University
Sept 18, 2020
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Question• What animal causes the most deaths in the U.S.?
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Objectives
• Prevention, Identification, Treatment• Bee stings
• Scorpion stings
• Mammal bites
• Snake bites
• Spider bites
• Tick bitesOHSU
Arthropod Bites in U.S.
Vaughn MG, Holzer KJ, Carbone JT, Salas-Wright CP. Arthropod Bites and Stings Treated in Emergency Departments: Recent Trends and Correlates. Wild & Env Med; 2019: 30(4): 394-400
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Hymenoptera
• Three families• Hornets, wasps, yellow jackets
• Bees
• Ants and fire ants
Source: Wikimedia commons
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Hymenoptera
• Allergic reactions leading to anaphylaxis are the most common reason for deaths
Source: Wikimedia commons
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Hymenoptera Treatment
• Remove stinger
• Wash with soap and water
• Ice
• Treat anaphylaxis• epinephrine
• diphenhydramine (Benadryl)
Source: Wikimedia commons
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Scorpions
• Most stings cause local symptoms
• Deaths rare, usually multiple stings• Elderly
• Children Source: NPS.gov
• Severe symptoms usually
from Centruroides species• “bark” scorpion
• Southwest U.S.
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Bear Attacks
Source: Wikimedia commons Source: Wikimedia commons
Source: nps.gov
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Cougar attacks
• Becoming more common
• Stalk, pounce and break the cervical spine
• May be scared off by aggressive behavior
• Fight back with any object available
• Do NOT run away
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Cougar attacks
• Becoming more common
• Stalk, pounce and break the cervical spine
• May be scared off by aggressive behavior
• Fight back with any object available
• Do NOT run away
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Animal bites
• Initial Treatment• Examine for blunt
trauma/crushing injury/bleeding
• Examine penetrating trauma for deep neurovascular and tissue damage
• Irrigate and debride wound
• Antibiotics
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Animal bites
• Rabies• Bats
• Racoons
• Skunks
• Foxes
• Coyotes
• Irrigate and debride, can use viricidal agent like povidone iodine
Source: https://www.cdc.gov/rabies/location/usa/surveillance/wild_animals.html
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Venomous Snakes
• 9,000 ED visits annually in U.S.3
• Venomous species account for approx 1/3 of these visits3
• Native to the U.S.• Pit vipers
• (subfamily Crotalinae)
• Coral snakes• (family Elapidae)
Coral Snake
Source: californiaherps.com
Northern Pacific Rattlesnake
Source: nps.gov
California Mountain King Snake
Source: OR Dept Fish & Wildlife
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US Pit Vipers• Anatomy
• Triangular heads
• Elliptical pupils
• Heat sensitive pits between their eyes and nose
• Hinged teeth that swing to 90ºOHSU
Pit Viper Envenomation
• Amount of venom varies among species
• Hemotoxic vs Neurotoxic
• Seriousness depends on:• Duration of fang contact
• How deep fangs pierce
• Health of patient
• Allergy to venom
• How agitated snake was
• Age of the snake
• Intravenous injectionSource: Encyclopedia Britannica
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Pit Viper Envenomation
• Venom causes local tissue necrosis and systemic symptoms
• Cannot determine severity of envenomation by initial symptoms
• 1 bite in 4 carries no venom (“dry bite”)
Source: www.nydailynews.com
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Snake bite field Treatment
Mechanical suction
Oral suction
Wound care
Sling
Ice packs
Electrotherapy
Incision & Bleeding
Pressure wrap
Evacuate
Tourniquet
How should you treat a snake bite in the field when you suspect envenomation?OHSU
Snake bite field Treatment
How should you treat a snake bite in the field when you suspect envenomation? Mechanical suction
Oral suction
Wound care
Sling
Ice packs
Electrotherapy
Incision & Bleeding
Pressure wrap
Evacuate
TourniquetOHSU
Spider bites
• At least 60 types of spiders are known to bite humans
• All spiders are venomous
• Just 3 spiders in N. America are venomous• Black widow
• Brown recluse
• Hobo
Source: Wikimedia Commons Source: nps.gov
Source: Wikimedia Commons
