Drinking water sources, quality, and associated health outcomes in Appalachian Virginia: A risk characterization study in two counties.

OBJECTIVES: In the US, violations of drinking water regulations are highest in lower-income rural areas overall, and particularly in Central Appalachia. However, data on drinking water use, quality, and associated health outcomes in rural Appalachia are limited. We sought to assess public and private drinking water sources and associated risk factors for waterborne pathogen exposures for individuals living in rural regions of Appalachian Virginia. METHODS: We administered surveys and collected tap water, bottled water, and saliva samples in lower-income households in two adjacent rural counties in southwest Virginia (bordering Kentucky and Tennessee). Water samples were tested for pH, temperature, conductivity, total coliforms, E. coli, free chlorine, nitrate, fluoride, heavy metals, and specific pathogen targets. Saliva samples were analyzed for antibody responses to potentially waterborne infections. We also shared water analysis results with households. RESULTS: We enrolled 33 households (83 individuals), 82% (n = 27) with utility-supplied water and 18% with private wells (n = 3) or springs (n = 3). 58% (n = 19) reported household incomes of <$20,000/year. Total coliforms were detected in water samples from 33% (n = 11) of homes, E. coli in 12%, all with wells or springs (n = 4), and Aeromonas, Campylobacter, and Enterobacter in 9%, all spring water (n = 3). Diarrhea was reported for 10% of individuals (n = 8), but was not associated with E. coli detection. 34% (n = 15) of saliva samples had detectable antibody responses for Cryptosporidium spp., C. jejuni, and Hepatitis E. After controlling for covariates and clustering, individuals in households with septic systems and straight pipes had significantly higher likelihoods of antibody detection (risk ratios = 3.28, 95%CI = 1.01-10.65). CONCLUSIONS: To our knowledge, this is the first study to collect and analyze drinking water samples, saliva samples, and reported health outcome data from low-income households in Central Appalachia. Our findings indicate that utility-supplied water in this region was generally safe, and individuals in low-income households without utility-supplied water or sewerage have higher exposures to waterborne pathogens.

Time outdoors and residential greenness are associated with reduced systemic inflammation and allostatic load.

Contacts with nature are linked with reduced morbidity and mortality. Hypothesized pathways include relaxation, physical activity, and improved immune function. This cross-sectional study of 320 adults in central North Carolina assessed health benefits of residential greenness using allostatic load (AL) and systemic inflammation (INFL) indices, composite biomarker-based measures of physiological dysregulation and inflammation, respectively. Distance-to-residence weighted tree cover and vegetated land cover measures were estimated within 500 m of each residence; 37 biomarkers of immune, neuroendocrine, cardiovascular, and metabolic functions were dichotomized at distribution or health-based cut-offs. AL was calculated as a sum of potentially unhealthy values of all biomarkers; INFL was based on a subset of 18 immune biomarkers. Regression analysis used generalized additive models for Poisson-distributed outcome. An interquartile range (IQR) increase in tree cover was associated with 0.89 (95 % Confidence Limits 0.82; 0.97) and 0.90 (0.79; 1.03)-fold change in AL and INFL, respectively. Greater daily outdoor time was associated with reduced AL and INFL, while leisure screen time, problems with sleeping, and common chronic infections were linked with increased AL and INFL. Among 138 individuals spending more than 1 h outdoors daily, an IQR increase in tree cover was associated with 0.76 (0.67; 0.86) and 0.81 (0.65; 1.02)-fold changes in AL and INFL, respectively. Among individuals with residential tree cover above the 50th percentile, spending more than 3 h outdoors daily was associated with 0.54 (0.37; 0.78) and 0.28 (0.15; 0.54)-fold changes in AL and INFL, respectively, compared to spending less than 30 min outdoors; there were no significant effects in the low tree cover stratum. Consistent but weaker effects were observed for vegetated land cover. Interaction effects of tree and vegetative cover and time spent outdoors on AL and INFL were statistically significant. This biomarker-based approach can help to assess public health benefits of green spaces.

Greener residential environment is associated with increased bacterial diversity in outdoor ambient air.

