1. Snake bites can cause local and systemic effects depending on the type of snake. Common snakes in Malaysia include cobras, pit vipers, and sea snakes. 2. Treatment involves first aid measures like immobilization, transport to hospital, and antivenom administration. Antivenom is indicated for signs of envenomation like bleeding, neurotoxicity, or severe swelling. 3. In hospital, treatment involves monitoring for toxicity, supportive care, antivenom if indicated, and managing antivenom reactions. Neurotoxic bites may also be treated with anticholinesterases. Overall management aims to prevent complications and reverse signs of envenomation.

1. SNAKE BITES
Dr. Wong
July '15

2. Case (1)
• 17 year old boy was brought to ED with
alleged snake bite over his left index finger
• Occurred at 1pm and arrived to ED at 2pm
• Patient was digging for worms for fish bait and
he was suddenly bitten by a small viper like
snake
• No bleeding or LOC
• Left hand becomes painful and tender

3. • Noted 2 superficial bite marks over index
finger with generalized swelling over his left
hand
• Pulses were palpable, able to move his fingers,
sensation intact
Case (2)

4. • Admission to ward, noted 6 hours after bite ,
Lt hand was swollen
• Swelling was decreasing on next day
• Noted INR 2.08 → 1.85
• Repeated next day, INR 9.75
Case (3)

5. • At 1pm, he was administered 2 vials of
monovalen antivenom
• Subsequently started on IV Piriton 10mg stat
• On the following day, noted that swelling was
subsiding and PT/INR was down-going in trend,
INR 1.45
• BP remains stable
• At D3 of bite, swelling has reduced and patient
was able to move his hands and discharge well
Case (4)

6. Introduction (1)
• Snakebite is a serious medical problem in
Malaysia
• From 1978 to 2000, there were 55000 cases of
snakebites recorded in the hospitals in Malaysia
• The mortality rate of snakebite in Malaysia is only
0.3 per 100000 population but the local necrotic
effects of some venoms can cause prolonged
morbidity or even crippling deformity

7. Types of snakes
• In Malaysia and the coastal waters of the region, there are
at least 18 different species of venomous front fanged land
snakes and more than 22 different species of sea snakes
• These venomous snakes belong to the following 5
subfamilies:
1. Crotalinae: represented by the two
genera Calloselasma and Trimeresurus.
2. Elapinae: represented by the five genera Naja, Bungarus,
Ophiophagus, Maticora and Calliophis;
3. Laticaudinae, represented by the genus Laticauda
4. Hydrophiini, represented by the six genera Enhydrina, Kerilia,
Hydrophis, Thalassophis, Pelamis and Kolpophis
5. Ephalophiini, represented by the only genus Aipysurus.

8. • not all snakes are venomous
• In Malaysia there are approximately 40 species of
venomous snakes (18 land snakes, all 22 of sea snakes)
belonging to two families:
• - Elapidae – have short, fixed front fangs. The family
includes cobras, kraits, coral snakes and sea snakes.
- Viperidae – have a triangular shaped head and long,
retractable fangs. The most important species in
Malaysia are Calloselasma rhodostoma (Malayan pit
viper) and Trimeresurus genus (green viper)

10. Introduction (2)
Malayan pit viper are common esp. in
northern peninsular, but not found in Sabah
& Sarawak
Cobra & Malayan pit vipers cause most of
snake bites in Malaysia
Bites by sea snakes, coral snakes and kraits
are uncommon

11. Introduction (3)
Snake venom is made up of > 20 components:
Procoagulant enzymes (activate coagulation
cascade)
Phospholipase A2 (myotoxic, neurotoxic, cardiotoxic
– cause haemolysis ( ↑ vascular permeability)
Proteases (tissue necrosis)
Polypeptide toxins (disrupt neuromuscular
transmission

12. Biochemical composition of Snake
Venoms (1)
• Dried snake venom contains mainly proteins (70-
90%) and small amounts of metals, amino acids,
peptides, nucleotides, carbohydrates, lipids and
biogenic amines
• The protein components include enzymes and
non-enzymatic proteins/polypeptides
• The main toxins in the venoms of elapid snakes
(cobras, kraits and sea snakes) include:
polypeptide postsynaptic neurotoxins,
cardiotoxins and phospholipases A that may
exhibit presynaptic neurotoxicity or myotoxicity

13. • The main toxins of crotalid (pit viper) snake
venoms, on the other hand, are thrombin-like
enzymes, hemorrhagic proteases and platelet-
aggregation inducers
Biochemical composition of Snake
Venoms (2)

