Snakebite Epidemiology in Humans and Domestic Animals Across Nepal's Terai: A Multi-Cluster Random Survey

Background: Each year, two million people worldwide suffer snakebite envenoming (SBE), resulting in up to 138,000 deaths. The World Health Organization has added SBE to the list of Neglected Tropical Diseases, calling for stronger epidemiological evidence in highly endemic countries such as Nepal. Methods: We conducted a cross-sectional survey in 249 randomly selected clusters across Nepal’s Terai region, including 13,879 geospatially selected households. We analysed snakebite incidence rates and outcomes in humans and domestic animals. Findings :Among 63,454 human participants, 166 suffered snakebites over the previous 12 months; 48·8% were envenomed and 7·8% died. This corresponded to annual incidence rates of 262 snakebites [95% CI 225–305] , 127 envenomings [102–158], and 20 [12–35] deaths per 100,000 individuals, extrapolating into 37,661 yearly victims [32,362–43,836] and 2,949 deaths [1,728–5,053] in the Terai. Victim median age was 30 years (IQR 20–45) and 60% were female. Children younger than 15 years (n=6; 46%) and females (n=10; 77%) were over-represented among the 13 deceased. Incidence was higher in Eastern, and mortality in Central regions. Of 184,999 animals, owners reported 144 snakebites, with annual incidence rates of 42-202 and mortality of 79-100 per 100,000 varying by animal type. Spatial and seasonal incidence were similar in humans and animals. Conclusion: This first One Health study on snakebite across Nepal’s Terai shows high incidence and mortality rates in humans and animals. These results call for strengthening of preventive measures and better access to life-saving treatments. Funding: Swiss National Science Foundation project 315130_176271 (SNAKE-BYTE) Declaration of Interest: None to declare. Ethical Approval: The study was approved by the Nepal Health Research Council (NHRC Reg. 585/2018), and Commission Cantonale d’Ethique de la Recherche Scientifique in Geneva, Switzerland (CCER/SwissEthics Registry No. 2018-01331).