In urban areas, exposure to greenspace has been found to be beneficial to human health. The biodiversity hypothesis proposed that exposure to diverse ambient microbes in greener areas may be one pathway leading to health benefits such as improved immune system functioning, reduced systemic inflammation, and ultimately reduced morbidity and mortality. Previous studies observed differences in ambient outdoor bacterial diversity between areas of high and low vegetated land cover but didn't focus on residential environments which are important to human health. This research examined the relationship between vegetated land and tree cover near residence and outdoor ambient air bacterial diversity and composition. We used a filter and pump system to collect ambient bacteria samples outside residences in the Raleigh-Durham-Chapel Hill metropolitan area and identified bacteria by 16S rRNA amplicon sequencing. Geospatial quantification of total vegetated land or tree cover was conducted within 500 m of each residence. Shannon's diversity index and weighted UniFrac distances were calculated to measure α (within-sample) and ß (between-sample) diversity, respectively. Linear regression for α-diversity and permutational analysis of variance (PERMANOVA) for ß-diversity were used to model relationships between vegetated land and tree cover and bacterial diversity. Data analysis included 73 ambient air samples collected near 69 residences. Analysis of ß-diversity demonstrated differences in ambient air microbiome composition between areas of high and low vegetated land (p = 0.03) and tree cover (p = 0.07). These relationships remained consistent among quintiles of vegetated land (p = 0.03) and tree cover (p = 0.008) and continuous measures of vegetated land (p = 0.03) and tree cover (p = 0.03). Increased vegetated land and tree cover were also associated with increased ambient microbiome α-diversity (p = 0.06 and p = 0.03, respectively). To our knowledge, this is the first study to demonstrate associations between vegetated land and tree cover and the ambient air microbiome's diversity and composition in the residential ecosystem.

Recreational water exposure and waterborne infections in a prospective salivary antibody study at a Lake Michigan beach.

In a prospective observational study, seroconversion to a specific pathogen can serve as a marker of an incident infection, whether or not that infection is symptomatic or clinically diagnosed. While self-reported symptoms can be affected by reporting bias, seroconversion is likely to be free of this bias as it is based on objective measurements of antibody response. Non-invasive salivary antibody tests can be used instead of serum tests to detect seroconversions in prospective studies. In the present study, individuals and families were recruited at a Lake Michigan beach in Wisconsin in August 2011. Data on recreational water exposure and baseline saliva samples (S1) were collected at recruitment. Follow-up data on gastrointestinal symptoms were collected via a telephone interview approximately 10 days post-recruitment. Follow-up saliva samples were self-collected approximately 2 weeks (S2) and 30-40 days post-recruitment (S3) and mailed to the study laboratory. Samples were analyzed for immunoglobulin (Ig) G responses to recombinant antigens of three noroviruses and Cryptosporidium, as well as protein purification tags as internal controls, using an in-house multiplex suspension immunoassay on the Luminex platform. Responses were defined as ratios of antibody reactivities with a target protein and its purification tag. Seroconversions were defined as at least four-fold and three-fold increases in responses in S2 and S3 samples compared to S1, respectively. In addition, an S2 response had to be above the upper 90% one-sided prediction limit of a corresponding spline function of age. Among 872 study participants, there were seven (0.8%) individuals with seroconversions, including six individuals with seroconversions to noroviruses and two to Cryptosporidium (one individual seroconverted to both pathogens). Among 176 (20%) individuals who reported swallowing lake water, there were six (3.4%) seroconversions compared to one (0.14%) seroconversion among the remaining 696 individuals: the crude and age-standardized risk differences per 1000 beachgoers were 32.7 (95% confidence limits 5.7; 59.6) and 94.8 (4.6; 276), respectively. The age-adjusted odds ratio of seroconversion in those who swallowed water vs. all others was 49.5 (4.5; 549), p = 0.001. Individuals with a norovirus seroconversion were more likely to experience vomiting symptoms within 4 days of the index beach visit than non-converters with an odds ratio of 34 (3.4, 350), p = 0.003. This study contributed further evidence that recreational water exposure is associated with symptomatic and asymptomatic waterborne infections, and that salivary antibody assays can be used in epidemiological surveys of norovirus and Cryptosporidium infections.

A Multiplex Noninvasive Salivary Antibody Assay for SARS-CoV-2 Infection and Its Application in a Population-Based Survey by Mail.

