Leptospirosis is a zoonotic disease of global importance with significant morbidity and mortality. However, the disease is frequently overlooked and underdiagnosed, leading to uncertainty of the true scale and severity of the disease. A neglected tropical disease, leptospirosis disproportionately impacts disadvantaged socioeconomic communities most vulnerable to outbreaks of zoonotic disease, due to contact with infectious animals and contaminated soils and waters. With growing evidence that Leptospira survives, persists, and reproduces in the environment, this paper reviews the current understanding of the pathogen in the environment and highlights the unknowns that are most important for future study. Through a systematic Boolean review of the literature, our study finds that detailed field-based study of Leptospira prevalence, survival, and transmission in natural waters and soils is lacking from the current literature. This review identified a strong need for assessment of physical characteristics and biogeochemical processes that support long-term viability of Leptospira in the environment followed by epidemiological assessment of the transmission and movement of the same strains of Leptospira in the present wildlife and livestock as the first steps in improving our understanding of the environmental stage of the leptospirosis transmission cycle.

Introduced in ~59 countries and native across Europe and Asia, wild pigs, Sus scrofa, are the most wide-spread swine species in the world. As ecosystem engineers, wild pigs are a significant source of disturbance in introduced ecosystems due to their numerous, complex impacts on ecosystem processes. Wild pigs are often found in the resource-rich habitat of coastal forests. Coastal forests are complex, dynamic systems with tremendous biodiversity. Exposed to recurrent disturbances, the biophysical characteristics of coastal forests contribute to their ability to return to their original state post-disturbance. However, compounding disturbances can weaken this ability and threaten the health and function of the ecosystem. In this review, through the model of the forests of the southeastern United States Coastal Plain, we (1) describe conditions found across the forested coastal landscape, (2) describe wild pig disturbance, and (3) discuss how wild pig impacts can add to significant anthropogenic and climate-related disturbances threatening coastal forests. Through this review, we find that the impacts of wild pig disturbance on coastal forests often have similar effects as anthropogenic and climate change-related disturbances that may enhance these significant threats to coastal forest function and resiliency.

Predicting public health risk associated with exposure to and recreational use of surface waters is often challenging due to substantial variability in concentrations of pathogenic bacteria, even among seemingly similar streams. In this study, we document significant differences in the surface water concentrations of the common bacteria indicators Escherichia coli and fecal coliform between two major stream types—blackwater and redwater streams (p < 0.001). We propose and present evidence that these findings result from natural biogeochemical variation between physiographic regions (p < 0.001). These findings suggest that physiographic stream type may influence the degree of exposure to waterborne pathogens and risk of waterborne disease. Future research is needed to assess whether the inclusion of stream type in risk assessments can improve public health modeling and mapping.