African Snakebite — Antivenom Dosing Nigeria · Kenya · Ghana
Species-specific envenomation severity grading, antivenom vial guidance, anaphylaxis preparedness
and emergency management protocol. Africa-specific species.
WHO Snakebite Guidelines 2016 · African Snakebite Research Group · Liverpool School of Tropical Medicine. Offline-capable.
For qualified healthcare professionals only — Clinician review mandatory before use.
Antivenom dosing for snakebite is complex, context-dependent and carries a significant risk of anaphylaxis. Species identification is often uncertain. This tool provides guidance based on published protocols — it does not replace specialist toxicology input where available. Always have IM adrenaline drawn and ready before administering antivenom: adult 0.5 mg IM; child 0.01 mg/kg IM up to max 0.5 mg.
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Snakebite envenomation is a WHO-recognised neglected tropical disease causing an estimated 81,000–138,000 deaths and up to 400,000 permanent disabilities annually, with the highest burden in sub-Saharan Africa and South Asia. Nigeria alone reports over 500,000 bites per year with an estimated case fatality rate of 3–5% in untreated victims. The saw-scaled carpet viper (Echis ocellatus) is responsible for the majority of snakebite deaths in Nigeria and West Africa, causing life-threatening coagulopathy. Early, correctly dosed antivenom administration is the only definitive treatment — first aid (immobilisation, calm transport) and rapid access to a health facility are critical to survival. This calculator covers the major medically important species in Nigeria, Kenya and East Africa.
Warrell DA. Snake bite. Lancet. 2010;375(9708):77–88.
Kenya MOH: Clinical guidelines for snakebite management
Frequently Asked Questions
For Echis ocellatus (carpet viper) with haemotoxic envenomation (positive 20-minute whole blood clotting test): initial dose of SAIMR polyvalent or EchiTAb-Plus antivenom 4–8 vials IV. If coagulopathy persists at 6 hours (repeat WBCT still positive), give an additional 4 vials. Repeat 20-minute WBCT at 6 and 24 hours to guide re-dosing. Children receive the same dose as adults.
Place 2 mL of fresh venous blood in a clean dry glass tube. Leave undisturbed at room temperature for 20 minutes. If the blood is still liquid (does not clot), the result is positive — indicating venom-induced consumption coagulopathy (VICC) and the need for antivenom. A clotted sample is negative. Repeat at 6 and 24 hours post-antivenom to confirm coagulopathy correction.
Subcutaneous adrenaline 0.25 mg (adult) or 0.01 mg/kg (child) given 15–20 minutes before antivenom infusion significantly reduces anaphylaxis risk (WHO recommended, supported by Sri Lanka RCT). Promethazine 25 mg IM and hydrocortisone 200 mg IV have weaker evidence but are commonly used. Always have IM adrenaline drawn and ready at the bedside during antivenom infusion regardless of premedication.
Antivenom dosing in snakebite is the same for children as for adults — it is based on the amount of venom injected, not on the body weight of the victim. A child actually receives the same or more venom per kg bodyweight than an adult from the same bite, meaning children may need equal or greater total antivenom doses. Common error: giving children half the adult antivenom dose because of their smaller size — this is wrong and leads to treatment failure. Always dose antivenom by species-specific protocol and clinical severity, not by weight.
Systemic envenomation signs requiring urgent antivenom in Nigerian snakebite: (1) Coagulopathy — non-clotting blood on 20WBCT, bleeding gums, haematuria, haemoptysis; (2) Neurotoxicity — ptosis, external ophthalmoplegia, bulbar palsy, respiratory failure (elapid envenomation, e.g. forest cobra); (3) Haemodynamic compromise — hypotension, tachycardia, collapse; (4) Local tissue necrosis extending proximally from the bite site; (5) AKI — oliguria, elevated creatinine. Do not wait for laboratory results if clinical signs are present — give antivenom immediately. The commonest envenoming species in Nigeria are Echis ocellatus (carpet viper) and Bitis arietans (puff adder).
📋 Guideline basis: WHO Antivenom Guidelines 2018 · FMOH Nigeria 2020 · Last reviewed: January 2025 · Next review due: January 2026 · Disclaimer · Report an error
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