Microbial Risk Analysis最新文献

Effects of risk-based control of Campylobacter spp. in Danish broiler farms and flocks were simulated, to assess potential reductions of human risk of campylobacteriosis, associated to the consumption of poultry meat produced in Denmark. Two national data streams were used and represented: Flock status by testing cloacal swabs (CS, 2018–2019) and carcass status by testing leg skin samples (LS, 2019). In the CS surveillance component all flocks slaughtered at the two major Danish slaughterhouses were tested with a polymerase chain reaction (PCR), while in LS one third randomly selected flocks were tested by culture (results in colony forming units per gram, cfu/g). Each farm was identified by its Central Husbandry Register (CHR) number. Two risk farm classification strategies (I-II) were based on CS data from 2018. Farms were classified as: always negative (Neg-CHRs), low risk (LowR-CHRs) and high risk (HighR-CHRs) farms. In strategy I, HighR-CHRs had more than five positive flocks, while in strategy II; they had more than 27.8% of the slaughtered flocks positive. Those two cut-offs were the annual 3^rd quartiles across positive farms. Thereafter, a risk assessment model was used to estimate the annual relative risk (RR) of human campylobacteriosis in 2019, compared to that of 2013. Three hypothetical levels of cfu/g reductions (A, B and C) were simulated on the LS positive flocks (> 10 cfu/g) slaughtered by HighR-CHRs and were pairwise combined with the two classification strategies, yielding six risk-mitigation scenarios (A I-II; B I-II; C I-II). In scenarios A I-II, zero cfu/g were simulated, while in scenarios B and C, the original cfu/g were divided by three and by two. For each scenario, RRs were compared to the RR of the original cfu/g (scenario O).

In 2018, if all flocks from HighR-CHRs had been negative, the annual CS flock prevalence would have reduced from 19.7% to 7.6% (strategy I) or 9.6% (strategy II). Whereas in 2019, it would have reduced from 17.1% to 7.8% or 11.6%. In both years, HighR-CHRs delivered a high percentage of the total annual positive flocks (61.4–54.4% under strategy I and 51.2–32.6% with strategy II). In 2019, if HighR-CHRs had delivered only LS negative flocks, the RR would have reduced from 0.94 (scenario “O”) to 0.51 (A-I). Other scenarios showed smaller RR reductions. Targeting high risk farms/flocks for intensive control could improve One Health-ness of national action plans against Campylobacter spp.

Quantitative microbiological risk assessment (QMRA) studies have suggested that control options to reduce the concentration of Campylobacter spp. in broiler chicken caeca may be highly effective at reducing the risk of human campylobacteriosis. These QMRA studies have been updated based on scientific evidence obtained in the past decade. The relationship between Campylobacter concentrations in the caeca and on broiler skins after industrial processing was modelled by means of linear regression and combined with a number of consumer phase models (CPM) and dose-response (DR) models. The reduction of caecal Campylobacter concentration as reported for selected feed additives and vaccines, was used to estimate the relative risk reduction expressed as the percentage decrease in human campylobacteriosis cases in the EU associated with consumption of broiler meat. The model outputs suggest that the effectiveness of these control options are less pronounced than previously indicated. For example, the median estimate for the relative risk reduction obtained through a 2 log₁₀ reduction in caecal concentrations was 39% (95% CI 9–73%), whereas previous estimates were between 76 and 98%. The main reason for this finding is that recent studies show lower values for the slope of the regression line; the impact of using newly published DR models and CPMs is smaller. Still, the uncertainty associated to the estimated effects is large, mainly due to uncertainty about the slope of the regression line. Additionally, data on the effectiveness of vaccination and the application of feed and water additives obtained under field conditions are scarce, but they are a prerequisite to assess the risk reduction that may be achieved by these control options when applied in practice.

