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Modeling Untreated Wastewater Evolution and Swimmer Illness for Four Wastewater Infrastructure Scenarios in the San Diego‐Tijuana (US/MX) Border Region

ABSTRACT: Abstract The popular beaches of the San Diego‐Tijuana (US/MX) border region are often impacted by untreated wastewater sourced from Mexico—via the Tijuana River Estuary (TJRE) and San Antonio de los Buenos outfall at the Pt. Bandera (SAB/PTB) shoreline, leading to impacted beaches and human illness. The US‐Mexico‐Canada trade agreement will fund border infrastructure projects reducing untreated wastewater discharges. However, estimating project benefits such as reduced human illness and beach impacts is challenging. We develop a coupled hydrodynamic, norovirus (NoV) pathogen, and swimmer illness risk model with the wastewater sources for the year 2017. The model is used to evaluate the reduction in human illness and beach impacts under baseline conditions and three infrastructure diversion scenarios which (Scenario A) reduce SAB/PTB discharges and moderately reduce TJRE inflows or (Scenarios B, C) strongly reduce TJRE in inflows only. The model estimates shoreline untreated wastewater and NoV concentrations, and the number of NoV ill swimmers at Imperial Beach CA. In the Baseline, the percentage of swimmers becoming ill is 3.8% over 2017, increasing to 4.5% during the tourist season (Memorial to Labor Day) due to south‐swell driven SAB/PTB plumes. Overall, Scenario A provides the largest reduction in ill swimmers and beach impacts for the tourist season and full year. The 2017 tourist season TJRE inflows were not representative of those in 2020, yet, Scenario A likely still provides the greatest benefit in other years. This methodology can be applied to other coastal regions with wastewater inputs. Key Points We develop a coupled hydrodynamic, a pathogen, and swimmer illness model to evaluate US/MX border region shoreline wastewater impacts Year 2017 model simulations quantitatively assess the benefits of four infrastructure scenarios that reduce regional wastewater inputs Tourist season has the most ill swimmers from plumes advecting north from MX, and mitigating this source yields the largest benefit

SUBMITTER: Feddersen F

PROVIDER: S-EPMC8581746 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundPeople who inject drugs may be at elevated SARS-CoV-2 risk due to their living conditions and/or exposures when seeking or using drugs. No study to date has reported upon risk factors for SARS-CoV-2 infection among people who inject drugs.Methods and findingsBetween October, 2020 and June, 2021, participants aged ≥18 years from San Diego, California, USA and Tijuana, Baja California, Mexico who injected drugs within the last month underwent interviews and testing for SARS-CoV-2 RNA and antibodies. Binomial regressions identified correlates of SARS-CoV-2 seropositivity.ResultsOf 386 participants, SARS-CoV-2 seroprevalence was 36.3% (95% CI: 31.5%-41.1%); 92.1% had detectable IgM antibodies. Only 37.5% had previously been tested. Seroprevalence did not differ by country of residence. None tested RNA-positive. Most (89.5%) reported engaging in ≥1 protective behavior [e.g., facemasks (73.5%), social distancing (46.5%), or increasing handwashing/sanitizers (22.8%)]. In a multivariate model controlling for sex, older age, and Hispanic/Latinx/Mexican ethnicity were independently associated with SARS-CoV-2 seropositivity, as was engaging in sex work (AdjRR: 1.63; 95% CI: 1.18-2.27) and having been incarcerated in the past six months (AdjRR: 1.49; 95% CI: 0.97-2.27). Comorbidities and substance using behaviors were not associated with SARS-CoV-2 seropositivity.ConclusionsIn this community-based study of people who inject drugs in the San Diego-Tijuana border region, over one third were SARS-CoV-2 seropositive, exceeding estimates from the general population in either city. We found no evidence that substance use behaviors were associated with an elevated risk of SARS-CoV-2 infection, but observed that circumstances in the risk environment, notably sex work and incarceration, were independently associated with higher SARS-CoV-2 seroprevalence. Our findings suggest that a binational policy response to COVID-19 mitigation is warranted beyond the closure of the U.S.-Mexico border. Furthermore, decriminalizing sex work and drug use could reduce the burden of COVID-19 among people who inject drugs.

