Amanda Marie Wilson

Interests

Research

risk assessment, environmental infectious disease transmission, occupational health

Teaching

risk assessment, environmental infectious disease transmission, occupational health

Courses

Scholarly Contributions

Journals/Publications

• Abney, S. E., Higham, C. A., Wilson, A. M., Ijaz, M. K., McKinney, J., Reynolds, K. A., & Gerba, C. P. (2024). Transmission of Viruses from Restroom Use: A Quantitative Microbial Risk Assessment. Food and environmental virology, 16(1), 65-78.
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  Restroom use has been implicated in a number of viral outbreaks. In this study, we apply quantitative microbial risk assessment to quantify the risk of viral transmission by contaminated restroom fomites. We estimate risk from high-touch fomite surfaces (entrance/exit door, toilet seat) for three viruses of interest (SARS-CoV-2, adenovirus, norovirus) through eight exposure scenarios involving differing user behaviors, and the use of hand sanitizer following each scenario. We assessed the impacts of several sequences of fomite contacts in the restroom, reflecting the variability of human behavior, on infection risks for these viruses. Touching of the toilet seat was assumed to model adjustment of the seat (open vs. closed), a common touch point in single-user restrooms (home, small business, hospital). A Monte Carlo simulation was conducted for each exposure scenario (10,000 simulations each). Norovirus resulted in the highest probability of infection for all exposure scenarios with fomite surfaces. Post-restroom automatic-dispensing hand sanitizer use reduced the probability of infection for each virus by up to 99.75%. Handwashing within the restroom, an important risk-reduction intervention, was not found to be as effective as use of a non-touch hand sanitizer dispenser for reducing risk to near or below 1/1,000,000, a commonly used risk threshold for comparison.
• Hamilton, K. A., Ciol Harrison, J., Mitchell, J., Weir, M., Verhougstraete, M., Haas, C. N., Nejadhashemi, A. P., Libarkin, J., Gim Aw, T., Bibby, K., Bivins, A., Brown, J., Dean, K., Dunbar, G., Eisenberg, J. N., Emelko, M., Gerrity, D., Gurian, P. L., Hartnett, E., , Jahne, M., et al. (2024). Research gaps and priorities for quantitative microbial risk assessment (QMRA). Risk analysis : an official publication of the Society for Risk Analysis, 44(11), 2521-2536.
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  The coronavirus disease 2019 pandemic highlighted the need for more rapid and routine application of modeling approaches such as quantitative microbial risk assessment (QMRA) for protecting public health. QMRA is a transdisciplinary science dedicated to understanding, predicting, and mitigating infectious disease risks. To better equip QMRA researchers to inform policy and public health management, an Advances in Research for QMRA workshop was held to synthesize a path forward for QMRA research. We summarize insights from 41 QMRA researchers and experts to clarify the role of QMRA in risk analysis by (1) identifying key research needs, (2) highlighting emerging applications of QMRA; and (3) describing data needs and key scientific efforts to improve the science of QMRA. Key identified research priorities included using molecular tools in QMRA, advancing dose-response methodology, addressing needed exposure assessments, harmonizing environmental monitoring for QMRA, unifying a divide between disease transmission and QMRA models, calibrating and/or validating QMRA models, modeling co-exposures and mixtures, and standardizing practices for incorporating variability and uncertainty throughout the source-to-outcome continuum. Cross-cutting needs identified were to: develop a community of research and practice, integrate QMRA with other scientific approaches, increase QMRA translation and impacts, build communication strategies, and encourage sustainable funding mechanisms. Ultimately, a vision for advancing the science of QMRA is outlined for informing national to global health assessments, controls, and policies.
• Heida, A., Maal-Bared, R., Veillette, M., Duchaine, C., Reynolds, K. A., Ashraf, A., Ogunseye, O. O., Jung, Y., Shulman, L., Ikner, L., Betancourt, W., Hamilton, K. A., & Wilson, A. M. (2024). Quantitative microbial risk assessment (QMRA) tool for modelling pathogen infection risk to wastewater treatment plant workers. Water research, 260, 121858.
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  Wastewater treatment plants (WWTPs) provide vital services to the public by removing contaminants from wastewater prior to environmental discharge or reuse for beneficial purposes. WWTP workers occupationally exposed to wastewater can be at risk of respiratory or gastrointestinal diseases. The study objectives were to: (1) quantify pathogens and pathogen indicators in wastewater aerosols near different WWTP processes/unit operations, (2) develop a QMRA model for multi-pathogen and multi-exposure pathway risks, and (3) create a web-based application to perform and communicate risk calculations for wastewater workers. Case studies for seven different WWTP job tasks were performed investigating infection risk across nine different enteric and respiratory pathogens. It was observed that the ingestion risk among job tasks was highest for "walking the WWTP," which involved exposure from splashing, bioaerosols, and hand-to-mouth contact from touching contaminated surfaces. There was also a notable difference in exposure risk during peak (5:00am-9:00am) and non-peak hours (9:00am- 5:00am), with risks during the peak flow hours of the early morning assumed to be 5 times greater than non-peak hours. N95 respirator usage reduced median respiratory risks by 77 %. The developed tool performs multiple QMRA calculations to estimate WWTP workers' infection risks from accidental ingestion or inhalation of wastewater from multiple pathogens and exposure scenarios, which can inform risk management strategies to protect occupational health. However, more data are needed to reduce uncertainty in model estimates, including comparative data for pathogen concentrations in wastewater during peak and non-peak hours. QMRA tools will increase accessibility of risk models for utilization in decision-making.
• Hernández-Zepeda, C., Negrete-Alcalde, L. J., Rosiles-González, G., Carrillo-Jovel, V. H., Abney, S. E., Betancourt, W. Q., Gerba, C. P., Chaidez-Quiroz, C., & Wilson, A. M. (2024). Human adenovirus-associated health risk in the recreational waters of the Yal-ku lagoon in the Mexican Caribbean. Journal of water and health, 22(2), 372-384.
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  The study objective was to evaluate human faecal contamination impacts in the Yal-ku lagoon in the Mexican Caribbean and to estimate adenovirus infection and illness risks associated with recreational exposure during water activities. A total of 20 water samples (10 from each site × two sites) (50 L) were collected monthly over a period of 12 months from two selected sampling sites in the swimming area of the Yal-ku lagoon. The occurrence of faecal-associated viruses was explored, and human adenovirus (HAdV) and pepper mild mottle virus (PMMoV) concentrations were quantified. A quantitative microbial risk assessment (QMRA) model was used to estimate exposure and subsequent adenovirus infection and illness risk for 1 h of swimming or snorkelling. Somatic and F + -specific coliphages occurred in 100% of the samples. Both HAdV and PMMoV were detected at a 60% frequency thereby indicating persistent faecal inputs. PMMoV concentrations (44-370 GC/L) were relatively lower than the concentrations of HAdV (64-1,000 GC/L). Estimated mean adenovirus risks were greater for snorkelling than for swimming by roughly one to two orders of magnitude and estimated mean illness risks for snorkelling were >32/1,000. Human faecal contamination is frequent in the Yal-ku lagoon, which is associated with human gastrointestinal illness.
• Nava, B., & Wilson, A. M. (2024). Access to hygiene facilities and experiences of hygiene-related disease: A pilot study of unsheltered individuals in Tucson, Arizona. Hygiene and environmental health advances, 11.
