Search Results (65)

Freshwater ecosystems play an important role in human survival, ecosystem functioning, and biodiversity conservation, yet industrialisation and urbanisation dump over 80% of untreated sewage into them. This inadequate wastewater management leads to enteric pathogens like Escherichia coli, Salmonella, Shigella, Campylobacter, Vibrio cholerae, Pseudomonas aeruginosa, and Legionella pneumophila that are responsible for a wide range of waterborne human diseases globally with extensive morbidity and mortality. The World Health Organization (WHO) estimates that at least 2 billion individuals drink water contaminated with pathogens, resulting in illnesses like cholera, dysentery, and diarrhoea, and approximately 50,000 diarrheal deaths annually. Classical epidemiology approaches are the basis for determining disease burden in public health, but they are limited in their capacity to predict future health risks. Quantitative microbial risk assessment (QMRA) addresses this by estimating the potential health risks of any exposure to microbial pathogens in any environment using four key elements, which include the identification of the microbial hazards, human exposure to the hazard through diverse activities, dose–response relationships, and the estimated risk of the infection. This review summarises information on freshwater pathogens, their occurrence, sources and health implications. The methodological approaches of QMRA in freshwater systems are reviewed with examples drawn from recreational activities, drinking water, and wastewater-impacted environments. Global QMRA studies indicate a wide range of infection risk estimates, reflecting differences in water sources, pathogens, and exposure conditions. Thus, QMRA is known to be a valuable public health tool for freshwater ecosystems, linking microbial contamination dynamics to health risk estimates that support proactive management and policy-relevant decision-making. Full article

Background/Objectives: Haemodynamic changes following ischaemic large-vessel occlusion (LVO) stroke might affect clinical outcome, including after endovascular recanalization. Using non-invasive quantitative MRA (qMRA), we report for the first time serial intracranial flow rate measurements following LVO and investigate flow rate changes, collateral pathway development, and their possible clinical significance. Methods: We report data from the prospective IMPreST study (Interplay of Microcirculation and Plasticity after Ischemic Stroke, registered at clinicaltrials.gov, no. NCT04035746). Patients with first-ever unilateral internal carotid artery (ICA) and/or M1/2 middle cerebral artery (MCA) occlusions were included. After being evaluated for gold-standard treatment, including endovascular thrombectomy, patients underwent early (<3 days) and late subacute (7 ± 3 days) qMRA flow measurements of the M1-MCA, A2-ACA (anterior cerebral artery), and P2-PCA (posterior cerebral artery) segments bilaterally. Results: Among 31 patients enrolled, 23 patients (17 recanalized, 6 non-recanalized) received both qMRA sessions. M1 volume flow rate (VFR) ratios (ischaemic/non-ischaemic hemisphere) in recanalized patients were symmetric (0.98–1.01) over time, while in non-recanalized patients M1 VFR ratios remained lower (0.74–0.77). P2 VFR ratios increased over time and were negatively correlated with M1 VFR ratios in late measurements (p = 0.016), possibly reflecting subacute activation of leptomeningeal collaterals via P2-PCA. In recanalized patients, lower M1 VFR ratios at 7 ± 3 days were significantly associated with a higher NIHSS at discharge after adjusting for infarct size, age, and NIHSS at admission (p = 0.02). Total hemispheric flow significantly decreased by up to 9% between early and late measurements in both the ischaemic and non-ischaemic hemispheres (p = 0.005). Conclusions: qMRA may help to understand flow status and collateral pathway activation after LVO stroke. Past the acute phase, low arterial flow to the affected region is associated with poorer neurological status, including after successful recanalization. Full article