Project description:San Diego and Tijuana configure two big cities that have faced each other across the international boundary between United States and Mexico for over 180 years. Within this context, the relationship emerging at the border can be characterized under different categories of individual, social, economic, and political situations connecting each side. Additionally, in recent years, the literature on cross-border conflicts has extensively focused on volunteers as informal agents helping children and other groups of population, but relatively little research has addressed the practical and managerial work and implications of the volunteers themselves. As actors of cross-border communities, volunteers play a relevant role in effective short-term migrants' settlement, but it is also observed that the profile of volunteers in religious organizations differs from those belonging to non-profit institutions. Grounded on the theories of Planned Behavior and Reasoned Action suggesting that intentions to cooperate with non-government institutions are influenced directly by attitudinal values and indirectly by their beliefs related to social conflicts, this paper analyzes the nature of volunteer commitment in religious and non-profit organizations (NPOs) providing information about managerial practices for newly arrived migrants. The main purpose of this study is to investigate the relevance of volunteer commitment as an instrument for managing cross-border conflicts in the particular context of San Diego and Tijuana Area. Based on research using interview data collected from beneficiaries by volunteers, institutional representatives, and documentary references, this manuscript highlights a psychological and individual-centric perspective of volunteer commitment, but it also explores a collective communicative action expanding the range of relevant voices in decisions about volunteering. Moreover, this study provides new insights into how organizational and relational elements impact sustainable volunteer management and points out the role played by attitudes toward non-government institutions such as religious and NPOs demonstrating the relevance of volunteer commitment, transforming part of the positive attitude toward social problems into a significant intention to cooperation. Understanding the importance of the organization's images in order to attract volunteers, these results show that commitment may become a key determinant of the volunteers' identity linked to strategies devoted to organizational activities.

Project description:Large-scale wastewater surveillance has the ability to greatly augment the tracking of infection dynamics especially in communities where the prevalence rates far exceed the testing capacity. However, current methods for viral detection in wastewater are severely lacking in terms of scaling up for high throughput. In the present study, we employed an automated magnetic-bead-based concentration approach for viral detection in sewage that can effectively be scaled up for processing 24 samples in a single 40-min run. The method compared favorably to conventionally used methods for viral wastewater concentrations with higher recovery efficiencies from input sample volumes as low as 10 ml and can enable the processing of over 100 wastewater samples in a day. The sensitivity of the high-throughput protocol was shown to detect 1 asymptomatic individual in a building of 415 residents. Using the high-throughput pipeline, samples from the influent stream of the primary wastewater treatment plant of San Diego County (serving 2.3 million residents) were processed for a period of 13 weeks. Wastewater estimates of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral genome copies in raw untreated wastewater correlated strongly with clinically reported cases by the county, and when used alongside past reported case numbers and temporal information in an autoregressive integrated moving average (ARIMA) model enabled prediction of new reported cases up to 3 weeks in advance. Taken together, the results show that the high-throughput surveillance could greatly ameliorate comprehensive community prevalence assessments by providing robust, rapid estimates.IMPORTANCE Wastewater monitoring has a lot of potential for revealing coronavirus disease 2019 (COVID-19) outbreaks before they happen because the virus is found in the wastewater before people have clinical symptoms. However, application of wastewater-based surveillance has been limited by long processing times specifically at the concentration step. Here we introduce a much faster method of processing the samples and show its robustness by demonstrating direct comparisons with existing methods and showing that we can predict cases in San Diego by a week with excellent accuracy, and 3 weeks with fair accuracy, using city sewage. The automated viral concentration method will greatly alleviate the major bottleneck in wastewater processing by reducing the turnaround time during epidemics.

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Modeling Untreated Wastewater Evolution and Swimmer Illness for Four Wastewater Infrastructure Scenarios in the San Diego‐Tijuana (US/MX) Border Region

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