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  Unsheltered individuals have limited access to restroom facilities. With this, many unsheltered individuals are forced to urinate, defecate, and engage in other hygiene practices outdoors. They may also lack access to necessary hygiene toiletries or wait to urinate or defecate until they are able to gain access to a facility. These challenges can lead to health issues, like urinary tract infections (UTIs), diarrhea, rashes, etc. The study objective was to understand the relationship between lack of access to basic hygiene facilities and health effects among unsheltered individuals. A verbal survey (English and Spanish) was used to explore the relationship between hygiene and unsheltered status. In Fall 2022, a researcher accompanied the homeless outreach team from El Rio Health, a Federally Qualified Health Center in Tucson, Arizona to verbally consent and recruit participants. Thirty consenting unsheltered adults ranging in ages from 29 to 68 years old participated in the study. Access to water was the greatest reported hygiene barrier, followed by access to soap, concerns for privacy, and concerns for safety. Eleven of thirty participants experienced a UTI at least once since becoming unsheltered and nine of thirty experienced a yeast infection at least once, with female participants having a statistically significant ( < 0.05) higher rate of occurrence than male participants. In addition, 19/30 of participants experienced a rash at least once and 17/30 of participants experienced diarrhea at least once. However, 20/30 of participants did not seek medical care for their health-related issues. Low healthcare utilization when there is a high need for care highlights the importance of community outreach and care for those experiencing homelessness. Next steps include replicating the project on a larger scale to determine generalizability.
• Ravi, P., Muralidhar, K., Madhivanan, P., Wilson, A. M., von Hippel, F. A., Salamova, A., Moya, E., & Gerald, L. B. (2024). Occupational exposures among women beedi workers in Mysore District, India: A mixed-methods study protocol. PloS one, 19(4), e0297638.
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  Beedi is the most common smoking form of tobacco used in India. The rolling of beedis is performed primarily by women in settings that lack occupational safeguards. The aims of this protocol are to establish methods for the study of occupational exposures among women beedi workers and their experiences and challenges working with unburnt tobacco. This protocol employs a convergent parallel mixed-methods approach. Qualitatively, we plan to explore the experiences and challenges faced by women beedi workers using photovoice, a community based participatory method. Occupational exposures to pesticides will be assessed through the use of silicone wristbands worn for seven days by workers, and exposure to toxic metals and metalloids will be assessed in dust samples collected in the homes of workers. The outcomes will be analyzed to form policy recommendations to improve the occupational health of women beedi workers.
• Ravi, P., Muralidhar, K., Ngaybe, M. G., Nanjaiah, S., Jayakrishna, P., Lowe, A. A., Krupp, K., Wilson, A. M., von Hippel, F. A., Chen, Z., Gerald, L. B., & Madhivanan, P. (2024). Qualitative Study to Explore the Occupational and Reproductive Health Challenges among Women Tobacco Farm Laborers in Mysore District, India. International journal of environmental research and public health, 21(5).
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  Tobacco farm laborers are primarily women and children working for very low wages. The aim of this study was to explore occupational and reproductive health challenges faced by women tobacco farm laborers in Mysore District, India. We conducted interviews and six focus group discussions among 41 women tobacco farm laborers. Codes and themes were generated based on deductive and inductive approaches using the socioecological model. Participants reported symptoms of green tobacco sickness including headaches, back pain, gastric problems, weakness, and allergies during menstruation, pre-natal, and post-natal periods. Participants had poor awareness about the health effects of tobacco farming, and there were gender inequalities in wages and the use of personal protective equipment. Participants received support from family and community health workers during their pregnancy and post-natal period. Women reported wanting maternity benefits from the tobacco board, as well as monetary support and nutritional supplements. There is a need for health education about the environmental dangers of tobacco among farm laborers, and more supportive policies for women farmworkers during pregnancy and post-natal periods.
• Verhougstraete, M., Cooksey, E., Walker, J. P., Wilson, A. M., Lewis, M. S., Yoder, A., Elizondo-Craig, G., Almoslem, M., Forysiak, E., & Weir, M. H. (2024). Impact of terminal cleaning in rooms previously occupied by patients with healthcare-associated infections. PloS one, 19(7), e0305083.
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  Healthcare associated infections (HAIs) are costly but preventable. A limited understanding of the effects of environmental cleaning on the riskiest HAI associated pathogens is a current challenge in HAI prevention. This project aimed to quantify the effects of terminal hospital cleaning practices on HAI pathogens via environmental sampling in three hospitals located throughout the United States. Surfaces were swabbed from 36 occupied patient rooms with a laboratory-confirmed, hospital- or community-acquired infection of at least one of the four pathogens of interest (i.e., Acinetobacter baumannii (A. baumannii), methicillin resistant Staphylococcus aureus (MRSA), vancomycin resistant Enterococcus faecalis/faecium (VRE), and Clostridioides difficile (C. difficile)). Six nonporous, high touch surfaces (i.e., chair handrail, bed handrail, nurse call button, desk surface, bathroom counter near the sink, and a grab bar near the toilet) were sampled in each room for Adenosine Triphosphate (ATP) and the four pathogens of interest before and after terminal cleaning. The four pathogens of interest were detected on surfaces before and after terminal cleaning, but their levels were generally reduced. Overall, C. difficile was confirmed on the desk (n = 2), while MRSA (n = 24) and VRE (n = 25) were confirmed on all surface types before terminal cleaning. After cleaning, only MRSA (n = 6) on bed handrail, chair handrail, and nurse call button and VRE (n = 5) on bathroom sink, bed handrail, nurse call button, toilet grab bar, and C. difficile (n = 1) were confirmed. At 2 of the 3 hospitals, pathogens were generally reduced by >99% during terminal cleaning. One hospital showed that VRE increased after terminal cleaning, MRSA was reduced by 73% on the nurse call button, and VRE was reduced by only 50% on the bathroom sink. ATP detections did not correlate with any pathogen concentration. This study highlights the importance of terminal cleaning and indicates room for improvement in cleaning practices to reduce surface contamination throughout hospital rooms.
• Wilson, A. M., Gerald, L. B., & Beamer, P. I. (2024). Recruitment strategies in marginalized industries for occupational health research: an example in a pilot study of cleaning staff during COVID-19. Annals of work exposures and health, 68(3), 226-230.
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  This commentary describes challenges in recruiting workers from marginalized industries with examples from a pilot study of janitors, custodians, and maids and their experiences of cleaning and disinfection protocols during COVID-19 and potentially associated respiratory symptoms. Recruitment strategies included contacting a local hospital, national workers' unions, and a large Arizona employer; using online Facebook groups; and contacting Arizona maid service companies and a school district. English and Spanish online and hard copy surveys about cleaning protocols and respiratory symptoms were used. Participants could also participate in online/phone interviews. Worker's compensation, liability, and confidentiality were concerns across organizations. Online surveys yielded unreliable data. Hard copy surveys were used due to workers' limited technology access. We reflect upon these challenges and discuss other strategies for recruiting from marginalized populations for occupational health research. Building trust with organizations and workers and considering technology access may ultimately increase recruitment feasibility.
• Jung, Y., Abney, S. E., Reynolds, K. A., Gerba, C. P., & Wilson, A. M. (2023). Evaluating infection risks and importance of hand hygiene during the household laundry process using a quantitative microbial risk assessment approach. American journal of infection control, 51(12), 1377-1383.
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  Contaminated laundry contributes to infectious disease spread in residential and home health care settings. The objectives were to (1) evaluate pathogen transmission risks for individuals doing laundry, and (2) compare hand hygiene timing to reduce risks.
• Wilson, A. M., Jung, Y., & Reynolds, K. A. (2023). Grappling with the Trade-offs of Cleaning and Disinfection: A Call for Targeted Hygiene. Environmental science & technology, 57(49), 20457-20459.
• Wilson, A. M., Jung, Y., Mooneyham, S. A., Klymko, I., Eck, J., Romo, C., Vaidyula, V. R., Sneed, S. J., Gerald, L. B., & Beamer, P. I. (2023). COVID-19 cleaning protocol changes, experiences, and respiratory symptom prevalence among cleaning services personnel. Frontiers in public health, 11, 1181047.