Background/Objectives: This study assessed the risk associated with third-generation cephalosporin- and fluoroquinolone-resistant Salmonella from pork consumption by integrating phenotypic resistance profiles with genetic data to characterize the risks and transmission pathways. Methods: Salmonella were isolated from raw pork meat samples (n = 793) collected from fresh markets and hypermarkets across Bangkok during 2021–2022, of which 150 were extended-spectrum β-lactamase (ESBL)-producing and 31 were fluoroquinolone-resistant isolates. Phenotypic and genotypic resistance profiles were characterized. Quantitative antimicrobial resistance risk assessment (AMR RA) was conducted using a dose–response model. Results: Salmonella spp. was detected in 42.75% of pork samples, with a higher prevalence in fresh markets (75.5%) than in hypermarket samples and with concentrations ranging from 1.3 to 180 MPN/g. Twenty-eight percent of isolates were ESBL producers, with ciprofloxacin and levofloxacin resistance observed in 5.3% and 3.0%, respectively. The bla_CTX-M55 genes were located on conjugative plasmids. Whole genome sequencing revealed both vertical and horizontal gene transfer. IncHI2/N and IncC plasmids shared conserved backbones and resistance gene architectures, indicating horizontal dissemination of resistance genes. Phylogenomics suggested possible clonal transmission among pigs, pork, and humans. AMR RA estimated 88,194 annual illness cases per 100,000 people from ESBL-producing Salmonella and 61,877 from ciprofloxacin-resistant strain, compared with 95,328 cases predicted by QMRA from Salmonella contamination. Cooking pork at ≥64 °C for 3 min eliminated the risk in all scenarios. Sensitivity analysis identified initial contamination level and cooking temperature as key determinants. Conclusions: Raw pork meat consumption represents the highest risk, which can be mitigated by thorough cooking (>64 °C, ≥3 min), while integrating genomic data enhances AMR hazard identification, source attribution, and exposure assessment. Therefore, promoting well-cooked meat consumption and safe cooking practices, alongside the use of AMR genetic data to inform targeted interventions, is recommended. Full article

In this paper, advanced sensorless control methods of an induction machine (IM) with the use of a model reference adaptive system (MRAS) estimator are presented, specifically an MRAS using reactive power (Q-MRAS) with an implemented feedforward artificial neural network. Advantages of the proposed solution in comparison with the conventional Q-MRAS include better robustness, less dependence on the IM parameters, and stable operation in the regenerative mode. The simulations were performed in the MATLAB Simulink interface to validate the proposed approach. The algorithm was implemented in a single-core TMS320F28335 real-time Digital Signal Controller with a LabVIEW control panel. The experimental results were obtained on a three-phase experimental induction motor drive with a nominal power of 2.2 kW. Full article

Listeria monocytogenes is a significant foodborne pathogen associated with high rates of hospitalization and death, especially among vulnerable populations. Despite established regulatory standards and available antimicrobial intervention strategies, L. monocytogenes remains as a pathogen of concern in ready-to-eat (RTE) foods. This ultimately can lead to food recalls or listeriosis outbreak, highlighting its ongoing risks to food safety and public health. This review consolidates publicly accessible surveillance case counts and recall data of L. monocytogenes contamination from Australia, Europe, Canada, and the United States to assess the contamination trends in the RTE food supply chain. It also evaluates the effectiveness of antimicrobial intervention strategies, including both those currently implemented in industry and those that have been studied as potential interventions but are not yet widely adopted. Key factors affecting the efficiency of those strategies are identified, including food matrix composition, water activity (a_w), fat content, and strain variability. Emerging multi-hurdle technology that integrates physical, chemical, and biological antimicrobial interventions are highlighted as promising approaches for maintaining both food safety and product quality. It also outlines the role of quantitative microbial risk assessment (QMRA) as a decision-support tool to select appropriate control strategies, predict recall risk and guide evidence-based risk management. Future research directions are proposed to expand the application of QMRA in managing recall risks throughout the RTE food supply chain due to L. monocytogenes. Full article

Extended-spectrum beta-lactamase (ESBL)-producing E. coli from broiler farms can reach watersheds used for recreational swimming. We assessed short-term swimmer exposure by extending a modular quantitative microbial risk assessment (QMRA) to the recreational water pathway linking land manure application to in-stream fate and transport with dilution and decay. We modeled single-event exposure doses and estimated loss of disability-adjusted life years (DALYs). We ran sensitivity analyses on several parameters and compared outputs to published recreational water assessments that include ESBL E. coli. Assuming a worst-case scenario, single-event doses were lower for adults (2.95 CFU; UI 0.14–6.11) and higher for children (8.78 CFU; UI 0.56–17.20) on day 1 after land application, then dropped below 0.01 CFU by day 200, with DALY losses from 10⁻⁷ to 10⁻¹⁰. Uncertainty was dominated by fate and transport. Stronger particle binding, faster in-stream decay, and larger effective volumes lowered exposure, while higher shedding, greater flow, and larger wash-off raised it. Estimates fell at the low end of prior studies. Swimmer exposure appears to be extremely low and short-lived. The modular QMRA links farm contamination to bathing-site risk and supports risk-based monitoring (after spreading or storms) and short-term forecasts that focus advisories on short, higher-risk windows after litter application. Full article

