Snakebites

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Snakebites can cause both local and systemic effects. Non-venomous snakes cause local effects (swelling, redness, laceration) and venomous snakes cause both local and systemic effects due to envenomation. Over 70% of snakes in Uganda are non-venomous and most bites are from non-venomous snakes. Of the venomous snakes, more than 50% of bites are “dry” i.e. no envenomation occurs. In the event that venom is injected, the effect of the venom depends on the type of venom, quantity,
location of the bite and size and general condition of the victim.


Cause
Common venomous snakes in Uganda: Puff adder, Gaboon viper, black mambas, Brown Forest cobra, Egyptian cobra and Boomslang (see below images of some of the common snakes in Uganda)


Clinical features

Local symptoms and signs Generalized (systemic) symptoms and signs
  • Fang marks
  • Malaise
  • Swelling
  • Local bleeding
  • Pain
  • Blistering
  • Redness
  • Skin discoloration (necrosis)
  • Vomiting
  • Difficulty in breathing
  • Abdominal pain
  • Weakness
  • Loss of consciousness
  • Confusion
  • Shock

 
If cytotoxic venom (Puff adder, Gaboon viper)
Extensive local swelling, pain, lymphadenopathy – starting 10-30 minutes after the bite.

If neurotoxic venom (Jameson’s mamba, Egyptian Cobra, Forest Cobra, Black mamba)
Weakness, paralysis, difficulty in breathing, drooping eye- lids, difficulty in swallowing, double vision, slurred speech – starting 15-30 minutes after the bite
Excessive sweating and salivation


If hemotoxic venom (Boomslang, Vine/Twig snake)
Excessive swelling and oozing from the site
Skin discoloration
Excessive bleeding, bloody blisters
Haematuria, haematemesis – even after some days
Shock

If combined venom toxicity
Late appearance of signs and symptoms


Investigations
Whole blood clotting test at arrival and every 4-6 hours after the first day:
Put 2-5 ml of blood in a dry tube and observe after 30 minutes
If incomplete or no clotting, it indicates coagulation ab- normalities
Other useful tests depending on severity, level of care and availability:
Oxygen Saturation/PR/BP/RR
Haemoglobin/PCV/Platelet count/PT/APTT/D-Dimer
Biochemistry for Serum Creatinine/Urea/Potassium
Urine Tests for Proteinuria/Haemoglobinuria/ Myoglobinuria
Imaging ECG/X-Ray/Ultrasound

Management

What to do What not to do
  • Reassure the patient to stay calm
  • Lay the patient on the side to avoid movement of affected areas
  • Remove all tight items around the affected area
  • Leave the wound/bite
  • area alone
  • Immobilize the patient
  • Do not panic
  • Do not lay the patient on their back as it may block airways
  • Do not apply a tourniquet
  • Do not squeeze or incise the wound
  • Do not attempt to suck the venom out
  • Do not try to kill or attack the snake
  • DON’T use traditional methods/herbs

Venom in eyes

  • Irrigate eyes with plenty of water
  • Cover with eye pads
Treatment LOC

Assess skin for fang penetration

If signs of fang penetration

  • Immobilise limb with a splint
  • Analgesic e.g. paracetamol (avoid aspirin)

If no signs and symptoms for 6-8 hours: most likely bite without envenomation

  • Observation for 12-24 hours recommended
  • Tetanus toxoid (TT) IM 0.5 ml if not previously immunised in the last 10 years

If local necrosis develops

  • Remove blisters, clean and dress daily, debride after lesions stabilise (minimum 15 days)
 HC2

Criteria for referral for administration of antivenom

  • Signs of systemic envenoming (paralysis, respiratory difficulty, bleeding)
  • Spreading local damage:
  1. Swelling of hand or foot (site of most bites) within 1 hour of bite
  2. Swelling of elbow or knee within 3 hours of bite
  3. Swelling of groin or chest at any time
  4. Significant swelling of head or neck
  • Antivenom sera polyvalent (Africa)
    - Check package insert for IV dosage details. Ensure the solution is clear and check that patient has no history of allergy
  • Antibiotics
    Indicated only if wound is infected