American Critter Bites and Stings

Kalpesh Patel, MD

Department of Pediatric Emergency Medicine

June 14, 2006

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Objectives

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

• Marine invertebrate injuries• Insect envenomations• Reptile 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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Marine Invertebrates

Irritants• Hydras• Anemones• Common purple jellyfish• Sea nettle

Toxin producers• Portuguese man-of-war• True jellyfish• Lion’s mane

Handle with care• Corals• Sea Urchins

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Irritants

Hydras• Maine to Florida and Texas coastline• Attaches to solid objects• Causes mild sting• Requires local care

Anemones• US tidal zones• Mildly toxic at worst – skin irritation

Sea nettle and common purple jellyfish• Atlantic coast• Mildly toxic - skin irritation

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Irritants - Treatment

Wash copiously with sea water or normal saline Benadryl Topical/Oral Steroids

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Toxin Producers

Nematocysts• Specialized organelles

which have toxin-coated barbed threads that fire when a tentacle is touched.

• Cannot penetrate human skin

• May discharge even when the creature is dead and washed up on the beach

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Toxin Producers

Size matters• Man of war can have tentacles

up to 75 feet long with 750,000 nematocysts each

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Toxin Producers

Toxin causes severe pain• Made of polypeptides and degradative enzymes• Causes release of inflammatory mediators,

histamine and histamine-releasing agents, serotonin

• May cause systemic symptoms N/V, abdominal rigidity Respiratory distress Arthralgias Hemolysis, renal failure Coma Severe envenomation can cause death

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Toxin Producers

Lion’s mane• Found on both coasts• Highly toxic

Instrument of death in Sherlock Holmes classic Adventure of the Lion’s Mane

• Causes severe burning• Prolonged exposure causes

muscle cramps and respiratory failure

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Toxin Producers - Treatment

3 goals:• Control shock – IV, fluids, etc.• Control venom effects

Remove tentacles from skin– Inactivate unexploded nematocysts with vinegar,

meat tenderizer, or baking soda slurry– Apply this to patient as well

• Pain relief Immobilize the wound area Codeine, Morphine, or Demerol Treat muscle spasms with 10% Calcium

gluconate 0.1ml/kg IV Topical/Oral steroids, Benadryl

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Handle with Care

Corals, Sea Urchins, Starfish• Have jagged edges or hard spines• Cause deep puncture wounds or sea lacerations• Easily leave foreign bodies• Stinging sensation, wheal formation, itching• Wound infection very common

Vibrio species, Erysipelothrix rhusiopathiae, Mycobacterium marinum

Fever Cellulitis Lymphangitis

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Handle with Care - Treatment

Copious irrigation with saline X-ray for foreign bodies

• Soak affected area in warm water• Use local anesthetic and explore sterilely

Wounds should be left open or loosely approximated

Antibiotics please• >8 y/o: Tetracycline for 10 mg/kg/dose QID• <8 y/o: Keflex or Bactrim• Add staphylococcal coverage for foreign bodies

Don’t forget tetanus prophylaxis

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Marine Vertebrates

Stingrays Catfish Scorpaenidea Sharks!

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Stingrays

Most common marine vertebrate injury Flat fish, bottom feeders, buried under sand or mud Easily stepped on causing reflex envenomation

• Venom apparatus is a serrated, retro-pointed caudal spine on the tail

• Coated in venom sheath which ruptures on skin penetration Heat labile toxin Can depress medullary respiratory centers Interfere with cardiac conduction PAINFUL

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Stingrays - Treatment

PreHospital:• Irrigate copiously with cold salt water• Flushing can help remove toxin• Control bleeding with pressure

ED:• IV fluids, Morphine 0.1mg/kg/dose for pain• Make an attempt to remove the spine• Soak extremity in hot water (104-113F) to

inactivate the venom until pain relieved• X-ray for foreign body (spine fragments)• Re-explore wound after soaking• Tetanus prophylaxis• No prophylactic antibiotics

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Scorpaenidae

Zebrafish, scorpionfish, stone fish Non-migratory, slow swimming, buried in sand Envenomation occurs when handling fish on fishing

trips Venom delivered by many small spines like the

stingray Venom also heat-labile Symptoms

• Pain, N/V• Hypotension• Tachypnea leading to apnea• MI with EKG changes

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Scorpaenidae - Treatment

Copious irrigation with saline Hot water immersion until pain relieved Morphine 0.1mg/kg/dose Close cardiopulmonary monitoring Admit to PICU if having significant systemic effects

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Catfish

Spines in the dorsal and pectoral fins• Puncture wounds and laceration• Easily break off as foreign body• Venom causes local inflammation, pain, edema,

hemorrhage, tissue necrosis Treatment

• Irrigation• Hot water immersion• Morphine 0.1mg/kg/dose• Antibiotics for gram negatives• Delayed primary closure

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Sharks!