14. Elapid Venom Poisoning (1)
• Elapid venoms (cobras, kraits and sea snakes)
generally exhibit neurotoxicity and
cardiotoxicity
• The earliest symptom of systemic elapid
poisoning is a feeling of drowsiness or
intoxication, which starts from 15 min to 5 hr
after cobra bites

15. • Difficulty in opening the eyes (bilateral ptosis:
eyelids may remain completely closed though
the patient usually remains conscious until
respiratory failure is advanced), speaking,
opening the mouth, moving the lips and in
swallowing follows within 1 to 4 hrs
• Breathing becomes increasingly difficult. In
severe poisoning, respiratory failure sets in
rapidly
Elapid Venom Poisoning (2)

16. Neurotoxicity (1)
Neurotoxins block
transmission at the
NM junction
Flaccid/Respiratory
paralysis
Non - physiologic
drowsiness

17. • The neurotoxic effects are mainly at the
postsynaptic level of the neuromuscular
junction where the neurotoxins block
acetylcholine receptors, thereby producing
muscular paralysis and respiratory failure
• The major neurotoxins are usually basic
polypeptides
Neurotoxicity (2)

18. Cardiotoxicity (1)
• Cardiotoxicity is caused by polypeptide
cardiotoxin that affects both excitable and
non-excitable cells, causing irreversible
depolarization of the cell membrane and
consequently impairing the structure and
function of various cells, thus contributing to
muscle paralysis and leading to circulatory and
respiratory failure and systolic arrest

19. • Cobra venom also causes extensive local
necrosis, which requires treatment
• The local necrosis is presumably caused by the
combine action of cardiotoxin and phospholipase
A2
• Sea snake venoms contain both polypeptide
neurotoxins (homologous to elapid neurotoxins)
and myotoxins, which are basic phospholipase A2.
• The venom causes respiratory failure (neurotoxic
effect), myonecrosis, myoglobinemia and acute
renal failure

20. Renal failure/rhabdomyolysis
ATN: hypotension/hypovolemia,
DIC, direct toxic effect on tubules,
hemoglobinuria, myoglobinuria
Generalized rhabdo: Release of
myoglobin, muscle enzymes, uric
acid, K (presynaptic neurotoxins)

21. Local necrosis
Increased vascular
permeability
Swelling and
brusing
Myotoxins
Ischemia/thrombosi
s
Venom ophthalmia

22. Pit Viper Venom Poisoning
(Viperidae)
• The venom of pit vipers causes local swelling,
necrosis and systemic bleeding. Hemorrhage is
the outstanding symptom of systemic pit viper
poisoning
• Clotting defect usually accompanies hemorrhage.
The commonest and earliest hemorrhagic
manifestation is hemoptysis, which may be seen
as early as 20 minutes after the bite
• Bleeding from the gum is less common and
follows later after the bite

23. • Discoid ecchymoses appear in the skin an hour
or so later
• Bleeding into the brain or other vital organ
may be fatal.
• In severe cases, loss of blood may lead to
hypovolemic shock
• In Malayan pit viper bite, the clotting defect is
primarily due to thrombocytopenia
aggravated by defibrination syndrome
Pit Viper Venom Poisoning
(Viperidae)

24. Recovery times
• In the absence of necrosis, pain after viper bites
rarely exceeds 2 weeks.
• When necrosis develops (in about 10% of cases)
pain may remain severe for a month.
• Swelling usually resolves completely in 2-3
weeks.
• Healing time of local necrotic lesions varies
greatly according to the extent of the lesion and
the treatment given, but may requires 1-6
months or longer.

25. 
Hemorrhagic effects in viper bites are also
short-lived and rarely exceed a week but the
coagulation defect may persist for 3-4 weeks

Neurotoxic symptoms usually resolve in 2-3
days

26. Management: (a) First aid (1)
Aims are to retard absorption of venom,
provide basic life support & prevent further
complications
Reassure victim (anxiety ↑ venom
absorption)
Immobilise bitten limb with splint/sling
(retard venom absorption)

27. Management: (a) First aid (2)
Apply firm bandage for some elapid bites
(delay absorption neurotoxic venom) but not
for viper whose venom cause local necrosis
Leave the wound alone – DO NOT incise,
apply ice/other remedies
Tight (arterial) tourniquet are not
recommended

28. Management: (a) First aid (3)
Do not attempt to kill the snake
However, if it is killed, bring snake to hospital
for identification
Do not handle snake with bare hands as even
a severed head can bite!
Transfer victim quickly to nearest health
facility

29. Management:
(b) Treatment in hospital (1)
Do rapid clinical assessment & resuscitation,
including Airway, Breathing, Circulation & level
of consciousness
Monitor vital signs (BP, RR, PR)
Establish IV access, give O2 & other resuscitation
as indicated
History: inquire part of body bitten, timing, type
of snake & h/o atopy

