snake bite management in developing contries ,

1. Snake bite management
Subodh Gyawali
MD Resident, first year
Internal medicine

2. Snake bite
• Potentially life-threatening disease caused
• by toxins in the bite of a venomous snake.
• by having venom sprayed into the eyes by some species.
• Occupational hazard affecting farmers, plantation workers, herders and
fishermen.
• Neglected tropical disease.

3. Epidemiology
• Out of more than 3000 species of snakes in the world, some 600 are
venomous and over 200 are considered to be medically important.
• According to the World Health Organization,
• more than 5 million snakebites occur worldwide each year
• approximately 2.5 million envenomations and
• 81,000 to 138,000 deaths

4. • In Nepal, WHO estimates that 20,000 people are bitten by snakes each year,
resulting in over 1000 deaths
• So far, 89 snake species have been recorded in Nepal .
• Among this great diversity of snakes, we know with certainty of 17 species
of snake that are found in Nepal.

9. • Not all bites by venomous snakes are accompanied by the injection of
venom.
• Approximately 20% of pit viper bites and higher percentages of other
snakebites (up to 75% for sea snakes) are “dry” bites; i.e., no venom is
released.
• Significant envenomation probably occurs in ~50% of all venomous
snakebites.

10. Venoms
• Complex chemical mixture of enzymes, polypeptides, non-enzymatic proteins,
nucleotides, and other substances
• Neurotoxins-
• Phospholipase A2 (PLA2) toxins (mostly beta-neurotoxins).
• Postsynaptic neurotoxins (alpha-neurotoxins).
• Hematotoxins- factor V activators, factor X activators, prothrombin activators, and
thrombin-like enzymes or fibrinogenase.
• Cytotoxins- phosphodiesterases, hyaluronidases, peptidases, metalloproteinases etc.

12. ASK
• Where were you bitten?
• What were you doing/ when were you bitten?
• Did anyone take the picture? What did it look like?
• How the bite occurred and whether there was more than one bite?
• Any signs or symptoms and the timing of onset?
• Initial treatment and first aid that was provided, including timing of first aid

13. Local effects
• Bite marks:
• Single puncture, dual puncture or marks of multiple tooth marks, only
scratch mark.
• Krait bite may leave no mark at all.
• Site : arm or lower limb , may occur in trunk or other parts also.

14. Local effects
Cobra
• Swelling and local pain
with or without erythema
or discoloration at the bite
site.
• Blistering, bullae
formation and local
necrosis are also common.
• If it is infected, there may
be abscess formation.
Krait
• Usually do not cause signs
of local envenoming and
can be virtually painless.
Viper
• Swelling, blistering,
bleeding, and necrosis at
the bite site, sometimes
extending to the whole
limb.
• Persistent bleeding from
fang marks, wounds or
any injured parts of the
body.
• Swelling or tenderness of
regional lymph node.

15. Systemic manifestations
General manifestations
• Nausea,
• Vomiting
• Pain abdomen
• Malaise
• Weakness
• Drowsiness
• Prostration
• Anxiety
• Excessive salivation, etc.

16. Systemic manifestations
Hematotoxic
• Bleeding may from
venipuncture site, gums,
• Epistaxis
• Hemoptysis
• Melena, rectal bleeding
• Hematuria, bleeding from
vagina
• Subconjunctival
hemorrhage
• Petechiae, purpura,
ecchymosis
Neurotoxic
• Ptosis
• Ophthalmoplegia
• Pupillary dilatation- often
non- responsive to light
• Inability (or limitation) to
open mouth
• Numbness around lips and
mouths
Neurotoxic
• Tongue extrusion- inability
to protrude the tongue
beyond incisors teeth.
• Inability to swallow
• Broken neck sign
• Skeletal muscle weakness.
• Loss of gag reflex
• Paradoxical breathing
• Respiratory failure

17. LONG TERM COMPLICATIONS (SEQUELAE)
• Chronic ulceration, infection, osteomyelitis or arthritis
• Physical disability
• Chronic kidney disease due to bilateral renal cortical necrosis
• Chronic pan-hypopituitarism may occur in Russell’s viper envenoming
• Sequelae of intracranial bleeding in hematotoxic envenoming
• Delayed psychological morbidity like depression and anxiety, impaired
functioning, post-traumatic stress disorder

18. Diagnosis
• No investigations available that can
help diagnose the neurotoxic
manifestations
Neurotoxic

19. Diagnosis
Hematotoxic
•20-minute whole blood clotting test (20WBCT)
•Bleeding time (BT) and clotting time (CT)
•Prothrombin time and International normalization ratio (INR)
•FDP, fibrinogen, d-dimer
•Kidney function test and liver function test
•Complete blood count, blood group
•Urine for RBCs or myoglobin
•Creatine kinase

20. 20 WBCT
• Place 3 ml of freshly sampled venous blood in a small, new, dry, glass tube.
• Leave the tube standing undisturbed for 20 minutes at ambient temperature.
• A positive 20WBCT is a reasonable indication for antivenom administration,
but a negative 20WBCT does not mean that antivenom should be withheld,
especially if other clinical findings of coagulopathy (eg, blood oozing at
puncture sites, bleeding gums, or epistaxis) are present.

