American Critter Bites
and Stings
Kalpesh Patel, MD
Department of Pediatric
Emergency Medicine
June 14, 2006
Objectives
2
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
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
3
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
4
Irritants - Treatment
 Wash copiously with sea water or normal saline
 Benadryl
 Topical/Oral Steroids
5
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
6
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
8
 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
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
9
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
10
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
11
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
12
Marine Vertebrates
 Stingrays
 Catfish
 Scorpaenidea
 Sharks!
13
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
14
Stingrays - Treatment
15
 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
Scorpaenidae
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 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
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
17
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
18
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
–
–
–
–
–
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Lacerations
Soft tissue loss
Amputation of limb
Comminuted fractures
Hemicorpectomy
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
21
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
23
Ticks
24
 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
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
25
Ticks – The Movie
Ticks – The Sequel
Revenge of the Tick
Brown Recluse Spider
Loxosceles reclusa
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 Southern and midwestern 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
Brown Recluse – Clinical Signs
30
 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
Brown Recluse - Management
31
 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
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
33
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
34
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
35
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
36
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
37
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
38
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
39
Insects - Management
40
 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
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
41
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
42
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
43
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
44
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
45
Snakes
 US has 120 different
species of snakes
• Only 15% poisonous
 Two families:
• Crotalidae (pit
vipers) 99% of
snakebites
• Elapidae 1% of
snakebites
46
Identifying Poisonous Snakes
47
Crotalids
48
 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
 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)
49
Crotalid Bites - Symptoms
50
 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
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
51
Snake Bite Kits
52
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
53
Crotalid Antivenin
54
 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
Crotalid - Management
55
 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
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
56
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”
57
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
58
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
59
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
60
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
61
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
62
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
63
Cat Bites
64
 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
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
65
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
66
Mammal Bites - Treatment
 Meticulous and prompt wound care
• Scrubbing with soft sponge and 1% povidoneiodine 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
67
Mammal Bites - Treatment
68
 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
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
69
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.
70
Questions?
71