Berg adder (Bitis atropos) envenoming: an analysis of 14 cases

Abstract

Introduction: The berg adder (Bitis atropos) is a little-studied, lesser-known viperid snake found in southern Africa and there is limited information available regarding the manifestations of envenoming.

Materials and methods: This observational series of 14 cases documents features of berg adder envenoming over a period of 16 years (1987-2003). Clinical features of envenomed patients: All 14 patients developed local cytotoxic effects. Thirteen patients developed systemic effects manifesting and documented in varying degrees. These include (1) prominent vomiting (2) disturbances in cranial nerve function (anosmia and altered taste, an ophthalmological triad of ptosis, mydriasis and visual disturbances including loss of accommodation, and dysphagia) (3) a global decrease in motor power where mechanical ventilation was often required for respiratory failure and (4) hyponatraemia (lowest value recorded 111 mmol/L), sometimes with associated convulsions.

Discussion: The full range of polypeptides present in berg adder venom is yet to be characterised. However, two closely related phospholipases A₂ (PLA₂; PLA₂-1 and PLA₂-2) have been purified from the venom of B. atropos and clinical evidence suggests that a natriuretic peptide is also possibly present. Envenoming results in distinctive, sometimes life-threatening, manifestations.

Keywords: Berg adder; cranial nerves; cytotoxic; hyponatraemia; neurotoxic; respiratory failure; snake.