Impacts of climate change on the microbial safety of pre-harvest leafy green vegetables as indicated by Escherichia coli O157 and Salmonella spp

Prevalence of STEC virulence markers and Salmonella as a function of abiotic factors in agricultural water in the southeastern United States

Fresh produce can be contaminated by enteric pathogens throughout crop production, including through contact with contaminated agricultural water. The most common outbreaks and recalls in fresh produce are due to contamination by Salmonella enterica and Shiga toxin-producing E. coli (STEC). Thus, the objectives of this study were to investigate the prevalence of markers for STEC (wzy, hly, fliC, eaeA, rfbE, stx-I, stx-II) and Salmonella (invA) in surface water sources (n = 8) from produce farms in Southwest Georgia and to determine correlations among the prevalence of virulence markers for STEC, water nutrient profile, and environmental factors. Water samples (500 mL) from eight irrigation ponds were collected from February to December 2021 (n = 88). Polymerase chain reaction (PCR) was used to screen for Salmonella and STEC genes, and Salmonella samples were confirmed by culture-based methods. Positive samples for Salmonella were further serotyped. Particularly, Salmonella was detected in 6/88 (6.81%) water samples from all ponds, and the following 4 serotypes were detected: Saintpaul 3/6 (50%), Montevideo 1/6 (16.66%), Mississippi 1/6 (16.66%), and Bareilly 1/6 (16.66%). Salmonella isolates were only found in the summer months (May-Aug.). The most prevalent STEC genes were hly 77/88 (87.50%) and stx-I 75/88 (85.22%), followed by fliC 54/88 (61.63%), stx-II 41/88 (46.59%), rfbE 31/88 (35.22%), and eaeA 28/88 (31.81%). The wzy gene was not detected in any of the samples. Based on a logistic regression analysis, the odds of codetection for STEC virulence markers (stx-I, stx-II, and eaeA) were negatively correlated with calcium and relative humidity (p < 0.05). A conditional forest analysis was performed to assess predictive performance (AUC = 0.921), and the top predictors included humidity, nitrate, calcium, and solar radiation. Overall, information from this research adds to a growing body of knowledge regarding the risk that surface water sources pose to produce grown in subtropical environmental conditions and emphasizes the importance of understanding the use of abiotic factors as a holistic approach to understanding the microbial quality of water.

Consideration of nutrition and sustainability in public definitions of 'healthy' food: an analysis of submissions to the US FDA

OBJECTIVE

To better understand how the public defines 'healthy' foods and to determine whether the public considers sustainability, implicitly and explicitly, in the context of healthy eating.

DESIGN

We conducted a content analysis of public comments submitted to the US FDA in 2016 and 2017 in response to an invitation for feedback on use of the term 'healthy' on food labels. The analysis explored the ways in which commenters' definitions of 'healthy' aligned with the 2015-2020 Dietary Guidelines for Americans and whether their definitions considered sustainability.

SETTING

The US Government's Regulations.gov website.

PARTICIPANTS

All 1125 unique comments from individuals and organisations.

RESULTS

Commenters' definitions of 'healthy' generally mirrored the recommendations that the Dietary Guidelines for Americans put forth to promote a 'healthy eating pattern'. Commenters emphasised the healthfulness of fruit, vegetables, whole grains, fish and other minimally processed foods and the need to limit added sugars, sodium, saturated and trans fats and other ingredients sometimes added during processing. One-third of comments (n 374) incorporated at least one dimension of sustainability, mainly the environmental dimension. Commenters who mentioned environmental considerations primarily expressed concerns about synthetic chemicals and genetic modification. Less than 20 % of comments discussed social or economic dimensions of sustainability, and less than 3 % of comments (n 30) used the word 'sustainability' explicitly.

CONCLUSIONS

This novel analysis provides new information about the public's perceptions of 'healthy' foods relative to nutrition and sustainability considerations. The findings can be used to advance policy discussions regarding nutrition labelling and guidance.

Biocontrol of Escherichia coli O157:H7 by Enterobacter asburiae AEB30 on intact cantaloupe melons

Escherichia coli O157:H7 causes >73,000 foodborne illnesses in the United States annually, many of which have been associated with fresh ready-to-eat produce including cantaloupe melons. In this study, we created a produce-associated bacterial (PAB) library containing >7500 isolates and screened them for the ability to inhibit the growth of E. coli O157:H7 using an in vitro fluorescence-based growth assay. One isolate, identified by 16S and whole-genome sequence analysis as Enterobacter asburiae, was able to inhibit the growth of E. coli by ~30-fold in vitro and produced zones of inhibition between 13 and 21 mm against 12 E. coli outbreak strains in an agar spot assay. We demonstrated that E. asburiae AEB30 was able to grow, persist and inhibit the growth of E. coli on cantaloupe melons under simulated pre- and post-harvest conditions. Analysis of the E. asburiae AEB30 genome revealed an operon encoding a contact-dependent growth inhibition (CDI) system that when mutated resulted in the loss of E. coli growth inhibition. These data suggest that E. asburiae AEB30 is a potential biocontrol agent to prevent E. coli contamination of cantaloupe melons in both pre- and post-harvest environments and that its mode of action is via a CDI system.

