II. Epidemiology: Incidence

  1. Total: 45,000 Snake Bites in U.S. per year
  2. Venomous bites: 8000 in U.S. per year
  3. Deaths from Snake Bite in U.S.: 12 or less per year
  4. Envonomation occurs in 75% of U.S. poisonous SnakeBites

III. Etiology: U.S. Poisonous snakes

  1. Coral Snakes (Family Elapidae)
    1. Nonaggressive snakes of the southern U.S.
    2. Transfer venom via chewing instead of injection
  2. Pit Vipers or Crotalidae (99% U.S. venomous bites)
    1. Rattlesnake (Crotalus or Sisturus genera)
      1. Most common poisonous snake in U.S.
      2. Potent venom
      3. Responsible for 95% of deaths (esp. Diamondback)
    2. Cottonmouth, water moccasin (Agkistrodon piscivorous)
      1. Aggressive water snakes in Southeastern U.S.
      2. Moderately potent venom
    3. Copperhead (Agkistrodan contortix)
      1. Least potent venom

IV. Signs and Symptoms: Pit Vipers (except Mojave rattler)

  1. Long movable fangs cause skin puncture marks
  2. Venom alters Coagulation Factors, tissue necrosis
    1. Immediate pain and burning at bite site
    2. Within a few minutes redness and swelling develops
    3. Bite site develops a purplish discoloration
  3. Generalized symptoms (Hemotoxic effects)
    1. Nausea and Vomiting
    2. Dizziness
    3. Weakness
    4. Sweats and chills
    5. Metallic or Rubbery taste in mouth
    6. Muscle fasciculations (U.S. West Coast Rattlesnakes with Mojave toxin)
  4. Systemic complications
    1. Disseminated Intravascular Coagulation (DIC)
    2. Acute Renal Failure
    3. Hypovolemic shock (7% of cases)
    4. Rhabdomyolysis (if muscle fasciculations)
  5. Course
    1. Not immediately fatal unless Envenomation into vein

V. Signs and Symptoms: Coral Snakes

  1. Small fixed fangs cause tiny semicircular scratches
  2. Venom contains a Neurotoxin
  3. Generalized symptoms may be delayed 1-8 hours
    1. Drowsiness, Weakness
    2. Paresthesias with numbness at bite site
    3. Blurred vision
    4. Slurred speech
    5. Salivation
    6. Seizures
  4. Systemic complications
    1. Paralysis
    2. Cardiac Arrest or respiratory arrest may occur

VI. Management: First Aid in field

  1. Get to a medical facility as soon as possible
  2. Calm and reassure patient
  3. Attempt to identify snake type from a distance
    1. Do not try to capture the snake for Identification
  4. Do not leave a patient alone
  5. Have the patient lie down
  6. Immobilize bite area below the level of the heart
  7. Remove jewelry or clothing that tighten with swelling
  8. Clean the bite area with soap and water
    1. Apply antiseptic solution and gauze if available
  9. Use a venom extractor device within 5 minutes of bite
    1. Do not cut wound or try to suck out venom
    2. Use vacuum-suction device to extract venom
    3. Venom extractor left in place for 30 minutes
    4. Avoid harmful methods (see below) at bite site
  10. Low pressure constriction band
    1. Indicated if medical assistance is >1 hour away and neurotoxic effects are expected
    2. Wrap a band (ACE, belt, sock) 2-3 inches above bite
      1. Band should be wide and flat
      2. Band applied between bite site and heart
    3. Do not cut off arterial circulation
      1. Pressure: 20 mmHg
      2. Be able to slip a finger between band and skin
    4. Leave band in place until medical facility
    5. Contraindications to low pressure constriction band
      1. Gila Monster
      2. Copperhead
      3. Water moccasin
      4. Pygmy Rattlesnake

VII. Labs

  1. Blood Type and cross match
  2. Urinalysis
  3. Chemistry panel (e.g. Chem8)
    1. Renal Function tests (BUN and Creatinine)
    2. Serum electrolytes
    3. Serum Glucose
  4. Complete Blood Count with Platelet Count
    1. Thrombocytopenia may be delayed (repeat Platelet Count in 7-10 days)
  5. Liver Function Tests
  6. Coagulation Factors (draw baseline and at 12 hours)
    1. Prothrombin Time (PT)
    2. Partial Thromboplastin Time (PTT)
    3. Fibrinogen
    4. D-Dimer
    5. Creatine Phosphokinase (CPK)
  7. Other studies that may be indicated
    1. Electrocardiogram (EKG)
    2. Arterial Blood Gas (ABG)
    3. Troponin I

VIII. Management: Emergency Department

  1. See Snake Antivenin
  2. Contact poison control immediately
  3. Clean wound
  4. Tetanus Toxoid or immune globulin if underimmunized
  5. Do not draw blood or start IV in affected extremity
  6. Start Intravenous Fluids
  7. Prophylactic antibiotics are not recommended
  8. Suspected pit viper bite management
    1. Observe asymptomatic patients 12 hours after bite
    2. Mark leading edge of bite site swelling every 30 minutes
    3. Indications for discharge
      1. No proximal spread of extremity findings
      2. Normal laboratory studies
      3. Patient able to return immediately for worsening
  9. Suspected Coral Snake bite management
    1. Observe asymptomatic patient for at least 24 hours
    2. Requires immediate treatment and antivenin

