Microbiological Risk Assessment Research Articles

Decision support tools for water reuse: a systematic review

ABSTRACT This article provides a comprehensive review of decision support tools for water reuse (DST4WR), focusing on microbiological risk assessment (MRA), life cycle analysis (LCA), life cycle cost (LCC), and multi-criteria decision analysis (MCDA). A systematic review of 35 articles published between 2020 and 2024, plus one from 2019, was conducted. The studies were categorised based on the DST4WR applied, with each tool discussed individually. MRA tools assess public health risks in different case studies. LCA identifies key environmental indicators, and its integration with LCC facilitates comprehensive cost analysis. MCDA, applied in various case studies, uses criteria like environmental, social, economic, technical, public health, and functional aspects. Integrating DST4WR tools identifies synergies and trade-offs between criteria, aiding informed decision-making. Combining MRA, LCA/LCC, and MCDA is especially beneficial, as each tool provides a distinct perspective. Using these tools together offers a holistic view of water reuse management, ensuring that all relevant factors are balanced. This approach enhances decision-making and builds stakeholder confidence and acceptance by transparently addressing public health, environmental, economic, and social concerns.

Antimicrobial resistance and genotypic attributes of virulence among Vibrio spp. isolated from Japanese retail seafood

Bacterial diseases caused by Vibrio spp. are a significant impediment to the aquaculture industry owing to difficult-to-treat infections and mortality in farmed animals, affecting socioeconomic development. This study aimed to evaluate the role of Japanese retail seafood in the production of antimicrobial-resistant Vibrio spp. and pathogenic factors. One hundred seafood samples purchased from various retail supermarkets in Hiroshima, Japan, were examined using microbiological, phenotypic, and molecular techniques. One hundred and twenty-eight Vibrio isolates belonging to more than 11 species were identified and characterized. Among the 100 samples, 26 (26 %) tested positive for Vibrio spp. with antimicrobial resistance, while 44 (44 %) were positive for those carrying virulence determinants. Out of 128 isolates, V. alginolyticus was predominant (38 %), followed by V. parahaemolyticus (29 %), V. neocaledonicus (7.0 %), V. cholerae (6.3 %), among others. For virulence gene assessment, only six of the 10 virulence attributes, tlh (34.4 %), VPI (29.7 %), ompW (7.0 %), toxR (5.5 %), hlyA (3.9 %), and ompU (3.1 %), were detected in the isolates. tcpA, ctxA, ctxB, and tdh are absent. Eight V. cholerae isolates of international origin were VPI-positive, seven of which harbored the toxR regulon and other virulence genes. The blaTEM resistance gene was identified in V. alginolyticus (22 isolates). All 46 antimicrobial resistance gene-harboring isolates were phenotypically susceptible to cephalosporins, aztreonam, meropenem, tetracycline, chloramphenicol, and ciprofloxacin. Ampicillin resistance was the highest (91.3 %), followed by colistin (30.4 %) and fosfomycin (15.2 %). The multiple-antibiotic resistance index ranged from 0.2 to 0.47, suggesting that some isolates originate from high-risk contamination sources. Our results shed light on the incidence of potentially pathogenic Vibrio spp. and highlighted the importance of continuous monitoring to improve food safety in the seafood supply chain. These findings will be useful for developing microbiological risk assessments for retail seafood management.

Harmonizing Campylobacter risk assessments across European countries – can the pooled process hygiene criteria data be used in the Danish risk assessment model?

