Characteristics of snakebite patients due to Naja samarensis in the Philippines: a prospective hospital-based study.

Background: Little is known about snakebites by Naja samarensis, a species unique to the Philippines. The aim here is to describe the clinical and epidemiological characteristics of patients bitten by this medically important cobra in the Eastern Visayas.

Methods: A hospital-based prospective study analysed the features of snakebite patients attending Eastern Visayas Medical Center between June 2022 and May 2023. Logistic regression analysis identified the factors associated with severity.

Results: A total of 175 snakebite patients with five fatalities were included. Naja samarensis was most commonly implicated (n=49, 28.0%), although it could be definitively identified, by examining photographs of the snake responsible, in only four cases. The N. samarensis bites occurred in grass or rice fields, in daytime, and during farming activities, but the people bitten were most frequently students (34.7%) who were bitten at home (36.7%). Patients bitten by N. samarensis often presented with cytotoxic (63.3%) and neurotoxic signs (46.9%). Traditional remedies were common, resulting in delayed presentation to the hospital. Bites by N. samarensis, and older age (>44 y) were independently associated with severity (adjusted OR of 10.33 and 7.89, respectively).

Conclusion: Naja samarensis is a major cause of severe snakebites in this region. Pre-hospital treatment frequently involves wasted time and unproven traditional methods. Enhancement of public awareness is urgently needed. Development of a diagnostic test for species identification is warranted to improve future surveys and management.