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  Cleaning protocols were changed in response to the COVID-19 pandemic with unknown occupational health impacts. There is evidence that COVID-19 transmission risks from contaminated surfaces are low and that exposure to cleaning products can increase risks of work-related asthma. The study objective was to investigate relationships between reported COVID-19-related changes in cleaning protocols and prevalence of asthma-related respiratory symptoms for asthmatic and non-asthmatic janitors and maids. A secondary objective was to characterize experiences of respiratory symptoms associated with cleaning and barriers to personal protective equipment (PPE) use.
• Wilson, A. M., O Ogunseye, O., Fingesi, T., McClelland, D. J., Gerald, L. B., Harber, P., Beamer, P. I., & Jones, R. M. (2023). Exposure frequency, intensity, and duration: What we know about work-related asthma risks for healthcare workers from cleaning and disinfection. Journal of occupational and environmental hygiene, 20(8), 350-363.
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  The objective of this review was to scope the current evidence base related to three exposure assessment concepts: frequency, intensity, and duration (latency) for cleaning and disinfection exposures in healthcare and subsequent work-related asthma risks. A search strategy was developed addressing intersections of four main concepts: (1) work-related asthma; (2) occupation (healthcare workers/nurses); (3) cleaning and disinfection; and (4) exposure. Three databases were searched: Embase, PubMed, and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) database. Data were extracted related to three main components of risk assessment: (1) exposure frequency, (2) exposure intensity, and (3) exposure duration. Latency data were analyzed using an exponential distribution fit, and extracted concentration data were compared to occupational exposure limits. The final number of included sources from which data were extracted was 133. Latency periods for occupational asthma were exponentially distributed, with a mean waiting time (1/λ) of 4.55 years. No extracted concentration data were above OELs except for some formaldehyde and glutaraldehyde concentrations. Data from included sources also indicated some evidence for a dose-response relationship regarding increased frequency yielding increased risk, but this relationship is unclear due to potential confounders (differences in role/task and associated exposure) and the healthy worker effect. Data priority needs to include linking concentration data to health outcomes, as most current literature does not include both types of measurements in a single study, leading to uncertainty in dose-response relationships.
• Wilson, A. M., Ravi, P., Pargas, N. T., Gerald, L. B., & Lowe, A. A. (2023). School health systems under strain: an example of COVID-19 experiences & burnout among school health staff in Pima County, Arizona. BMC public health, 23(1), 1626.
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  School health staff lead and provide a variety of care for children in schools. As school districts have navigated the COVID-19 pandemic, school health staff have faced unprecedented challenges in protecting the health of students and school staff. Our objective was to qualitatively characterize these pandemic challenges and experiences of school health staff in Pima County, Arizona to identify gaps in school health staff support for improving future emergency preparedness.
• Abney, S. E., Wilson, A. M., Ijaz, M. K., McKinney, J., Reynolds, K. A., & Gerba, C. P. (2022). Minding the matrix: The importance of inoculum suspensions in finger transfer efficiency. Journal of Applied Microbiology.
• Abney, S. E., Wilson, A. M., Ijaz, M. K., McKinney, J., Reynolds, K. A., & Gerba, C. P. (2022). Minding the matrix: The importance of inoculum suspensions on finger transfer efficiency of virus. Journal of applied microbiology, 133(5), 3083-3093.
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  The aim of this study was to determine how the transfer efficiency of MS-2 coliphage from the toilet seat to hands and fingertip to lip differs according to the suspension of the inoculum.
• Beamer, P., Burgess, J. L., Latura, J., Larson, D., Cabrera, N. L., Reynolds, K. A., Victory, K. R., & Wilson, A. M. (2022). Measured and modeled comparisons of chemical and microbial contaminants in tap, bottled and vended water in a U.S.-Mexico Border community. Environmental Science & Technology Water, 2(12), 2657-2667.
• Kerton, K. R., Beamer, P., Beamer, P., Joyce, L., Joyce, L., Wilson, A. M., Cabrera, N. L., Reynolds, K. A., Reynolds, K. A., Daniela, L., Daniela, L., Daniela, L., Reynolds, K. A., Cabrera, N. L., Cabrera, N. L., Joyce, L., Wilson, A. M., Wilson, A. M., Kerton, K. R., , Kerton, K. R., et al. (2022). Risk perceptions of drinking bottled vs. tap water in a low-income Latinx community in Nogales, Arizona. BMC Public Health.
• King, M., Wilson, A. M., Weir, M. H., Lopez-Garcia, M., Proctor, J., Hiwar, W., Khan, A., Fletcher, L. A., Sleigh, P. A., Clifton, I., Dancer, S. J., Wilcox, M., Reynolds, K. A., & Noakes, C. J. (2021). Modeling fomite-mediated SARS-CoV-2 exposure through personal protective equipment doffing in a hospital environment. Indoor Air. doi:10.1111/ina.12938
• Lee, S., Wilson, A. M., Cooksey, E., Boccelli, D., & Verhougstraete, M. (2022). Exploring vulnerable nodes, impactful viral intrusion sites, and viral infection risk reductions offered by chlorine boosters in municipal drinking water networks. Journal of Water Resources Planning and Management.
• Lowe, A. A., Ravi, P., Gerald, L. B., & Wilson, A. M. (2021). The changing job of school nurses during the COVID-19 pandemic: a media content analysis. Annals of Work Exposures and Health.
• Verhougstraete, M., Boccelli, D. L., Cooksey, E., Wilson, A. M., & Lee, S. (2022). Exploring Vulnerable Nodes, Impactful Viral Intrusion Sites, and Viral Infection Risk Reductions Offered by Chlorine Boosters in Municipal Drinking Water Networks. Journal of Water Resources Planning and Management, 148(9), 04022048. doi:10.1061/(ASCE)WR.1943-5452.0001589
• Victory, K. R., Wilson, A. M., Cabrera, N. L., Larson, D., Reynolds, K. A., Latura, J., & Beamer, P. I. (2022). Risk perceptions of drinking bottled vs. tap water in a low-income community on the US-Mexico Border. BMC public health, 22(1), 1712.
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  Previous studies have shown that low-income Latinos generally drink bottled water over tap water and might be at increased risks for cavities from unfluoridated bottled water. In order to better design interventions, it is important to understand the risk perceptions of this unique high-risk yet historically marginalized group.
• Wilson, A. M., Canter, K., Abney, S. E., Gerba, C. P., Myers, E. R., Hanlin, J., & Reynolds, K. A. (2022). An application for relating Legionella shower water monitoring results to estimated health outcomes. Water research, 221, 118812.
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  Exposure models are useful tools for relating environmental monitoring data to expected health outcomes. The objective of this study was to (1) compare two Legionella shower exposure models, and (2) develop a risk calculator tool for relating environmental monitoring data to estimated Legionella infection risks and Legionnaires' Disease (LD) illness risks. Legionella infection risks for a single shower event were compared using two shower Legionella exposure models. These models varied in their description of partitioning of Legionella in aerosols and aerosol deposition in the lung, where Model 1 had larger and fewer aerosol ranges than Model 2. Model 2 described conventional vs. water efficient showers separately, while Model 1 described exposure for an unspecified shower type (did not describe it as conventional or water efficient). A Monte Carlo approach was used to account for variability and uncertainty in these aerosolization and deposition parameters, Legionella concentrations, and the dose-response parameter. Methods for relating infection risks to illness risks accounting for demographic differences were used to inform the risk calculator web application ("app"). Model 2 consistently estimated higher infection risks than Model 1 for the same Legionella concentration in water and estimated deposited doses with less variability. For a 7.8-min shower with a Legionella concentration of 0.1 CFU/mL, the average infection risks estimated using Model 2 were 4.8 × 10 (SD=3.0 × 10) (conventional shower) and 2.3 × 10 (SD=1.7 × 10) (water efficient). Average infection risk estimated by Model 1 was 1.1 × 10 (SD=9.7 × 10). Model 2 was used for app development due to more conservative risk estimates and less variability in estimated dose. While multiple Legionella shower models are available for quantitative microbial risk assessments (QMRAs), they may yield notably different infection risks for the same environmental microbial concentration. Model comparisons will inform decisions regarding their integration with risk assessment tools. The development of risk calculator tools for relating environmental microbiology data to infection risks will increase the impact of exposure models for informing water treatment decisions and achieving risk targets.