Population dynamics of Listeria spp., Salmonella spp., and Escherichia coli on fresh produce: A scoping review

Collation of the current scope of literature related to population dynamics (i.e., growth, die-off, survival) of foodborne pathogens on fresh produce can aid in informing future research directions and help stakeholders identify relevant research literature. A scoping review was conducted to gather and synthesize literature that investigates population dynamics of pathogenic and non-pathogenic Listeria spp., Salmonella spp., and Escherichia coli on whole unprocessed fresh produce (defined as produce not having undergone chopping, cutting, homogenization, irradiation, or pasteurization). Literature sources were identified using an exhaustive search of research and industry reports published prior to September 23, 2021, followed by screening for relevance based on strict, a priori eligibility criteria. A total of 277 studies that met all eligibility criteria were subjected to an in-depth qualitative review of various factors (e.g., produce commodities, study settings, inoculation methodologies) that affect population dynamics. Included studies represent investigations of population dynamics on produce before (i.e., pre-harvest; n = 143) and after (i.e., post-harvest; n = 144) harvest. Several knowledge gaps were identified, including the limited representation of (i) pre-harvest studies that investigated population dynamics of Listeria spp. on produce (n = 13, 9% of pre-harvest studies), (ii) pre-harvest studies that were carried out on non-sprouts produce types grown using hydroponic cultivation practices (n = 7, 5% of pre-harvest studies), and (iii) post-harvest studies that reported the relative humidity conditions under which experiments were carried out (n = 56, 39% of post-harvest studies). These and other knowledge gaps summarized in this scoping review represent areas of research that can be investigated in future studies.

Multi-laboratory validation study of a real-time PCR method for detection of Salmonella in baby spinach

The FDA Bacteriological Analytical Manual (BAM) Salmonella culture method takes at least 3 days for a presumptive positive result. The FDA developed a quantitative PCR (qPCR) method to detect Salmonella from 24-h preenriched cultures, using ABI 7500 PCR system. The qPCR method has been evaluated as a rapid screening method for a broad range of foods by single laboratory validation (SLV) studies. The present multi-laboratory validation (MLV) study was aimed to measure the reproducibility of this qPCR method and compare its performance with the culture method. Sixteen laboratories participated in two rounds of MLV study to analyze twenty-four blind-coded baby spinach test portions each. The first round yielded ∼84% and ∼82% positive rates across laboratories for the qPCR and culture methods, respectively, which were both outside the fractional range (25%-75%) required for fractionally inoculated test portions by the FDA's Microbiological Method Validation Guidelines. The second round yielded ∼68% and ∼67% positive rates. The relative level of detection (RLOD) for the second-round study was 0.969, suggesting that qPCR and culture methods had similar sensitivity (p > 0.05). The study demonstrated that the qPCR yields reproducible results and is sufficiently sensitive and specific for the detection of Salmonella in food.

Predictive Population Dynamics of Escherichia coli O157:H7 and Salmonella enterica on Plants: a Mechanistic Mathematical Model Based on Weather Parameters and Bacterial State

Weather affects key aspects of bacterial behavior on plants but has not been extensively investigated as a tool to assess risk of crop contamination with human foodborne pathogens. A novel mechanistic model informed by weather factors and bacterial state was developed to predict population dynamics on leafy vegetables and tested against published data tracking Escherichia coli O157:H7 (EcO157) and Salmonella enterica populations on lettuce and cilantro plants. The model utilizes temperature, radiation, and dew point depression to characterize pathogen growth and decay rates. Additionally, the model incorporates the population level effect of bacterial physiological state dynamics in the phyllosphere in terms of the duration and frequency of specific weather parameters. The model accurately predicted EcO157 and S. enterica population sizes on lettuce and cilantro leaves in the laboratory under various conditions of temperature, relative humidity, light intensity, and cycles of leaf wetness and dryness. Importantly, the model successfully predicted EcO157 population dynamics on 4-week-old romaine lettuce plants under variable weather conditions in nearly all field trials. Prediction of initial EcO157 population decay rates after inoculation of 6-week-old romaine plants in the same field study was better than that of long-term survival. This suggests that future augmentation of the model should consider plant age and species morphology by including additional physical parameters. Our results highlight the potential of a comprehensive weather-based model in predicting contamination risk in the field. Such a modeling approach would additionally be valuable for timing field sampling in quality control to ensure the microbial safety of produce. IMPORTANCE Fruits and vegetables are important sources of foodborne disease. Novel approaches to improve the microbial safety of produce are greatly lacking. Given that bacterial behavior on plant surfaces is highly dependent on weather factors, risk assessment informed by meteorological data may be an effective tool to integrate into strategies to prevent crop contamination. A mathematical model was developed to predict the population trends of pathogenic E. coli and S. enterica, two major causal agents of foodborne disease associated with produce, on leaves. Our model is based on weather parameters and rates of switching between the active (growing) and inactive (nongrowing) bacterial state resulting from prevailing environmental conditions on leaf surfaces. We demonstrate that the model has the ability to accurately predict dynamics of enteric pathogens on leaves and, notably, sizes of populations of pathogenic E. coli over time after inoculation onto the leaves of young lettuce plants in the field.