21. SYNDROME FEATURES
SYNDROME 1 Local swelling or other features of local envenoming with paralysis with NO features of
bleeding or clotting disturbances.
COBRA or KING COBRA
SYNDROME 2 Nocturnal bite while sleeping on ground and paralysis with NO/or minimal local sign of
envenoming.
KRAIT
SYNDROME 3 Neurotoxicity with dark brown urine, severe muscle pain, without local swelling, bleeding or
clotting disturbances and with or without renal failure. Bitten on land while sleeping indoors.
KRAIT (B. niger)
SYNDROME 4 Marked swelling (sometime with blisters and necrosis) with incoagulable blood and /or
spontaneous systemic bleeding. RUSSELL’S VIPER (Daboia russelii)
SYNDROME 5 Marked swelling on bitten limb/part often with blisters (sometime with severe pain) without
bleeding or clotting disturbances. PITVIPERS (Ovophis monticola, Trimeresurus sp.: T.
albolabris, and T. popeiorum).

22. TREATMENT OF SNAKEBITE ENVENOMING
• First aid treatment and transport to the hospital
• Rapid clinical assessment and resuscitation
• Antivenom treatment
• Supportive/ancillary treatment
• Treatment of the bitten part

23. Recommended first aid treatment
REASSURANCE
• Most are nonvenomous snakes. Many are dry bites.
• Treatable condition.
IMMOBILIZAT
ION
• With a splint or sling.
• Pressure immobilization in case of purely neurotoxic snake bite
• Pressure pad immobilization
• Remove rings, jewelries, tight fittings and clothing
RAPID
TRANSPORT
• To decrease the delay in accessing the emergency care and reduce mortility

24. CAUTION
• Tight arterial tourniquet must never be recommended
• Delay the release of tight tourniquets if patient has already applied this popular
method of first-aid
• These practices must be discouraged
• Cutting and sucking of bite site.
• Application of snake stone (Jharmauro).
• Application of electric current.
• Application of various chemicals, cow dung etc

25. Rapid clinical assessment and resuscitation
• Airway
• Breathing
• Circulation
• Disability of the nervous system
• Exposure and environmental control

26. Antivenom treatment
• Phisalix and Bertrand and Calmette simultaneously, but independently,
presented their observations in the year 1894 on the antitoxic properties of
the serum of rabbits and guinea-pigs immunized against cobra and viper
venoms, respectively.
• The first horse-derived antivenom sera that he prepared were already in
clinical use in 1895 by Haffkine in India and by Lépinay in Viet Nam. The
latter reported the first successful use of antivenin serum therapy in patients
in 1896.

27. Antivenom in Nepal
• Imported from India and is polyvalent.
• Effective against the four common species of snakes;
• Russell's Viper (Daboia russelii),
• Common Cobra (Naja naja),
• Common Krait (Bungarus caeruleus) and
• Saw Scaled Viper (Echis carinatus).

28. Indications for administering antivenom
Evidence of Neurotoxicity Ptosis, ophthalmoplegia, broken neck sign, respiratory difficulty, etc.
Evidence of Coagulopathy Evidence of coagulopathy primarily detected by 20 WBCT or visible
spontaneous systemic bleeding, bleeding gums, etc., including
myoglobinuria and hemoglobinuria, deranged PT/INR, etc
Rapid extension of local swelling (more than half of limb) which is not due
to tight tourniquet application.
Evidence of Cardiovascular
Collapse
Shock and hypotension (in case of Russell’s viper bite).
Evidence Of Acute Kidney Injury AKI is an indication for antivenom therapy.

29. Contradications
• No absolute contraindication to antivenom treatment,
• But patients who have reacted to horse (equine) or sheep (ovine) serum in
the past (for example after treatment with equine anti-tetanus serum, equine
anti-rabies serum or equine or bovine antivenom) and those with a strong
history of atopic diseases (especially severe asthma) are at high risk of severe
reactions and
• Should therefore be given antivenom only if they have signs of systemic
envenoming.

30. How long after the bite can antivenom be
expected to be effective?
• Antivenom treatment should be given as soon as it is indicated.
• It may reverse systemic envenoming even when this has persisted for several
days or, in the case of haemostatic abnormalities, for two or more weeks.

31. Route of administration
• Each vial is diluted with 10 ml. of sterile water as supplied with the antivenom.

32. • Randomized, controlled, double-blind trial in Nepal (Damak & Charali
snakebite treatment centres and Bharatpur Hospital)
• To compare the efficacy of a ten vials initial dose versus a two vials initial
dose of Polyvalent Anti-Snake Venom Serum in the treatment of snake bite
• Result : Similar efficacy and safety of low vs high initial dose regimen of
anti-venom in patients with neurotoxic envenoming in Nepal .Recovery is
faster with high initial dose

35. Response to treatment
• General symptoms may disappear vary quickly.
• Spontaneous systemic bleeding usually stops within 15-30 min.
• Blood pressure may increase within 30-60 min.
• Neurotoxicity may improve as early as 30 min.
• Blood coagulability is usually restored in 3-9 hrs.