• Wilson, A. M., Canter, K., Abney, S. E., Gerba, C. P., Myers, E., Hanlin, J., & Reynolds, K. A. (2022). An application for relating Legionella shower monitoring results to estimated health outcomes. Water Research.
• Wilson, A. M., Martin, S. L., Verhougstraete, M. P., Kendall, A. D., Zimmer-Faust, A. G., Rose, J. B., Bell, M. L., & Hyndman, D. W. (2022). Detangling Seasonal Relationships of Fecal Contamination Sources and Correlates with Indicators in Michigan Watersheds. Microbiology spectrum, 10(4), e0041522.
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  Despite the widely acknowledged public health impacts of surface water fecal contamination, there is limited understanding of seasonal effects on (i) fate and transport processes and (ii) the mechanisms by which they contribute to water quality impairment. Quantifying relationships between land use, chemical parameters, and fecal bacterial concentrations in watersheds can help guide the monitoring and control of microbial water quality and explain seasonal differences. The goals of this study were to (i) identify seasonal differences in Escherichia coli and Bacteroides thetaiotaomicron concentrations, (ii) evaluate environmental drivers influencing microbial contamination during baseflow, snowmelt, and summer rain seasons, and (iii) relate seasonal changes in B. thetaiotaomicron to anticipated gastrointestinal infection risks. Water chemistry data collected during three hydroclimatic seasons from 64 Michigan watersheds were analyzed using seasonal linear regression models with candidate variables including crop and land use proportions, prior precipitation, chemical parameters, and variables related to both wastewater treatment and septic usage. Adaptive least absolute shrinkage and selection operator (LASSO) linear regression with bootstrapping was used to select explanatory variables and estimate coefficients. Regardless of season, wastewater treatment plant and septic system usage were consistently selected in all primary models for B. thetaiotaomicron and E. coli. Chemistry and precipitation-related variable selection depended upon season and organism. These results suggest a link between human pollution (e.g., septic systems) and microbial water quality that is dependent on flow regime. In this study, a data set of 64 Michigan watersheds was utilized to gain insights into fecal contamination sources, drivers, and chemical correlates across seasons for general E. coli and human-specific fecal indicators. Results reaffirmed a link between human-specific sources (e.g., septic systems) and microbial water quality. While the importance of human sources of fecal contamination and fate and transport variables (e.g., precipitation) remain important across seasons, this study provides evidence that fate and transport mechanisms vary with seasonal hydrologic condition and microorganism source. This study contributes to a body of research that informs prioritization of fecal contamination source control and surveillance strategy development to reduce the public health burden of surface water fecal contamination.
• Wilson, A. M., Martin, S. L., Verhougstraete, M., Kendall, A. D., Zimmer-Faust, A. G., Rose, J. B., Bell, M. L., & David, H. W. (2022). Explaining seasonal Bacteriodes thetaiotaomicron and Escherichia coli concentrations in Michigan watersheds for informing microbial risk assessments. Microbiology Spectrum.
• Wilson, A. M., Mussio, I., Chilton, S., Gerald, L. B., Jones, R. M., Drews, F. A., LaKind, J. S., & Beamer, P. I. (2022). A Novel Application of Risk-Risk Tradeoffs in Occupational Health: Nurses' Occupational Asthma and Infection Risk Perceptions Related to Cleaning and Disinfection during COVID-19. International journal of environmental research and public health, 19(23).
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  Nurses face the risk of new onset occupational asthma (OA) due to exposures to cleaning and disinfection (C&D) agents used to prevent infections in healthcare facilities. The objective of this study was to measure nurses' preferences when presented with simultaneous OA and respiratory viral infection (e.g., COVID-19) risks related to increased/decreased C&D activities.
• Wilson, A. M., Ogunseye, O. O., DiGioia, O., Gerald, L. B., & Lowe, A. A. (2022). Barriers to COVID-19 Intervention Implementation in K-5 Classrooms: A Survey of Teachers from a District with Mask Mandates despite a Statewide Mask Mandate Ban. International journal of environmental research and public health, 19(14).
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  The study objective was to characterize K-5 teachers' risk perceptions and experiences with CDC COVID-19 classroom guidance in an Arizona school district with a mask mandate, conflicting with a statewide mask mandate ban.
• Wilson, A. M., Sleeth, D. K., Schaefer, C., & Jones, R. M. (2022). Transmission of Respiratory Viral Diseases to Health Care Workers: COVID-19 as an Example. Annual review of public health.
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  Health care workers (HCWs) can acquire infectious diseases, including coronavirus disease 2019 (COVID-19), from patients. Herein, COVID-19 is used with the source-pathway-receptor framework as an example to assess evidence for the role of aerosol transmission and indirect contact transmission of viral respiratory infectious diseases. Evidence for both routes is strong for COVID-19 and other respiratory viruses, but aerosol transmission is likely dominant for COVID-19. Key knowledge gaps about transmission processes and control strategies include the distribution of viable virus among respiratory aerosols of different sizes, the mechanisms and efficiency by which virus deposited on the facial mucous membrane moves to infection sites inside the body, and the performance of source controls such as face coverings and aerosol containment devices. To ensure that HCWs are adequately protected from infection, guidelines and regulations must be updated to reflect the evidence that respiratory viruses are transmitted via aerosols. Expected final online publication date for the , Volume 43 is April 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
• Wilson, A. M., Victory, K. R., Reynolds, K. A., Cabrera, N. L., Larson, D., Latura, J., Sexton, J. D., Burgess, J. L., & Beamer, P. (2022). Measured and modeled comparisons of chemical and microbial contaminants in tap, bottled and vended water in a U.S.-Mexico Border community. Environmental Science & Technology: Water.
• Wilson, A. M., Victory, K. R., Reynolds, K. A., Cabrera, N. L., Larson, D., Latura, J., Sexton, J. D., Burgess, J. L., & Beamer, P. I. (2022). Measured and Modeled Comparisons of Chemical and Microbial Contaminants in Tap and Bottled Water in a US-Mexico Border Community. ACS ES&T water, 2(12), 2657-2667.
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  Tap water quality concerns and advertisements often drive increased bottled water consumption, especially in communities with historical tap water quality problems (e.g., Nogales, Arizona). The study objective was to assess contamination of municipal tap and bottled water in Nogales, Arizona. Bottled (sealed, open/partially consumed bottles, and reusable containers for vended water) and tap water samples were collected from 30 homes and analyzed for chemical and microbial contaminants. Fisher exact tests and Wilcoxon rank sum tests were used to compare proportions of positive samples and contaminant concentrations between tap and bottled water samples. While none of the chemical contaminants were above MCLs, there were statistically significantly greater concentrations and proportions of positive samples for some contaminants, including arsenic, in tap vs. bottled water. coli concentrations were >0 CFU/100mL in some unsealed bottled water samples but not for sealed bottles. This study demonstrates that 1) the measured concentrations in tap and bottled water likely pose low risks, as they are below the MCLs, 2) more education in this community on hygiene maintenance of refillable or opened bottled water containers is needed, and 3) using tap water over bottled water is advantageous due to likely lower risk and lower cost.