Bacteriophages for the Targeted Control of Foodborne Pathogens

Foodborne illness is exacerbated by novel and emerging pathotypes, persistent contamination, antimicrobial resistance, an ever-changing environment, and the complexity of food production systems. Sporadic and outbreak events of common foodborne pathogens like Shiga toxigenic E. coli (STEC), Salmonella, Campylobacter, and Listeria monocytogenes are increasingly identified. Methods of controlling human infections linked with food products are essential to improve food safety and public health and to avoid economic losses associated with contaminated food product recalls and litigations. Bacteriophages (phages) are an attractive additional weapon in the ongoing search for preventative measures to improve food safety and public health. However, like all other antimicrobial interventions that are being employed in food production systems, phages are not a panacea to all food safety challenges. Therefore, while phage-based biocontrol can be promising in combating foodborne pathogens, their antibacterial spectrum is generally narrower than most antibiotics. The emergence of phage-insensitive single-cell variants and the formulation of effective cocktails are some of the challenges faced by phage-based biocontrol methods. This review examines phage-based applications at critical control points in food production systems with an emphasis on when and where they can be successfully applied at production and processing levels. Shortcomings associated with phage-based control measures are outlined together with strategies that can be applied to improve phage utility for current and future applications in food safety.

Comprehensive Dynamic Influence of Multiple Meteorological Factors on the Detection Rate of Bacterial Foodborne Diseases under Spatio-Temporal Heterogeneity

Foodborne diseases are a critical public health problem worldwide and significantly impact human health, economic losses, and social dynamics. Understanding the dynamic relationship between the detection rate of bacterial foodborne diseases and a variety of meteorological factors is crucial for predicting outbreaks of bacterial foodborne diseases. This study analyzed the spatio-temporal patterns of vibriosis in Zhejiang Province from 2014 to 2018 at regional and weekly scales, investigating the dynamic effects of various meteorological factors. Vibriosis had a significant temporal and spatial pattern of aggregation, and a high incidence period occurred in the summer seasons from June to August. The detection rate of Vibrio parahaemolyticus in foodborne diseases was relatively high in the eastern coastal areas and northwestern Zhejiang Plain. Meteorological factors had lagging effects on the detection rate of V. parahaemolyticus (3 weeks for temperature, 8 weeks for relative humidity, 8 weeks for precipitation, and 2 weeks for sunlight hours), and the lag period varied in different spatial agglomeration regions. Therefore, disease control departments should launch vibriosis prevention and response programs that are two to eight weeks in advance of the current climate characteristics at different spatio-temporal clustering regions.

Uncovering the Research Gaps to Alleviate the Negative Impacts of Climate Change on Food Security: A Review

Climatic variability has been acquiring an extensive consideration due to its widespread ability to impact food production and livelihoods. Climate change has the potential to intersperse global approaches in alleviating hunger and undernutrition. It is hypothesized that climate shifts bring substantial negative impacts on food production systems, thereby intimidating food security. Vast developments have been made addressing the global climate change, undernourishment, and hunger for the last few decades, partly due to the increase in food productivity through augmented agricultural managements. However, the growing population has increased the demand for food, putting pressure on food systems. Moreover, the potential climate change impacts are still unclear more obviously at the regional scales. Climate change is expected to boost food insecurity challenges in areas already vulnerable to climate change. Human-induced climate change is expected to impact food quality, quantity, and potentiality to dispense it equitably. Global capabilities to ascertain the food security and nutritional reasonableness facing expeditious shifts in biophysical conditions are likely to be the main factors determining the level of global disease incidence. It can be apprehended that all food security components (mainly food access and utilization) likely be under indirect effect via pledged impacts on ménage, incomes, and damages to health. The corroboration supports the dire need for huge focused investments in mitigation and adaptation measures to have sustainable, climate-smart, eco-friendly, and climate stress resilient food production systems. In this paper, we discussed the foremost pathways of how climate change impacts our food production systems as well as the social, and economic factors that in the mastery of unbiased food distribution. Likewise, we analyze the research gaps and biases about climate change and food security. Climate change is often responsible for food insecurity issues, not focusing on the fact that food production systems have magnified the climate change process. Provided the critical threats to food security, the focus needs to be shifted to an implementation oriented-agenda to potentially cope with current challenges. Therefore, this review seeks to have a more unprejudiced view and thus interpret the fusion association between climate change and food security by imperatively scrutinizing all factors.