The transmission of antimicrobial resistance (AMR) between animals, their environment, food and humans is a complex issue. Previous pharmacokinetic-pharmacodynamic (PKPD) models indicate that extended-spectrum β-lactamase (ESBL) resistant bacterial populations may be self-sustaining through horizontal and vertical gene transfer, even in the absence of antimicrobial pressure. However, models focusing purely on the biochemical aspects fail to incorporate the complicated host population dynamics which occur within a farm environment. Models of disease transmission within commercial farm environments can provide further insight to the on-farm transmission dynamics of AMR between animals and their environment, as well as predict the effect of various on-farm interventions. Here, we present a risk assessment which predicts the likelihood that slaughter-aged pigs would carry resistant bacteria after a single introduction of ESBL E. coli on commercial pig farms. We incorporate outputs from a PKPD model which explores the complex host/gastrointestinal bacteria interplay after antimicrobial treatment; with an on-farm model of bacterial transmission. The risk assessment is designed to be adaptable for the simultaneous transmission of multiple bacteria and resistant strains. We predicted that after introduction onto a pig farm, ESBL E. coli bacteria are likely to persist on the farm for more than a year, leading to a high batch prevalence (39.4% slaughter pigs, 5th and 95th percentiles: 0.0–57.5) and high faecal shedding. A comparison of different farm management types suggested that all-in-all-out housing was a protective measure for both prevalence in slaughter-aged pigs and faecal shedding rates. We applied two main interventions at the farm level, an enhanced cleaning and disinfectant (C&D) protocol and isolation of pigs in sick pens for the duration of their antibiotic treatment. Both interventions were able to reduce the number of pigs shedding more than 2 log₁₀ ESBL E. coli from 18.7% (5th and 95th percentiles: 5.9–30.4) in the baseline scenario, to 7.2% (5th and 95th percentiles: 0.0–21.5) when an enhanced C&D protocol was applied, 0.1% (5th and 95th percentiles: 0.0–0.3) when sick pens were used and 0.1% (5th and 95th percentiles: 0.0–0.3) when a combination of enhanced C&D plus sick pens was used. Both scenarios also reduced the prevalence in batches of pigs going to slaughter. This effect was largest when sick pens were used, where 75% of batches had 0% positive pigs. The results suggest that a single introductory event is sufficient to cause a substantial risk of carriage in slaughter-aged pigs. Further quantitative microbial risk assessments (QMRA) are needed to consider the onwards risk posed to later parts of the food chain.

Combined sewer overflows (CSOs) are known contributors of human fecal pollution in urban waterways. Exposure to these waterways occurs during recreational activities, including swimming, wading, and fishing. This study used quantitative microbial risk assessment (QMRA) to estimate the risk of acute gastrointestinal illness (AGI) due to recreation during CSO-impacted (< 24 h after a CSO) and non-impacted (> 24 h after a CSO) conditions. Water samples (n = 69) were collected from two creeks and one river in Philadelphia from June–August 2017–2019. HF183 concentrations were measured to estimate concentrations of five reference pathogens: Cryptosporidium, Giardia, norovirus, E. coli O157:H7, and Salmonella. Observational data on the types and frequency of recreational exposures were also collected. Results found that recreating < 24 h after a CSO increased AGI risk by 39–75%, compared to recreating > 24 h after a CSO. However, estimated health risks were still high for some exposure scenarios that occurred > 24 h after a CSO. Crudes estimates determined that recreational activities along known CSO-impacted sites may account for 1–8% of all cases of salmonellosis, cryptosporidiosis, and giardiasis in the city of Philadelphia. Findings support risk reduction strategies that aim to reduce the frequency of CSOs in urban settings and may help target risk mitigation strategies.

Effective measures to reduce the risk of coronavirus disease 2019 (COVID-19) infection in overseas travelers are urgently needed. However, the effectiveness of current testing and isolation protocols is not yet fully understood. Here, we examined how the timing of testing and the number of tests conducted affect the spread of COVID-19 infection associated with airplane travel. We used two mathematical models of infectious disease dynamics to examine how different test protocols changed the density of infected individuals traveling by airplane and entering another country. We found that the timing of testing markedly affected the spread of COVID-19 infection. A single test conducted on the day before departure was the most effective at reducing the density of infected individuals travelling; this effectiveness decreased with increasing time before departure. After arrival, immediate testing was found to overlook individuals infected on the airplane. With respect to preventing infected individuals from entering the destination country, isolation with a single test on day 7 or 8 after arrival was comparable with isolation only for 11 or 14 days, respectively, depending on the model used, indicating that isolation length can be shortened with appropriately timed testing.