• King, M. F., Wilson, A. M., López-García, M., Proctor, J., Peckham, D. G., Clifton, I. J., Dancer, S. J., & Noakes, C. J. (2021). Why is mock care not a good proxy for predicting hand contamination during patient care?. The Journal of hospital infection, 109, 44-51.
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  Healthcare worker (HCW) behaviours, such as the sequence of their contacts with surfaces and hand hygiene moments, are important for understanding disease transmission.
• King, M. F., Wilson, A. M., Weir, M. H., López-García, M., Proctor, J., Hiwar, W., Khan, A., Fletcher, L. A., Sleigh, P. A., Clifton, I., Dancer, S. J., Wilcox, M., Reynolds, K. A., & Noakes, C. J. (2021). Modeling fomite-mediated SARS-CoV-2 exposure through personal protective equipment doffing in a hospital environment. Indoor air.
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  Self-contamination during doffing of personal protective equipment (PPE) is a concern for healthcare workers (HCW) following SARS-CoV-2-positive patient care. Staff may subconsciously become contaminated through improper glove removal; so, quantifying this exposure is critical for safe working procedures. HCW surface contact sequences on a respiratory ward were modeled using a discrete-time Markov chain for: IV-drip care, blood pressure monitoring, and doctors' rounds. Accretion of viral RNA on gloves during care was modeled using a stochastic recurrence relation. In the simulation, the HCW then doffed PPE and contaminated themselves in a fraction of cases based on increasing caseload. A parametric study was conducted to analyze the effect of: (1a) increasing patient numbers on the ward, (1b) the proportion of COVID-19 cases, (2) the length of a shift, and (3) the probability of touching contaminated PPE. The driving factors for the exposure were surface contamination and the number of surface contacts. The results simulate generally low viral exposures in most of the scenarios considered including on 100% COVID-19 positive wards, although this is where the highest self-inoculated dose is likely to occur with median 0.0305 viruses (95% CI =0-0.6 viruses). Dose correlates highly with surface contamination showing that this can be a determining factor for the exposure. The infection risk resulting from the exposure is challenging to estimate, as it will be influenced by the factors such as virus variant and vaccination rates.
• Wilson, A. M., & Jones, R. M. (2021). Exploring spatial averaging of contamination in fomite microbial transfer models and implications for dose. Journal of exposure science & environmental epidemiology.
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  When modeling exposures from contact with fomites, there are many choices in defining the sizes of compartments representing environmental surfaces and hands, and the portions of compartments involved in contacts. These choices impact dose estimates, yet there is limited guidance for selection of these model parameters.
• Wilson, A. M., Aviles, N., Petrie, J. I., Beamer, P. I., Szabo, Z., Xie, M., McIllece, J., Chen, Y., Son, Y. J., Halai, S., White, T., Ernst, K. C., & Masel, J. (2021). Quantifying SARS-CoV-2 Infection Risk Within the Google/Apple Exposure Notification Framework to Inform Quarantine Recommendations. Risk analysis.
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  Most early Bluetooth-based exposure notification apps use three binary classifications to recommend quarantine following SARS-CoV-2 exposure: a window of infectiousness in the transmitter, ≥15 minutes duration, and Bluetooth attenuation below a threshold. However, Bluetooth attenuation is not a reliable measure of distance, and infection risk is not a binary function of distance, nor duration, nor timing. We model uncertainty in the shape and orientation of an exhaled virus-containing plume and in inhalation parameters, and measure uncertainty in distance as a function of Bluetooth attenuation. We calculate expected dose by combining this with estimated infectiousness based on timing relative to symptom onset. We calibrate an exponential dose-response curve based on infection probabilities of household contacts. The probability of current or future infectiousness, conditioned on how long postexposure an exposed individual has been symptom-free, decreases during quarantine, with shape determined by incubation periods, proportion of asymptomatic cases, and asymptomatic shedding durations. It can be adjusted for negative test results using Bayes' theorem. We capture a 10-fold range of risk using six infectiousness values, 11-fold range using three Bluetooth attenuation bins, ∼sixfold range from exposure duration given the 30 minute duration cap imposed by the Google/Apple v1.1, and ∼11-fold between the beginning and end of 14 day quarantine. Public health authorities can either set a threshold on initial infection risk to determine 14-day quarantine onset, or on the conditional probability of current and future infectiousness conditions to determine both quarantine and duration.
• Wilson, A. M., Jones, R. M., Lugo Lerma, V., Abney, S. E., King, M. F., Weir, M. H., Sexton, J. D., Noakes, C. J., & Reynolds, K. A. (2021). Respirators, face masks, and their risk reductions via multiple transmission routes for first responders within an ambulance. Journal of occupational and environmental hygiene, 18(7), 345-360.
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  First responders may have high SARS-CoV-2 infection risks due to working with potentially infected patients in enclosed spaces. The study objective was to estimate infection risks per transport for first responders and quantify how first responder use of N95 respirators and patient use of cloth masks can reduce these risks. A model was developed for two Scenarios: an ambulance transport with a patient actively emitting a virus in small aerosols that could lead to airborne transmission (Scenario 1) and a subsequent transport with the same respirator or mask use conditions, an uninfected patient; and remaining airborne SARS-CoV-2 and contaminated surfaces due to aerosol deposition from the previous transport (Scenario 2). A compartmental Monte Carlo simulation model was used to estimate the dispersion and deposition of SARS-CoV-2 and subsequent infection risks for first responders, accounting for variability and uncertainty in input parameters (i.e., transport duration, transfer efficiencies, SARS-CoV-2 emission rates from infected patients, etc.). Infection risk distributions and changes in concentration on hands and surfaces over time were estimated across sub-Scenarios of first responder respirator use and patient cloth mask use. For Scenario 1, predicted mean infection risks were reduced by 69%, 48%, and 85% from a baseline risk (no respirators or face masks used) of 2.9 × 10 ± 3.4 × 10 when simulated first responders wore respirators, the patient wore a cloth mask, and when first responders and the patient wore respirators or a cloth mask, respectively. For Scenario 2, infection risk reductions for these same Scenarios were 69%, 50%, and 85%, respectively (baseline risk of 7.2 × 10 ± 1.0 × 10). While aerosol transmission routes contributed more to viral dose in Scenario 1, our simulations demonstrate the ability of face masks worn by patients to additionally reduce surface transmission by reducing viral deposition on surfaces. Based on these simulations, we recommend the patient wear a face mask and first responders wear respirators, when possible, and disinfection should prioritize high use equipment.
• Wilson, A. M., Kaur, K., Jones, R. M., & Kelly, K. E. (2021). Feasibility of a High-Volume Filter Sampler for Detecting SARS-CoV-2 RNA in COVID-19 Patient Rooms. Annals of work exposures and health.
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  Aerosolization of SARS-CoV-2 by COVID-19 patients can put healthcare workers and susceptible individuals at risk of infection. Air sampling for SARS-CoV-2 has been conducted in healthcare settings, but methods vary widely and there is need for improvement. The objective of this study was to evaluate the feasibility of using a high-volume filter sampler, BioCapture z720, to detect SARS-CoV-2 in COVID-19 patient rooms in a medical intensive care unit, a dedicated COVID-19 ward, and at nurses' stations. In some locations, the BioSpot-VIVAS, known for high efficiency in the collection of virus-containing bioaerosols, was also operated. The samples were processed for SARS-CoV-2 RNA with multi-plex nested polymerase chain reaction. One of 28 samples collected with the high-volume filter sampler was positive for SARS-CoV-2; all 6 samples collected with BioSpot-VIVAS were negative for SARS-CoV-2. The high-volume filter sampler was more portable and less intrusive in patient rooms than the BioSpot-VIVAS, but limits of detection remain unknown for this device. This study will inform future work to evaluate the reliability of these types of instruments and inform best practices for their use in healthcare environments for SARS-CoV-2 air sampling.