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Black Widow
• Red hourglass
• Venom is potent neurotoxin
• Rarely fatal
• Signs/Symptoms• Headache, chills, fever, heavy sweating, dizziness,
nausea and vomiting, and severe abdominal pain
• Occur within 30 to 60 minutes of the bite
• Treatment• Ice (pain control)
• Antivenin
Source: Wikimedia CommonsOHSU
http://watchingtheworldwakeup.blogspot.com/2008/06/black-widows-part-1-chemistry-of-venom.html
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Brown Recluse• Violin marking on top of body
• Signs/Symptoms• Initially painless (may be 2-8 hrs before onset of
symptoms)
• Necrotic lesion
• Treatment• Clean with soap and water
• Elevate and loosely immobilize the extremity
• Cold compress
• Oral analgesics
• Hospitalize if systemic symptoms
Source: nps.gov
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Brown Recluse• Violin marking on top of body
• Signs/Symptoms• Painless (may be 2-8 hrs before symptoms)
• Rash that may become necrotic over days to weeks
• Treatment• Clean with soap and water
• Elevate and loosely immobilize the extremity
• Cold compress
• Oral analgesics
• Hospitalize if systemic symptoms
Source: nps.gov
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Brown Recluse• Violin marking on top of body
• Signs/Symptoms• Painless (may be 2-8 hrs before symptoms)
• Rash that may become necrotic over days to weeks
• Treatment• Clean with soap and water
• Elevate and loosely immobilize the extremity
• Cold compress
• Oral analgesics
• Hospitalize if systemic symptoms
Source: nps.gov
Source: Pattie et al. Brown Recluse Bite. JET EM. 2019
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Hobo Spider
• 10-15 mm with yellow-green tint
• Builds funnel webs
• Signs/Symptoms• Local necrosis usually within 36 hrs
• Treatment• Supportive
• Clean site with soap and water
• Oral analgesics
Source: Wikimedia CommonsOHSU
Source: https://utahpests.usu.edu/uppdl/hobo-spiders
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TIcks
Source: CDC
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Source: igenex.com
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TIcks
• Prevention• Long-sleeved, loose-fitting clothes
tucked in
• DEET, permethrin
• Tick checks
• Treatment• Remove tick as soon as possible
• Infection less likely if tick
removed in < 24 hrs
• Use tweezers
• Grab tick near skin, pull
back with gentle, steady
pressure
• Clean bite areaSource: CDCOHSU
Recall
• In what type of bite should ice be avoided?
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Summary
• Hymenoptera• Responsible for many deaths in U.S.
• Treat anaphylaxis
• Scorpions• Most cause mild-moderate pain
• Bark scorpions responsible for significant symptoms that require evacuation
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Summary
• Bites from terrestrial animals• Wound cleansing
• Evaluate for foreign bodies
• Monitor for signs of infection
• Consider rabies and tetanus risk
• Snakes• Evacuate unless you know for sure it was a
nonvenomous snake bite
• Local wound care
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Summary
• Ticks• Remove with gentle traction
• Monitor for development of systemic symptoms
• Spiders• Black widow bites require significant
analgesia
• All others can be monitored as risks are low
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References
1. Center for Disease Control and Prevention: https://www.cdc.gov/rabies/index.html
2. Forrester JA, Weiser TG, Forrester JD. An Update on Fatalities Due to Venomous and Nonvenomous Animals in the United States (2008–2015). Wild & Environ Med, 2018; 29 (1): 36
3. Kanaan NC, Ray J, Stewart M, Russell K, Fuller M, Bush SP, Caravati EM, Cardwell MD, Norris RL, Weinstein SA. Wilderness Medical Society Practice Guidelines for the Treatment of Pitviper Envenomations in the United States and Canada. Wild & Environ Med 2015: 26, 472-87.
4. Patti LA, Landgraf B, Bryczkowski C. Brown Recluse Spider Bite. JET EM. 2019: 4(3)
5. Quinn RH, Wedmore I, Johnson E, Islas A, Anglim A, Zafren K, Bitter C, Mazzorana V. Wilderness Medical Society Practice Guidelines for Basic Wound Management in the Austere Environment: 2014 Update
6. Vaughn MG, Holzer KJ, Carbone JT, Salas-Wright CP. Arthropod Bites and Stings Treated in Emergency Departments: Recent Trends and Correlates. Wild & Env Med; 2019: 30(4): 394-400OHSU