# Assessing territorial disparities in snakebite surveillance data in Brazil: Implications for public health

## TL;DR

Brazil's snakebite surveillance data is incomplete and inconsistent, especially in remote regions, which hinders effective public health responses and antivenom distribution.

## Contribution

The study provides the first comprehensive evaluation of Brazil's snakebite surveillance data quality across multiple dimensions and regions.

## Key findings

- Basic demographic data is well reported, but clinical and treatment details are often missing or inconsistent.
- Antivenom use frequently deviates from national guidelines in regions with high snakebite burdens.
- Data quality issues are most severe in the Amazon and other remote areas with high disease incidence.

## Abstract

Snakebite envenoming (SBE) is a neglected tropical disease with high incidence and impact in rural and remote areas of Brazil. Although the country maintains a national reporting system (SINAN) for SBE, few studies have systematically evaluated the quality of these surveillance data, which are essential for informing public health planning and antivenom distribution strategies.

This is a descriptive study analyzing all snakebite notifications recorded in SINAN between 2007 and 2023. Data quality was evaluated across three dimensions: completeness, internal consistency, and reliability. Sociodemographic, clinical, and treatment-related variables were assessed by region using standardized classifications. Inter-database agreement for fatal outcomes was analyzed between SINAN and the Mortality Information System (SIM) using the Intraclass Correlation Coefficient (ICC).

The results showed excellent completeness for core demographic variables such as sex and age, but poor or very poor completeness for education level, occupation, race/ethnicity, and clinical manifestations. Internal inconsistencies, although infrequent, were present across all regions. The overall ICC for fatal outcomes was 0.95, with regional variation. Antivenom use was frequently inconsistent with national treatment guidelines, particularly in cases involving Crotalus, Lachesis, and Micrurus genera.

Despite the availability of a national notification system, snakebite surveillance in Brazil faces substantial limitations in data completeness and consistency, especially for clinical and treatment variables. These gaps are more pronounced in high-burden and remote regions, such as the Amazon, and may hinder equitable resource allocation and policy development. Strengthening notification practices, investing in training, and integrating clinical and epidemiological workflows are critical to improving the quality and utility of SBE data for public health action.

Snakebite envenoming remains a significant but often overlooked public health issue in Brazil, particularly in rural and remote regions where Indigenous and underserved communities are most affected. Although Brazil has a national notification system (SINAN) to track cases and guide antivenom distribution, the quality of this data varies widely across regions. In this study, we analyzed over 500,000 snakebite records from 2007 to 2023 to evaluate the completeness, consistency, and reliability of surveillance data. We found that while basic demographic information is usually well reported, important clinical and treatment-related details are frequently missing or inconsistent—especially in regions with the highest burden of disease, such as the Amazon. In some cases, antivenom use did not align with national guidelines. Our findings suggest that strengthening surveillance practices and adapting reporting systems to the realities of remote and intercultural settings are critical to improving snakebite care and reducing health disparities in Brazil.