Effect of Temperature and Rainfall on Sporadic Salmonellosis Notifications in Melbourne, Australia 2000-2019: A Time-Series Analysis

Weather can impact infectious disease transmission, particularly for heat-sensitive pathogens, such as Salmonella. We conducted an ecological time-series analysis to estimate short-term associations between nonoutbreak-related notifications of Salmonella and weather conditions-temperature and rainfall-in Melbourne, Australia from 2000 to 2019. Distributed lag nonlinear models were created to analyze weather-salmonellosis associations and potential lag times on a weekly time scale, controlling for seasonality and long-term trends. Warmer temperatures were associated with increased risk of notification. Effects were temporally lagged, with the highest associations observed for warm temperatures 2-6 (greatest at 4) weeks before notification. The overall estimated relative risk of salmonellosis increased twofold at 33°C compared to the average weekly temperature (20.35°C) for the 8-week period preceding the disease notification. For Salmonella Typhimurium alone, this occurred at temperatures over 32°C. There were no statistically significant associations with rainfall and notification rates in any of the analyses performed. This study demonstrates the short-term influences of warm temperatures on Salmonella infections in Melbourne over a 20-year period. Salmonelloses are already the second most notified gastrointestinal diseases in Victoria, and these findings suggest that notifications may increase with increasing temperatures. This evidence contributes to previous findings that indicate concerns for public health with continued warm weather.

Associations between ambient temperature and enteric infections by pathogen: a systematic review and meta-analysis

BACKGROUND

Numerous studies have quantified the associations between ambient temperature and enteric infections, particularly all-cause enteric infections. However, the temperature sensitivity of enteric infections might be pathogen dependent. Here, we sought to identify pathogen-specific associations between ambient temperature and enteric infections.

METHODS

We did a systematic review and meta-analysis by searching PubMed, Web of Science, and Scopus for peer-reviewed research articles published from Jan 1, 2000, to Dec 31, 2019, and also hand searched reference lists of included articles and excluded reviews. We included studies that quantified the effects of ambient temperature increases on common pathogen-specific enteric infections in humans. We excluded studies that expressed ambient temperature as a categorical or diurnal range, or in a standardised format. Two authors screened the search results, one author extracted data from eligible studies, and four authors verified the data. We obtained the overall risks by pooling the relative risks of enteric infection by pathogen for each 1°C temperature rise using random-effects modelling and robust variance estimation for the correlated effect estimates. Between-study heterogeneity was measured using I², τ², and Q-statistic. Publication bias was determined using funnel plot asymmetry and the trim-and-fill method. Differences among pathogen-specific pooled estimates were determined using subgroup analysis of taxa-specific meta-analysis. The study protocol was not registered but followed the PRISMA guidelines.

FINDINGS

We identified 2981 articles via database searches and 57 articles from scanning reference lists of excluded reviews and included articles, of which 40 were eligible for pathogen-specific meta-analyses. The overall increased risks of incidence per 1°C temperature rise, expressed as relative risks, were 1·05 (95% CI 1·04-1·07; I² 97%) for salmonellosis, 1·07 (1·04-1·10; I² 99%) for shigellosis, 1·02 (1·01-1·04; I² 98%) for campylobacteriosis, 1·05 (1·04-1·07; I² 36%) for cholera, 1·04 (1·01-1·07; I² 98%) for Escherichia coli enteritis, and 1·15 (1·07-1·24; I² 0%) for typhoid. Reduced risks per 1°C temperature increase were 0·96 (95% CI 0·90-1·02; I² 97%) for rotaviral enteritis and 0·89 (0·81-0·99; I² 96%) for noroviral enteritis. There was evidence of between-pathogen differences in risk for bacterial infections but not for viral infections.

INTERPRETATION

Temperature sensitivity of enteric infections can vary according to the enteropathogen causing the infection, particularly for bacteria. Thus, we encourage a pathogen-specific health adaptation approach, such as vaccination, given the possibility of increasingly warm temperatures in the future.

FUNDING

Japan Society for the Promotion of Science (Kakenhi) Grant-in-Aid for Scientific Research.