This study investigated the possibility of harmonizing quantitative microbiological risk assessment (QMRA) for Campylobacter spp. across European (EU) countries. French Campylobacter data (2020–2021) from neck skin (NS) pools, sampled at slaughterhouses under the European surveillance component for Food Business Operators (FBOs), were adapted to inform a QMRA model that, among others, has been used within the Danish Action Plan against Campylobacter, on the basis of single leg skins (LS) data. Datasets included culture results (in colony forming unit per gram, CFU/g) from 1,284 broiler flocks slaughtered at 13 slaughterhouses representing broiler production in western France. Five pools (of 2–4 NS samples each) per flock were tested. One pool per tested flock was randomly chosen for the analysis. After conducting descriptive statistics (on flock prevalence and meat contaminations across months and years), three contamination transformation factors (CTFs) were estimated to translate NS pools contaminations into single LS contamination, based on data from French and Danish studies. A reference simulation scenario (ScenRef) was set with CTF = 3.2 (i.e. NS pool concentration divided by 3.2); while other 13 scenarios represented an alternative scenario analysis to investigate the impact of: the CTF value (ScenMin with CTF = 2 and ScenMax with CTF = 10), censored test results (ScenUncens) and random choice of pool per flock (ScenSampling-1 to 10), on the risk estimates. The average monthly/annual risk of human disease per poultry meal and the monthly/annual relative risk (RR) of 2021 compared to 2020, were estimated. In ScenRef, the annual RR was 1.22, suggesting an increase of risk of ≈ 22 % in 2021 compared to 2020. The impact of CTFs, censored data and randomized pool sampling per flock, on the annual and (most) monthly RRs, appeared limited. This study gives an overview of the strengths and limitations to be considered for adapting the French FBO data into the Danish model and to harmonize risk assessments across EU countries, accordingly. To reduce uncertainty in risk estimates, it could be considered increasing representativeness of NS tested flock populations and/or using LS rather than NS samples; because LS samples are more representative of actually retailed meat contaminations. If NS pools are maintained, the relationships between concentrations on NS pools and those on consumed meat requires further investigation.

Salinity and microbiological risk assessment in surface runoff and main tributaries to La Vega Dam in Teuchitlán, Jalisco, Mexico.

Objective: This research aimed to evaluate the water quality of the main tributaries to the La Vega Dam for irrigation purposes through the physicochemical and microbiological parameters. Design/methodology/approach: The 10 main tributaries to the La Vega Dam were selected. The variables evaluated were pH, Temperature, Electrical Conductivity, Total Dissolved Solids and Dissolved Oxygen, boron calcium, magnesium, sodium, SAR, and RCS. Results: 50% of samples presented low sodicity risk, 10% medium risk, 20% and 20% very high risk. In the CSR results, only one site (10%) presented a low risk, and the remaining four tributaries (40%) of this area presented a medium risk. Five sites (50%) located east of the dam presented a high risk. Also, high boron concentration was observed, corresponding to El Salado River. Fecal pollution was detected in 100% of sites, limiting their use as irrigation water. Limitations on study/implications: Continuous water quality monitoring of the main tributaries to and into La Vega Dam should be followed up. Findings/conclusions: The most significant contribution of contamination to the dam was observed in the eastern part, with the entrance of El Salado River. High concentrations of boron were also observed. A high concentration of total and fecal coliforms was also found, in addition to the presence of Pseudomonas spp., which indicates fecal contamination. The effluent at the east of La Vega Dam is unsuitable for irrigation.

Identification of microbiological genomes carrying antibiotic resistance genes and virulence factor genes for microbiological risk assessment in filter backwash water

Social development and environmental pollution have worsened the scarcity of global water resources. Recycling filter backwash water (FBW) can enhance water resource efficiency. Systematically investigating the biological risk of FBW for public health is essential. Biological risks such as widely publicized pathogens, emerging antibiotic resistance genes (ARGs), and virulence factor genes (VFGs) were studied. The sand filter backwash water (SFBW) and biological activated carbon filter backwash water (BACFBW) from a DWTP in southern China were sampled over two years. Pathogens and community structure were investigated using 16S and 18S rRNA gene sequencing. ARGs and VFGs were studied using metagenomic sequencing. The BACFBW contained 110 pathogens, 37 ARGs, and 740 virulence factors (VFs), and the SFBW contained 103 pathogens, 75 ARGs, and 832 VFs. The relative abundance of pathogens was higher in summer than in winter for BACFBW. The richness of both ARGs and VFGs in SFBW was higher than in BACFBW. Shortening the backwash cycle could reduce the relative abundance of pathogens in FBW but had no significant effect on ARGs and VFGs in FBW. BACFBW in summer can be reused after appropriately shortening the backwash cycle when controlling the risk of pathogens. The risk of SFBW cannot be reduced by shortening the backwash cycle when controlling ARGs and VFGs. This study provided a basis for safely reusing the sand filter backwash water and biological activated carbon filter backwash water.

