Critical Illness in Migrant Workers in the Windsor-Essex Region: A Descriptive Analysis.

Despite their essential role in Canadian agriculture, migrant workers face numerous healthcare barriers. There is a knowledge gap regarding the healthcare experiences of migrant workers with critical illness in the Windsor-Essex region. Our objective was to collect information on the experiences of migrant workers experiencing a critical illness at Windsor Regional Hospital (WRH) between 31 December 2011 and 31 December 2021. We conducted a retrospective chart review and interviews with migrant workers. We identified 14 migrant workers who presented to WRH with a critical illness over these 10 years. Despite occasional barriers regarding access to care, the migrant workers received an appropriate standard of care in Canada. Five of the fourteen patients identified were repatriated to their home countries. The migrant worker patients interviewed expressed satisfaction with the care they received in Canada but identified repatriation as a specific concern to receiving continuity of care. The health and financial burden imposed by critical illness on migrant workers and their employers makes critically ill workers vulnerable to medical repatriation as a unique social determinant of health. Considering the critical role of migrant workers in Canada's food security, policy changes should be considered to ensure critically ill workers are able to remain until recovery.

Quantitative Microbial Risk Assessment for Contaminated Private Wells in the Fractured Dolomite Aquifer of Kewaunee County, Wisconsin.

BACKGROUND: Private wells are an important source of drinking water in Kewaunee County, Wisconsin. Due to the region's fractured dolomite aquifer, these wells are vulnerable to contamination by human and zoonotic gastrointestinal pathogens originating from land-applied cattle manure and private septic systems. OBJECTIVE: We determined the magnitude of the health burden associated with contamination of private wells in Kewaunee County by feces-borne gastrointestinal pathogens. METHODS: This study used data from a year-long countywide pathogen occurrence study as inputs into a quantitative microbial risk assessment (QMRA) to predict the total cases of acute gastrointestinal illness (AGI) caused by private well contamination in the county. Microbial source tracking was used to associate predicted cases of illness with bovine, human, or unknown fecal sources. RESULTS: Results suggest that private well contamination could be responsible for as many as 301 AGI cases per year in Kewaunee County, and that 230 and 12 cases per year were associated with a bovine and human fecal source, respectively. Furthermore, Cryptosporidium parvum was predicted to cause 190 cases per year, the most out of all 8 pathogens included in the QMRA. DISCUSSION: This study has important implications for land use and water resource management in Kewaunee County and informs the public health impacts of consuming drinking water produced in other similarly vulnerable hydrogeological settings. https://doi.org/10.1289/EHP7815.

Sources and Risk Factors for Nitrate and Microbial Contamination of Private Household Wells in the Fractured Dolomite Aquifer of Northeastern Wisconsin.

BACKGROUND: Groundwater quality in the Silurian dolomite aquifer in northeastern Wisconsin, USA, has become contentious as dairy farms and exurban development expand. OBJECTIVES: We investigated private household wells in the region, determining the extent, sources, and risk factors of nitrate and microbial contamination. METHODS: Total coliforms, Escherichia coli, and nitrate were evaluated by synoptic sampling during groundwater recharge and no-recharge periods. Additional seasonal sampling measured genetic markers of human and bovine fecal-associated microbes and enteric zoonotic pathogens. We constructed multivariable regression models of detection probability (log-binomial) and concentration (gamma) for each contaminant to identify risk factors related to land use, precipitation, hydrogeology, and well construction. RESULTS: Total coliforms and nitrate were strongly associated with depth-to-bedrock at well sites and nearby agricultural land use, but not septic systems. Both human wastewater and cattle manure contributed to well contamination. Rotavirus group A, Cryptosporidium, and Salmonella were the most frequently detected pathogens. Wells positive for human fecal markers were associated with depth-to-groundwater and number of septic system drainfield within 229m. Manure-contaminated wells were associated with groundwater recharge and the area size of nearby agricultural land. Wells positive for any fecal-associated microbe, regardless of source, were associated with septic system density and manure storage proximity modified by bedrock depth. Well construction was generally not related to contamination, indicating land use, groundwater recharge, and bedrock depth were the most important risk factors. DISCUSSION: These findings may inform policies to minimize contamination of the Silurian dolomite aquifer, a major water supply for the U.S. and Canadian Great Lakes region. https://doi.org/10.1289/EHP7813.