Coupled Effects of Pore Water Velocity and Soil Heterogeneity on Bacterial Transport: Intact vs. Repacked Soils

Transport of pathogenic bacteria from land surface to groundwater is largely influenced by rainfall intensity and geochemical and structural heterogeneities of subsurface sediments at different depths. It has been assumed that the change in rainfall intensity has different effects on bacterial transport as a function of soil depth. In this study, repacked and intact column systems were used to investigate the influences of pore water velocity on the transport of Escherichia coli 652T7 through a loamy soil collected from varying soil depths. The soils differed in geochemical properties and soil structures. The concentrations of bacteria in soil and liquid samples were measured using plate counting method. The breakthrough percentages of E. coli 652T7 increased with pore water velocity at each depth in both intact and disturbed soils. Among the different soil depths, the largest velocity effect was observed for the transport through the top soil (0-5 cm) of both disturbed and intact soil profiles. This depth-dependent effect of pore water velocity was attributed to down gradients of soil organic matter (SOM) and iron oxide contents with depth because SOM and iron oxides were favorable for bacterial attachment on soil surfaces. In addition, less bacteria broke through the disturbed soil than through the intact soil at the same depth, and the pore water velocity effect was stronger with the disturbed than intact soils. Specifically, the maximum C/C0 (i.e., ratio of effluent to influent concentration) doubled (i.e., from 0.36 to 0.76) in the 0-5 cm intact soil columns and tripled (i.e., from 0.16 to 0.43) in the 0-5 cm repacked soil columns. This structure-dependent effect of pore water velocity was attributed to larger pore tortuosity and a narrower range of pore sizes in the disturbed soil than in the intact soil. These findings suggest that change in pore water velocity could trigger bacterial remobilization especially in surface soils, where more bacteria are retained relative to deep soils.

Climate Change and Emerging Food Safety Issues: A Review

ABSTRACT

Throughout the past decades, climate change has been one of the most complex global issues. Characterized by worldwide alterations in weather patterns, along with a concomitant increase in the temperature of the Earth, climate change will undoubtedly have significant effects on food security and food safety. Climate change engenders climate variability: significant variations in weather variables and their frequency. Both climate variability and climate change are thought to threaten the safety of the food supply chain through different pathways. One such pathway is the ability to exacerbate foodborne diseases by influencing the occurrence, persistence, virulence and, in some cases, toxicity of certain groups of disease-causing microorganisms. Food safety can also be compromised by various chemical hazards, such as pesticides, mycotoxins, and heavy metals. With changes in weather patterns, such as lower rainfall, higher air temperature, and higher frequency of extreme weather events among others, this translates to emerging food safety concerns. These include the shortage of safe water for irrigation of agricultural produce, greater use of pesticides due to pest resistance, increased difficulty in achieving a well-controlled cold chain resulting in temperature abuse, or the occurrence of flash floods, which cause runoff of chemical contaminants in natural water courses. Together, these can result in foodborne infection, intoxication, antimicrobial resistance, and long-term bioaccumulation of chemicals and heavy metals in the human body. Furthermore, severe climate variability can result in extreme weather events and natural calamities, which directly or indirectly impair food safety. This review discusses the causes and impacts of climate change and variability on existing and emerging food safety risks and also considers mitigation and adaptation strategies to address the global warming and climate change problem.

HIGHLIGHTS

Isolation of Ciprofloxacin and Ceftazidime-Resistant Enterobacterales From Vegetables and River Water Is Strongly Associated With the Season and the Sample Type

The dissemination of antibiotic-resistant bacteria (ARB) from water used for crop irrigation to vegetables is poorly studied. During a year, five farmer markets in a city in Central Chile were visited, and 478 vegetable samples (parsleys, corianders, celeries, lettuces, chards, and beets) were collected. Simultaneously, 32 water samples were collected from two rivers which are used to irrigate the vegetables produced in the area. Resistant Enterobacterales were isolated and identified. Colistin resistance gene mcr-1 and extended spectrum β-lactamases (ESBL) were molecularly detected. The association of environmental factors was evaluated, with the outcomes being the presence of Enterobacterales resistant to four antibiotic families and the presence of multidrug resistance (MDR) phenotypes. Parsley, coriander, and celery showed the highest prevalence of resistant Enterobacterales (41.9% for ciprofloxacin and 18.5% for ceftazidime). A total of 155 isolates were obtained, including Escherichia coli (n=109), Citrobacter sp. (n=20), Enterobacter cloacae complex (n=8), Klebsiella pneumoniae (n=8), and Klebsiella aerogenes (n=1). Resistance to ampicillin (63.2%) and ciprofloxacin (74.2%) was most frequently found; 34.5% of the isolates showed resistance to third-generation cephalosporins, and the MDR phenotype represented 51.6% of the isolates. In two E. coli isolates (1.29%), the gene mcr-1 was found and ESBL genes were found in 23/62 isolates (37%), with bla_CTX-M being the most frequently found in 20 isolates (32%). Resistant Enterobacterales isolated during the rainy season were less likely to be MDR as compared to the dry season. Understanding environmental associations represent the first step toward an improved understanding of the public health impact of ARB in vegetables and water.