Microbiological risk assessment of Bacillus cereus in popular hot dishes eaten by plant-based diet consumers in France

There is a current trend towards plant-based diets in Western countries. Since changes in the diet imply possible changes in exposure to foodborne pathogens, there is an increasing need to assess the microbiological risks associated with these diets. This study aims to assess microbiological risks for French adults associated with Bacillus cereus group III and group IV in hot, homemade cereal- and lentil-based dishes. A probabilistic retail-to-fork risk assessment model was developed considering cooking, cooling at ambient temperature, and storage under chilled conditions. Data came from a representative national survey, public database and literature. The model was developed in R, and uncertainty and variability were separated using second-order Monte Carlo simulations. Not all consumers have the same storage and cooling practices, so the results were expressed by probabilistic distributions built by specific storage time. The mean concentration of Bacillus cereus in portions at the time of consumption after 72 h of storage was 1.2 log CFU.g−1 for cereal-based dishes and 3.4 log CFU.g−1 for lentil-based dishes. After 72 h of storage under chilled conditions, the risk per portion, defined as the probability of contamination over 5 log CFU.g−1, was 0 (95 % CI: 0 - 0) for cereal-based dishes and 7.95 × 10−4 (95 % CI: 5.55 × 10−4 - 1.12 × 10−3) for lentils-based dishes. However, if cooling time at room temperature reached 24 h, the risk for cereal- and lentil-based dishes increased to 2.39 × 10−3 (95 % CI: 1.15 × 10−3 - 4.90 × 10−3) and 4.66 × 10−1 (95 % CI: 3.16 × 10−1 - 6.07 × 10−1), respectively. The sensitivity analysis indicated that the initial prevalence and level of contamination were key factors in limiting the risk, ranking before cooling time or refrigeration conditions. Besides, the scenario analysis revealed an influence of consumer behaviour regarding cooling and storage time on the risk per portion. The environmental trend towards plant-forward diets, combined with the emerging no-food waste and batch cooking practices in France, will likely favour new consumption patterns and increase the risk associated with Bacillus cereus. Our model will help quantify this extra burden.

Ecotoxicological and Microbiological Risk Assessment of Groundwater from Dimba Cave, Democratic Republic of the Congo.

Dimba Cave is a large array of natural galleries in limestone mountains of the Democratic Republic of the Congo that contains highly valued pre-historic archaeological artifacts. The cave attracts a high number of tourists every year and is used by local populations as a water supply source. The main objective of the research undertaken in Dimba Cave consisted of assessing the quality of water and sediments from Dimba Cave ponds through evaluating contamination by heavy metals (15 elements analyzed, including As, Cd, Pb, and Hg) and by microbial populations (including Escherichia coli and total coliforms) in order to estimate the ecotoxicological risk to humans and to non-human biota. All water samples collected in the cave ponds showed very high metal concentrations exceeding the internationally recommended limits for drinking water, particularly for Cr, Mn, As, Pb, and Hg. Most sediment samples from cave ponds also displayed high heavy metal concentrations. The calculated pollution parameters, such as the enrichment factor (EF), and ecological risk parameters, such as the ecological risk index (Eri), indicated that the sediment may be toxic to aquatic biota. Furthermore, the microbiological analysis of pond waters indicated a widespread contamination with bacteria such as Escherichia coli, Enterococcus spp., total coliforms, and Pseudomonas spp., probably from anthropogenic and/or animal sources. Therefore, the consumption of Dimba Cave water as a drinking water represents a threat to public health. Urgent management measures should be enforced to protect public health and the cave ecosystem.

Multipathogen quantitative risk assessment in raw milk soft cheese

We propose a multipathogen Quantitative Microbiological Risk Assessment (QMRA) model to estimate the risk of foodborne illness from bacterial pathogens in raw milk soft cheese. Our work extends an existing QMRA model for pathogenic Shiga toxin-producing Escherichia coli (STEC) (Basak et al.,under review; Perrin et al., 2014) by incorporating the effects of Salmonella and Listeria monocytogenes. This multipathogen model integrates microbial contamination of raw milk at the farm level, as well as the growth and survival of these bacteria during cheese fabrication, ripening, and storage. The public health impact of multipathogen risk associated with raw milk cheese consumption is assessed using Disability-Adjusted Life Years (DALYs). The model evaluates intervention strategies at both pre- and post-harvest stages to estimate intervention costs. Furthermore, it tests various scenarios of these strategies and optimizes intervention parameters to minimize multipathogen risk and associated costs. This article discusses challenges in QMRA model validation, emphasizes model limitations, and explores future perspectives for improvement.