This study presents a comprehensive Quantitative Microbial Risk Assessment (QMRA) for Escherichia coli in northeastern Greece’s riverine and deltaic aquatic systems, evaluating potential human health risks from recreational water exposure. The analysis integrates seasonal microbiological monitoring data—E. coli, total coliforms, enterococci, Salmonella spp., Clostridium perfringens (spores and vegetative forms), and physicochemical parameters (e.g., pH, temperature, BOD₅)—across multiple sites. A beta-Poisson dose–response model within a Monte Carlo simulation framework (10,000 iterations) was applied to five exposure scenarios, simulating varying ingestion volumes for different population groups. Median annual infection risks ranged from negligible to high, with several locations (e.g., Mandra River, Konsynthos South, and Delta Evros) surpassing the World Health Organization (WHO)’s benchmark of 10⁻⁴ infections per person per year. A Gradient Boosting Regressor (GBR) model was developed to enhance predictive capacity, demonstrating superior accuracy metrics. Permutation Importance analysis identified enterococci, total coliforms, BOD₅, temperature, pH, and seasons as critical predictors of E. coli concentrations. Additionally, sensitivity analysis highlighted the dominant role of ingestion volume and E. coli levels across all scenarios and sites. These findings support the integration of ML-based tools and probabilistic modelling in water quality risk governance, enabling proactive public health strategies in vulnerable or high-use recreational zones. Full article

(1) The beach areas of Galveston, Texas, USA are heavily used for recreational activities and often experience elevated fecal indicator bacteria levels, representing a potential threat to ecosystem services, human health, and tourism-based economies that rely on suitable water quality. (2) During the span of 15 months (March 2022–May 2023), water samples that exceeded the U.S. Environmental Protection Agency-accepted alternative Beach Action Value (BAV) for enterococci of 104 MPN/100 mL were analyzed via microbial source tracking (MST) through quantitative polymerase chain reaction (qPCR) assays. The Bacteroides HF183 and DogBact as well as the Catellicoccus LeeSeaGull markers were used to detect human, dog, and gull fecal sources, respectively. The qPCR MST data were then utilized in a quantitative microbial risk assessment (QMRA) to assess human health risks. Additionally, samples collected in July and August 2022 were sequenced for 16S rRNA and matched with fecal sources through the Bayesian SourceTracker2 program. (3) Overall, 26% of the 110 samples with enterococci exceedances were positive for at least one of the MST markers. Gull was revealed to be the primary source of identified fecal contamination through qPCR and SourceTracker2. Human contamination was detected at very low levels (<1%), whereas dog contamination was found to co-occur with human contamination through qPCR. QMRA identified Campylobacter from canine sources as being the primary driver for human health risks for contact recreation for both adults and children. (4) These MST results coupled with QMRA provide important insight into water quality in Galveston that can inform future water quality and beach management decisions that prioritize public health risks. Full article

The transmission of infectious diseases via the use of public restrooms has been previously documented. The goal of this study was to compare bacterial contamination in public vs. household restrooms and, using quantitative microbial risk assessment (QMRA), to assess the probability of infection from fomite contact with selected high-touch sites within the restrooms. Fomite surfaces in four public and four household restrooms were sampled over a period of two months. The public restrooms were in an office building occupied by 80 individuals and were considered moderate usage. The toilet seat, toilet flush handle, countertops, and floor were sampled for heterotrophic, coliform, and Escherichia coli bacteria. The highest numbers of heterotrophic bacteria and coliforms were detected on the countertops, followed by the floor. The greatest numbers of E. coli were recovered from the countertops in the household restroom, but the greatest numbers in the public restroom were recovered from the toilet flush handle. Numbers of heterotrophic bacteria and coliforms were 10 to 100 times greater in household restrooms than in public restrooms. The QMRA suggested that the greatest risk of acquiring a norovirus infection involved the touching of the countertops in household restrooms and the toilet flush handles in public restrooms. Full article