Climate change, extreme events, and increased risk of salmonellosis: foodborne diseases active surveillance network (FoodNet), 2004-2014

BACKGROUND

Infections with nontyphoidal Salmonella cause an estimated 19,336 hospitalizations each year in the United States. Sources of infection can vary by state and include animal and plant-based foods, as well as environmental reservoirs. Several studies have recognized the importance of increased ambient temperature and precipitation in the spread and persistence of Salmonella in soil and food. However, the impact of extreme weather events on Salmonella infection rates among the most prevalent serovars, has not been fully evaluated across distinct U.S. regions.

METHODS

To address this knowledge gap, we obtained Salmonella case data for S. Enteriditis, S. Typhimurium, S. Newport, and S. Javiana (2004-2014; n = 32,951) from the Foodborne Diseases Active Surveillance Network (FoodNet), and weather data from the National Climatic Data Center (1960-2014). Extreme heat and precipitation events for the study period (2004-2014) were identified using location and calendar day specific 95^th percentile thresholds derived using a 30-year baseline (1960-1989). Negative binomial generalized estimating equations were used to evaluate the association between exposure to extreme events and salmonellosis rates.

RESULTS

We observed that extreme heat exposure was associated with increased rates of infection with S. Newport in Maryland (Incidence Rate Ratio (IRR): 1.07, 95% Confidence Interval (CI): 1.01, 1.14), and Tennessee (IRR: 1.06, 95% CI: 1.04, 1.09), both FoodNet sites with high densities of animal feeding operations (e.g., broiler chickens and cattle). Extreme precipitation events were also associated with increased rates of S. Javiana infections, by 22% in Connecticut (IRR: 1.22, 95% CI: 1.10, 1.35) and by 5% in Georgia (IRR: 1.05, 95% CI: 1.01, 1.08), respectively. In addition, there was an 11% (IRR: 1.11, 95% CI: 1.04-1.18) increased rate of S. Newport infections in Maryland associated with extreme precipitation events.

CONCLUSIONS

Overall, our study suggests a stronger association between extreme precipitation events, compared to extreme heat, and salmonellosis across multiple U.S. regions. In addition, the rates of infection with Salmonella serovars that persist in environmental or plant-based reservoirs, such as S. Javiana and S. Newport, appear to be of particular significance regarding increased heat and rainfall events.

Interactions between Microbial Food Safety and Environmental Sustainability in the Fresh Produce Supply Chain

Improving the environmental sustainability of the food supply chain will help to achieve the United Nations Sustainable Development Goals (SDGs). This environmental sustainability is related to different SDGs, but mainly to SDG 2 (Zero Hunger), SDG 12 (Responsible Production and Consumption), SDG 13 (Climate Action), and SDG 15 (Life on Land). The strategies and measures used to improve this aspect of the food supply chain must remain in balance with other sustainability aspects (economic and social). In this framework, the interactions and possible conflicts between food supply chain safety and sustainability need to be assessed. Although priority must be given to safety aspects, food safety policies should be calibrated in order to avoid unnecessary deleterious effects on the environment. In the present review, a number of potential tensions and/or disagreements between the microbial safety and environmental sustainability of the fresh produce supply chain are identified and discussed. The addressed issues are spread throughout the food supply chain, from primary production to the end-of-life of the products, and also include the handling and processing industry, retailers, and consumers. Interactions of fresh produce microbial safety with topics such as food waste, supply chain structure, climate change, and use of resources have been covered. Finally, approaches and strategies that will prove useful to solve or mitigate the potential contradictions between fresh produce safety and sustainability are described and discussed. Upon analyzing the interplay between microbial safety and the environmental sustainability of the fresh produce supply chain, it becomes clear that decisions that are taken to ensure fresh produce safety must consider the possible effects on environmental, economic, and social sustainability aspects. To manage these interactions, a global approach considering the interconnections between human activities, animals, and the environment will be required.

The effect of vegetation barriers at reducing the transmission of Salmonella and Escherichia coli from animal operations to fresh produce