• Wilson, A. M., King, M. F., López-García, M., Clifton, I. J., Proctor, J., Reynolds, K. A., & Noakes, C. J. (2021). Effects of patient room layout on viral accruement on healthcare professionals' hands. Indoor air, 31(5), 1657-1672.
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  Healthcare professionals (HCPs) are exposed to highly infectious viruses, such as norovirus, through multiple exposure routes. Understanding exposure mechanisms will inform exposure mitigation interventions. The study objective was to evaluate the influences of hospital patient room layout on differences in HCPs' predicted hand contamination from deposited norovirus particles. Computational fluid dynamic (CFD) simulations of a hospital patient room were investigated to find differences in spatial deposition patterns of bioaerosols for right-facing and left-facing bed layouts under different ventilation conditions. A microbial transfer model underpinned by observed mock care for three care types (intravenous therapy (IV) care, observational care, and doctors' rounds) was applied to estimate HCP hand contamination. Viral accruement was contrasted between room orientation, care type, and by assumptions about whether bioaerosol deposition was the same or variable by room orientation. Differences in sequences of surface contacts were observed for care type and room orientation. Simulated viral accruement differences between room types were influenced by mostly by differences in bioaerosol deposition and by behavior sequences when deposition patterns for the room orientations were similar. Differences between care types were likely driven by differences in hand-to-patient contact frequency, with doctors' rounds resulting in the greatest predicted viral accruement on hands.
• Wilson, A. M., King, M., Lopez-Garcia, M., Clifton, I. J., Proctor, J., Reynolds, K. A., & Noakes, C. J. (2021). Integrating CFD and exposure modeling for estimating viral exposures at the air-surface interface. AIAA, Session: Special Session: CFD and COVID-19. doi:10.2514/6.2021-2740
• Wilson, A. M., Verhougstraete, M. P., Beamer, P. I., King, M. F., Reynolds, K. A., & Gerba, C. P. (2021). Frequency of hand-to-head, -mouth, -eyes, and -nose contacts for adults and children during eating and non-eating macro-activities. Journal of exposure science & environmental epidemiology, 31(1), 34-44.
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  Hand-to-face contacts are important for estimating chemical and microbial exposures. Few studies describe children's hand-to-eye or -nose contacts or adults' hand-to-face contacts. The study objective was to characterize hand-to-head (mouth, eyes, nose, and other) contacts for children in a daycare and adults in multiple locations. Macro-activities and sequences of hand-to-face contacts were recorded for 263 people observed for 30 min each. Statistically significant differences between locations, males and females, adults and children, and during eating and non-eating macro-activities were evaluated. Discrete Markov chains were fit to observed contact sequences and compared among adults and children during eating and non-eating macro-activities. No significant differences in contact frequency were observed between males and females with the exception of hand-to-nose contacts. Children tended to touch the mouth, eyes, and nose more frequently than adults during non-eating macro-activities. Significant differences in contact frequency were observed between locations. Transitional probabilities indicated that children make repetitive mouth, eye, and nose contacts while adults frequently transition to contacts of the head other than the mouth, eyes, or nose. More data are needed to evaluate the effect of age on adults' contact frequencies and to confirm lack of statistically significant differences between adults and children during eating macro-activities.
• Wilson, A. M., Verhougstraete, M. P., Donskey, C. J., & Reynolds, K. A. (2021). An agent-based modeling approach to estimate pathogen exposure risks from wheelchairs. American journal of infection control, 49(2), 206-214.
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  Contributions of contaminated wheelchairs to nosocomial pathogen transmission are relatively unknown. Our aim was to develop a model predicting pathogen exposures for patients utilizing wheelchairs and estimate exposure reduction potential of wheelchair disinfection between rides.
• Wilson, A. M., Weir, M. H., Bloomfield, S. F., Scott, E. A., & Reynolds, K. A. (2021). Modeling COVID-19 infection risks for a single hand-to-fomite scenario and potential risk reductions offered by surface disinfection. American journal of infection control, 49(6), 846-848.
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  We used a quantitative microbial risk assessment approach to relate log disinfection reductions of SARS-CoV-2 bioburden to COVID-19 infection risks. Under low viral bioburden, minimal log reductions may be needed to reduce infection risks for a single hand-to-fomite touch to levels lower than 1:1,000,000, as a risk comparison point. For higher viral bioburden conditions, log reductions of more than 2 may be needed to achieve median infection risks of less than 1:1,000,000.
• Wilson, A. M., Weir, M. H., King, M. F., & Jones, R. M. (2021). Comparing approaches for modelling indirect contact transmission of infectious diseases. Journal of the Royal Society, Interface, 18(182), 20210281.
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  Mathematical models describing indirect contact transmission are an important component of infectious disease mitigation and risk assessment. A model that tracks microorganisms between compartments by coupled ordinary differential equations or a Markov chain is benchmarked against a mechanistic interpretation of the physical transfer of microorganisms from surfaces to fingers and subsequently to a susceptible person's facial mucosal membranes. The primary objective was to compare these models in their estimates of doses and changes in microorganism concentrations on hands and fomites over time. The abilities of the models to capture the impact of episodic events, such as hand hygiene, and of contact patterns were also explored. For both models, greater doses were estimated for the asymmetrical scenarios in which a more contaminated fomite was touched more often. Differing representations of hand hygiene in the Markov model did not notably impact estimated doses but affected pathogen concentration dynamics on hands. When using the Markov model, losses due to hand hygiene should be handled as separate events as opposed to time-averaging expected losses. The discrete event model demonstrated the effect of hand-to-mouth contact timing on the dose. Understanding how model design influences estimated doses is important for advancing models as reliable risk assessment tools.
• Contreras, R. D., Wilson, A. M., Garavito, F., Sexton, J. D., Reynolds, K. A., & Canales, R. A. (2020). Assessing virus infection probability in an office setting using stochastic simulation. Journal of occupational and environmental hygiene, 17(1), 30-37.
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  Viral infections are an occupational health concern for office workers and employers. The objectives of this study were to estimate rotavirus, rhinovirus, and influenza A virus infection risks in an office setting and quantify infection risk reductions for two hygiene interventions. In the first intervention, research staff used an ethanol-based spray disinfectant to clean high-touch non-porous surfaces in a shared office space. The second intervention included surface disinfection and also provided workers with alcohol-based hand sanitizer gel and hand sanitizing wipes to promote hand hygiene. Expected changes in surface concentrations due to these interventions were calculated. Human exposure and dose were simulated using a validated, steady-state model incorporated into a Monte Carlo framework. Stochastic inputs representing human behavior, pathogen transfer efficiency, and pathogen fate were utilized, in addition to a mixed distribution that accounted for surface concentrations above and below a limit of detection. Dose-response curves were then used to estimate infection risk. Estimates of percent risk reduction using mean values from baseline and surface disinfection simulations for rotavirus, rhinovirus, and influenza A infection risk were 14.5%, 16.1%, and 32.9%, respectively. For interventions with both surface disinfection and the promotion of personal hand hygiene, reductions based on mean values of infection risk were 58.9%, 60.8%, and 87.8%, respectively. This study demonstrated that surface disinfection and the use of personal hand hygiene products can help decrease virus infection risk in communal offices. Additionally, a variance-based sensitivity analysis revealed a greater relative importance of surface concentrations, assumptions of relevant exposure routes, and inputs representing human behavior in estimating risk reductions.
• King, M. F., López-García, M., Atedoghu, K. P., Zhang, N., Wilson, A. M., Weterings, M., Hiwar, W., Dancer, S. J., Noakes, C. J., & Fletcher, L. A. (2020). Bacterial transfer to fingertips during sequential surface contacts with and without gloves. Indoor air, 30(5), 993-1004.
