Socioeconomic and ecological drivers of snakebite incidence in Mexico: A spatial analysis of risk factors

Background: Snakebite envenoming constitutes a significant public health challenge in tropical and subtropical regions, with Mexico reporting substantial incidence rates in the Americas. While previous investigations have documented the socioeconomic burden of snakebites, particularly in economically marginalized regions, a comprehensive understanding of the relative contributions of biological and socioeconomic determinants to spatial heterogeneity in snakebite incidence remains poorly understood. This study aimed to identify and quantify the main determinants of snakebite spatial heterogeneity across Mexico while accounting for potential reporting biases in surveillance data. Methods/principal findings: We implemented a rigorous Bayesian analytical framework utilizing a conditional autoregressive zero-inflated Poisson model to examine snakebite incidence across 2,463 Mexican municipalities. Our methodological approach integrated three critical components: environmental suitability indices for venomous snake species derived from refined species distribution models, socioeconomic vulnerability metrics, and healthcare accessibility parameters. Conclusions: Our findings demonstrate that snakebite risk in Mexico is driven by a complex interaction between social vulnerability, infrastructure development, and the distribution of key venomous snake species. The identification of systematic reporting biases offers critical insights for optimizing surveillance protocols and implementing targeted interventions in high-risk municipalities. Author summary: Snakebites represent a significant health challenge in tropical and subtropical regions, including Mexico. Despite their importance, it remains poorly understood why some areas experience more snakebites than others. Our study aimed to identify the key factors that influence where snakebites occur across Mexico. We examined data from over 2,400 municipalities, considering environmental factors (like where venomous snakes live), social conditions (like poverty levels), and infrastructure (like road networks and hospitals). We found that three main factors explain most of the pattern: the level of social marginalization in a community, the density of road networks, and the environmental suitability for a particular venomous snake species called Bothrops asper. Importantly, we discovered that the official records of snakebite cases are strongly influenced by the availability of healthcare facilities - areas with more hospitals report more cases, which doesn’t necessarily mean they have more snakebites. When we accounted for this reporting bias, we identified different high-risk areas than those suggested by official reports. These findings can help authorities better target prevention efforts and distribute antivenoms to the communities that need them most.