Pathogen Prevalence in Fractured versus Granular Aquifers and the Role of Forward Flow Stagnation Zones on Pore-Scale Delivery to Surfaces.

Lesser pathogen prevalence is well recognized in granular versus fractured aquifers; however, the impact of residence time (inactivation/death) versus removal (pore-scale delivery to surfaces) on pathogen prevalence remains unaddressed. The objective of this study was to examine the specific role of pore-scale delivery to surfaces (removal) as an explanation of contrasting pathogen prevalence in granular versus fractured media from Wisconsin. Inactivation/death was obviated by the use of nonbiological colloids in column transport experiments conducted in representative media from the two Wisconsin sites. Trends in retention as a function of colloid size were examined using nano- to microsized (0.1-4.2 µm) carboxylate-modified polystyrene latex microspheres that represented virus- to protozoa-sized pathogens. Several orders of magnitude greater removal of all colloid sizes were observed in granular relative to those in fractured media, whereas the size corresponding to minimum retention contrasted between the two media. Particle trajectory simulations in collectors (flow fields with surfaces) representing granular versus fractured media captured the observed contrasting retention and trends with colloid size. These results demonstrate that flow impingement on surfaces at forward flow stagnation zones drives contrasting pore-scale delivery to surfaces in granular versus fractured media and potentially the observed contrasting pathogen prevalence in granular versus fractured aquifers.

Automated Time Series Measurement of Microbial Concentrations in Groundwater-Derived Water Supplies.

Fecal contamination by human and animal pathogens, including viruses, bacteria, and protozoa, is a potential human health hazard, especially with regards to drinking water. Pathogen occurrence in groundwater varies considerably in space and time, which can be difficult to characterize as sampling typically requires hundreds of liters of water to be passed through a filter. Here we describe the design and deployment of an automated sampler suited for hydrogeologically and chemically dynamic groundwater systems. Our design focused on a compact form to facilitate transport and quick deployment to municipal and domestic water supplies. We deployed a sampler to characterize water quality from a household well tapping a shallow fractured dolomite aquifer in northeast Wisconsin. The sampler was deployed from January to April 2017, and monitored temperature, nitrate, chloride, specific conductance, and fluorescent dissolved organic matter on a minute time step; water was directed to sequential microbial filters during three recharge periods that ranged from 5 to 20 days. Results from the automated sampler demonstrate the dynamic nature of the household water quality, especially with regard to microbial targets, which were shown to vary 1 to 2 orders of magnitude during a single sampling event. We believe assessments of pathogen occurrence and concentration, and related assessments of drinking well vulnerability, would be improved by the time-integrated characterization provided by this sampler.

Site characterization in densely fractured dolomite: comparison of methods.

One of the challenges in characterizing fractured-rock aquifers is determining whether the equivalent porous medium approximation is valid at the problem scale. Detailed hydrogeologic characterization completed at a small study site in a densely fractured dolomite has yielded an extensive data set that was used to evaluate the utility of the continuum and discrete-fracture approaches to aquifer characterization. There are two near-vertical sets of fractures at the site; near-horizontal bedding-plane partings constitute a third fracture set. Eighteen boreholes, including five coreholes, were drilled to a depth of approximately 10.6 m. Borehole geophysical logs revealed several laterally extensive horizontal fractures and dissolution zones. Flowmeter and short-interval packer testing identified which of these features were hydraulically important. A monitoring system, consisting of short-interval piezometers and multilevel samplers, was designed to monitor four horizontal fractures and two dissolution zones. The resulting network consisted of >70 sampling points and allowed detailed monitoring of head distributions in three dimensions. Comparison of distributions of hydraulic head and hydraulic conductivity determined by these two approaches suggests that even in a densely fractured-carbonate aquifer, a characterization approach using traditional long-interval monitoring wells is inadequate to characterize ground water movement for the purposes of regulatory monitoring or site remediation. In addition, traditional multiwell pumping tests yield an average or bulk hydraulic conductivity that is not adequate for predicting rapid ground water travel times through the fracture network, and the pumping test response does not appear to be an adequate tool for assessing whether the porous medium approximation is valid.