Restrooms are associated with the transmission of bacterial and viral illnesses. Disinfecting contaminated surfaces is associated with reducing transmission risk. The goal of this study was to determine how cleaning/disinfecting frequency affects restroom pathogen contamination. The Phase 1 intervention included cleaning toilet surfaces (the toilet bowl, water, and rim) using 9.5% w/w hydrochloric acid. The Phase 2 intervention used fomite-specific products to clean/disinfect additional restroom surfaces, including the vanity countertop, sink faucet handle, toilet seat, flush handle, floor, and doorknob. A designated household member was responsible for cleaning/disinfecting surfaces at the beginning of each interval. Fomite sample collection was randomized, and samples were tested for heterotrophic, coliform, and Escherichia coli bacteria after specified intervals: 1, 2, 3, or 7 days. The greatest numbers of bacteria and largest reductions occurred on fomites after three days. A statistically significant difference was found for heterotrophic bacteria (p = 0.009), coliforms (p = 0.10), and E. coli (p = 0.13) with cleaning/disinfecting every three days. A quantitative microbial risk assessment (QMRA) estimated a >98% reduction in risk of infection by norovirus with an every-3-day cleaning/disinfection routine on the most heavily contaminated sites. Results indicate an optimal cleaning frequency of twice weekly for minimizing exposure to pathogens. Full article

Karst aquifers can be highly productive water sources but are vulnerable to contamination by pathogens because of integrated surface and subsurface drainage. Our study focuses on the karstic Royal Spring basin in Kentucky, encompassing urban and agricultural land uses. The city of Georgetown distributes treated water from Royal Spring to over 33,000 customers. We examined E. coli dynamics at Royal Spring from June 2021 through June 2022, assessing variability under wet versus dry weather conditions. We also used quantitative microbial risk assessment (QMRA) to estimate potential health risks from the pathogenic bacterium E. coli O157:H7. E. coli concentrations in weekly water samples varied from 12 to 1732.8 MPN/100 mL, with a geometric mean of 117.2 MPN/100 mL. The mean concentration in wet periods was approximately double that during dry conditions. Because the pathogen was not detected by quantitative PCR (qPCR), we conducted QMRA based on literature data for water treatment plant operations (occupational) and recreational activities near the spring. The median probability of annual infection was 5.11 × 10⁻³ for occupational exposure and 1.45 × 10⁻² for recreational exposure. Uncertainty and sensitivity analyses revealed that health risks were most sensitive to the pathogen/E. coli ratio and ingestion rate. Although the pathogen was not detected by qPCR, the presence of E. coli suggests potential fecal contamination. This highlights the importance of continued monitoring and investigation of different detection methods to better understand potential health risks in karst systems. Full article

Groundwater is one of the major sources of water supply for human needs. But anthropic activities such as agriculture are causing significant volume depletion and quality deterioration, favoring microbial contamination that has a negative impact on human health. The geological characteristics of the ground can influence the transport of microorganisms, especially if made of permeable rock. Furthermore, irrigation with untreated or partially treated wastewater can represent an additional health risk due to the potential transmission of pathogens to food. The aim of our research is to provide an interdisciplinary perspective on this issue by integrating hygienic, geological, and agronomic skills. Water samplings are scheduled seasonally by four monitoring campaigns in five sampling points placed in two Southern Italy regions, Apulia (one point at the outlet and two wells near the wastewater plant at Carpignano Salentino, Lecce province, Italy) and Sicily (two wells at Scicli and Pozzallo, Ragusa province, Italy) Laboratory experiments of microorganism transport in permeable rocks will be carried out under saturated and unsaturated conditions. A mathematical model of transport through porous media will be implemented and validated with laboratory measurements. The model will be used to develop a monitoring tool to control sites in Apulia and Sicily where periodic cultural and molecular detection of pathogenic bacteria, viruses, and protozoa will also be taken. In addition, an analysis of the microbiological contamination of herbaceous crops due to the use of low-quality water will be conducted to assess the Quantitative Microbial Risk Assessment (QMRA). The project will provide methodological tools to evaluate anthropogenic pressures and their impact on environmental matrices. The results will allow these pressures to be modulated to minimize environmental and agri-food microbiological contamination and protect public health. Full article

