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

Introduction The 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. 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 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. Results Between December 2020 and September 2021, 15 patients were admitted with a suspected 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 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. 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 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. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study was funded by the National Institute for Health Research grant awarded to RAH, GOO, NRC and DGL entitled ‘NIHR Global Health Research Group on African Snakebite Research’ (#16.137.114). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The views expressed are those of the author(s) and not necessarily those of the NIHR or the Department of Health and Social Care. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethical approval for the case series portion of this study was obtained from the Kenyatta National Hospital - University of Nairobi and Ethics Research Committee, Nairobi, Kenya (P149/03/2020) and the Liverpool School of Tropical Medicine Research Ethics Committee (Research Protocol 18-058). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The data used for writing and interpreting our findings are available in the manuscript