Flood-associated disease outbreaks and transmission in Southeast Asia - Introduction 13

Shidonna Raven

2 hours ago

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Authors: Boonfei Tan ¹

Patrick De Vera ²

Josephine Abrazaldo ²

Charmaine Ng ^1*

Source: Frontiers

Photo/Image Source: Unsplash

SEA with varied and diverse environmental niches such as rice paddies, wells, open water, and soils serve as environmental reservoirs for harboring dormant Leptospira that can reactivate under saturated wet conditions (Yanagihara et al., 2022). The pathogen has also been detected in contaminated surface waters, creating exposure risks through recreational and occupational activities (Narkkul et al., 2020; Narkkul et al., 2021). Populations living in rural areas and engaged in agriculture or farming practices are particularly vulnerable to infection (Sawangpol et al., 2025; Chadsuthi et al., 2021; Suttirat et al., 2025; Douchet et al., 2022), often occurring through direct contact with contaminated water or soil, when the skin is broken or abraded (Sakundarno et al., 2014). Within human settlements in urban and rural areas, zoonotic reservoirs play a major role in sustaining transmission, with high densities of commensal rodents consistently linked to infection risk (Sutiningsih et al., 2024; Widawati et al., 2023; Ribas et al., 2016; Villanueva et al., 2010; Ciano et al., 2021; Wuthiekanun et al., 2007; Krairojananan et al., 2025; Griffiths et al., 2022). Rodents are frequently found in environments such as wet markets and soils of paddy fields, where water samples from these areas test positive for Leptospira (Ling et al., 2025). In addition, exposure to stray animals (e.g., dogs, cats) (Narkkul et al., 2021; Chadsuthi et al., 2017; Ngasaman et al., 2020; Sprißler et al., 2019; Altheimer et al., 2020; Andityas et al., 2025) and livestock, (e.g., cattle, goat, sheep) (Sunaryo and Priyanto, 2022; Widiasih et al., 2021), carrying the pathogen, also represent a significant risk; as these animals can become hosts through infection after floods, or when exposed to contaminated water used for farming purposes (Lea et al., 2025; Widiasih et al., 2021; Rahman et al., 2023).