# Leptospirosis in Campinas, Brazil: The interplay between drainage, impermeable areas, and social vulnerability

## TL;DR

This study shows how urban drainage, impermeable surfaces, and social vulnerability increase leptospirosis risk in Campinas, Brazil, offering insights for public health and urban planning.

## Contribution

The study introduces a spatial analysis approach linking environmental and socio-economic factors to leptospirosis risk in urban settings.

## Key findings

- Leptospirosis cases are most concentrated within 200 meters of drainage systems.
- Socially vulnerable and highly impermeable areas show elevated disease risk.
- Combining environmental and socio-economic data improves public health interventions.

## Abstract

Leptospirosis is an epidemic disease caused by bacteria of the Leptospira genus. Its risk is closely associated with inadequate sanitation and flooding, a common public health challenge in large urban centers together with urban environmental modifications, and socio-economic factors. This retrospective observational research investigated the association between the distribution of leptospirosis cases and three contextual factors, drainage, soil impermeability and social vulnerability in Campinas city, São Paulo, Brazil. We hypothesized that the number of cases will increase in areas that are impermeable and in proximity to drainage systems as well as where social vulnerability is high. We investigated the associations based on 86 autochthonous cases, comparing cases where infection risk was linked to contact with floodwater or mud (n = 54) to cases associated with other exposures (n = 32). Spatial statistics were used to map disease distribution and investigate the relationship between leptospirosis cases and contextual factors. Our results indicate that leptospirosis cases density rises near drainage systems, peaking at 200 m. Risk is elevated in socially vulnerable areas, particularly where floodwater or mud exposure is high, and in highly impermeable areas. This study demonstrated that leptospirosis risk remains highly determined by living and working conditions. These findings support targeted strategies to deliver effective prevention, treatment and control interventions in highly populated urban areas of the Global South and similar contexts. Furthermore, combining local contextual environmental information with spatial analysis produces relevant evidence for guiding health public policy and spatial planning and provides precise parameters for future epidemiological models and prevention actions.

This study explores the links between environmental and contextual factors that influence the risk of leptospirosis transmission to humans in Campinas, São Paulo, Brazil. Leptospirosis is an infectious disease caused by the Leptospira bacteria. We investigated how drainage systems, impermeable soil area, and social vulnerability contribute to disease distribution, mapping spatial conditions for 86 cases associated with water and mud contact and other risks. Our findings highlight how environmental and socio-economic factors intersect to influence public health, shedding light on the role of urban planning and drainage infrastructure in the transmission risk of infectious diseases. Our approach reveals that flood-related transmission risk is highest within 200 meters of drainage systems and in socially vulnerable, highly impermeable areas. These findings provide actionable insights for urban planners and public health officials, demonstrating how targeted infrastructure improvements and flood management can potentially reduce disease risk in the most affected communities. The study contributes to practical parameters for epidemiological modeling and offers a replicable methodology for addressing climate-sensitive diseases in rapidly urbanizing areas of the Global South.