A systematic review of Leptospira in water and soil environments

Abstract

Background Leptospirosis, caused by pathogenic Leptospira, is a zoonosis of global distribution. This infectious disease is mainly transmitted by indirect exposure to urine of asymptomatic animals via the environment. As human cases generally occur after heavy rain, an emerging hypothesis suggests that rainfall re-suspend leptospires together with soil particles. Bacteria are then carried to surface water, where humans get exposed. It is currently assumed that pathogenic leptospires can survive in the environment but do not multiply. However, little is known on their capacity to survive in a soil and freshwater environment. Methods We conducted a systematic review on Leptospira and leptospirosis in the environment in order to collect current knowledge on the lifestyle of Leptospira in soil and water. In total, 86 scientific articles retrieved from online databases or institutional libraries were included in this study. Principals findings/significance This work identified evidence of survival of Leptospira in the environment but major gaps remain about the survival of virulent species associated with human and animal diseases. Studies providing quantitative data on Leptospira in soil and water are a very recent trend, but must be interpreted with caution because of the uncertainty in the species identification. Several studies mentioned the presence of Leptospira in soils more frequently than in waters, supporting the hypothesis of the soil habitat and dispersion of Leptospira with resuspended soil particles during heavy rain. In a near future, the growing use of high throughput sequencing will offer new opportunities to improve our understanding of the habitat of Leptospira in the environment. This better insight into the risk of leptospirosis will allow implementing efficient control measures and prevention for the human and animal populations exposed.

Circulating genotypes of Leptospira in French Polynesia : An 9-year molecular epidemiology surveillance follow-up study

“…The fact that most of the patients in our sample set (83%) were males corresponds well with the findings of many other epidemiological studies, where males were found to be the major victims of this pathogen [3,6]. In addition, leptospirosis is known to be seasonal, and strongly associated with rainfalls in tropical settings.…”

“…can colonize the renal tubules of a wide variety of wild and domesticated mammals. The bacteria are shed in the urine of infected animals and persist in freshwater [3]. Transmission to a new host usually occurs after exposure to this contaminated water [4].…”

Seasonal shifts in the presence of pathogenic leptospires, Escherichia coli, and physicochemical properties in coastal rivers and streams of Puerto Rico

“…Therefore, it appears that heavy rainfall increases the chance of surface water contamination of Leptospira from the urine of carrier animals such as rats, mongoose, and other animals in Puerto Rico. It is assumed that rainfall can resuspend and transport Leptospira attached to soil particles into rivers and streams (Bierque et al, 2020). These findings are supported by several studies that have reported outbreaks of Leptospirosis after heavy rainfall and flooding events (Goarant et al, 2009;Sharp et al, 2016;Smith et al, 2013).…”

Molecular and Serological Prevalence of Leptospira spp. in Feral Pigs (Sus scrofa) and their Habitats in Alabama, USA

“…The bacterium can survive for about a week in moist soil and mud when temperature and other conditions are favorable [ 3 ], although Thibeaux et al (2017) [ 16 ] found that pathogenic leptospires remained viable in soils for several weeks under laboratory conditions. Emerging evidence also supports the hypothesis that rainfalls re-suspend Leptospira with soil particles, which are carried to surface water, where animals and humans get exposed [ 17 ].…”