30. Management:
(b) Treatment in hospital (2)
Examine:
Bitten part for fang marks, swelling, tenderness,
necrosis
Distal pulses ( ↓ / or in compartment syndrome)
For bleeding (tooth sockets, conjunctiva, puncture
sites)
For neurotoxicity (ptosis, ophthalmoplegia, bulbar
& respiratory paralysis)

31. Management:
(b) Treatment in hospital (3)
For muscle tenderness, rigidity (sea snakes)
Urine for myoglobinuria
Send blood investigations (FBC, RFT, PT/PTT,
GXM)
Perform a 20-min whole blood clotting test
(if unclotted after 20 min → suggests
hypofibrinogenaemia due to pit viper bite & rule
out elapid)

32. Management:
(b) Treatment in hospital (4)

Review immunisation history: give booster ATT if indicated

Venom detection kits to identify species of snake are not
available in Malaysia

Admit to ward for at least 24 hours (unless snake is
definitely non-venomous)

All cases should be supervised by a physician or clinical
toxinologist who are familiar and experienced with snakebite
and envenomation management in Malaysia

33. Management:
(c) Antivenom treatment
Antivenom is only specific treatment for
envenomation
Give early for best result
However, it can be given as long as signs of
systemic envenomation are still present
For local effect, antivenom is not effective if
given > few hours after envenomation

34. Antivenom in Hosp. Sg Bakap

35. Management:
(d) Indications for antivenom (1)
Haemostatic abnormalities e.g. spontaneous
systemic bleeding, incoagulable
blood/thrombocytopenia (<100 x 109
/L)
Neurotoxicity
CV dysfunction eg hypotension/shock
Generalised rhabdomyolysis (muscle ache &
pain)

36. Management:
(d) Indications for antivenom (2)
Significant local effect, e.g. local swelling > ½
bitten limb, extensive blistering/bruising, bites on
digit/rapid progression of swelling
Helpful laboratory investigations suggesting
envenomation include anaemia,
thrombocytopenia, leucocytosis, raised serum
enzymes (CK, AST, ALT), hyperkalaemia,
myolobinuria

37. Management:
(e) Choice of antivenom (1)
If biting species is known, give
monospecific/monovalent antivenom (more
effective, less adverse reactions)
If unknown, clinical manifestations may
suggest offending species:
• Local swelling + neurological signs = cobra bites
• Extensive local swelling + bleeding tendency =
Malayan pit viper

38. Management:
(e) Choice of antivenom (2)
If still uncertain, give polyvalent antivenom
No antivenom is available for Malaysian
kraits, coral snakes & some species of green
vipers
Fortunately, bites by these species are rare &
usually cause only trivial envenoming

39. Management:
(f) Dosage & route administration (1)
Amount given is usually empirical
Recommendations from manufacturers are
usually conservative as they are mainly based
on animal studies

40. Management:
(f) Dosage & route administration (2)
Repeat antivenom administration until signs
of envenomation resolved
Give through IV route only
Dilute antivenom in any isotonic solution (5-
10ml/kg)
Bigger children dilute in 500ml / IV solution)
& infuse whole amount in 1h

41. Management:
(f) Dosage & route administration (3)
Infusion may be discontinued when
satisfactory improvement occurs, even if
recommended dose has not been completed
Do not perform sensitivity test as it poorly
predicts anaphylactic reactions
Do not inject locally at bite site

42. Management:
(f) Dosage & route administration (4)
Prepare adrenaline, hydrocortisone,
antihistamine & resuscitative equipment &
be ready if allergic reactions occur
Pretreatment with adrenaline SC remains
controversial
Small controlled studies in adults showed it
effective in reducing risk of reactions

43. Management:
(f) Dosage & route administration (5)
However, its effectiveness & appropriate
dosing in children have not been evaluated
There is no strong evidence to support use of
hydrocortisone/antihistamine as
premedications
Consider their use in patients with atopy

44. Management:
(g) Antivenom reactions (1)
3 types:
(a) Early anaphylactic reactions
Occur 10-180mins after starting antivenom
Symptoms range from itching, urticaria,
nausea, vomiting, palpitation to severe
systemic anaphylaxis – hypotension,
bronchospasm & laryngeal oedema

45. Management:
(g) Antivenom reactions (2)(contd)
Stop antivenom infusion: give adrenaline IM
(0.01ml/kg of 1 in 1000)
Antihistamines eg. Chlorpheniramine
0.2mg/kg, hydrocortisone 4mg/kg dose & IV
fluid (if hypotensive)
If mild reactions restart infusion at a slower
rate