IX. Precautions: Avoid harmful methods

  1. Do not cut skin at bite site
  2. Fasciotomy is rarely indicated
    1. Compartment Syndrome may be controlled by antivenin
    2. Only Consider if hourly serial ICP >30 mmHg
  3. Do not use electric shock or stun gun at bite site
  4. Do not apply tightly constricting Tourniquet
  5. Do not administer antivenin in the field
    1. Risk of Anaphylaxis
  6. Delayed Thrombocytopenia (antivenin-refractory) may occur
    1. Recheck Platelet Count again in 7-10 days

X. Prevention

  1. On coming upon a snake:
    1. Slowly and quietly move away, and allow it to escape
    2. Do not expect a warning before they strike
      1. Most snakes do not hiss or rattle before striking
    3. Do not handle any snake (even if snake appears dead)
  2. Be alert in areas commonly inhabited by snakes
    1. Hiking, picnicking, camping and firewood areas
    2. Water areas
    3. Tall grass, underbrush, abandoned buildings
    4. Piles of logs, rocks, and branches
  3. Be careful of areas of decreased visibility
    1. Avoid reaching into holes and crevices
    2. Avoid jumping over logs and fences
    3. Pull logs or rocks toward you when turning over
    4. Avoid placing fingers under objects being lifted
  4. Prepare for a hike
    1. Wear boots and long pants
    2. Carry a flashlight for nighttime conditions
    3. Hike with a companion
  5. Reduce residential risks of Snake Bite
    1. Provide lighting for yard, sidewalks, and patio
    2. Keep yard mowed and bushes pruned
    3. Keep home free of mice

Images: Related links to external sites (from Bing)

Related Studies (from Trip Database) Open in New Window

Ontology: Snake Bites (C0037379)

Definition (MSH) Bites by snakes. Bite by a venomous snake is characterized by stinging pain at the wound puncture. The venom injected at the site of the bite is capable of producing a deleterious effect on the blood or on the nervous system. (Webster's 3d ed; from Dorland, 27th ed, at snake, venomous)
Concepts Injury or Poisoning (T037)
MSH D012909
ICD10 T63.0
SnomedCT 83527007, 269782003, 61288004
English Snake Bite, Snake Envenomation, Envenomation, Snake, Envenomations, Snake, Snake Envenomations, Bite, Snake, Bites, Snake, Snake venom, Snake venom - toxic effect, Toxic effect of snake venom, Snake Bites, Snakebites, Snakebite, Snake Bites [Disease/Finding], Adverse effect;venom;snake, snake bites, snake envenomations, snake bite, Toxic effect of bite of venomous snake (disorder), Snake venom poison, Snake envenomation, Snake venom causing toxic effect, Poisoning by venomous snake (disorder), Poisoning by venomous snake, Snake bite poisoning, Snake venom poisoning, Toxic effect of bite of venomous snake, snake bite poison, bite; poisoning, snake, Poisoning by venomous snake, NOS, Snake bite poisoning, NOS, Snake venom poisoning, NOS, Toxic effect of bite of venomous snake, NOS, Toxic effect of bite of venomous snake -RETIRED-, snake envenomation
Swedish Ormbett
Czech hadi - uštknutí
Finnish Käärmeenpuremat
German Toxische Wirkung: Schlangengift, Schlangenbisse, Schlangenvergiftung
Korean 뱀독의 중독작용
Polish Ukąszenie przez węża
Japanese ヘビ咬傷, だ咬症, ヘビ中毒症, 毒蛇咬症, 蛇咬傷(ダコウショウ), 蛇咬症, 蛇中毒症, 蛇咬傷
Norwegian Ormebitt, Slangebitt
Spanish Mordeduras de Serpientes, efecto tóxico de la mordedura de serpiente venenosa - RETIRADO -, efecto tóxico de la mordedura de serpiente venenosa - RETIRADO - (concepto no activo), Mordedura de Serpiente, Mordeduras de Serpiente, envenenamiento por mordedura de serpiente, envenenamiento por serpiente venenosa (trastorno), envenenamiento por serpiente venenosa, envenenamiento por veneno de serpiente, Envenenamiento por Serpiente
Portuguese Mordeduras de Serpentes, Envenenamento por Serpente, Acidente Ofídico, Mordedura de Cobra, Mordedura de Serpente, Mordidas de Cobra, Picadas de Cobras, Mordida de Cobra, Picada de Cobra, Picadas de Ofídios, Mordeduras de Serpente, Mordeduras de Cobra, Picada de Serpente, Acidentes Ofídicos, Envenenamento por Cobra, Picada de Serpentes, Picadas de Cobra, Picadas de Serpentes
Dutch beet; giftig, slang, Slangengif, Beet, slangen-, Beten, slangen-, Slangenbeet, Slangenbeetvergiftiging, Slangenbeten
Italian Morsi di serpente
French Envenimation par les serpents, Morsures de serpent