Due to the recent outbreaks of Salmonella and Escherichia coli in fresh produce in the United States, the transfer of foodborne pathogens between animal feeding operations and fresh produce continues to be a considerable risk. The purpose of this study was to determine if the establishment of a vegetation barrier (VB) on small-scale sustainable farms could prevent the transmission of Salmonella and E. coli to nearby fresh produce fields. A 5-layer VB (31 × 49 m) was constructed between a dairy farm, a poultry farm, and a nearby produce field. Fresh produce (i.e., romaine lettuce and tomato), animal feces, and environmental (i.e., air, soil, and barrier) samples were collected for 15 months from 2018 to 2019. Four replicates of soil and fresh produce samples were taken from three plots located 10 m, 61 m, and 122 m away from the respective animal locations and processed for Salmonella and E. coli. Air and vegetative strip samples were sampled at 15-day intervals. Multiple colonies were processed from each positive sample, and a total of 143 positive Salmonella (n = 15) and E. coli (n = 128) isolates were retrieved from the soil, produce, air, and fecal samples. Interestingly, 18.2% of the Salmonella and E. coli isolates (n = 26) were recovered from fresh produce (n = 9) samples. Surprisingly, Salmonella isolates (n = 9) were only found in fecal (n = 3) samples collected from the dairy pasture. Data analysis suggests that the VB is an effective tool at reducing the transmission of E. coli and Salmonella from animal farms to fresh produce fields. However, based on phenotypic and genotypic testing, it is clear that fecal samples from animal farms are not the only source of pathogen contamination. This indicates that the environment (e.g., soil and wind), as well as the initial setup of the farm (e.g., proximity to service roads and produce plot placement), can contribute to the contamination of fresh produce. Our study recommends the need for more effective bioremediation and prevention control measures to use in conjunction with VBs to reduce pathogen transmission.

Colonization of toxic cyanobacteria on the surface and inside of leafy green: A hidden source of cyanotoxin production and exposure

Cyanobacteria are a threat to the safety of water sources for drinking, recreation, and food production, because some cyanobacteria, such as Microcystis, produce cyanotoxins. However, the colonization of plants by Microcystis and the fate of their toxin, microcystins (MCs), in agricultural environments have not been thoroughly studied. This study examined the colonization of lettuce, as a representative of leafy greens, by Microcystis and its potential impact on food safety and crop health. The surfaces of lettuce leaves were exposed to environmentally relevant concentrations of M. aeruginosa (104, 106, and 108mcyE gene copies/mL) by mimicking contamination scenarios during cultivation, such as spraying irrigation with contaminated water or deposits of airborne Microcystis. Scanning electron microscope (SEM) and droplet digital PCR were used. The results showed that M. aeruginosa colonized the surface of leaves and MCs accumulated in the edible part of the lettuce (>20 μg/kg of lettuce). Crop productivity (length, weight, and number of leaves) was negatively affected. The SEM images provide evidence that M. aeruginosa deposited on the lettuce surface can be internalized via natural opening sites of the leaves and then proliferate within the plants. Our findings imply that toxic cyanobacteria contamination in agricultural environments can be a significant cyanotoxin exposure pathway.

Harnessing the Four Horsemen of Climate Change: A Framework for Deep Resilience, Decarbonization, and Planetary Health in Ontario, Canada

Widespread implementation of nature-based solutions like green infrastructure, provides a multi-functional strategy to increase climate resilience, enhance ecological connectivity, create healthier communities, and support sustainable urban development. This paper presents a decision-support framework to facilitate adoption of green infrastructure within communities using the Climate Change Local Adaptation Action Model (CCLAAM) developed for this purpose. It also presents an ecosystems-based approach to bridging the gap between climate change mitigation and adaptation actions in Ontario, Canada. Green infrastructure could be a viable strategy to address multiple climate change impacts and support the implementation of the UN Sustainable Development Goals (SDGs).

Prevalence of Cryptosporidium and Giardia in vegetables in Iran: a nineteen-years meta-analysis review

Cryptosporidium and Giardia are two major protozoa reported from vegetables and environment. The prevalence of these parasites supposes to be different regarding the climate zones. This review aimed to evaluate the prevalence of Cryptosporidium and Giardia in vegetables according to the major climate zones in Iran. The results showed pooled prevalence 7% (95% CI: 2%, 14%) and 4% (95% CI: 3%, 6%) for Cryptosporidium spp., and Giardia spp., respectively. The prevalence of Giardia spp. in mountain, desert and semi-desert, and Mediterranean regions was 4% (95% CI: 2%, 6%), 5% (95% CI: 3%, 8%) and 7% (95% CI: 1%, 18%), respectively. Cryptosporidium spp. was reported 8% (95% CI: 0%, 65%), 6% (95% CI: 0%, 18%) and 4% (95% CI: 0%, 77%) from mountain, desert and semi-desert, and Mediterranean climate zones, respectively. This review suggests the higher prevalence of Giardia and Cryptosporidium in Mediterranean and mountain regions, respectively.

