Impact of the Rainy Season to the Incidence of Leptospirosis : A Literature Review

Abstract

Background:
Leptospirosis is a zoonotic disease with high morbidity and mortality, particularly in tropical regions. Rainfall and floods are key drivers of transmission. Eligible studies include observational and review articles addressing rainfall or floods in relation to leptospirosis. Data was synthesized narratively and thematically.

Objective:
This study reviews the relationship between the rainy season and leptospirosis incidence to inform effective prevention strategies.

Methods:
A systematic search was performed in PubMed, Scopus, Web of Science, and Google Scholar for articles published between 2019–2025. The PRISMA framework guided study selection. Eligible studies included observational and review articles addressing rainfall or flood in relation to leptospirosis. Data were synthesized narratively and thematically.

Results:
Findings consistently show that rainy seasons increase leptospirosis cases through prolonged Leptospira survival in moist environments and heightened human exposure to contaminated water. Populations at greatest risk include agricultural workers, fishermen, and residents of flood-prone areas with poor sanitation. Studies emphasized that rainfall patterns correlate with outbreak peaks, often overwhelming local health systems.

Conclusions:
The rainy season significantly elevates leptospirosis incidence in endemic regions. Comprehensive interventions combining environmental management, risk communication, and health system readiness are crucial to reduce disease burden and mortality.