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  Bacterial transmission from contaminated surfaces via hand contact plays a critical role in disease spread. However, the fomite-to-finger transfer efficiency of microorganisms during multiple sequential surface contacts with and without gloves has not been formerly investigated. We measured the quantity of Escherichia coli on fingertips of participants after 1-8 sequential contacts with inoculated plastic coupons with and without nitrile gloves. A Bayesian approach was used to develop a mechanistic model of pathogen accretion to examine finger loading as a function of the difference between E coli on surfaces and fingers. We used the model to determine the coefficient of transfer efficiency (λ), and influence of swabbing efficiency and finger area. Results showed that λ for bare skin was higher (49%, 95% CI = 32%-72%) than for gloved hands (30%, CI = 17%-49%). Microbial load tended toward a dynamic equilibrium after four and six contacts for gloved hands and bare skin, respectively. Individual differences between volunteers' hands had a negligible effect compared with use of gloves (P 
• Pearce-Walker, J., Bright, K. R., Canales, R. A., Wilson, A. M., & Verhougstraete, M. (2020). Managing leafy green safety from adenoviruses and enteroviruses in irrigation water. Agricultural Water Management, 240, 106272. doi:10.1016/j.agwat.2020.106272
• Wilson, A. M., Abney, S. E., King, M., Weir, M. H., Lopez-Garcia, M., Sexton, J. D., Dancer, S., Proctor, J., Noakes, C. J., & Reynolds, K. A. (2020). COVID-19 and non-traditional mask use: How do various materials compare in reducing the infection risk for mask wearers?. Journal of Hospital Infection, 105, 640-642. doi:10.1016/j.jhin.2020.05.036
• Wilson, A. M., King, M. F., López-García, M., Weir, M. H., Sexton, J. D., Canales, R. A., Kostov, G. E., Julian, T. R., Noakes, C. J., & Reynolds, K. A. (2020). Evaluating a transfer gradient assumption in a fomite-mediated microbial transmission model using an experimental and Bayesian approach. Journal of the Royal Society, Interface, 17(167), 20200121.
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  Current microbial exposure models assume that microbial exchange follows a concentration gradient during hand-to-surface contacts. Our objectives were to evaluate this assumption using transfer efficiency experiments and to evaluate a model's ability to explain concentration changes using approximate Bayesian computation (ABC) on these experimental data. Experiments were conducted with two phages (MS2, X174) simultaneously to study bidirectional transfer. Concentrations on the fingertip and surface were quantified before and after fingertip-to-surface contacts. Prior distributions for surface and fingertip swabbing efficiencies and transfer efficiency were used to estimate concentrations on the fingertip and surface post contact. To inform posterior distributions, Euclidean distances were calculated for predicted detectable concentrations (log PFU cm) on the fingertip and surface post contact in comparison with experimental values. To demonstrate the usefulness of posterior distributions in calibrated model applications, posterior transfer efficiencies were used to estimate rotavirus infection risks for a fingertip-to-surface and subsequent fingertip-to-mouth contact. Experimental findings supported the transfer gradient assumption. Through ABC, the model explained concentration changes more consistently when concentrations on the fingertip and surface were similar. Future studies evaluating microbial transfer should consider accounting for differing fingertip-to-surface and surface-to-fingertip transfer efficiencies and extend this work for other microbial types.
• Wilson, A. M., Reynolds, K. A., Jaykus, L. A., Escudero-Abarca, B., & Gerba, C. P. (2020). Comparison of estimated norovirus infection risk reductions for a single fomite contact scenario with residual and nonresidual hand sanitizers. American journal of infection control, 48(5), 538-544.
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  The purpose of this study was to relate experimentally measured log human norovirus reductions for a nonresidual (60% ethanol) and a residual (quaternary ammonium-based) hand sanitizer to infection risk reductions.
• Canales, R. A., Reynolds, K. A., Wilson, A. M., Fankem, S. L., Weir, M. H., Rose, J. B., Abd-Elmaksoud, S., & Gerba, C. P. (2019). Modeling the role of fomites in a norovirus outbreak. Journal of occupational and environmental hygiene, 16(1), 16-26.
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  Norovirus accounts for a large portion of the gastroenteritis disease burden, and outbreaks have occurred in a wide variety of environments. Understanding the role of fomites in norovirus transmission will inform behavioral interventions, such as hand washing and surface disinfection. The purpose of this study was to estimate the contribution of fomite-mediated exposures to infection and illness risks in outbreaks. A simulation model in discrete time that accounted for hand-to-porous surfaces, hand-to-nonporous surfaces, hand-to-mouth, -eyes, -nose, and hand washing events was used to predict 17 hr of simulated human behavior. Norovirus concentrations originated from monitoring contamination levels on surfaces during an outbreak on houseboats. To predict infection risk, two dose-response models (fractional Poisson and F hypergeometric) were used to capture a range of infection risks. A triangular distribution describing the conditional probability of illness given an infection was multiplied by modeled infection risks to estimate illness risks. Infection risks ranged from 70.22% to 72.20% and illness risks ranged from 21.29% to 70.36%. A sensitivity analysis revealed that the number of hand-to-mouth contacts and the number of hand washing events had strong relationships with model-predicted doses. Predicted illness risks overlapped with leisure setting and environmental attack rates reported in the literature. In the outbreak associated with the viral concentrations used in this study, attack rates ranged from 50% to 86%. This model suggests that fomites may have accounted for 25% to 82% of illnesses in this outbreak. Fomite-mediated exposures may contribute to a large portion of total attack rates in outbreaks involving multiple transmission modes. The findings of this study reinforce the importance of frequent fomite cleaning and hand washing, especially when ill persons are present.
• Canales, R. A., Wilson, A. M., Sinclair, R. G., Soto-Beltran, M., Pearce-Walker, J., Molina, M., Penny, M., & Reynolds, K. A. (2019). Microbial study of household hygiene conditions and associated Listeria monocytogenes infection risks for Peruvian women. Tropical medicine & international health : TM & IH, 24(7), 899-921.
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  To develop an exposure and risk assessment model to estimate listeriosis infection risks for Peruvian women.
• Wilson, A. M., Reynolds, K. A., & Canales, R. A. (2019). Estimating the effect of hand hygiene compliance and surface cleaning timing on infection risk reductions with a mathematical modeling approach. American journal of infection control, 47(12), 1453-1459.
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  Quantitative tools are needed to relate infection control interventions to infection risk reductions.
• Wilson, A. M., Reynolds, K. A., Verhougstraete, M. P., & Canales, R. A. (2019). Validation of a Stochastic Discrete Event Model Predicting Virus Concentration on Nurse Hands. Risk Analysis, 39(8), 1812-1824.
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  Understanding healthcare viral disease transmission and the effect of infection control interventions will inform current and future infection control protocols. In this study, a model was developed to predict virus concentration on nurses' hands using data from a bacteriophage tracer study conducted in Tucson, Arizona, in an urgent care facility. Surfaces were swabbed 2 hours, 3.5 hours, and 6 hours postseeding to measure virus spread over time. To estimate the full viral load that would have been present on hands without sampling, virus concentrations were summed across time points for 3.5- and 6-hour measurements. A stochastic discrete event model was developed to predict virus concentrations on nurses' hands, given a distribution of virus concentrations on surfaces and expected frequencies of hand-to-surface and orifice contacts and handwashing. Box plots and statistical hypothesis testing were used to compare the model-predicted and experimentally measured virus concentrations on nurses' hands. The model was validated with the experimental bacteriophage tracer data because the distribution for model-predicted virus concentrations on hands captured all observed value ranges, and interquartile ranges for model and experimental values overlapped for all comparison time points. Wilcoxon rank sum tests showed no significant differences in distributions of model-predicted and experimentally measured virus concentrations on hands. However, limitations in the tracer study indicate that more data are needed to instill more confidence in this validation. Next model development steps include addressing viral concentrations that would be found naturally in healthcare environments and measuring the risk reductions predicted for various infection control interventions.
