Leptospirosis: An emerging zoonotic disease

Introduction: Leptospirosis is a globally distributed waterborne zoonosis with significant public health impact, accounting for over one million annual cases and approximately 60,000 deaths. Once considered an occupational disease confined to endemic tropical regions, its epidemiology has recently undergone profound changes.
Methods: This narrative review synthesizes evidence from published literature on the epidemiological transition, ecological drivers, diagnostic challenges, and prevention strategies of leptospirosis, with a focus on recent global trends.
Results: Human infection occurs primarily through contact with urine of carrier animals, particularly rodents, cattle, and pigs. Increasingly, outbreaks are reported among urban populations, recreational water users, and flood affected communities, indicating a shift beyond traditional occupational risk groups. Climate change—manifested as rising temperatures, extreme flooding, and hurricanes—creates favorable conditions for bacterial survival and amplifies human exposure. Despite advances in understanding Leptospira pathogenesis, diagnosis remains difficult due to nonspecific early symptoms that mimic dengue, malaria, and other febrile illnesses, often leading to delayed treatment. Additionally, the high genetic and serological diversity of the pathogen hinders the development of a broadly protective human vaccine.
Conclusion: Leptospirosis is no longer a neglected tropical disease restricted to certain endemic foci; it has evolved into a dynamic global health challenge exacerbated by climate change, urbanization, and complex human animal environment interactions. Effective control requires a paradigm shift from reactive outbreak response to proactive integrated surveillance, improved diagnostics, strengthened international collaboration, and sustained investment in research and public health preparedness.