Clinical features of puff adder envenoming: case series of Bitis arietans snakebites in Kenya and a scoping review of the literature

Abstract

Introduction The puff adder (Bitis arietans) is a medically important snake species found across much of Africa, yet there is limited literature on the clinical features and pathophysiology of envenoming after a puff adder bite. Methods We conducted a case-series study to describe the clinical features of patients with puff adder bites who were treated in two primary healthcare facilities in Kenya and comple-mented our case-series with a scoping review of all published cases of puff adder enven-oming that contained sufficient clinical details to highlight the major features. Results Between December 2020 and September 2021, 15 patients were admitted with a sus-pected puff adder bite (based on the patient’s description of the biting snake or confirmed in patients who brought the dead snake or a picture of the biting snake for identification) at the Chemolingot and Mwingi sub-county hospitals in Baringo and Kitui counties, central Kenya. Common local and systemic features on admission included pain (n=15, 100%), swelling (n=14, 93%), and haemorrhage (n=9, 60%). Coagulopathy (n=2, 13%), blistering (n=1, 8%) and shock (n=1, 8%) were less common. In addition, we conducted a literature review and identified 23 studies with detailed descriptions of the clinical features of puff adder envenoming from 37 patients. Local features were common and consistent across cases—swelling (100%, n=37) and pain (95%, n=35). Systemic features were less consistent, with 10 (27%) patients exhibiting hypotension on admission, 10 (27%) patients reporting a fever, and 13 (35%) developing anaemia. Some complications were more common in patients with bites by captive snakes (amputations), compared to patients with bites by wild snakes (hypotension). Snake identification was easier and more accu-rate after bites by captive snakes, but more challenging for patients bitten in community settings. Conclusion We combined clinical cases and a literature review to describe the common and less common clinical features of puff adder envenoming. Further clinical research incorporating serial laboratory assays of patients with definitively identified puff adder bites is crucial to better understand the pathophysiology of envenoming by this medically important snake species.