Terrestrial Bites and Stings

Brian Costello, MD

Department of Pediatric Emergency Medicine

June 24, 2010

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Objectives

By the end of this lecture you should be able to: Describe the management and treatment for

• Reptile envenomations• Arthropod envenomations• Mammalian bites and common associated

infections Understand and perform initial management of

these injuries, such as• Local wound care• Venom specific antidotes• Stinger and tick removal

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Snakes

US has 120 different species of snakes• Only 15% poisonous

Two families:• Crotalidae (pit

vipers) 99% of snakebites

• Elapidae 1% of snakebites

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Identifying Poisonous Snakes

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Include Water Moccasin (aka Cottonmouth), Rattlesnake, and Copperhead

Venom is a combination of necrotizing, hemotoxic, neurotoxic, nephrotoxic and cardiotoxic substances

• Mojave rattlesnake has a large fraction of neurotoxin

• Neurotoxin prevents depolarizing action of acetylcholine (paralytic)

• Proteolytic enzyme acts like hyaluronidase causing local tissue destruction, swelling

• Increased capillary leak – shock, respiratory failure

• Hemotoxic effects include hemolysis, thrombocytopenia and fibrinogen proteolysis leading to bleeding diathesis

Crotalids

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Crotalids

Small children are more susceptible to venom given their size compared to adults causing more systemic symptoms

Bites on the head, neck or trunk hasten systemic absorption

Most bites are on the extremities Measure the distance between the two fang marks

to estimate snake size• 8 mm = small snake• 8-12 mm = medium snake• >12 mm = large snake

10-20% of rattlesnake strikes are “dry” (no venom)

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Crotalid Bites - Symptoms

5-10 min – Intense pain, erythema, and edema Perioral numbness with metallic taste N/V, chills, weakness, syncope, sweating Neuromuscular symptoms after a few hours:

• Diplopia, difficulty swallowing, lethargy, progressive weakness

Next 8 hours – Progressive edema at wound site Shock – usually 6-24 hrs (may be as soon as 1 hr) Vesicles and hemorrhagic blebs by 24 hours Edema may lead to compartment syndrome and

necrosis Secondary infection – gram-negative bacteria

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Crotalid - Management

Pre-Hospital • ABCs• Rest• Take off jewelry and clothing from affected

extremity• Immobilize extremity and keep below level of

heart• Keep warm• NPO• Constriction band (experienced hands only)• Incision and Suction kit if available (must use

within 5-10 minutes of bite)• Rapid transport to medical facility

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Snake Bite Kits

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Crotalid - Management

ED• IV access, fluids, (central line & CVP?), morphine• If snake is brought to ED, treat it with respect

Many people bitten by “dead” snake Decapitated snakes bite reflexively for up to 1

hour• Measure circumference of extremity at leading

point of edema and 10 cm proximal Q30min X 6 hours, then Q4 for 24 hours

• CBC with platelets, coags, type and cross, U/A • If moderate or severe poisoning, then also get

BMP, fibrinogen and ABG• Repeat labs Q4-6 hours

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Crotalid Antivenin

AVCP polyvalent antivenom• Horse serum, highly antigenic – needs skin

testing prior to giving• Don’t use it if you can get CroFAB

CroFAB• Sheep derived antibody with cleaved Fc portion

Cleared from kidneys fast• Less adverse reactions

For maximal binding, use antivenom within 4 hours of bite.

Dosage NOT based on weight. Kids need more.

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Crotalid - Management

CroFAB• Initial dose is 4-6 vials• Repeat initial dose if there is progression of

symptoms• Once there is no progression, then give either:

2 vials Q6h for 3 doses OR 2-6 vials if progression of symptoms recur

• Admit to PICU• All patients must be reexamined in 2-5 days after

bite• Watch for serum sickness up to 3 weeks out

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Crotalid - Management

Local wound care Tetanus prophylaxis NO ice to wound Watch for signs of compartment syndrome, call

surgery Superficial debridement needed in 3-6 days

• Local oxygen, aluminum acetate 1:20 solution, triple dye

Blood products for coagulopathy No prophylactic antibiotics (current thinking) Physical therapy in healing phase

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Elapids

Only 3 poisonous Elapids in US:• Eastern Coral Snake –

Found in Georgia• Texas Coral Snake• Arizona Coral Snake• “Red on yellow, kill a

fellow; Red on black, venom lack”

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Elapids

Coral snakes are relatively passive (10-15 bites/yr in US)

Share physical characteristics of non-venomous snakes (round pupils, blunt head) but have fangs

