Leptospirosis Chemoprophylaxis Following Floods

Siripen Kanchanasuwan

Abstract

Leptospirosis is a globally important zoonotic infection with a high burden in tropical regions, including Thailand, where transmission is strongly associated with rainfall and flooding. In endemic settings, predictable exposure patterns and identifiable high-risk populations have prompted interest in antibiotic chemoprophylaxis as a preventive strategy. This narrative review summarizes the current evidence on antibiotic chemoprophylaxis for leptospirosis, with emphasis on flood-associated exposure and data from Thailand. Doxycycline is the most extensively studied agent. Early randomized trials demonstrated substantial protection against clinical disease, while later studies reported inconsistent findings, particularly regarding prevention of infection. Evidence suggests that doxycycline may reduce the incidence and severity of symptomatic leptospirosis rather than completely preventing infection. Data from southern Thailand provide important real-world evidence supporting post-exposure prophylaxis. A prospective study during flooding showed that a single 200 mg dose of doxycycline reduced the risk of leptospiral infection and clinical disease, with particularly high efficacy among individuals with skin wounds. Systematic reviews, including Cochrane analyses, indicate a modest benefit in preventing clinical illness but highlight limitations related to study heterogeneity and methodological quality. Overall, current evidence supports a targeted approach to chemoprophylaxis in high-risk populations rather than universal use. In endemic regions such as southern Thailand, post-exposure doxycycline may be considered for individuals with significant exposure, particularly in the presence of skin breaches, alongside non-pharmacological preventive measures.

 Keywords

chemoprophylaxis; floods; leptospirosis; Thailand

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References

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DOI: http://dx.doi.org/10.31584/jhsmr.20261425

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