46. Management:
(g) Antivenom reactions (3)
(b) Pyrogenic reactions
Develops 1-2h after treatment & are due to
endotoxins in antivenom
Symptoms include fever, rigors, vomiting,
tachycardia & hypotension
Give treatment as above
Treat fever with paracetamol & tepid
sponging

47. Management:
(g) Antivenom reactions (4)
(c) Late reactions
Occur about 1 wk later
It is a serum sickness-like illness (fever,
arthralgia, lymphadenopathy, etc)
Treat with chlorpheniramine 0.2mg/kg/day in
divided doses x 5d
If severe, give oral prednisolone (0.7-
1mg/kg/day) x 5-7d

48. Management:
(h) Anticholinesterases (1)
They should always be tried in severe
neurotoxic envenoming, especially when no
specific antivenom is available eg. bites by
Malaysian krait & coral snakes
These drugs have a variable but potentially
useful effect

49. Management:
(h) Anticholinesterases (2)
Give test dose of edrophonium chloride
(Tensilon) IV (0.25mg/kg, adult 10mg) with
atropine sulphate IV (50-100ug/kg; adult
0.6mg)
If patients respond convincingly, maintain
with neostigmine methylsulphate IV (50-
100ug/kg) & atropine, 4hrly by continuous
infusion

50. Management:
(i) Supportive / Ancillary treatment (1)
Clean wound with antiseptics
Give analgesia to relief pain (avoid aspirin)
In severe pain, use morphine (watch for
respiratory depression)
Give antibiotics if wound look contaminated /
necrosed e.g. IV C Pen + gentamicin, amoxy-clav,
erythromycin / 3rd
generation cephalosporin

51. Management:
(i) Supportive / Ancillary treatment (2)
Respiratory support – respiratory failure may
require assisted ventilation
Watch for intracompartment syndrome –
pain, swelling, cold distal limbs & muscle
paresis
Get early orthopaedic / surgical opinion

52. Management:
(i) Supportive / Ancillary treatment (3)
Patient may require urgent fasciotomy
Correct coagulation abnormalities with fresh
frozen plasma & platelets before any surgery
Desloughing of necrotic tissues should be
carried out as required

53. Management:
(i) Supportive / Ancillary treatment (4)
For oliguria & renal failure, e.g. due to sea
snake envenomation, measure daily urine
output, Sr creatinine, urea & electrolytes
If urine output fails to increase after
rehydration & diuretics (e.g. frusemide), start
renal dose of dopamine (2.5ug/kg/min IV
infusion) & place on strict fluid balance
Dialysis is rarely required

54. Pitfalls in management (1)
(a) Giving antivenom “prophylactically” to all
snake bite victims
Not all snake bite by venomous snakes will
result in envenoming
On average, 30% bites by cobra, 50% by
Malayan pit vipers & 75% by sea snakes DO
NOT result in envenoming

55. Pitfalls in management (2)(contd)
Antivenom is expensive & carries risk of
causing severe anaphylactic reactions (as
derived from horse / sheep serum)
Hence it should be used only in patients in
whom the benefits of antivenom are
considered to exceed risks

56. Pitfalls in management (3)
(b) Delaying in giving antivenom in district
hospitals until victims are transferred to
referral hospitals
Antivenom should be given as soon as it is
indicated to prevent morbidity & mortality
District hospitals should stock important
antivenoms & provide care & safe monitoring
for antivenom infusion

57. Pitfalls in management (4)
(c) Giving polyvalent antivenom for
envenoming by all types of snakes
Polyvalent antivenom does not cover ALL
types of snakes
E.g. Sii polyvalent (India) is effective in cobra
& some kraits envenomation but is not
effective against Malayan pit viper
Refer to manufacturer drug insert for details

58. Pitfalls in management (5)
(d) Giving smaller doses of antivenom for
children
Dose should be same as for adults
Amount given depends on the amount of
venom injection rather than size of victim

59. Pitfalls in management (6)
(e) Giving pretreatment with hydrocortisone /
antihistamine for snake bite victim
Snakebites do not cause allergic / anaphylactic
reactions
These drugs may be considered in those who are
given ANTIVENOM

61. Resources:
http://mstoxinology.blogspot.com/p/recs.html
Snakebite Management Guide for Healthcare Providers in Malaysia (2014)
Image Gallery of Land Snakes of Medical Importance in Malaysia (2013)
Snake Antivenom Guide for UKMMC (2014)
Snake Antivenom Guide for Sabah (2014)
http://www.junglecraft.com.my/index.php/snake-bite/