In the consumer goods sector, there is a rapid increase in launches of products that affect the human microbiome. Whilst more and more studies and product claims focus on the health benefits of the manipulation of microbiomes, ensuring that perturbations of the microbiome by the application of beauty and personal care products do not have potential unwanted consequences on the health of consumers is less well described in the scientific literature. There is currently no agreement on approaches to assess the possible impacts on consumer safety nor quantitatively defined endpoints of concern. We propose a 3-tier framework to qualitatively assess the potential impact of skin and oral microbiome perturbations on consumer health. The framework is established in accordance with the next generation risk assessment principles used in toxicology and avoids the use of animal testing. It was developed using a collaborative consultation including oral and skin microbiome experts, bioinformaticians and microbiological risk assessors. The first tier is based on a “history of safe use” concept, where the efficacy of a bioactive of interest is benchmarked against formulations generally regarded as safe because of their long history of consumer use. One of the endpoints identified during the development of the approach is that the microbiome's resilience is not compromised, that is its capacity to respond to challenges without going to dysbiosis. Therefore, the second tier is based on the notion of microbiome stability and its resilience to short term perturbations. The third tier aims to utilise next generation sequencing data and relate these to health status. Whilst 16S rRNA data have brought unprecedented resolution in determining the species present in microbiomes, we illustrate the challenges associated with predicting potential consequences for consumer health and disease from this type of data in a case study. With the development of whole genome sequencing technology and progress with integration of -omics data, we propose that the active functions of the microbiome rather than taxonomic classification should be the basis of a safety assessment. We suggest a research strategy to define the potential endpoints of concern quantitatively, based on a concomitant development of in vitro 3D tissue models in which the host response can be assessed, in silico approaches to describe the microbiome and longitudinal human studies to validate learnings in situ.

Lumpy skin disease (LSD) is a transboundary disease affecting bovine animals, which may result in severe economic implications. Ukraine is considered particularly vulnerable to LSD due to its proximity to regions where the virus is circulating. In addition, its ecological and environmental parameters can sustain, in summer, the spread of the disease in case it entered the country.

This qualitative risk assessment aimed to investigate the probability that LSD virus is introduced to Ukraine and, if introduced, what would be the probability of onward transmission in the country within the next year. The risk assessment followed the OIE import risk analysis for animals and animal products guidelines and was undertaken with the support of local experts via an expert elicitation workshop. A modified Delphi approach was used to gather experts inputs.

The illegally traded cattle was the pathway considered to have the highest probability of LSD introduction; however the probability was estimated to be low. When assessing the probability of an animal being exposed to the virus and further onward transmission in Ukraine, the highest probability estimate was related to flying vectors (high probability). During the expert opinion workshop, the Delphi approach helped to increase the agreement between experts and to assess the uncertainty related to some of the probability estimates.

Throughout the risk assessment, some data gaps were identified and highlighted. The lack of reliable data on animal movements and biosecurity in Ukraine were emphasized. Based on the elicited probability estimates, the local experts generated recommendations for risk management practices. To our knowledge, this is the first risk assessment performed on LSDV in Eastern Europe and the conceptual framework adopted can help other countries willing to do a risk assessment in a similar data scarce environment.