Uses a potent neurotoxin Local signs are minimal with little pain Several hours later, pt will develop malaise, N/V,

muscle fasiculations and weakness Neurologic signs include diplopia, difficulty talking

or swallowing, bulbar dysfunction, and generalized weakness

Risk of respiratory failure

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Elapids - Management

Tourniquets, incision & suction, etc. don’t work for coral snakes

If eastern or Texas coral snake is suspected, give antivenin• Horse serum derived, requires skin testing before

giving• Dosage is 3-5 vials IV• Repeat if signs of venom toxicity continue• Antivenin not in production as of 2008

No antivenin available for Arizona coral snake Admit to PICU

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Quiz: Name Georgia’s Venomous Snakes…

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Georgia Venomous Snakes

Georgia Carolina Pygmy Rattlesnake - Sistrurus miliarius miliarius Dusky Pygmy Rattlesnake - Sistrurus miliarius barbouri Eastern Coral Snake - Micrurus fulvius Eastern Cottonmouth - Agkistrodon piscivorus piscivorus Eastern Diamondback Rattlesnake - Crotalus adamanteus Florida Cottonmouth - Agkistrodon piscivorus conanti Northern Copperhead - Agkistrodon contortrix mokasen Southern Copperhead - Agkistrodon contortrix contortrix Timber Rattlesnake - Crotalus horridus Western Cottonmouth - Agkistrodon piscivorus leucostoma

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Exotic Snakes

Consult a medical herpetologist or poison control (1-800-222-1222)

Contact your local zoo• Required by law to carry antivenin for the snakes

they have Report illegally possessed reptiles to the police

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Arthropods (“Bugs”)

Largest phylum in the animal kingdom Terrestrial Invertebrates

• Centipedes/Millipedes• Ticks• Spiders• Scorpions

Insects• Bees• Hornets• Yellow Jackets• Wasps• Fire Ants

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Very few are dangerous to humans in North America• Centruroides sculpturatus (“Arizona bark

scorpion”) -- southwestern U.S. Grasps prey by pincers and then stings with tail Nocturnal

• Crawl into sleeping bags and unoccupied clothing

Injects an excitatory neurotoxin affecting autonomic and skeletal nervous systems -minimal local edema• Pain, restlessness, hyperactivity, roving eye

movements, respiratory distress/failure• Convulsions, drooling, hyperthermia,

HTN/tachycardia

Scorpions

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Scorpions - Management

Cryotherapy (ice) at sting site and supportive care Antivenin if symptoms persist after supportive care

• Tachycardia• Fever• Severe hypertension• Agitation• Available from Antivenom Production Laboratory,

Arizona State University, Tempe, Az. Phenobarbital or other sedative/anticonvulsants for

persistent hyperactivity, convulsions or agitation Calcium gluconate 10% 0.1ml/kg for muscle

contractions (used but unproven)

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Brown Recluse Spider (Loxosceles)

Brown violin shaped mark on dorsum of cephalothorax (“Fiddleback”)

Usually outdoors, but make indoor nests in closets

Shy and will only attack when provoked

Venom is cytotoxic (hyaluronidase-like factor)

Loxosceles reclusa

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Loxosceles Geographic Distribution

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2-8 hours• Local reaction with mild-moderate pain• Erythema, central blister or pustule

24 hours• Fever, chills, malaise weakness, N/V, rash with

petechiae, joint pain, DIC, hematuria, renal failure, hemolysis, respiratory failure

• Subcutaneous discoloration that spreads over 3-4 days

• Spreads to 10-15 cm• Pustule drains leaving ulcerated crater that scars

Scar formation is rare if no necrosis after 72 hrs Reaction varies according to amount of

envenomation

Brown Recluse – Clinical Signs

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Brown Recluse Bite Mimics in Children

Staph/strep (MRSA) Herpes simplex Herpes zoster E. multiforme Lyme disease Fungal infection P. gangrenosum Chemical burn Poison ivy/oak

Other spider bite:1.Golden orb weaver (North

America)

2.Running (or sac) spider (U.S.)

3.Wolf spider (U.S.)

4.Black jumping spider (Atlantic coast to Rocky Mountains)

5.Hobo spider (Pacific Northwest)

6.Fishing spider (U.S.—lakes and streams)

7.Green lynx spider (Southern U.S.)

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It’s NOT a brown recluse if…

It's really BIG!  The size of the body, not including legs, of a recluse is smaller than a dime.

It's really HAIRY!  Brown recluses have only very fine hairs that are invisible to the naked eye.

It JUMPS!  Jumping spiders live up to their name, and some other spiders including wolf spiders occasionally jump, but recluses don't.

I found it in a WEB!  Brown recluses don't spin a web to catch prey; they spin silk retreats and egg cases, but don't form a typical recognizable web.