36. Reasons for failure to respond to antivenom
• Excessive delay in administration of antivenom
• Patient with established respiratory failure.
• If antivenom administered does not contain neutralizing antibodies against
the venom of biting species.
• Insufficient dose of antivenom.
• Inactive or poor quality antivenom.

37. Prophylactic adrenaline
• Prophylactic adrenaline should be routinely used before initiation of anti-
venom treatment to prevent anti-venom reaction except in older patients
with evidence or suspicion of underlying ischemic heart disease or
cerebrovascular disease.

38. Antivenom reactions
• within 3 hours of antivenom initiation.
• itching, urticaria, fever, angio-edema, dyspnea, laryngeal edema,
hypotension etc. .
Early
anaphylactic
reactions
• Usually develops 1-2 hrs. after treatment initiation.
• Chills, rigors, fever, fall of blood pressure, febrile convulsion may
develop in children.
Pyrogenic
reaction
• May develop 1- 12 (mean 7) days after treatment.
• Fever, itching, recurrent urticaria, arthralgia, myalgia, lymphadenopathy,
proteinuria etc.
Late reaction
(serum
sickness type)

39. Treatment of Early Anaphylaxis
Reaction/Anaphylaxis
• INTERRUPT antivenom
• IM adrenaline
• IV chlorpheniramine
• IV fluids
• Oxygen
• IV hydrocortisone
• Nebulized salbutamol

40. IF ANTIVENOM HAS TO BE RESTARTED
• Consider transfer to ICU.
• Continue IV hydrocortisone.
• IV adrenaline infusion will be required and should be started before giving
antivenom.
• Stop infusion 30 minutes after resolution of all symptoms and signs.

41. Treatment
Pyrogenic reaction
• Do not interrupt antivenom
unless hypotension is present.
• Give injection paracetamol.
• Treat hypotension with rapid
infusion of normal saline.
Serum sickness
• Anti-histaminic Pheniramine
maleate
• If no response to
antihistaminic Prednisolone

42. SUPPORTIVE/ANCILLARY TREATMENT
• Fluid resuscitation
• Oxygen
• Intubation and ventilation
• Dialysis
• Fasciotomies

43. When antivenom is not available or not effective
• Neostigmine: 0.5 mg SC/IV/IM (0.02mg/kg). Repeat 4 hourly until
neurotoxicity improves (maximum 10 mg/24hrs)/ Edrophonium
• Atropine: 0.6mg IV / Glycopyrolate
• FFP and cryoprecipitate or whole blood

44. TREATMENT OF THE BITTEN PART
• Elevation of limb with rest.
• Simple washing with antiseptic solution like chlorhexidine, povidone iodine
etc.
• Broad-spectrum antibiotic if features of infection.
• In case of local necrosis and gangrene: Surgical debridement.
• Tetanus toxoid IM injection should be given. If patient presents with
coagulopathy, it should be postponed until after resolution of coagulopathy.

45. Recent advances
• A 2016 study by Lewin et al. demonstrated that nanomolar and picomolar
concentrations of varespladib effectively inhibit the phospholipase A2 (PLA2)
activities of selected snake venoms from various continents.
• In 2019, the U.S. Food and Drug Administration (FDA) granted
varespladib orphan drug status for its potential to treat snakebite.
• Other examples of promising small molecule inhibitors include the matrix
metalloproteinase inhibitors batimastat and marimastat. The molecules prolonged
survival, but did not provide full protection.
• In the field of recombinant antivenoms, attention to the use of camelid VHHs (also
known as nanobodies) as therapeutic agents has increased.

46. ADDovenom: Novel Snakebite Therapy Platform of
Unparalleled Efficacy, Safety and Affordability
• Based on a new disruptive protein-based
nanoscaffold called ADDomer – a megadalton-
sized, thermostable synthetic virus-like particle
with 60 high-affinity binding sites to neutralise
and eliminate venom toxins from the
bloodstream.

47. PREVENTION OF SNAKEBITE
• Community based education.
• Keep household clean by cutting grasses, bushes, and plants, remove heaps of
rubbish, building materials etc. from near and around house.
• Bamboo, wood piles should be removed from household so that snake cannot hide.
• Close door, windows properly.
• Try to avoid sleeping on floor. If it is unavoidable, then mosquito net should be
used and tucked well under the mattress or sleeping mat. It not only prevents from
krait bite but also from mosquito bite.
• Keep your granary away from the house, it may attract rodents that snakes will hunt

48. PREVENTION OF SNAKEBITE
• Use high shoes or boots while walking in paddy field, bushes, long grasses.
• In dark, use light or strike the path using stick.
• Never play with snakes, or irritate them even if they are dead. Never provoke them,
they usually do not bite if not irritated or provoked.
• Never insert hands into long grasses, tree holes or mud holes. Take care while
pulling straw.
• Shoes and cloths should be check before wearing, in an area where snakes are
abundant.