Noninvasive salivary antibody immunoassays can enable low-cost epidemiological surveillance of infections. This study involved developing and validating a multiplex suspension immunoassay on the Luminex platform to measure immunoglobulin G (IgG) responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid and spike (S) proteins, and the spike protein's S1 and S2 subunits and receptor binding domain. Multiple versions of these recombinant proteins acquired from commercial and noncommercial sources were evaluated. Assay development and validation utilized saliva and serum samples from coronavirus disease 2019 (COVID-19) cases procured from commercial sources and negative controls from a prepandemic survey. Saliva was also collected in a demonstration survey by mail involving adult individuals in the United States who were diagnosed with SARS-CoV-2 infection 15 to 80 days prior to sample collection. The survey had an 83% valid sample return rate (192 samples from 38 states). Most COVID-19 cases (93%) reported mildly symptomatic or asymptomatic infections. The final salivary assay based on the best-performing spike and nucleocapsid proteins had a sensitivity of 87.1% (95% bootstrap confidence interval, 82.1 to 91.7%) and specificity of 98.5% (95.0 to 100%) using 227 and 285 saliva samples, respectively. The same assay had 95.9% (92.8 to 98.9%) sensitivity and 100% (98.4 to 100%) specificity in serum (174 and 285 serum samples, respectively). Salivary and serum antibody responses to spike and nucleocapsid proteins were strongly correlated in 22 paired samples (r = 0.88 and r = 0.80, respectively). Antibody responses peaked at approximately 50 days postonset; greater illness severity was associated with stronger responses. This study demonstrated that a salivary antibody assay can be used in large-scale population surveys by mail to better characterize public health impacts of COVID-19. IMPORTANCE Given the enormous impacts of the COVID-19 pandemic, developing tools for population surveillance of infection is of paramount importance. This article describes the development of a multiplex immunoassay on a Luminex platform to measure salivary immunoglobulin G responses to the spike protein, its two subunits and receptor binding domain, and the nucleocapsid protein of SARS-CoV-2. The assay validation utilized serum and saliva samples from prepandemic controls and recent COVID-19 cases. A survey by mail targeting recent COVID-19 cases across the United States also demonstrated the utility of safe, at-home self-collection of saliva. By incorporating multiple SARS-CoV-2 proteins, this assay may differentiate responses to natural SARS-CoV-2 infections from responses to most vaccines. Application of this noninvasive immunoassay in COVID-19 surveillance can help provide estimates of cumulative incidence rates of symptomatic and asymptomatic infections in various communities and subpopulations, temporal patterns of antibody responses, and risk factors for infection.

Acute health effects associated with satellite-determined cyanobacterial blooms in a drinking water source in Massachusetts.

BACKGROUND: The occurrence of cyanobacterial blooms in freshwater presents a threat to human health. However, epidemiological studies on the association between cyanobacterial blooms in drinking water sources and human health outcomes are scarce. The objective of this study was to evaluate if cyanobacterial blooms were associated with increased emergency room visits for gastrointestinal (GI), respiratory and dermal illnesses. METHODS: Satellite-derived cyanobacteria cell concentrations were estimated in the source of drinking water for the Greater Boston area, during 2008-2011. Daily counts of hospital emergency room visits for GI, respiratory and dermal illnesses among drinking water recipients were obtained from an administrative record database. A two-stage model was used to analyze time-series data for an association between cyanobacterial blooms and the occurrence of illnesses. At the first stage, predictive autoregressive generalized additive models for Poisson-distributed outcomes were fitted to daily illness count data and daily predictive variables. At the second stage, residuals from the first stage models were regressed against lagged categorized cyanobacteria concentration estimates. RESULTS: The highest cyanobacteria concentration (above the 75th percentile) was associated with an additional 4.3 cases of respiratory illness (95% confidence interval: 0.7, 8.0, p = 0.02, n = 268) compared to cyanobacteria concentrations below the 50th percentile in a two-day lag. There were no significant associations between satellite derived cyanobacterial concentrations and lagged data on GI or dermal illnesses. CONCLUSION: The study demonstrated a significant positive association between satellite-derived cyanobacteria concentrations in source water and respiratory illness occurring 2 days later. Future studies will require direct measures of cyanotoxins and health effects associated with exposure to cyanobacteria-impacted drinking water sources.

Latent Toxoplasma gondii infections are associated with elevated biomarkers of inflammation and vascular injury.

