Abstract
Agro-pastoral operations have the potential to threaten public health with loading of diverse pathogens into surface waters through overland flow; increasing awareness of the limitations of fecal indicators has led to development of a number of advancements in detection, source tracking and predictive modeling of public health risk. These tools and techniques are beginning to be integrated into management strategies. The objective of this review was to determine the status of current knowledge and challenges of the fate and transport of Escherichia coli in overland flow and their interaction within vegetative filter strip (VFS) as one of these implemented best management practices and to critically evaluate its use in that setting as an indicator organism. With few studies directly focusing on VFS removal of E. coli from overland flow, we critically evaluated the available data on movement of E. coil from fecal source loading to retention and decay or re-release for potential contamination of water ways and pointed out potential limitations in both pathogen-specific removal and its use as an indicator organisms within overland flow and VFS. Critical areas of focus for future studies to reduce gaps in knowledge were identified, and the integration of newer approaches in source tracking, alternative indicators and the use of non-pathogenic surrogates for field testing of existing VFS models was encouraged. With VFS as a growing field of interest as an economical conservation practice and as an avenue for conservation of resources for small-scale agro-pastoral operations, management strategies to reduce initial fecal load from either applied manure constituents or shedding from free-range animals will continue to test the limits in the applications of models to overland flow and VFS management strategies. Further studies at the microscale in understanding discrepancies between low and high pathogenicity strains of E. coil and between E. coil and other fecal pathogens in the context of VFS will be critical. However, nuanced studies are needed to understand either biological or environmental differences in the fate and transport of the diverse types of fecal pathogens within these settings.