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

IntroductionThe puff adder (Bitis arietans) is a medically important snake species found across much of Africa, yet there is a limited understanding of the clinical features and pathophysiology of envenoming after a puff adder bite. MethodsWe 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 complemented our case-series with a review of all published cases of puff adder envenoming that contained sufficient clinical details to highlight the major features. ResultsBetween December 2020 and September 2021, 15 patients were admitted with a suspected puff adder bite (based on the patients 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 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%) 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 common in patients with bites by captive snakes (amputations), compared to patients with bites by wild snakes (hypotension). Snake identification was easier and more accurate after bites by captive snakes, but for patients bitten in community settings, identification was challenging and often less objective. ConclusionWe combined clinical cases and a literature review to describe the common and less common clinical features of puff adder envenoming. Further clinical research with serial laboratory assays of patients with definitively identified puff adder bites is crucial to further understand the pathophysiology of envenoming by this medially important snake species.