Estimating the microbiological risks associated with inland flood events: Bridging theory and models of pathogen transport

Abstract

Flooding is known to facilitate infectious disease transmission, yet quantitative research on microbiological risks associated with floods has been limited. Pathogen fate and transport models provide a framework to examine interactions between landscape characteristics, hydrology, and waterborne disease risks, but have not been widely developed for flood conditions. We critically examine capabilities of current hydrological models to represent unusual flow paths, non-uniform flow depths, and unsteady flow velocities that accompany flooding. We investigate the theoretical linkages between hydrodynamic processes and spatio-temporally variable suspension and deposition of pathogens from soils and sediments; pathogen dispersion in flow; and concentrations of constituents influencing pathogen transport and persistence. Identifying gaps in knowledge and modeling practice, we propose a research agenda to strengthen microbial fate and transport modeling applied to inland floods: 1) development of models incorporating pathogen discharges from flooded sources (e.g., latrines), effects of transported constituents on pathogen persistence, and supply-limited pathogen transport; 2) studies assessing parameter identifiability and comparing model performance under varying degrees of process representation, in a range of settings; 3) development of remotely sensed datasets to support modeling of vulnerable, data-poor regions; and 4) collaboration between modelers and field-based researchers to expand the collection of useful data in situ.

Distribution and Antibiotic Resistance Profiles of Salmonella enterica in Rural Areas of North Carolina After Hurricane Florence in 2018

“…Collender et al. (2016) reported that, in addition to the overland flow, the characteristics of a water body can also affect the spread of pathogens, and our findings are in agreement with this description. Studies conducted by Walters et al.…”

“…Moreover, the different distributions of culturable S. enterica versus qPCR detection of the ttrC gene suggested that though the ttrC gene was prevalent in the sampling region after the flood event, many of its host cells might be dormant or nonviable, and the high copy number of ttrC was not necessarily related to the culturability of Salmonella in this region. Collender et al (2016) reported that, in addition to the overland flow, the characteristics of a water body can also affect the spread of pathogens, and our findings are in agreement with this description. Studies conducted by Walters et al (2013) and Shellenbarger et al (2008) suggested water bodies with different characteristics had different frequencies of the detection of Salmonella.…”

Hydrometeorology and flood pulse dynamics drive diarrheal disease outbreaks and increase vulnerability to climate change in surface-water-dependent populations: A retrospective analysis

“…Across land types, the flow of water (ground water, surface water, and rainfall) has been demonstrated to influence infectious disease transmission dynamics across scales, from microbial to host levels [ 1 – 4 ]. Degradation of freshwater ecosystems and declines in water quality in surface water represent a growing public health threat across Africa [ 5 ].…”

CFD Modelling of the Transport of Soluble Pollutants from Sewer Networks to Surface Flows during Urban Flood Events

“…Understanding the concentrations, transport and fate of harmful contaminants in urban floodwaters for effective health risk assessment is challenging [10]. Current state of the art urban flood risk models consider urban hydrological processes and utilise hydrodynamic principles to route resulting flows in both piped drainage and surface overland systems, with interaction (i.e., mass transfer) nodes such as manholes or gullies, which are commonly represented by weir or orifice equations [11][12][13].…”

“…Recently, Mark et al [15] developed an approach to integrate an understanding of contaminant transport and health risk into flood models, utilising the 2D Advection Dispersion Equation to simulate the mixing and transport of wastewater surcharging from drainage systems within overland surface flow (assuming a constant pathogen level within the surcharging flow). However, such approaches can significantly simplify a number of processes concerning sources, transport, survival and transformations of harmful contaminants (e.g., see in [10]). The number of additional terms and associated parameters required to account for transport and fate processes exacerbate non-identifiability and equifinality issues which are a common problem for complex integrated models [16].…”