Publications by authors named "Juan S LeOn"

Retinol binding protein (RBP) is used as a proxy for retinol in population-based assessments of vitamin A deficiency (VAD) for cost-effectiveness and feasibility. When the cut-off of < 0·7 μmol/l for retinol is applied to RBP to define VAD, an equivalence of the two biomarkers is assumed. Evidence suggests that the relationship between retinol and RBP is not 1:1, particularly in populations with a high burden of infection or inflammation.

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Background: Despite Colombia's robust well-child visits program, Colombian children and mothers still suffer from anemia, especially in populations of lower socioeconomic status. In this study, we aimed to quantify the prevalence and risk factors among mothers and their children attending their well-child visits in Apartadó, a municipality in the Urabá region of the Colombian Caribbean.

Methods: There were 100 mother-child pairs enrolled in this secondary data-analysis study from a health facility in the municipality of Apartadó, Urabá, Colombia, during well-child visits.

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Essential food workers experience elevated risks of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection due to prolonged occupational exposures in food production and processing areas, shared transportation (car or bus), and employer-provided shared housing. Our goal was to quantify the daily cumulative risk of SARS-CoV-2 infection for healthy susceptible produce workers and to evaluate the relative reduction in risk attributable to food industry interventions and vaccination. We simulated daily SARS-CoV-2 exposures of indoor and outdoor produce workers through six linked quantitative microbial risk assessment (QMRA) model scenarios.

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Countries continue to debate the need for decontamination of cold-chain food packaging to reduce possible severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) fomite transmission among frontline workers. While laboratory-based studies demonstrate persistence of SARS-CoV-2 on surfaces, the likelihood of fomite-mediated transmission under real-life conditions is uncertain. Using a quantitative microbial risk assessment model of a frozen food packaging facility, we simulated 1) SARS-CoV-2 fomite-mediated infection risks following worker exposure to contaminated plastic packaging; and 2) reductions in these risks from masking, handwashing, and vaccination.

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The SARS-CoV-2 global pandemic poses significant health risks to workers who are essential to maintaining the food supply chain. Using a quantitative risk assessment model, this study characterized the impact of risk reduction strategies for controlling SARS-CoV-2 transmission (droplet, aerosol, fomite-mediated) among front-line workers in a representative indoor fresh fruit and vegetable manufacturing facility. We simulated: 1) individual and cumulative SARS-CoV-2 infection risks from close contact (droplet and aerosols at 1-3 m), aerosol, and fomite-mediated exposures to a susceptible worker following exposure to an infected worker during an 8 h-shift; and 2) the relative reduction in SARS-CoV-2 infection risk attributed to infection control interventions (physical distancing, mask use, ventilation, surface disinfection, hand hygiene, vaccination).

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In the agricultural setting, core global food safety elements, such as hand hygiene and worker furlough, should reduce the risk of norovirus contamination on fresh produce. However, the effect of these practices has not been characterized. Using a quantitative microbial risk model, we evaluated the individual and combined effect of farm-based hand hygiene and worker furlough practices on the maximum risk of norovirus infection from three produce commodities (open leaf lettuce, vine tomatoes, and raspberries).

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Background: Countries continue to debate the need for decontamination of cold-chain food packaging to reduce possible SARS-CoV-2 fomite transmission among workers. While laboratory-based studies demonstrate persistence of SARS-CoV-2 on surfaces, the likelihood of fomite-mediated transmission under real-life conditions is uncertain.

Methods: Using a quantitative risk assessment model, we simulated in a frozen food packaging facility 1) SARS-CoV-2 fomite-mediated infection risks following worker exposure to contaminated plastic packaging; and 2) reductions in these risks attributed to masking, handwashing, and vaccination.

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Introduction: Limited existing research suggests that immigration climate and enforcement practices represent a social determinant of health for immigrants, their families, and communities. However, national research on the impact of specific policies is limited. The goal of this article is to estimate the effect of county-level participation in a 287(g) immigration enforcement agreement on very preterm birth (VPTB, <32 weeks' gestation) rates between 2005-2016 among US-born and foreign-born Hispanic women across the United States.

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Unlabelled: The SARS-CoV-2 global pandemic poses significant health risks to workers who are essential to maintaining the food supply chain. Using a quantitative risk assessment model, this study characterized the impact of risk reduction strategies for controlling SARS-CoV-2 transmission (droplet, aerosol, fomite-mediated) among front-line workers in a representative enclosed food manufacturing facility. We simulated: 1) individual and cumulative SARS-CoV-2 infection risks from close contact (droplet and aerosols at 1-3m), aerosol, and fomite-mediated exposures to a susceptible worker following exposure to an infected worker during an 8h-shift; and 2) the relative reduction in SARS-CoV-2 infection risk attributed to infection control interventions (physical distancing, mask use, ventilation, surface disinfection, hand hygiene).

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Background: Underserved subgroups are less likely to have optimal health prior to pregnancy. We describe preconception health indicators (behavior, pregnancy intention, and obesity) among pregnant Latina women with and without chronic stress in metro Atlanta.

Design: We surveyed 110 pregnant Latina women enrolled in prenatal care at three clinics in Atlanta.