It has DISTINCT MARKINGS VISIBLE TO THE NAKED EYE, such as stripes, diamonds, chevrons, spots, etc. that are easily seen!  The "violin" is very small and located on the front half of the body.  The violin is also indistinct in some, especially young spiders. They're really pretty dull looking.

http://department.monm.edu/biology/recluse-project/identify.htm

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Quiz: Indentify 2 Brown Recluses…

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Brown Recluse - Management

Unless spider is brought for ID, definitive diagnosis cannot be made

Good local wound care If systemic symptoms, then CBC with platelets,

U/A, BUN, creatinine• Vigorous supportive care in PICU as needed

Surgical excision and (rarely) skin grafting after necrosis is demarcated

Steroids, heparin, and hyperbaric O2 don’t work

No Dapsone for kids – methemoglobinemia No antivenom available Have wound rechecked daily for progression

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Black Widow (Latrodectus)

Shiny black spider with brilliant red hourglass marking on abdomen

Only the female bite is dangerous• Male spiders are ¼ the size of

females and bite cannot penetrate human skin

Females not aggressive unless provoked or guarding egg sac

Produces a neurotoxin—stimulates myoneuronal junctions, nerves, nerve endings

Latrodectus mactans

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No local symptoms 1-8 hours after bite

• Generalized pain and muscle rigidity Cramping pain to abdomen, flanks, thighs,

chest – “rigid abdomen”• Chills, N/V• HTN, Tachycardia• Respiratory distress• Urinary retention• Priapism• Death from cardiovascular collapse

Mortality 50% in young children

Black Widow – Clinical Signs

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Black Widow - Management

Children < 40kg: Antivenin given as soon as bite confirmed• Dose: 2.5ml (one vial)

Children >40kg: not as urgent to give immediately; indicated in age <16, respiratory difficulty, significant hypertension

Morphine or Demerol Calcium gluconate 10% solution 0.1ml/kg IV over 5

minutes for muscle cramps• Recent series showed effective in only 4% of

cases• Valium can be used, but is short lived with

variable effects; Robaxin is ineffective Admit to PICU

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Other Spiders

Tarantulas• Do not bite unless provoked• Venom is mild and not a problem

Wolf Spider and Jumping spider• Mild venom only causes local reaction

Treatment is good local wound care

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Centipede/Millipede

Centipedes• Bites with jaws that act like stinging pincers• Extremely painful• Toxin is innocuous – local reaction only

Millipedes - harmless Treatment

• Local anesthetic at wound site• Local wound care

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Ticks

Transmit many other infectious diseases:• Spirochetes – Lyme Disease, relapsing fever• Viruses – Colorado tick fever• Rickettsiae – Rocky Mountain spotted fever• Bacteria – tularemia, ehrlichiosis, babesiosis• Protozoa

Tick paralysis – wood tick, dog tick, deer tick• Tick releases neurotoxin producing cerebellar

dysfunction and ASCENDING Weakness• Latent period for 4-7 days• Restlessness, irritability, ascending flaccid

paralysis, respiratory paralysis, death

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Tick Paralysis - Management

Diligently search for the tick Remove using blunt forceps held close to skin Do not squeeze – can release infective agents Admit to hospital for ascending paralysis, PICU if

worried about respiration

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Bees have a barbed stinger next to a venom sac which can remain in the victim’s skin

Bees die after the stinger is dislodged

The stinger must be removed if seen – don’t delay, move venom is released with time• Scraping works best, don’t pull

or squeeze Wasps, Yellow Jackets, and

Hornets can sting multiple times

Bees, Hornets, Yellow Jackets, & Wasps

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Insects

Venoms contain protein antigens which elicit an IgE antibody response

Major problem is allergic reactions and anaphylaxis• Group I – local response• Group II – Mild systemic reactions

Generalized itching and urticaria• Group III – Severe systemic reactions

Wheezing, angioneurotic edema, N/V• Group IV – Life threatening reactions

Laryngoedema, hypotension, shock Occurs in 0.5-5% of the population from insects

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Insect - Management

Group I – cold compresses Group II – Benadryl 4-5 mg/kg/day divided QID Group III

• Epinephrine 1:1000 0.01 ml SQ (max 0.3ml) (IM?)

• Benadryl PO

• H2 blockers

• Steroids (?)• Admit to hospital for 23 hr obs

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Insects - Management

Group IV – may need intubation• All of the above, plus• Wheezing refractory to epinephrine may need

aminophylline 6mg/kg bolus over 20 minutes, then 1.1 mg/kg/hr infusion

• Hypotension Fluid bolus IV epinephrine 1:10,000 IV Hydrocortisone 2mg/kg Q6h

• Admit to PICU

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Insects - Management

Group III or IV reactions need referral to an allergist for hyposensitization

After obs, D/C home with EpiPen Jr.• Spring loaded autoinjectors self-administered in

the thigh• Always write for the twin pack

Contains practice syringe and 2 loaded syringes

• Parents should give this in the field AND seek further care

Avoid wearing bright colored clothing, perfumes Wear long sleeved garments, gloves when

gardening and hats Medical alert bracelets or necklaces

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Fire Ants

Wingless member of Hymenoptera

Bites with jaws and pivots head to give multiple stings

Venom is an alkaloid with direct effect on mast cell membranes

Solenopsis richteri and Solenopsis invicta

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Red Imported Fire Ant (RIFA)

Arrived in 1930s from South America via port of Mobile, Ala.