BACKGROUND: Toxoplasma gondii is a protozoan parasite that infects cats as definitive hosts and other warm-blooded animals including humans as intermediate hosts. It forms infectious cysts in the brain, muscle and other tissues establishing life-long latent infection. Approximately 10% of the US population is infected. While latent infections are largely asymptomatic, they are associated with neurological deficits and elevated risks of neuropsychiatric diseases. METHODS: This cross-sectional epidemiological study investigated associations of T. gondii infections with biomarkers of inflammation and vascular injury: soluble intercellular adhesion molecule 1 (ICAM-1), soluble vascular cell adhesion molecule 1 (VCAM-1), C-reactive protein (CRP), and serum amyloid A (SAA). Serum samples from 694 adults in the Raleigh-Durham-Chapel Hill, North Carolina metropolitan area were tested for IgG antibody response to T. gondii, and for the above biomarkers using commercially available assays. RESULTS: T. gondii seroprevalence rate in this sample was 9.7%. Seropositivity was significantly associated with 11% (95% confidence limits 4, 20%) greater median levels of VCAM-1 (p = 0.003), and marginally significantly with 9% (1, 17%), and 36% (1, 83%) greater median levels of ICAM-1, and CRP, respectively (p = 0.04 for each) after adjusting for sociodemographic and behavioral covariates, while the 23% (- 7, 64%) adjusted effect on SAA was not statistically significant (p = 0.15). CONCLUSIONS: Latent infections with T. gondii are associated with elevated biomarkers of chronic inflammation and vascular injury that are also known to be affected by ambient air pollution.

Human Cytomegalovirus Infections Are Associated With Elevated Biomarkers of Vascular Injury.

Background: Human cytomegalovirus (HCMV) infects ~50% of adults in the United States. HCMV infections may cause vascular inflammation leading to cardiovascular disease, but the existing evidence is inconsistent. Objective: We investigated demographic predictors of HCMV infection and explored associations between HCMV infection status, the intensity of anti-HCMV Immunoglobulin G (IgG) antibody response, and biomarkers of inflammation and endothelial function which are known predictors of cardiovascular disease. Methods: We conducted a cross-sectional study of 694 adults residing in the Raleigh-Durham-Chapel Hill, NC metropolitan area. Serum samples were tested for IgG antibody response to HCMV, and for biomarkers of vascular injury including soluble intercellular adhesion molecule 1 (sICAM-1), soluble vascular cell adhesion molecule 1 (sVCAM-1), C-reactive protein (CRP), and serum amyloid A (SAA). Associations between HCMV and biomarker levels were analyzed using two approaches with HCMV serostatus modeled as a binary variable and as an ordinal variable with five categories comprised of seronegative individuals and quartiles of anti-HCMV antibody responses in seropositive individuals. Results: HCMV seroprevalence in the study population was 56%. Increased body mass index, increased age, female gender, racial/ethnic minority status, and current smoking were significantly associated with HCMV seropositivity in a multivariate regression analysis. HCMV seropositivity was also associated with 9% (95% confidence interval 4-15%) and 20% (0.3-44%) increases in median levels of sICAM-1 and CRP, respectively, after adjusting for covariates. The association between HCMV seropositivity and median levels of sVCAM-1 and SAA were positive but not statistically significant. Significant positive associations were observed between the intensity of anti-HCMV IgG responses and levels of sICAM-1 and sVCAM-1 (p-values 0.0008 and 0.04 for linear trend, respectively). To our knowledge, this is the first epidemiological study to show a relationship between anti-HCMV IgG responses and vascular injury biomarkers sICAM-1 and sVCAM-1 in the general population. Conclusion: HCMV infections are associated with vascular injury and inflammation biomarkers in adult residents of North Carolina.

Greater tree cover near residence is associated with reduced allostatic load in residents of central North Carolina.

BACKGROUND: Among urban residents, increased contacts with nature are associated with reduced morbidity and mortality. The concept of allostatic load, a biomarker-based composite measure of physiological dysregulation, can be applied to study subclinical benefits of exposure, and to elucidate pathways leading to improved health. OBJECTIVE: This research explored associations between residential vegetated land cover and an allostatic load index calculated using the statistical distance measure known as Mahalanobis distance. METHODS: This cross-sectional population-based study involved 186 adult residents of the Durham-Chapel Hill, North Carolina metropolitan area. Measures of tree and grass cover within 500 m of residence were derived from the U.S. Environmental Protection Agency's EnviroAtlas land cover database. Fifteen biomarkers of immune, neuroendocrine, and metabolic functions were analyzed in serum samples. Regression analysis was conducted using generalized additive models with thin-plate spline functions of geographic coordinates, adjusting for modelled traffic air pollution from local sources and sociodemographic covariates. RESULTS: The second and third tertiles of distance-weighted tree cover were associated with 14% (95% Confidence Limits 20%; 8%) and 15% (21%; 8%) reduction in adjusted median allostatic load, respectively, compared to the first tertile. The same tertiles of tree cover were also associated with 0.16 (0.03; 0.76) and 0.04 (0.01; 0.35) adjusted odds ratios of having allostatic load index above the 90th percentile of the sample distribution. Grass cover was inversely correlated with tree cover and was not associated with reduced allostatic load. CONCLUSIONS: Subclinical beneficial health effects of green spaces demonstrated in this study are consistent with reduced susceptibility to acute environmental and social stressors, and reduced risks of morbidity and mortality.