1 in 5,000,000 chance of attack in North America Gray reef, great white, blue, mako sharks Risk factors:

• Swimming near sewer outlets• Swimming in the late afternoon/early evening• Murky warm water• Increased commotion• Deep channels• Wearing bright objects• Surfers – boards are mistaken for elephant seals,

the shark’s usual diet in California

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Sharks!

Two types of bites:• Tangential injury

Close pass slashing movement teeth of open shark mouth

• Definitive bite Vary according to the part of the body bitten

– Lacerations– Soft tissue loss– Amputation of limb– Comminuted fractures– Hemicorpectomy

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Sharks!

Hypovolemic shock• Control bleeding with pressure• DON’T EXPLORE WOUNDS PREHOSPITAL• IV fluids, blood products as soon as available• Warmth• Oxygen• Surgery• Prophylactic antibiotics – 3rd gen cephalosporin

or bactrim• Tetanus prophylaxis• Admit to PICU for significant injury

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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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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 Do not squeeze – can release infective agents Admit to hospital for ascending paralysis, PICU if

worried about respiration

Ticks – The Movie

Ticks – The Sequel

Revenge of the Tick

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Brown Recluse Spider

Southern and mid-western states

Brown violin shaped mark on dorsum of cephalothorax

Usually outdoors, but make indoor nests in closets

Shy and will only attack when provoked

Venom is cytotoxic and contains hyaluronidase like factor

Loxosceles reclusa

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Brown Recluse – Clinical Signs

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

• Subcutaneous discoloration that spreads over 3-4 days

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

Scar formation is rare after 72 hrs Reaction varies according to amount of

envenomation

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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

Surgical excision and 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

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

Latrodectus mactans

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Black Widow – Clinical Signs

No local symptoms 1-8 hours after bite

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

chest• Chills• Urinary retention• Priapism• Death from cardiovascular collapse

Mortality 50% in young children

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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 unless having respiratory difficulty or significant hypertension

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

minutes for muscle cramps• Robaxin doesn’t work as well• Valium can be used, but is short lived with

variable effects 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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Bees, Hornets, Yellow Jackets, & Wasps

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

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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)• Benadryl PO

• H2 blockers

• No 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

Common in the South 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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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 Systemic reactions are rare

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Scorpions

Very few are dangerous to humans in North America• Centruroides sculpturatus

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• Pain, restlessness, hyperactivity, roving eye

movements, respiratory distress• Convulsions, drooling, wheezing, fever, cyanosis,

respiratory failure

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Scorpions - Management

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

• Tachycardia• Fever• Severe hypertension• Agitation

Phenobarbital or other sedative/anticonvulsants for persistent hyperactivity, convulsions or agitation

Calcium gluconate 10% 0.1ml/kg for muscle contractions

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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 Cottonmouth, Rattlesnake, Water moccasin, and Copperhead

Venom is a combination of necrotizing, hemotoxic, nephrotoxic and cardiotoxic substances• Mojave rattlesnake has a large fraction of

neurotoxin• Neurotoxin prevents depolarizating action of

acetylcholine (paralytic)• Proteolytic enzyme acts like hyaluronidase

causing local tissue destruction• 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• 8mm = small snake• 8-12mm = medium snake• >12mm = large snake

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

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Crotalid Bites - Symptoms

5-10 min – Intense burning pain and erythema Perioral numbness 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 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 • ABC’s• Rest• Take off jewelry and clothing from affected

extremity• Immobilize extremity and keep below level of

heart• Keep warm• NPO• Venous tourniquet (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. Use after 12 hours is questionable. Don’t use after 24 hours.

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

CroFAB2

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Crotalid - Management

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

surgery Debridement needed in 3-6 days

• Oxygen, Aluminum acetate 1:20 solution, triple dye

Blood products for coagulopathy No prophylactic antibiotics

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Elapids

Only 2 poisonous Elapids in US:• Eastern Coral Snake –

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

fellow; Red on black, venom lack”

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Elapids

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

muscle fasciculations and weakness Neurologic signs include diplopia, difficulty talking

or swallowing, bulbar dysfunction, and generalized weakness

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Elapids - Management

Venous tourniquet, Incision and suction don’t work for coral snakes

If eastern 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

No antivenin available for Arizona coral snake Admit to PICU

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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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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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Human Bites

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 syndrome

• Also consider Hepatitis B and syphilis being spread by bites

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Rodent Bites and Other Mammals

Ratbite fever (10% infection rate) 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

AND 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, and

28 = 5 total doses.

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Questions?