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Cantaloupes contaminated with pathogens have led to many high-profile outbreaks and illnesses. Since bacterial virulence genes (VGs) can act in tandem with antibiotic-resistance and mobile genetic elements, there is a need to evaluate these gene reservoirs in fresh produce, such as cantaloupes. The goal of this study was to assess the distribution of antibiotic-resistance, virulence, and mobile genetic elements genes (MGEGs) in cantaloupe farm environments.

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Stress across the life course is highly prevalent, particularly among immigrant and racial/ethnic minority women who face adversities associated with structural and interpersonal racism. Understanding how women perceive and describe stress and resilience can provide cultural context to inform interventions to improve health among pregnant women facing adversity. The goal of this project was to examine how external stressors and coping strategies prior to and during pregnancy are reflected in Latina women's narratives about their lives through an Ecosocial framework.

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Severe acute respiratory syndrome coronavirus 2 can persist on surfaces, suggesting possible surface-mediated transmission of this pathogen. We found that fomites might be a substantial source of transmission risk, particularly in schools and child daycares. Combining surface cleaning and decontamination with mask wearing can help mitigate this risk.

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Cantaloupe melons, which have been responsible of an increasing number of foodborne disease outbreaks, may become contaminated with microbial pathogens during production. However, little information is available on the microbial populations in the cantaloupe farm environment. The purpose of this work was to characterize the bacterial communities present on cantaloupe farms.

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Fresh-produce consumers may be at risk of pathogen infection due to fecal contamination of the agricultural environment. Indicators of fecal contamination may be used as a proxy to evaluate the potential presence of human pathogens, such as norovirus and hepatitis A, on agricultural samples. The objective of this systematic review was to determine whether the presence of human norovirus or hepatitis A was associated with microbial indicators in agricultural samples including fresh produce, equipment surfaces, and hands.

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Hand hygiene interventions are critical for reducing farmworker hand contamination and preventing the spread of produce-associated illness. Hand hygiene effectiveness may be produce-commodity specific, which could influence implementation strategies. This study's goal was to determine if produce commodity influences the ability of handwashing with soap and water or two-step alcohol-based hand sanitizer (ABHS) interventions to reduce soil and bacteria on farmworker hands.

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More efficient sampling and detection methods of pathogens on fresh produce are needed. The purpose of this study was to compare a novel rinse-membrane filtration method (RMFM) to a more traditional sponge rubbing or stomaching method in processing jalapeño peppers and cantaloupe samples for detection of Escherichia coli, Salmonella enterica, and Listeria monocytogenes. For jalapeño peppers inoculated with 106, 104, and 102 CFU of each pathogen and cantaloupes inoculated at 106 and 104 CFU, all pathogens were detected in all (100%) samples by RMFM at a 10-mL filtration volume, as well as by the stomacher and sponge rubbing methods.

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Background: Human noroviruses (HuNoV) are the leading cause of gastroenteritis. No vaccine is currently available to prevent norovirus illness or infection. Safe, infectious challenge strains are needed to assess vaccine efficacy in the controlled human infection model (CHIM).

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Immigration policy climate may have pervasive effects on the health of immigrants and their families. We examine how living in a state at the time of delivery with a more restrictive immigration policy climate impacts risk of very preterm birth (VPTB) among Hispanic mothers in the United States. We used data from the United States live birth files, 2005-2016.

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Background: To accurately assess micronutrient status, it is necessary to characterize the effects of inflammation and the acute-phase response on nutrient biomarkers.

Objective: Within a norovirus human challenge study, we aimed to model the inflammatory response of C-reactive protein (CRP) and α-1-acid glycoprotein (AGP) by infection status, model kinetics of micronutrient biomarkers by inflammation status, and evaluate associations between inflammation and micronutrient biomarkers from 0 to 35 d post-norovirus exposure.

Methods: Fifty-two healthy adults were enrolled into challenge studies in a hospital setting and followed longitudinally; all were exposed to norovirus, half were infected.

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Background: Open drains are common methods of transporting solid waste and excreta in low-income urban neighborhoods. Open drains can overflow due to blockages with solid waste and during rainfall, posing exposure risks. The goal of this study was to evaluate whether pediatric enteric infection was associated with open drains and flooding in a dense, low-income, urban neighborhood.

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To describe norovirus outbreaks at colleges and universities. None. Conducted September 2016 to March 2018.

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Norovirus is the leading cause of acute gastroenteritis and foodborne disease in the United States. The Food and Drug Administration recommends that food workers infected with norovirus be excluded from the workplace while symptomatic and for 48 hours after their symptoms subside. Compliance with this recommendation is not ideal, and the population-level impacts of changes in food-worker compliance have yet to be quantified.

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Globally, vitamin A deficiency (VAD) affects nearly 200 million children with negative health consequences. VAD can be measured by a retinol-binding protein (RBP) and serum retinol concentrations. Their concentrations are not always present in a 1:1 molar ratio and are affected by inflammation.

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Because anemia is one of the markers of morbidity associated with schistosomiasis, it has been proposed as a potential measure to evaluate the impact of control programs. However, anemia is also a common consequence of malaria, and schistosomiasis and malaria are often co-endemic. To estimate the attributable fraction of anemia due to and infections, we applied a log-binomial model to four studies measuring these parameters of a combined 5,849 children in western Kenya.

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