Re-emergence of Leptospirosis in Urban Tropical Settings: A Systematic Review of Climate, Environmental, and Socioeconomic Drivers

Introduction

Leptospirosis is a neglected zoonotic disease with increasing global incidence, particularly in tropical urban environments. Rapid urbanization, climate change, inadequate sanitation, and expanding rodent populations have driven the re-emergence of leptospirosis, leading to recurrent outbreaks and substantial morbidity and mortality. We conducted a systematic review to synthesize current evidence on the climatic, environmental, and socioeconomic determinants of urban leptospirosis.

Methods

A systematic search of PubMed, Embase, Web of Science, and Scopus was conducted from January 2000 to December 2025 following PRISMA guidelines. Eligible studies included observational, ecological, and modeling studies evaluating environmental, climatic, and social drivers of leptospirosis transmission in urban settings. Primary outcomes were incidence, outbreak occurrence, and mortality. Secondary outcomes included environmental risk factors and socioeconomic vulnerability indicators. Qualitative synthesis and random-effects meta-analysis were performed when feasible.

Results

Forty-eight studies from 32 countries were included. Heavy rainfall, flooding events, and elevated temperatures were consistently associated with increased leptospirosis incidence, with pooled relative risks ranging from 1.6 to 3.4 following extreme precipitation events. Informal housing, poor sanitation infrastructure, high rodent density, and occupational exposure were major socioeconomic determinants. Urban slums accounted for a disproportionate burden of severe disease and mortality. Climate anomalies, including El Niño-related rainfall surges, were strongly linked to large-scale outbreaks. Integrative One Health surveillance models demonstrated improved outbreak prediction and early warning capacity.

Conclusions

Leptospirosis is rapidly re-emerging in urban tropical environments due to the synergistic effects of climate change, environmental degradation, and social vulnerability. Integrated One Health approaches combining environmental monitoring, rodent control, infrastructure investment, and climate-adaptive public health policies are urgently needed to reduce disease burden and prevent future epidemics.