Terrestrial Bites and Stings

1. Terrestrial Bites and Stings Brian Costello, MD Department of Pediatric Emergency Medicine June 24, 2010

2. 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

3. Snakes • US has 120 different species of snakes • Only 15% poisonous • Two families: • Crotalidae (pit vipers) 99% of snakebites • Elapidae 1% of snakebites

4. Identifying Poisonous Snakes

5. Crotalids • 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

6. 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)

7. 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

8. 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

9. Snake Bite Kits

10. 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

11. 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.

12. 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

13. 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

14. 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”

15. 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

16. 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

17. Quiz: Name Georgia’s Venomous Snakes…

18. 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

19. 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

20. Arthropods (“Bugs”) • Largest phylum in the animal kingdom • Terrestrial Invertebrates • Centipedes/Millipedes • Ticks • Spiders • Scorpions • Insects • Bees • Hornets • Yellow Jackets • Wasps • Fire Ants

21. Scorpions • 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 excitatoryneurotoxin affecting autonomic and skeletal nervous systems -minimal local edema • Pain, restlessness, hyperactivity, roving eye movements, respiratory distress/failure • Convulsions, drooling, hyperthermia, HTN/tachycardia

22. 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)

23. 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

24. Loxosceles Geographic Distribution

25. 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, 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

26. 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: • Golden orb weaver (North America) • Running (or sac) spider (U.S.) • Wolf spider (U.S.) • Black jumping spider (Atlantic coast to Rocky Mountains) • Hobo spider (Pacific Northwest) • Fishing spider (U.S.—lakes and streams) • Green lynx spider (Southern U.S.)

28. 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

29. Quiz: Indentify 2 Brown Recluses…

30. 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

31. 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

32. Black Widow – Clinical Signs • 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

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; 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

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. 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

36. 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

37. 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

38. 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

39. 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

40. 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

41. 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

42. 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

43. 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

44. 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

45. 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

46. 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)

47. 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

48. 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

49. 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

50. 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