Build mounds in sunny, open areas (e.g., lawns and parks)

Aggressively attack anyone who disrupts their mound

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Fire Ants – Clinical Presentation

Immediate – wheal and flare

4 hrs – vesicle 8-10 hours – vesicle

becomes umbilicated pustule

24 hrs – vesicle surrounded by painful erythematous area that lasts 3-10 days

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Fire Ants - Treatment

Symptomatic care• Ice• Cleansing• Antihistamines for itching• Steroids, antibiotics and antihistamines don’t

have an effect on the lesions Occasional systemic reactions (hives, anaphylaxis)

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Mammalian Bites

Dog bites account for 80-90% of all mammal bites Cats 5-10% Rodents 2-3% Humans 2-3% Other wild or domestic animals make up the rest

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Mammal Bites

Dogs generate strong forces and cause local crush injuries

Only 5-10% of bites become infected because wound is easily cared for and not very deep

Cat bites cause deep puncture wounds with 50% infection rate• May penetrate fascial compartments, tendons,

vessels and bones Most common bacteria: Staphylococcus &

Pasturella species Human bites are Strep viridans or Staph aureus Also many anaerobes are mixed in: Bacteroides,

Peptostreptococcus, Eikenella corrodens

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Dog Bites

Usually attack head and neck in most victims Cause lacerations of lips, nose and cheek May penetrate the skull and cause depressed skull

fracture

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Cat Bites

Usually attack upper extremities Pasturella infections are very aggressive

• Symptoms begin at 12-24 hours with erythema, significant edema and intense pain

Cats also scratch, especially the face Consider corneal abrasions Bartonella henselae

• Papule at site of scratch with later regional lymphadenopathy

• Self limited, resolves in 2-3 months• May have unusual manifestations:

encephalopathy, hepatitis, atypical pneumonia

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Typically involve the hand when punching someone in the mouth• Wound overlies the MCP joint, consider Boxer’s

fracture• Mild swelling in 1-2 days to site• If there is pain with active or passive finger

motion, then consider tendonitis or deep compartment infection

• Also consider Hepatitis B and syphilis being spread by bites

Human Bites

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Rodent Bites and Other Mammals

Rat-bite fever (rare) Pet owners and lab workers

• 2 forms: Haverhill fever (Streptobacillus moniliformis) Sodoku (spirullum minus)

• 1-3 week incubation period• Chills, fever, malaise, rash, headache• Both forms responsive to IV penicillin

Rabbits – tularemia

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Mammal Bites - Treatment

Meticulous and prompt wound care• Scrubbing with soft sponge and 1% povidone-

iodine solution Stronger solutions retard wound healing

• Pressure irrigation Facial wounds require primary closure for cosmesis Hand wounds should have delayed primary closure

or heal by secondary intention due to infection rate• Place a few deep sutures to bring wound

together• Skin sutures placed in 3-5 days

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Mammal Bites - Treatment

Antibiotic prophylaxis• No perfect drug, but Augmentin is close• If allergic, then a combination of clindamycin

PLUS a 2nd or 3rd gen cephalosporin OR Bactrim• First dose should be given in the ED

Infected bites require aggressive drainage and debridement• Obtain aerobic and anaerobic deep would

cultures• Leading edge would culture for cellulitis• Admit for IV antibiotics

Tetanus prophylaxis

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Rabies

Rabies virus• Virus transmitted through scratches, abrasions

and animal saliva contact with mucous membranes

• Causes an progressive, irreversible encephalopathy traveling up peripheral nerves to the brain Anxiety, insomnia, confusion, agitation,

hypersalivation, hydrophobia• Unprovoked attacks• Wild carnivorous animals, BATS• Rodents, squirrels and rabbits are considered

no-risk

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Rabies

If the animal can be observed, then prophylaxis can be delayed

If the animal shows signs of rabid behavior, then start the patient on prophylaxis immediately• Animal will be sacrificed and brain biopsy will be

done to look for rabies Prophylaxis is with passive antibody (RIG) and

vaccine HDCV• RIG is given once, half IM and the other half

infiltrated around bite• HDVC is given 1.0 ml IM on days 0,3,7,14

(Reduced 4-dose vaccine schedule as of 2010)

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Questions?