Rural Ghanaian households are more likely to use alternative unimproved water sources when water from boreholes has undesirable organoleptic characteristics.

Sustainable Development Goal (SDG) 6 aims to achieve universal access to safe drinking water sources. However, the health benefits of meeting this goal will only be fully realized if improved sources are used to the exclusion of unimproved sources. Very little is known about how rural African households balance the use of improved and unimproved water sources when multiple options are present. We assessed parallel use of untreated surface water and unimproved hand-dug wells (HDWs) in the presence of boreholes (BHs) using a semi-quantitative water use survey among 750 residents of 15 rural Ghanaian communities, distributed across three BH water quality clusters: control, high salinity, and high iron. Multivariate mixed effects logistic regression models were used to assess the impact of water quality cluster on the use of BHs, HDWs, and surface water, controlling for distance to the nearest source of each type. Reported surface water use was significantly higher in the high salinity and high iron clusters than in the control cluster, especially for water-intensive activities. Respondents in the non-control clusters had approximately eight times higher odds of clothes washing with surface water (p < 0.01) than in the control. Respondents in the high salinity cluster also had 4.3 times higher odds of drinking surface water (p < 0.05). BH use was high in all clusters, but decreased substantially when distance to the nearest BH exceeded 300 m (OR = 0.17-0.25, p < 0.001). Water use from all sources was inversely correlated with distance, with the largest effect observed on HDW use in multivariate models (OR = 0.02, p < 0.001). Surface water and HDW use will likely continue despite the presence of BHs when perceived groundwater quality is poor and other water sources are in close proximity. It is essential to account for naturally-occurring but undesirable groundwater quality parameters in rural water planning to ensure that SDG 6 is met and health benefits are realized.

Application of a multiplex salivary immunoassay to detect sporadic incident norovirus infections.

Norovirus is one of the most common causes of gastroenteritis. Following infection, anti-norovirus salivary immunoglobulin G (IgG) rises steeply within 2 weeks and remains elevated for several months; this immunoconversion can serve as an indicator of infection. We used a multiplex salivary immunoassay to study norovirus infections among 483 visitors to a Lake Michigan beach in 2015. Saliva was collected on the day of the beach visit (S1); after 10-14 days (S2); and after 30-40 days (S3). Luminex microspheres were coupled to recombinant antigens of genogroup I (GI) and II (GII) noroviruses and incubated with saliva. Immunoconversion was defined as at least 4-fold increase in anti-norovirus IgG antibody response from S1 to S2 and a 3-fold increase from S1 to S3. Ten (2.1%) immunoconverted to either GI (2) or GII (8) norovirus. Among those who immunoconverted, 40% reported at least one gastrointestinal symptom and 33% reported diarrhea, compared to 15% (p = 0.06) and 8% (p = 0.04) among those who did not immunoconvert, respectively. The two participants who immunoconverted to GI norovirus both swallowed water during swimming (p = 0.08). This study demonstrated the utility of a non-invasive salivary immunoassay to detect norovirus infections and an efficient approach to study infectious agents in large cohorts.

Environmental risk factors for Toxoplasma gondii infections and the impact of latent infections on allostatic load in residents of Central North Carolina.

BACKGROUND: Toxoplasma gondii infection can be acquired through ingestion of infectious tissue cysts in undercooked meat or environmental oocysts excreted by cats. This cross-sectional study assessed environmental risk factors for T. gondii infections and an association between latent infections and a measure of physiologic dysregulation known as allostatic load. METHODS: Serum samples from 206 adults in the Durham-Chapel Hill, North Carolina area were tested for immunoglobulin (IgG) responses to T. gondii using commercial ELISA kits. Allostatic load was estimated as a sum of 15 serum biomarkers of metabolic, neuroendocrine and immune functions dichotomized at distribution-based cutoffs. Vegetated land cover within 500 m of residences was estimated using 1 m resolution data from US EPA's EnviroAtlas. RESULTS: Handling soil with bare hands at least weekly and currently owning a cat were associated with 5.3 (95% confidence limits 1.4; 20.7) and 10.0 (2.0; 50.6) adjusted odds ratios (aOR) of T. gondii seropositivity, respectively. There was also a significant positive interaction effect of handling soil and owning cats on seropositivity. An interquartile range increase in weighted mean vegetated land cover within 500 m of residence was associated with 3.7 (1.5; 9.1) aOR of T. gondii seropositivity. Greater age and consumption of undercooked pork were other significant predictors of seropositivity. In turn, T. gondii seropositivity was associated with 61% (13%; 130%) greater adjusted mean allostatic load compared to seronegative individuals. In contrast, greater vegetated land cover around residence was associated with significantly reduced allostatic load in both seronegative (p < 0.0001) and seropositive (p = 0.004) individuals. CONCLUSIONS: Residents of greener areas may be at a higher risk of acquiring T. gondii infections through inadvertent ingestion of soil contaminated with cat feces. T. gondii infections may partially offset health benefits of exposure to the natural living environment.