Resuspended particles from human activities can contribute to pathogen exposure via airborne fomite contamination in built environments. Studies investigating the dissemination of resuspended viruses are limited. The goal of this study was to explore viral dissemination after aerosolized resuspension via human activities on indoor flooring. Nylon carpet or wood flooring was seeded with virus (MS2) or virus laden dust then evaluated after activities, i.e., walking and vacuuming. Statistically significant differences were found in dispersal of virus laden dust after vacuuming carpet (p-value = 5.8 × 10⁻⁶) and wood (p-value = 0.003, distance > 12 in/30 cm). Significant differences were also found between floor materials and virus laden dust dispersal vacuuming (p = 2.09 × 10⁻⁵) and walking (p = 2.68 × 10⁻²). A quantitative microbial risk assessment (QMRA) scenario using Norovirus and a single fomite touch followed by a single hand-to-mouth touch indicated a statistically significant difference associated with virus laden dust particles and vacuuming carpet(p < 0.001). Infection risks were 1 to 5 log₁₀ greater for dust exposure. The greatest risk reductions from fomites were seen across vacuuming carpet no-dust scenarios for surfaces <30 cm from flooring. More research is needed to determine the role resuspension plays in exposure and transmission of potentially infectious agents. Full article

A quantitative microbial risk assessment model was developed to estimate the probability that the aerosolization of fecal droppings from wild birds in the vicinity of poultry farms would result in the infection of indoor-housed poultry with highly pathogenic avian influenza virus (HPAIv) in the Netherlands. Model input parameters were sourced from the scientific literature and experimental data. The availability of data was diverse across input parameters, and especially parameters on the aerosolization of fecal droppings, survival of HPAIv and dispersal of aerosols were uncertain. Model results indicated that the daily probability of infection of a single poultry farm is very low, with a median value of 7.5 × 10⁻⁹. Accounting for the total number of poultry farms and the length of the bird-flu season, the median overall probability of at least one HPAIv-infected poultry farm during the bird-flu season is 2.2 × 10⁻³ (approximately once every 455 years). This is an overall estimate, averaged over different farm types, virus strains and wild bird species, and results indicate that uncertainty is relatively high. Based on these model results, we conclude that it is unlikely that this introduction route plays an important role in the occurrence of HPAIv outbreaks in indoor-housed poultry. Full article

The presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in wastewater has been reported in several studies and similar research can be used as a proxy for an early warning of potential Coronavirus disease 2019 (COVID-19) outbreaks. This study focused on profiling the incidence of SARS-CoV-2 genomes in wastewater samples obtained from facilities located in the Buffalo City Municipality. Raw samples were collected weekly using the grab technique for a period of 48 weeks. Ribonucleic acids were extracted from the samples, using the QIAGEN Powersoil Total RNA Extraction kit, and extracted RNA samples were further profiled for the presence of SARS-CoV-2 genomes using Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) technique. Furthermore, various environmental matrices were utilized to estimate the potential health risk to plant operators associated with exposure to SARS-CoV-2 viral particles using the quantitative microbiological risk assessment (QMRA) model. Our findings revealed the prevalence of SARS-CoV-2 genomes with concentrations that ranged from 0.22 $\times {10}^3$ to 17.60 $\times {10}^3$ genome copies per milliliter (GC/mL). Different exposure scenarios were employed for the QMRA model, and the findings indicate a probability of infection (P(i)) ranging from 0.93% to 37.81% across the study sites. Similarly, the P(i) was highly significant (p < 0.001) for the 20 mL volumetric intake as compared to other volumetric intake scenarios, and high P(i) was also observed in spring, autumn, and winter for all WWTPs. The P(i) was significantly different (p < 0.05) with respect to the different seasons and with respect to different volume scenarios. Full article