Snakebites
Description General Measures Medical Treatment Referral ICD-10 code: T63.0 + (X20.99/W59.99) DESCRIPTION Of all the snake species found in South Africa less than 10% are potentially harmful to humans. However, all snakebites should be considered dangerous until proven otherwise. In the majority of snakebite incidents, the offending snake is not identified. South African poisonous sn
ICD-10 code: T63.0 + (X20.99/W59.99)
DESCRIPTION
Of all the snake species found in South Africa less than 10% are potentially harmful to humans. However, all snakebites should be considered dangerous until proven otherwise. In the majority of snakebite incidents, the offending snake is not identified.
South African poisonous snakes can be broadly divided into 3 groups according to the action of their venom, although there may be overlap of toxic effects from some snake venoms.
1. Cytotoxic venoms
- Venom causes local tissue damage and destruction around the area of bite, including swelling, discolouration of the skin, and blister formation.
- Bite is painful and symptoms usually start within 10–30 minutes.
- Examples include: puff adder, Gaboon adder, Mozambique spitting cobra, other smaller adders and spitting cobras, stiletto snake, rinkhals (cytotoxic as well as neurotoxic).
2. Neurotoxic venoms
- Neurotoxic venom causes weakness, ptosis, drooling, dysphagia, pins and needles, sweating, blurred vision, hypotension, paralysis of skeletal muscles and respiratory compromise.
- Bite is not as painful as cytotoxic venom bites.
- Symptoms usually start in 15–30 minutes.
- Examples include: black and green mamba, non-spitting cobras (Cape, forest, snouted), berg adder (neurotoxic as well as cytotoxic), rinkhals (cytotoxic as well as neurotoxic).
3. Haemotoxic venoms
- Venom affects the clotting of blood causing bleeding tendency that may present within hours or up to a few days after the bite.
- Examples include: boomslang, vine snake
Symptoms and signs of snakebite envenomation include:
Local
- Bite marks with or without pain.
- Swelling around the bite, which may be severe with discolouration of skin and/or blister formation.
- Bleeding or oozing from bite site.
Note: the absence of bite marks does not exclude envenomation.
Systemic
- Nausea, vomiting.
- Sweating, hypersalivation and hypotension.
- Pins and needles.
- Skeletal muscle weakness (descending paralysis), which may cause:
- drooping eyelids
- difficulty in swallowing
- double vision
- difficulty in breathing
- Shock.
- Rarely bleeding (epistaxis, haematuria, haematemesis or haemoptysis).
CAUTION
Do not apply a tourniquet.
Do not apply a restrictive bandage to the head, neck or trunk.
Do not squeeze or incise the wound.
Do not attempt to suck the venom out.
GENERAL MEASURES
- Remove clothing from site of the bite and jewellery e.g. rings if an extremity bite.
- Clean the wound thoroughly with chlorhexidine 0.05%, aqueous solution.
- Immobilise the affected limb with a splint or sling.
- Be prepared to support ventilation in neurotoxic bites as this can be life-saving.
- For neurotoxic bites only:
- Immediately apply a wide crepe bandage firmly from just below the bite site up to 10–15 cm proximal to the bite site. Apply no tighter than for a sprained ankle.
- Obtain an accurate history e.g. time of the bite, type of snake.
- If the snake is unidentified, observe for 24 hours with repeated examinations. Absence of symptoms and signs for 6–8 hours usually indicates a harmless bite.
MEDICINE TREATMENT
Venom in the eyes:
ICD-10 code: S05.9 + (X20.99)
Irrigate the eye thoroughly for 15–20 minutes with water or sodium chloride, 0.9 %.
- Local anaesthetic ophthalmic drops, e.g.:
- Tetracaine 1%, drops (if available), instil 1 drop into the affected eye(s) before irrigation.
Refer patient.
Pain:
- Non-opioid analgesics according to severity. See: Chronic Non-Cancer Pain
Note:
The use of NSAIDs is not recommended due to the antiplatelet effect and the potential danger of renal failure in a hypotensive patient.
Shock:
Treat if present. See: Shock
Tetanus prophylaxis:
ICD-10 code: Z23.5
If not previously immunised within the last 5 years:
- Tetanus toxoid (TT), IM, 0.5 mL.
Note:
- The majority of patients do not need and should not be given antivenom.
- Adverse reactions to antivenom (including anaphylaxis) are common and may be severe.
- The dose of antivenom is the same for adults and children.
- Polyvalent antivenom does NOT include antivenom for Berg adders or Stiletto snakes. Management for these is symptomatic and supportive only.
- Antibiotics are seldom needed, except for secondary infection
Criteria for antivenom administration
- Signs of neurotoxicity.
- Positively identified puff adder, Gaboon adder, Mozambique spitting cobra or rinkhals bites AND evidence of severe progressive cytotoxicity.
- Unidentified snakebites and evidence of severe progressive cytotoxicity envenomation, i.e.:
- swelling of whole hand or foot within 1 hour
- swelling to the knee or elbow in <6 hours
- swelling of the whole limb in <12 hours
- swelling progression >2.5 cm per hour
- a threatened airway due to swelling
- evidence of complication, e.g. compartment syndrome
REFERRAL
- All patients with bites or likely bites even if puncture marks are not seen. If possible, take the dead snake to the referral centre for identification. Referral centre will determine if antivenom is indicated.
- If patient presents at the clinic with their own antivenom, contact the secondary level hospital for advice (antivenom should be given as soon as possible, however administration may be considered even as late as 48-72 hours after the bite, if there is continued clinical deterioration indicating ongoing venom activity).
For guidance on the identification and clinical management of snake/spider/scorpion bites, contact:
Poisons Information Helpline: 0861555777
For procurement of snake/spider/scorpion antivenom, contact:
South African Vaccine Producers (SAVP):
Telephone (011) 386 6062/6063/6078 (0ffice hours only) or
Email: Benita.mouton@nhls.ac.za
In the rare event that antivenom needs to be released/procured afterhours: Tel 071 680 9897
Click here for the NEMLC Recommendations for medicine amendments (2020-4 review cycle).
Standard Treatment Guidelines and Essential Medicines List for South Africa, Primary Healthcare, 2020-4_Version 1.1_October 2024
Chapter 21: Emergencies and Injuries
Drugs mentioned
ICD-10 codes
- S05.9Injury of eye and orbit, unspecified
- T63.0Toxic effect, snake venom
- W59.99Bitten or crushed by other reptiles, unspecified place, during unspecified activity
- X20.99Contact with venomous snakes and lizards, unspecified place, during unspecified activity
- Z23.5Need for immunization against tetanus alone