Ontology: Snake Venoms (C0037380)

Definition (MSH) Solutions or mixtures of toxic and nontoxic substances elaborated by snake (Ophidia) salivary glands for the purpose of killing prey or disabling predators and delivered by grooved or hollow fangs. They usually contain enzymes, toxins, and other factors.
Concepts Hazardous or Poisonous Substance (T131) , Biologically Active Substance (T123)
MSH D012910
SnomedCT 27831002
English Snake Venoms, Venoms, Snake, Snake Venom, Venom, Snake, Snake Venoms [Chemical/Ingredient], snake venom, snake venoms, venom snake, Snake venom, Snake toxin, Snake venom (substance), Snake toxin, NOS, Snake venom, NOS
Swedish Ormgifter
Czech hadí jedy
Finnish Käärmeenmyrkyt
French Venins de serpent
Polish Jady węży
Japanese 蛇毒(ジャドク), ヘビ毒, 蛇毒(ダドク), 蛇毒, ヤマカガシ毒
Spanish Ponzoñas de Serpiente, toxina de serpiente, veneno de serpiente (sustancia), veneno de serpiente, veneno de víbora, Venenos de Serpiente
German Gifte, Schlangen-, Schlangengifte, Toxine, Schlangen-
Italian Veleni dei serpenti
Portuguese Venenos de Serpentes

Ontology: Cottonmouth (C0206282)

Concepts Reptile (T014)
MSH D017836
SnomedCT 23448000
English Cottonmouth, Cottonmouths, cottonmouth, Agkistrodon piscivorus (Lacepede, 1789), Agkistrodon piscivorus, Agkistrodon piscivorus (organism)
Portuguese Boca de Algodão
Spanish Mocasin, Agkistrodon piscivorus (organismo), Agkistrodon piscivorus
French Agkistrodon piscivorus
German Wassermokassinschlange
Czech Agkistrodon piscivorus
Norwegian Vannmokasin
Italian Bocca di cotone
Dutch Watermocassinslang

Ontology: Micrurus (C0206287)

Concepts Reptile (T014)
MSH D017815
SnomedCT 376006, 55469004
English Coral Snake, Micrurus, Coral Snakes, Snake, Coral, Snakes, Coral, Coral snake, Micrurus (organism), Genus Micrurus (organism), Genus Micrurus, coral snake, micrurus, Coral snake (organism), American coral snake, Coral snake, NOS, Micrurus, NOS
Spanish género Micrurus, serpiente de coral americana, género Micrurus (organismo), Micrurus (organismo), Micrurus, serpiente coral, serpiente coral (organismo), Serpiente Coral
French Serpent corail, Micrurus
Portuguese Micrurus, Cobra Coral
German Micrurus, Korallenschlange
Norwegian Korallslange, Micrurus
Italian Micrurus, Serpente corallo
Dutch Koraalslang, Micrurus

Ontology: Copperhead (C0206310)

Concepts Reptile (T014)
MSH D017836
SnomedCT 54216008
English Copperheads, copperhead, Agkistrodon contortrix, Agkistrodon contortrix (organism), Copperhead, NOS, Copperhead
Portuguese Cabeça de Cobre
Spanish Cabeza Cobriza, Agkistrodon contortrix (organismo), Agkistrodon contortrix
German Kupferkopf
Czech Agkistrodon contortrix
French Mocassin à tête cuivrée
Norwegian Kopperhode
Italian Testa di rame
Dutch Koperkop

Ontology: Crotalus (C0206317)

Definition (MSH) A genus of snakes of the family VIPERIDAE, one of the pit vipers, so-called from the pit hollowing out the maxillary bone, opening between the eye and the nostril. They are distinctively American serpents. Most of the 25 recognized species are found in the southwestern United States and northern Mexico. Several species are found as far north as Canada and east of the Mississippi, including southern Appalachia. They are named for the jointed rattle (Greek krotalon) at the tip of their tail. (Goin, Goin, and Zug: Introduction to Herpetology, 3d ed; Moore: Poisonous Snakes of the World, 1980, p335)
Concepts Reptile (T014)
MSH D017839
SnomedCT 420914006, 81572007
English Rattlesnake, Crotalus, Rattlesnakes, Genus Crotalus (organism), Genus Crotalus, rattlesnake, rattlesnakes, crotalus, Rattlesnake (organism), Rattlesnake, NOS
Spanish género Crotalus, género Crotalus (organismo), Crotalus, serpiente cascabel (organismo), serpiente cascabel, Culebra Cascabel
French Crotale, Crotalus
Swedish Crotalus
Czech Crotalus, chřestýš
Finnish Kalkkarokäärme
Italian Serpente a sonagli, Crotalo
Polish Grzechotniki właściwe
Japanese ガラガラヘビ属, ガラガラヘビ
Norwegian Klapperslanger, Crotalus
German Crotalus, Klapperschlange
Dutch Crotalus, Ratelslang
Portuguese Cascavel, Crotalus