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