Risk factors for human leptospirosis following flooding: A meta-analysis of observational studies

Abstract

Leptospirosis is probably the most widespread zoonotic disease in the world especially in tropical countries. There has been an increase in individual studies, which assessed the frequency of leptospirosis in flood conditions. Some studies showed contact with floods was significantly associated with the occurrence of leptospirosis while other studies reported differently. The objective of this meta-analysis was to synthesize the evidence on the risk factors which are associated with human leptospirosis following flooding. We set up the inclusion criteria and searched for the original studies, addressing leptospirosis in human with related to flood in health-related electronic databases including PubMed, Embase, Ovid Medline, google scholar and Scopus sources. We used the terms ‘leptospirosis’, ‘flood’, ‘risk factor’ and terms from the categories were connected with “OR” within each category and by “AND” between categories. The initial search yielded 557 citations. After the title and abstract screening, 49 full-text papers were reviewed and a final of 18 observational studies met the pre-specified inclusion criteria. Overall, the pooled estimates of 14 studies showed that the contact with flooding was a significant factor for the occurrence of leptospirosis (pooled OR: 2.19, 95%CI: 1.48–3.24, I 2 :86%). On stratification, the strength of association was greater in the case-control studies (pooled OR: 4.01, 95%CI: 1.26–12.72, I 2 :82%) than other designs (pooled OR:1.77,95%CI:1.18–2.65, I 2 :87%). Three factors such as ‘being male’(pooled OR:2.06, 95%CI:1.29–2.83), the exposure to livestock animals (pooled OR: 1.95, 95%CI:1.26–2.64), the lacerated wound (pooled OR:4.35, 95%CI:3.07–5.64) were the risk factors significantly associated with the incidence of leptospirosis following flooding in the absence of within-study heterogeneity ( I 2 : 0%). We acknowledge study limitations such as publication bias and type 2 statistical errors. We recommended flood control and other environmental modifications that are expected to reduce the risk of leptospiral infection, and a multi-sectoral effort to this aspect would have long-term benefits.

Significant Clinical Presentation of Leptospirosis in Relation to Sociodemographic and Risk Factors in a Tertiary Hospital, Malaysia

“…The transmission circle of leptospirosis involves a complex interaction between humans, animal reservoirs, and the environment. Changes of human involvement in the environment such as deforestation and rapid urbanization might cause flooding, which was significantly associated with the incidence of leptospirosis (Naing et al 2019). In more developed countries, outdoor activities facilitate leptospirosis infection through activities such as wading, swimming, and rafting, especially among travelers participating in ''adventure tourism'' and water-related activities (Plank andDean 2000, Lau et al 2010).…”

“…As one of the developing countries, Malaysia is also affected by urbanization resulting in urban population growth and urban decay. Besides that, we have seasonal heavy rainfall with occasional flooding that assists the movement of infectious leptospires from soil or sewers into water surface leading to leptospirosis outbreak (Radi et al 2018, Naing et al 2019).…”

Human and environmental risk factors of leptospirosis in Gunungkidul, Indonesia: a case-control study

“…7,8 At present, a large number of leptospirosis studies in Indonesia. 9,[10][11][12][13][14][15][16][17][18][19][20] However, none of them combine the human risk factor and environmental coordinates such as topography and soil type. That type of research is essential to comprehensively see the pattern for a better understanding of the situation and build effective evidence-based prevention programs.…”

Beyond diversity loss and climate change: Impacts of Amazon deforestation on infectious diseases and public health

“…The presence of pathogens in water (considering quantity and diversity) is modified by hydrological events, modulating the exposure of humans to such pathogens. As a result, many infectious diseases spread during rainfall, periods of high river levels and floods, including leptospirosis and gastroenteritis, which are important public health problems not only in the Amazon region but also in other parts of Brazil (Gracie et al 2014, Rodrigues et al 2015, Nava et al 2017, Vieira et al 2016, Duarte et al 2019b, Duarte & Giatti 2019, Naing et al 2019, Péres et al 2019.…”