Salmonella Prevalence in Raw Cocoa Beans and a Microbiological Risk Assessment to Evaluate the Impact of Cocoa Liquor Processing on the Reduction of Salmonella

Salmonella in raw cocoa beans (n = 870) from main sourcing areas over nine months was analyzed. It was detected in 71 (ca. 8.2%) samples, with a contamination level of 0.3–46 MPN/g except for one sample (4.1 × 104 CFU/g). Using prevalence and concentration data as input, the impact of thermal treatment in cocoa processing on the risk estimate of acquiring salmonellosis by a random Belgian chocolate consumer was calculated by a quantitative microbiological risk assessment (QMRA) approach. A modular process risk model from raw cocoa beans to cocoa liquor up to a hypothetical final product (70–90% dark chocolate tablet) was set up to understand changes in Salmonella concentrations following the production process. Different thermal treatments during bean or nib steam, nib roasting, or liquor sterilization (achieving a 0–6 log reduction of Salmonella) were simulated. Based on the generic FAO/WHO Salmonella dose–response model and the chocolate consumption data in Belgium, salmonellosis risk per serving and cases per year at population level were estimated. When a 5 log reduction of Salmonella was achieved, the estimated mean risk per serving was 3.35 × 10−8 (95% CI: 3.27 × 10−10–1.59 × 10−7), and estimated salmonellosis cases per year (11.7 million population) was 88 (95% CI: <1–418). The estimated mean risk per serving was 3.35 × 10−9 (95% CI: 3.27 × 10−11–1.59 × 10−8), and the estimated salmonellosis cases per year was 9 (95% CI: <1–42), for a 6 log reduction. The current QMRA model solely considered Salmonella reduction in a single-step thermal treatment in the cocoa process. Inactivation obtained during other process steps (e.g. grinding) might occur but was not considered. As the purpose was to use QMRA as a tool to evaluate the log reduction in the cocoa processing, no postcontamination from the processing environment and ingredients was included. A minimum of 5 log reduction of Salmonella in the single-step thermal treatment of cocoa process was considered to be adequate.

Nature-based solutions for antibiotics and antimicrobial resistance removal in tertiary wastewater treatment: Microbiological composition and risk assessment

This field-scale study evaluates the seasonal effectiveness of employing nature-based solutions (NBSs), particularly surface flow and horizontal subsurface flow constructed wetland configurations, as tertiary treatment technologies for the removal of antibiotics (ABs) and antibiotic resistance genes (ARGs) compared to a conventional treatment involving UV and chlorination. Out of the 21 monitored ABs, 13 were detected in the influent of three tertiary wastewater treatments, with concentrations ranging from 2 to 1218 ng·L-1. The ARGs sul1 and dfrA1 exhibited concentrations ranging from 1 × 105 to 9 × 106 copies/100 mL. NBSs were better at reducing ABs (average 69 to 88 %) and ARGs (2–3 log units) compared to the conventional tertiary system (average 36 to 39 % and no removal to 2 log units) in both seasons. Taxonomic compositions in influent water samples shifted from wastewater-impacted communities (Actinomycetota and Firmicutes) to a combination of plant rhizosphere-associated and river communities in NBS effluents (Alphaproteobacteria). In contrast, the conventional technology showed no substantial differences in community composition. Moreover, NBSs substantially reduced the ecotoxicological risk assessment (cumulative RQs). Furthermore, NBSs reduced the ecotoxicological risk (cumulative RQs) by an average of over 70 % across seasons, whereas the benchmark technology only achieved a 6 % reduction. In conclusion, NBSs present a robust alternative for minimizing the discharge of ABs and ARGs into surface water bodies.

Public health aspects of Vibrio spp. related to the consumption of seafood in the EU.