Application of a salivary immunoassay in a prospective community study of waterborne infections.

Quantifying sporadic waterborne infections in community settings can be challenging. Salivary antibody immunoassays are a promising non-invasive tool that can be used in prospective studies of common infections, especially those involving children. This study was conducted in a Massachusetts city, which uses a microbiologically contaminated river as its water source, during summer-early winter periods before and after construction of a new drinking water treatment plant. Monthly saliva samples (7480 samples from 1170 children and 816 adults) were analyzed for immunoglobulin G (IgG) responses to recombinant proteins of Cryptosporidium, one genogroup I (GI) and two GII noroviruses. Immunoconversion was defined as at least four-fold increase in specific antibody responses between two monthly samples with a post-conversion response above a flexible age-dependent cut-off. Episodes of gastroenteritis (diarrhea or vomiting or cramps) were associated with 3.2 (95% confidence limits 1.1; 9.5) adjusted odds ratio (aOR) of immunoconversion to Cryptosporidium; episodes of combined diarrhea and vomiting symptoms were associated with 3.5 (0.8; 15.0) and 4.6 (1.7; 12.6) aORs of an immunoconversion to GI and GII noroviruses, respectively. Swimming in natural water bodies or chlorinated pools was associated with 2.3 (0.4; 15.4) and 4.9 (1.6; 15.5) aORs of immunoconversion to Cryptosporidium, respectively. In a subset of study participants who did not use home water filters, consumption of at least some amount of non-boiled tap water reported in a monthly recall survey was associated with 11.1 (1.2; 100.0) and 0.6 (0.1; 2.5) aORs of immunoconversion to Cryptosporidium before and after the new water treatment plant construction, respectively. Among individuals who used home water filters, associations between non-boiled tap water consumption and Cryptosporidium immunoconversion were not significant before and after new plant construction with aORs of 0.8 (0.2; 3.3) and 0.3 (0.1; 1.6), respectively. The interaction effect of study phase and non-boiled tap water consumption on Cryptosporidium immunoconversions was statistically significant in the entire study population with aOR of 5.4 (1.1; 25.6). This was the first study that has used a salivary antibody immunoassay to demonstrate significant associations between gastrointestinal symptoms and Cryptosporidium and norovirus infections, and between water-related exposures and Cryptosporidium infections.

Asymptomatic norovirus infection associated with swimming at a tropical beach: A prospective cohort study.

BACKGROUND: Swimming in fecally-contaminated waterbodies can result in gastrointestinal infections. However, the pathogenic microorganisms responsible are not well understood because sporadic cases of illness are not reported completely, exposure information is often not collected, and epidemiology studies rely on self-reported symptoms. Noroviruses are considered a likely cause because they are found in high densities in sewage, resistant to wastewater treatment and survive in the environment. In this study, saliva samples were collected from subjects at a beach in Puerto Rico and tested for evidence of norovirus-specific IgG responses as an indicator of incident norovirus infection. METHODS: Saliva samples were collected from 1298 participants using an oral swab. Samples were collected on the day of the beach visit (S1); after 10-12 days (S2); and after three weeks (S3). Saliva was tested for IgG responses to GI.1 and GII.4 noroviruses using a microsphere based multiplex salivary immunoassay. Immunoconversion was defined as a four-fold increase in median fluorescence intensity (MFI) from S1 to S2 with the S3 sample at least three times above the S1 MFI. RESULTS: Thirty-four subjects (2.6%) immunoconverted to GI.1 or GII.4 norovirus. Swimmers who immersed their head in water had a higher rate of immunoconversion (3.4%), compared to either non-swimmers (0.0%, p = 0.003) or waders and non-swimmers combined (0.4%, Odds Ratio: 5.07, 95% Confidence Interval:1.48-17.00). Immunoconversion was not associated with gastrointestinal symptoms. CONCLUSIONS: This is the first study to demonstrate an association between swimming at a beach impacted by fecal contamination and asymptomatic norovirus infection. The findings implicate recreational water as potentially important transmission pathway for norovirus infection.

