Siamese Russell's viper bite: epidemiology, clinical characteristics, and outcomes

Daboia siamensis envenoming is a major cause of hematotoxicity and acute kidney injury in Southeast Asia. In Thailand, D. siamensis is a clinically important snake, yet detailed national data on its bites are limited. Hence, we aimed to determine the clinical characteristics, management, and outcomes of D. siamensis bites in Thailand, identify factors associated with acute kidney injury and hemodialysis, and analyze antivenom administration with reference to acute kidney injury and hemodialysis.

We conducted a 10-year retrospective cross-sectional study using data from the Ramathibodi Poison Center Toxic Exposure Surveillance System (2014-2023). All diagnosed D. siamensis bites were reviewed. Definite cases were defined when the snake species was identified via a live specimen, carcass, or photograph.

A total of 185 patients were included, with 101 definite cases. Most (82.7%) were male, and the mean (±SD) age was 43.0 ± 16.6 years. Overall clinical manifestations included local effects (20.5%), coagulopathy (89.2%), acute kidney injury (50.3%), thrombocytopenia (31.4%), and rhabdomyolysis (28.1%). Antivenom was administered in 89.2% of cases. The median (IQR) length of hospital stay was 5 (3-7) days. The mortality rate was 3.8%. Tachycardia at presentation, initial proteinuria, and rhabdomyolysis were found to prognosticate the development of acute kidney injury. Metabolic acidosis at presentation and rhabdomyolysis were predictors of the requirement for hemodialysis. In addition, receiving antivenom within two hours may reduce the need for hemodialysis (odds ratio 0.153, 95% CI 0.035-0.674).

Discrepancies between our findings and those of others on D. siamensis bites may have resulted from geographic variation in the venom composition and/or differences in the study period and population. Although antivenom treatment did not reverse renal injury, it may have prevented progression.

Systemic hematotoxicity and nephrotoxicity generally developed after a D. siamensis bite. Several clinical characteristics are potential markers of acute kidney injury and hemodialysis requirement after a D. siamensis bite, and early administration of antivenom may reduce the need for hemodialysis.