Vibrio parahaemolyticus, Vibrio vulnificus and non-O1/non-O139 Vibrio cholerae are the Vibrio spp. of highest relevance for public health in the EU through seafood consumption. Infection with V. parahaemolyticus is associated with the haemolysins thermostable direct haemolysin (TDH) and TDH-related haemolysin (TRH) and mainly leads to acute gastroenteritis. V. vulnificus infections can lead to sepsis and death in susceptible individuals. V. cholerae non-O1/non-O139 can cause mild gastroenteritis or lead to severe infections, including sepsis, in susceptible individuals. The pooled prevalence estimate in seafood is 19.6% (95% CI 13.7-27.4), 6.1% (95% CI 3.0-11.8) and 4.1% (95% CI 2.4-6.9) for V. parahaemolyticus, V. vulnificus and non-choleragenic V. cholerae, respectively. Approximately one out of five V. parahaemolyticus-positive samples contain pathogenic strains. A large spectrum of antimicrobial resistances, some of which are intrinsic, has been found in vibrios isolated from seafood or food-borne infections in Europe. Genes conferring resistance to medically important antimicrobials and associated with mobile genetic elements are increasingly detected in vibrios. Temperature and salinity are the most relevant drivers for Vibrio abundance in the aquatic environment. It is anticipated that the occurrence and levels of the relevant Vibrio spp. in seafood will increase in response to coastal warming and extreme weather events, especially in low-salinity/brackish waters. While some measures, like high-pressure processing, irradiation or depuration reduce the levels of Vibrio spp. in seafood, maintaining the cold chain is important to prevent their growth. Available risk assessments addressed V. parahaemolyticus in various types of seafood and V. vulnificus in raw oysters and octopus. A quantitative microbiological risk assessment relevant in an EU context would be V. parahaemolyticus in bivalve molluscs (oysters), evaluating the effect of mitigations, especially in a climate change scenario. Knowledge gaps related to Vibrio spp. in seafood and aquatic environments are identified and future research needs are prioritised.

Microbiological Risk Assessment of High-Demand Food from Three Major Cities in Ecuador

The current study was carried out to estimate the risk of disease probability from the consumption of foods such as meats, poultry, unpasteurized cheeses, fruit-based drinks, ready-to-eat fruits, and typical preparations such as Encebollado, ceviche, and Bolón de Verde contaminated with Salmonella, Escherichia coli and Listeria monocytogenes in Ecuador using a quantitative microbiological risk assessment (QMRA). A first-order Monte Carlo simulation probabilistic distribution approach was adopted to assess the occurrence of pathogens in the tested foods. 27 The scenario was simulated using the concentration levels concerning the contaminant and food consumption obtained through an online survey with a sample size of 202 people. A model (100,000 iterations) was run and created in an Excel spreadsheet using @Risk software. The results obtained are the risk of infection (possibilities of becoming infected by eating the food evaluated) and the contaminant dose per portion consumed. Additionally, an exponential model with a single dose was used for risk characterization to determine the probability of becoming ill from contaminated food. The QMRA model performed a prediction for the mean risk of Salmonella infection from ground beef consumption of 1.33 E - 04 log 10 cfu / serving, while the exponential model estimated a value of 1.0 log cfu - serving. In the case of Listeria monocytogenes, the QMRA estimated an average probability of infection in unpasteurized fresh cheese of 5.9E-05 compared to the average disease risk estimated in the risk characterization for L. monocytogenes of 9.50E-13. The QMRA estimated an average risk of infection by E. coli for Encebollado and ceviches of 5.6E -03 compared to the average risk of disease estimated in the risk characterization for Escherichia coli of 0.387 log cfu -ration. These results suggest the need to adopt effective mitigation strategies. Control parameters such as temperature during the supply chain and good hygiene practices during manufacturing can effectively control food-associated pathogens. More data is necessary toimprove the evaluation of the risk developed. Keywords: Microbiological risk análisis, Infectious biological agents (Salmonella, Listeria monocytogenes, Escherichia coli), QMRA (Quantitative Microbial Risk Assessment), Typical foods in Ecuador, Population food consumption in three main cities of Ecuador.

Microbiological Risk Assessment of High-Demand Food from Three Major Cities in Ecuador

The current study was carried out to estimate the risk of disease probability from the consumption of foods such as meats, poultry, unpasteurized cheeses, fruit-based drinks, ready-to-eat fruits, and typical preparations such as Encebollado, ceviche, and Bolón de Verde contaminated with Salmonella, Escherichia coli and Listeria monocytogenes in Ecuador using a quantitative microbiological risk assessment (QMRA). A first-order Monte Carlo simulation probabilistic distribution approach was adopted to assess the occurrence of pathogens in the tested foods. The scenario was simulated using the concentration levels concerning the contaminant and food consumption obtained through an online survey with a sample size of 202 people. A model (100,000 iterations) was run and created in an Excel spreadsheet using @Risk software. The results obtained are the risk of infection (possibilities of becoming infected by eating the food evaluated) and the contaminant dose per portion consumed. Additionally, an exponential model with a single dose was used for risk characterization to determine the probability of becoming ill from contaminated food. The QMRA model performed a prediction for the mean risk of Salmonella infection from ground beef consumption of 1.33 E - 04 log 10 cfu / serving, while the exponential model estimated a value of 1.0 log cfu - serving. In the case of Listeria monocytogenes, the QMRA estimated an average probability of infection in unpasteurized fresh cheese of 5.9E-05 compared to the average disease risk estimated in the risk characterization for L. monocytogenes of 9.50E-13. The QMRA estimated an average risk of infection by E. coli for Encebollado and ceviches of 5.6E -03 compared to the average risk of disease estimated in the risk characterization for Escherichia coli of 0.387 log cfu -ration. These results suggest the need to adopt effective mitigation strategies. Control parameters such as temperature during the supply chain and good hygiene practices during manufacturing can effectively control food-associated pathogens. More data is necessary toimprove the evaluation of the risk developed. Keywords: Microbiological risk análisis, Infectious biological agents (Salmonella, Listeria monocytogenes, Escherichia coli), QMRA (Quantitative Microbial Risk Assessment), Typical foods in Ecuador, Population food consumption in three main cities of Ecuador.