• Canales, R. A., Wilson, A. M., Pearce-Walker, J. I., Verhougstraete, M. P., & Reynolds, K. A. (2018). Methods for Handling Left-Censored Data in Quantitative Microbial Risk Assessment. Applied and environmental microbiology, 84(20).
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  Data below detection limits, left-censored data, are common in environmental microbiology, and decisions in handling censored data may have implications for quantitative microbial risk assessment (QMRA). In this paper, we utilize simulated data sets informed by real-world enterovirus water data to evaluate methods for handling left-censored data. Data sets were simulated with four censoring degrees (low [10%], medium [35%], high [65%], and severe [90%]) and one real-life censoring example (97%) and were informed by enterovirus data assuming a lognormal distribution with a limit of detection (LOD) of 2.3 genome copies/liter. For each data set, five methods for handling left-censored data were applied: (i) substitution with LOD/[Formula: see text], (ii) lognormal maximum likelihood estimation (MLE) to estimate mean and standard deviation, (iii) Kaplan-Meier estimation (KM), (iv) imputation method using MLE to estimate distribution parameters (MI method 1), and (v) imputation from a uniform distribution (MI method 2). Each data set mean was used to estimate enterovirus dose and infection risk. Root mean square error (RMSE) and bias were used to compare estimated and known doses and infection risks. MI method 1 resulted in the lowest dose and infection risk RMSE and bias ranges for most censoring degrees, predicting infection risks at most 1.17 × 10 from known values under 97% censoring. MI method 2 was the next overall best method. For medium to severe censoring, MI method 1 may result in the least error. If unsure of the distribution, MI method 2 may be a preferred method to avoid distribution misspecification. This study evaluates methods for handling data with low (10%) to severe (90%) left-censoring within an environmental microbiology context and demonstrates that some of these methods may be appropriate when using data containing concentrations below a limit of detection to estimate infection risks. Additionally, this study uses a skewed data set, which is an issue typically faced by environmental microbiologists.
• Sexton, J. D., Wilson, A. M., Sassi, H. P., & Reynolds, K. A. (2018). Tracking and controlling soft surface contamination in health care settings. American journal of infection control, 46(1), 39-43.
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  Study objectives were to track the transfer of microbes on soft surfaces in health care environments and determine the efficiency of an Environmental Protection Agency (EPA)-registered soft surface sanitizer in the health care environment.
• Wilson, A. M., Reynolds, K. A., Sexton, J. D., & Canales, R. A. (2018). Modeling Surface Disinfection Needs To Meet Microbial Risk Reduction Targets. Applied and environmental microbiology, 84(18).
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  Nosocomial viral infections are an important cause of health care-acquired infections where fomites have a role in transmission. Using stochastic modeling to quantify the effects of surface disinfection practices on nosocomial pathogen exposures and infection risk can inform cleaning practices. The purpose of this study was to predict the effect of surface disinfection on viral infection risks and to determine needed viral reductions to achieve risk targets. Rotavirus, rhinovirus, and influenza A virus infection risks for two cases were modeled. Case 1 utilized a single fomite contact approach, while case 2 assumed 6 h of contact activities. A 94.1% viral reduction on surfaces and hands was measured following a single cleaning round using an Environmental Protection Agency (EPA)-registered disinfectant in an urgent care facility. This value was used to model the effect of a surface disinfection intervention on infection risk. Risk reductions for other surface-cleaning efficacies were also simulated. Surface reductions required to achieve risk probability targets were estimated. Under case 1 conditions, a 94.1% reduction in virus surface concentration reduced infection risks by 94.1%. Under case 2 conditions, a 94.1% reduction on surfaces resulted in median viral infection risks being reduced by 92.96 to 94.1% and an influenza A virus infection risk below one in a million. Surface concentration in the equations was highly correlated with dose and infection risk outputs. For rotavirus and rhinovirus, a >99.99% viral surface reduction would be needed to achieve a one-in-a-million risk target. This study quantifies reductions of infection risk relative to surface disinfectant use and demonstrates that risk targets for low-infectious-dose organisms may be more challenging to achieve. It is known that the use of EPA-registered surface disinfectant sprays can reduce infection risk if used according to the manufacturer's instructions. However, there are currently no standards for health care environments related to contamination levels on surfaces. The significance of this research is in quantifying needed reductions to meet various risk targets using realistic viral concentrations on surfaces for health care environments. This research informs the design of cleaning protocols by demonstrating that multiple applications may be needed to reduce risk and by highlighting a need for more models exploring the relationship among microbial contamination of surfaces, patient and health care worker behaviors, and infection risks.

Reviews

• Lowe, A. A., Ravi, P., Gerald, L. B., & Wilson, A. M. (2023. The Changing Job of School Nurses during the COVID-19 Pandemic: A Media Content Analysis of Contributions to Stress(pp 101-117).
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  School nurses and unlicensed assistive personnel (UAPs) are essential to the health and wellness of school children. However, most US schools do not have a full-time licensed nurse. During the COVID-19 pandemic, school nurses and UAPs have been integral in ensuring that the health needs of students were met. They have seen a marked increase in their responsibilities included implementing COVID-19 mitigation strategies, screening for symptoms, testing students and staff, conducting contact tracing and data collection, and ensuring the implementation of rapidly changing COVID-19 guidelines and protocols for schools. The objective of this study was to explore COVID-19 occupational changes and their contributions to stress among school nurses and UAPs through a content analysis of local and national media articles. A Google search of articles published between February 2020 and September 2021 was conducted using the following search terms: 'school nurse', 'COVID-19', 'health aide', 'stress', and 'experiences'. A search was also conducted in Nexis Uni. Articles were included if the topic discussed school nurses or UAPs and COVID-19. All articles that examined nurses in other settings were excluded from the review. We examined topics and themes temporally (from February 2020 to September 2021) and spatially (i.e. the frequency by US state). Overall, 496 media articles discussing school nurses and COVID-19 were included in our review. The highest volume of articles was from September 2021 (22%, 111/496). Other months with relatively high volume of articles included August 2020 (9%, 43/496), January 2021 (10%, 47/496), February 2021 (9%, 44/496), and August 2021 (8%, 39/496). These larger article volumes coincided with notable COVID-19 events, including returning to school in the fall (August 2020 and August 2021), school nurses assisting with vaccine rollouts among adults in the USA (January/February 2021), concerns regarding the delta variant (August/September 2021), and vaccine rollouts for children ages 12-15 (September 2021). The representation of articles spatially (national, state, regional, or local) was 66 (13%) articles at national level, 217 (44%) state level, 25 (5%) regional level, and 188 (38%) local news at the city and/or village level. Pennsylvania had the highest frequency of articles, but when standardized to the state population, Alaska had the highest rate of media per 100 000 people. Three major themes were identified in our analysis: (i) safety; (ii) pandemic-related fatigue/stress; and (iii) nursing shortage/budget. The most represented theme for articles before September 2021 was that of safety. Over time, the themes of pandemic-related fatigue/stress and nursing shortage/budget increased with the most notable increase being in September 2021. The COVID-19 pandemic has resulted in new occupational risks, burdens, and stressors experienced by school nurses and UAPs. School nurses play a critical role in disease surveillance, disaster preparedness, wellness and chronic disease prevention interventions, immunizations, mental health screening, and chronic disease education. Furthermore, they provide a safety net for our most vulnerable children. Given that school nurses were already over-burdened and under-resourced prior to the pandemic, characterization of these new burdens and stressors will inform emergency preparedness resources for school health personnel during future pandemics or outbreaks.