Vegetated land cover near residence is associated with reduced allostatic load and improved biomarkers of neuroendocrine, metabolic and immune functions.

BACKGROUND: Greater exposure to urban green spaces has been linked to reduced risks of depression, cardiovascular disease, diabetes and premature death. Alleviation of chronic stress is a hypothesized pathway to improved health. Previous studies linked chronic stress with a biomarker-based composite measure of physiological dysregulation known as allostatic load. OBJECTIVE: This study's objective was to assess the relationship between vegetated land cover near residences and allostatic load. METHODS: This cross-sectional population-based study involved 206 adult residents of the Durham-Chapel Hill, North Carolina metropolitan area. Exposure was quantified using high-resolution metrics of trees and herbaceous vegetation within 500m of each residence derived from the U.S. Environmental Protection Agency's EnviroAtlas land cover dataset. Eighteen biomarkers of immune, neuroendocrine, and metabolic functions were measured in serum or saliva samples. Allostatic load was defined as a sum of potentially unhealthy biomarker values dichotomized at 10th or 90th percentile of sample distribution. Regression analysis was conducted using generalized additive models with two-dimensional spline smoothing function of geographic coordinates, weighted measures of vegetated land cover allowing decay of effects with distance, and geographic and demographic covariates. RESULTS: An inter-quartile range increase in distance-weighted vegetated land cover was associated with 37% (95% Confidence Limits 46%; 27%) reduced allostatic load; significantly reduced adjusted odds of having low level of norepinephrine, dopamine, and dehydroepiandrosterone, and high level of epinephrine, fibrinogen, vascular cell adhesion molecule-1, and interleukin-8 in serum, and α-amylase in saliva; and reduced odds of previously diagnosed depression. CONCLUSIONS: The observed effects of vegetated land cover on allostatic load and individual biomarkers are consistent with prevention of depression, cardiovascular disease and premature mortality.

Physicochemical parameters affecting the perception of borehole water quality in Ghana.

Rural Ghanaian communities continue using microbiologically contaminated surface water sources due in part to undesirable organoleptic characteristics of groundwater from boreholes. Our objective was to identify thresholds of physical and chemical parameters associated with consumer complaints related to groundwater. Water samples from 94 boreholes in the dry season and 68 boreholes in the rainy season were analyzed for 18 parameters. Interviews of consumers were conducted at each borehole regarding five commonly expressed water quality problems (salty taste, presence of particles, unfavorable scent, oily sheen formation on the water surface, and staining of starchy foods during cooking). Threshold levels of water quality parameters predictive of complaints were determined using the Youden index maximizing the sum of sensitivity and specificity. The probability of complaints at various parameter concentrations was estimated using logistic regression. Exceedances of WHO guidelines were detected for pH, turbidity, chloride, iron, and manganese. Concentrations of total dissolved solids (TDS) above 172mg/L were associated with salty taste complaints. Although the WHO guideline is 1000mg/L, even at half the guideline, the likelihood of salty taste complaint was 75%. Iron concentrations above 0.11, 0.14 and 0.43mg/L (WHO guideline value 0.3mg/L) were associated with complaints of unfavorable scent, oily sheen, and food staining, respectively. Iron and TDS concentrations exhibited strong spatial clustering associated with specific geological formations. Improved groundwater sources in rural African communities that technically meet WHO water quality guidelines may be underutilized in preference of unimproved sources for drinking and domestic uses, compromising human health and sustainability of improved water infrastructure.

Use of Pathogen-Specific Antibody Biomarkers to Estimate Waterborne Infections in Population-Based Settings.

PURPOSE OF REVIEW: This review discusses the utility of pathogen-specific antibody biomarkers for improving estimates of the population burden of waterborne infections, assessing the fraction of infections that can be prevented by specific water treatments, and understanding transmission routes and the natural history and ecology of disease in different populations (including asymptomatic infection rates). RECENT FINDINGS: We review recent literature on the application of pathogen-specific antibody response data to estimate incidence and prevalence of acute infections and their utility to assess the contributions of waterborne transmission pathways. Advantages and technical challenges associated with the use of serum versus minimally invasive salivary antibody biomarkers in cross-sectional and prospective surveys are discussed. We highlight recent advances and challenges and outline future directions for research, development, and application of antibody-based and other immunological biomarkers of waterborne infections.