A recipe for safer food: The theory of change underpinning risk analysis in the context of the Codex Alimentarius

Food safety has benefited from systematic approaches to assess and control risks. The paradigm of risk analysis calls for the components of risk assessment and risk management to be bridged and complemented with risk communication, yet still be separate activities. In practical terms, risk assessment and risk management are, in fact, heavily interdependent upon one another. Collectively, risk assessments, risk management and risk communications are tools or processes that deliver specific outputs. For food safety enhancement, these outputs must be translated into outcomes to yield the desired impacts—improved food safety, human health, and livelihoods. The purpose of this paper to illustrate, using the example of listeriosis, how steps in the risk analysis process used by the Codex Alimentarius Commission's, Codex Committee on Food Hygiene (CCFH), of the and the FAO/WHO Joint Expert Meeting on Microbiological Risk Assessment (JEMRA) align with the various components of the theory change, ultimately leading to impacts on food safety, enhanced health and livelihoods on the global scale.

Distribution of SARS-CoV-2 Genomes in Wastewaters and the Associated Potential Infection Risk for Plant Workers in Typical Urban and Peri-Urban Communities of the Buffalo City Region, South Africa.

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 × 103 to 17.60 × 103 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.

Integrating quantitative microbiological risk assessment and disability-adjusted life years to evaluate the effects of urbanization on health risks for river recreationists

Urban rivers provide an excellent opportunity for water recreation. This study probabilistically assessed health risks associated with water recreation in urban rivers in the Bitan Scenic Area, Taiwan, by employing quantitative microbial risk assessment and disability-adjusted life years (DALYs). Moreover, the effects of urbanization on the health risks of river recreation induced by waterborne pathogenic Escherichia coli (E. coli) were investigated. First, data on river E. coli levels were collected in both the Bitan Scenic Area and the upstream river section, and model parameters were obtained through a questionnaire administered to river recreationists. Monte Carlo simulation was then employed to address parameter uncertainty. Finally, DALYs were calculated to quantify the cumulative effects in terms of potential life lost and years lived with disability. The results indicated that the 90 % confidence intervals for the disease burden (DB) were 0.2–74.1 × 10−6, 0.01–94.0 × 10−6, and 0.3–128.9 × 10−6 DALY per person per year (pppy) for canoeing, swimming, and fishing, respectively, in the Bitan Scenic Area. Furthermore, urbanization near the Bitan Scenic Area approximately doubled the DB risks to river recreationists in upstream rural areas. At the 95th percentile, the DB risks exceeded the tolerances recommended by the World Health Organization (1 × 10−6) or U.S. Environmental Protection Agency (1 × 10−4). The findings suggest that the simultaneous implementation of effluent sewer systems and best management practices can reduce health risks to river recreationists by at least half, reducing the DALY levels below 1 × 10−4 or even 1 × 10−5 pppy.