Populations in Arctic Canada are strongly connected to, and draw sustenance from, the physical environment. Recreation and food harvesting locations, however, may be impacted by the basic wastewater treatment and disposal processes used in the region. Within these mixed socio-ecological systems, people may unknowingly be exposed to wastewater pathogens, either by direct contact or indirectly through activities resulting in exposure to contaminated locally harvested food. The objectives of this research are to estimate microbial health risks attributable to wastewater effluent exposure in Arctic Canada and evaluate potential mitigation options. A participatory quantitative microbial risk assessment (QMRA) approach was used. Specifically, community knowledge and information describing human activity patterns in wastewater-impacted environments was used with microbial water quality data to model a range of exposure scenarios and risk mitigation options. In several exposure scenario results, estimated individual annual risk of acute gastrointestinal illness exceeds a proposed tolerable target of 10⁻³. These scenarios include shore recreation and consumption of shellfish harvested near primary mechanical treatment plants at low tide, as well as travel in wetland portions of passive treatment sites during spring freshet. These results suggest that wastewater effluent exposures may be contributing to gastrointestinal illness in some Arctic communities. Mitigation strategies, including improved treatment and interventions aimed at deterring access to disposal areas reduce risk estimates across scenarios to varying degrees. Overall, well-designed passive systems appear to be the most effective wastewater treatment option for Arctic Canada in terms of limiting and managing associated microbial health risks. This research demonstrates a novel application of QMRA and provides science-based evidence to support public health, water, and sanitation decisions and investment in Arctic regions.

To bridge the data gap on food poisoning caused by coagulase-positive staphylococci (CoPS), especially related to mayonnaise sauce served at Algerian pizzerias, this study aimed to assess the concentration of CoPS in mayonnaise and the probability of exceeding a critical concentration of ≥ 5 log CFU/g. The city of Ain Témouchent in West Algeria was taken as a case study.

A probabilistic assessment model was built, taking into account the initial contamination in freshly made mayonnaise and the potential growth before serving. Uncertainty and variability were integrated separately in the model. Uncertainty came from lack of data and model fitting error, variability from natural heterogeneity of biological materials (e.g., microbial strains) and temperature during cold storage.

The second-order Monte Carlo procedure was implemented in R using the mc2d package. The following pieces of data were generated to populate the model: CoPS were enumerated and characterized from 57 samples of mayonnaise served at pizzeria in Ain Témouchent city; challenge tests at 23 °C were performed in mayonnaise using three CoPS isolates. The following existing data were also gathered: meteorological data from Ain Témouchent were analysed to build a realistic scenario of storage, while a set of 43 and 35 values of the minimal and maximal growth limits of CoPS, respectively, were collected from the literature and analysed to inform a secondary predictive model describing the growth rate at various storage temperature conditions. A sensitivity analysis was performed to facilitate the interpretation of the results.

The results revealed a CoPS prevalence in freshly made mayonnaise of 25% [15%; 37%] with concentrations varying from 0.4 [0.3; 0.9] to 2.9 [2.4; 3.0] log CFU/g. The growth rates at 23 °C, based on challenge tests in mayonnaise, had a median value estimated to be 1.41 [1.17; 1.65] h ^− 1.

Concentration levels according to various scenarios of temperature and serving conditions were calculated. For instance, the median contamination of CoPS in mayonnaise after storage in a refrigerated display counter for 14 h during the hottest months of the year was estimated to be zero. However, the 95th percentile was estimated to be 3.6 [2.9; 4.2] log CFU/g. In this scenario, the probability of exceeding a critical concentration of ≥ 5 log CFU/g was estimated to be 1% [0.3%; 2%], which is low but not negligible.

These findings could be used to improve food safety policies and develop a risk management strategy to reduce the food poisoning associated with the consumption of ready-to-use foods in Algerian fast food restaurants.

In food processing, it is essential to guarantee the safety of microbial hazards. Microorganisms exist, transit and continuously grow along the food processing with hybrid evolutionary characteristics and uncertainties. Thus, a particular risk assessment is essential to effectively predict and evaluate the risk of microbial hazards in food processing. For such a purpose, we propose a comprehensive dynamic risk assessment approach based on a stochastic hybrid system (SHS). First, we formulate a dynamic evolution of microorganisms in food processing according to the SHS model. Second, we employ a Monte Carlo simulation to obtain the probability density functions of process characteristic information for microorganisms during processing. Additionally, we design a novel risk indicator of “hazard degree” to quantify the potential risks of microorganisms based on this process information. Finally, we present a case study of wheat flour processing to estimate the risk of mixed mildew on the basis of the SHS approach. Experimental results show that the proposed approach is feasible in modeling the hybrid evolution and handling uncertainties in predictions of microbial hazards. This study should prove to be a valuable reference to ensure food safety for risk management and decision-making departments.