Development of an urban green space indicator and the public health rationale.

AIMS: In this study, the aim was to develop and test an urban green space indicator for public health, as proposed by the World Health Organisation (WHO) Regional Office for Europe, in order to support health and environmental policies. METHODS: We defined the indicator of green space accessibility as a proportion of an urban population living within a certain distance from a green space boundary. We developed a Geographic Information System (GIS)-based method and tested it in three case studies in Malmö, Sweden; Kaunas, Lithuania; and Utrecht, The Netherlands. Land use data in GIS from the Urban Atlas were combined with population data. Various population data formats, maximum distances to green spaces, minimum sizes of green spaces, and different definitions of green spaces were studied or discussed. RESULTS: Our results demonstrated that with increasing size of green space and decreased distance to green space, the indicator value decreased. As compared to Malmö and Utrecht, a relatively bigger proportion of the Kaunas population had access to large green spaces, at both shorter and longer distances. Our results also showed that applying the method of spatially aggregated population data was an acceptable alternative to using individual data. CONCLUSIONS: Based on reviewing the literature and the case studies, a 300 m maximum linear distance to the boundary of urban green spaces of a minimum size of 1 hectare are recommended as the default options for the indicator. The indicator can serve as a proxy measure for assessing public accessibility to urban green spaces, to provide comparable data across Europe and stimulate policy actions that recognise the importance of green spaces for sustainable public health.

Application of salivary antibody immunoassays for the detection of incident infections with Norwalk virus in a group of volunteers.

Norovirus infection is the most common cause of acute gastroenteritis in developed countries. Developing an assay based on a non-invasive biomarker for detecting incident norovirus infections could improve disease surveillance and epidemiological investigations. This project involved analysis of IgA and IgG norovirus-specific antibody responses in saliva samples from a Norwalk virus (Genogroup I, genotype 1 norovirus) challenge study involving infected and symptomatic, and non-infected asymptomatic individuals. Saliva was collected at the challenge, and two weeks and 40 days post-challenge. Samples were analyzed using the Luminex fluorometric and Meso Scale Discovery (MSD) electrochemiluminescence immunoassays. Recombinant P domains of Norwalk virus capsid protein, as well as similar recombinant proteins of two genogroup II noroviruses (VA387 and VA207) were used as antigens. Immunoconversions were defined as >4-fold increase in antibody responses to the norovirus antigens. Various sample pre-treatment options, buffers, saliva dilution ratios, and data adjustment approaches to control for sample-to-sample variability in saliva composition were compared using the Luminex assay. The results suggest that adjusting responses to the norovirus antigens for responses to the protein purification tag, glutathione-S-transferase (GST), significantly improved the odds of producing a correct immunoconversion test result. IgG-based tests were more accurate compared to IgA-based tests. At optimal conditions, both Luminex and MSD assays for Norwalk-specific IgG antibodies correctly identified all infected and non-infected individuals. There was no evidence of cross-reactivity of anti-Norwalk virus antibodies with genogroup II noroviruses. These results suggest that salivary antibody responses can be used for the detection of incident infections with Norwalk virus in prospective surveys.

Biomonitoring-based environmental public health indicators.

This chapter discusses the use ofbiomonitoring-based indicators of exposure to environmental pollutants in environmental health information systems. Matrices for biomonitoring, organization and standardization of surveillance programs, the use of intake and body burden data, and the interpretation of surveillance data are discussed. The concept of environmental public health indicators is demonstrated using the "Persistent organic pollutants in human milk" indicator implemented in the Environment and Health Information System (ENHIS) of the WHO Regional Office for Europe. This indicator is based on the data from the WHO-coordinated surveillance of persistent organic pollutants in human milk as well as data from selected national studies. The WHO survey data demonstrate a steady decline in breast milk concentrations of dioxins across Europe. The data from biomonitoring surveys in Sweden also show a steady decline of breast milk concentrations of most persistent organic pollutants since 1970s with the exception of polybrominated diphenyl ethers (PBDEs) which increased rapidly until the late 1990s and then started to decline after the implementation of policy measures aiming at reducing exposures. The application of human biomonitoring data in support of environmental public health policy actions requires carefully designed standardized and sustainable surveillance, comprehensive interpretation of the data, and an effective communication strategy based on credible information presented in the form of indicator factsheets.