A secondary model for the effect of pH on the variability in growth fitness of Listeria innocua strains

Variability in microbial growth is a keystone of modern Quantitative Microbiological Risk Assessment (QMRA). However, there are still significant knowledge gaps on how to model variability, with the most common assumption being that variability is constant. This is implemented by an error term (with constant variance) added on top of the secondary growth model (for the square root of the growth rate). However, this may go against microbial ecology principles, where differences in growth fitness among bacterial strains would be more prominent in the vicinity of the growth limits than at optimal growth conditions.This study coins the term “secondary models for variability”, evaluating whether they should be considered in QMRA instead of the constant strain variability hypothesis. For this, 21 strains of Listeria innocua were used as case study, estimating their growth rate by the two-fold dilution method at pH between 5 and 10. Estimates of between-strain variability and experimental uncertainty were obtained for each pH using mixed-effects models, showing the lowest variability at optimal growth conditions, increasing towards the growth limits. Nonetheless, the experimental uncertainty also increased towards the extremes, evidencing the need to analyze both sources of variance independently. A secondary model was thus proposed, relating strain variability and pH conditions. Although the modelling approach certainly has some limitations that would need further experimental validation, it is an important step towards improving the description of variability in QMRA, being the first model of this type in the field.

Estimation and evaluation of the risks of protozoa infections associated to the water from a treatment plant in southern Brazil using the Quantitative Microbiological Risk Assessment Methodology (QMRA).

In this study, the Quantitative Microbial Risk Assessment (QMRA) methodology was applied to estimate the annual risk of Giardia and Cryptosporidium infection associated with a water treatment plant in southern Brazil. The efficiency of the treatment plant in removing protozoa and the effectiveness of the Brazilian legislation on microbiological protection were evaluated, emphasizing the relevance of implementing the QMRA in this context. Two distinct approaches were employed to estimate the mechanical removal of protozoa:The definitions provided by the United States Environmental Protection Agency (USEPA), and the model proposed by Neminski and Ongerth.Although the raw water collected had a higher concentration of Giardia cysts than Cryptosporidium oocysts, the estimated values for the annual risk of infection were significantly higher for Cryptosporidium than for Giardia. From a general perspective, the risk values of protozoa infection were either below or very near the limit set by the World Health Organization (WHO). In contrast, all the risk values of Cryptosporidium infection exceeded the threshold established by theUSEPA. Ultimately, it was concluded that the implementation of the QMRA methodology should be considered by the Brazilian authorities, as the requirements and guidelines provided by the Brazilian legislation proved to be insufficient to guarantee the microbiological safety of drinking water. In this context, the QMRA application can effectively contribute to the prevention and investigation of outbreaks of waterborne disease.

Identification of cost-effective biosecurity measures to reduce Salmonella along the pork production chain.

The continued occurrence of salmonellosis cases in Europe attributed to the consumption of pork products highlights the importance of identifying cost-effective interventions. Certain biosecurity measures (BSMs) may be effective in reducing the prevalence of specific pathogens along the pork production chain and their presence in food products. The objective of this study was to identify pathogen-specific, cost-effective BSMs to reduce Salmonella at different stages of the pork production chain in two European countries - Austria (AT) and the United Kingdom (UK). For this purpose, a cost-benefit analysis was conducted based on the epidemiological output of an established quantitative microbiological risk assessment that simulated the implementation effect of the BSMs based on their risk ratios. For each of the BSMs, the associated costs and benefits were assessed individually and country-specifically. For both AT and UK, nine different BSMs were evaluated assuming a countrywide implementation rate of 100%. The results showed that four BSMs were cost-effective (benefit-cost ratio > 1) for AT and five for the UK. The uncertainty regarding the cost-effectiveness of the BSMs resulted from the variability of individual risk ratios, and the variability of benefits associated with the implementation of the BSMs. The low number of cost-effective BSMs highlights the need for holistic risk-based models and economic assessments. To increase the willingness to implement BSMs and maximize the benefits for stakeholders, who carry the majority of the implementation costs, epidemiological assessments of BSM effectiveness should consider the impact on several relevant pathogens simultaneously.

Addition of selected cereal grains as non-dairy ingredients to dairy products: A microbiological risk assessment approach

The addition of cereal grains to dairy products in the dairy industry has the potential to contaminate final products with pathogenic and spoilage microorganisms. In this study, the microbial risks involved in the addition of cereal grains to dairy products with low, intermediate, and high-water activity/moisture content were assessed using a semi-quantitative risk assessment method.The results showed that the most critical microbiological hazard in the selected cereal grains is Bacillus cereus (B. cereus) due to its ability to form spores and persist in cereal grains. The addition of cereal grains to dairy products with high water activity/moisture content such as liquid breakfast products were found to pose the highest theoretical risk, and processing mitigations, such as UHT, would need to be implemented. The results of this study have identified some knowledge gaps in conducting risk assessments and have also provided background information about the microbial risks involved in the addition of cereal grains to dairy products.