Sociodemographic, geographic and temporal patterns of snakebites in Brazil: a descriptive study, 2010-2022

To analyze snakebite accidents that occurred in Brazil between 2010 and 2022, focusing on the sociodemographic characteristics of victims, snake genus involved, seasonality, geographic distribution, degree of risk and relationship with biomes. This descriptive study was based on data taken from the Notifiable Health Conditions Information System on accidents caused by Bothrops, Crotalus, Lachesis and Elapidae.

Incidence rates, mortality rates and case fatality ratios were calculated according to snake genus, age and sex. Spatial analysis used Bayesian statistics and the Getis-Ord index (Gi*) to identify areas with the highest concentration of cases and classify regional risk (from very low to very high).

Between 2010 and 2022, 329,269 snakebite accidents were recorded in Brazil, with a predominance of bothropic cases (70.6%). In the same period, 1,514 deaths occurred, 74.2% of which were associated with bothropic snakebites, 20.7% with crotalic snakebits, 4.7% with lachetic snakebites and 0.4% with elapid snakebites. Despite their lower frequency, crotalic snakebites had the highest annual case fatality ratio (0.1%). Most victims were males (77.8%), of Brown skin color (58.4%), adults (76.3%), with low levels of schooling (48.0%), and living in rural areas (63.9%). Deaths were associated with delays in care. Bothropic snakebites remained stable, crotalic and elapid snakebites increased, while lachetic snakebites decreased. Cases occurred mostly between October and March, except in the Northeast, where they were mostly between December and June. Geographically, the patterns followed the biomes.

The results reinforce the need for specific regional strategies for surveillance, prevention and effective management, based on the observed geographic, seasonal and demographic patterns.