Assessing the Food Safety Risk Posed by Birds Entering Leafy Greens Fields in the US Southwest

In the US Southwest, it is common to observe birds in leafy green fields, though the risk they contribute to foodborne outbreaks remains unclear. In this study, we investigated and recorded the relationship between birds near leafy green fields and the risk for contaminated irrigation water or leafy green plants. We monitored the presence of birds for over two years and performed cloacal swab analysis for non-pathogenic Escherichia coli, E. coli O157:H7 and Salmonellaenterica, while also monitoring the incidence of other microbial indicators. We also assessed the risks from bird feces by performing observations in a commercial field reported with Salmonella positive samples and by analyzing the survival of foodborne pathogens in bird feces. Our results showed that most of the birds near the crop fields were resident small birds. We did not observe a correlation between the number of birds in sites and the incidence of indicator bacteria (e.g., coliforms, E. coli) in irrigation canal water, with the exception of one out of four sites where water flow was low or stagnant. Using walk-in-traps, 305 birds were captured and placed in short-term captivity to determine the presence of various bacteria. None of the birds tested positive for E. coli O157:H7 or Salmonella. However, nearly 40% of the birds captured were confirmed positive for non-pathogenic E. coli. We found no correlation between age (young, adult, unknown), gender (male, female, unknown) and the incidence of E. coli positive birds, but we observed significantly higher probability of incidence during October-December. The role of relative humidity and temperature on bacterial survival appeared to play a key role in the survival of Salmonella on the leaves of spinach plants in a commercial field. This was also confirmed in laboratory conditions where Salmonella inoculated in bird feces and exposed to 15 °C and 80% RH(Relative humidity) survived beyond 133 days, while at 26 °C and 40% RH, the organism was undetectable after 63 days. Our results suggest that local birds associated with leafy green fields likely pose a minimal impact of risk for food contamination, but also points out the need for increased analysis specifically for E. coli O157:H7. Furthermore, our study suggests the need for expanding research that addresses risks associated with large migratory birds, especially in areas where stagnated water sources would be used for overhead sprinkle irrigation.

Associations of five food- and water-borne diseases with ecological zone, land use and aquifer type in a changing climate

BACKGROUND

Food- and water-borne pathogens exhibit spatial heterogeneity, but attribution to specific environmental processes is lacking while anthropogenic climate change alters these processes. The goal of this study was to investigate ecology, land-use and health associations of these pathogens and to make future disease projections.

METHODS

The rates of five acute gastrointestinal illnesses (AGIs) (campylobacteriosis, Verotoxin- producing Escherichia coli, salmonellosis, giardiasis and cryptosporidiosis) from 2000 to 2013 in British Columbia, Canada, were calculated across three environmental variables: ecological zone, land use, and aquifer type. A correlation analysis investigated relationships between 19 climatic factors and AGI. Mean annual temperature at the ecological zone scale was used in a univariate regression model to calculate annual relative AGI risk per 1 °C increase. Future cases attributable to climate change were estimated into the 2080s.

FINDINGS

Each of the bacterial AGI rates was correlated with several annual temperature-related factors while the protozoan AGIs were not. In the regression model, combined relative risk for the three bacterial AGIs was 1.1 [95% CI: 1.02-1.21] for every 1 °C in mean annual temperature. Campylobacteriosis, salmonellosis and giardiasis rates were significantly higher (p < 0.05) in the urban land use class than in the rural one. In rural areas, bacteria and protozoan AGIs had significantly higher rates in the unconsolidated aquifers. Verotoxin-producing Escherichia coli rates were significantly higher in watersheds with more agricultural land, while rates of campylobacteriosis, salmonellosis and giardiasis were significantly lower in agricultural watersheds. Ecological zones with higher bacterial AGI rates were generally projected to expand in range by the 2080s.

INTERPRETATION

These findings suggest that risk of AGI can vary across ecosystem, land use and aquifer type, and that warming temperatures may be associated with an increased risk of food-borne AGI. In addition, spatial patterns of these diseases are projected to shift under climate change.

Associations between climatic parameters and the human salmonellosis in Yazd province, Iran

Salmonella is one of the most common causes of foodborne disease outbreaks in developing countries. Climatic factors such as temperature, rainfall, and relative humidity can directly increase the growth and spread of these pathogens. Therefore, the aim of this study was to investigate long-term temporal trends and seasonal patterns of Salmonella infections as well as evaluating the effects of demographic and climatic factors on the infection incidence in Yazd province, Iran during 2012-2015. The incidence of Salmonella infections was highest among patients with the age group of ≤5 years and peaked in summer, especially during June. Contrary to expectations, no significant associations were seen between the average monthly temperature, rainfall or humidity and incidence rate (IR) of salmonellosis. Interestingly, atmospheric dust hovering was significantly associated with an increased risk of salmonellosis. Transmission pathways of Salmonella spp. in communities should be considered as a complex ecological process that animal reservoirs, socio-economic factors, and lifestyle behaviors need to be addressed in future studies.

Pandemics and food systems - towards a proactive food safety approach to disease prevention & management

Recent large-scale pandemics such as the covid19, H1N1, Swine flu, Ebola and the Nipah virus, which impacted human health and livelihoods, have come about due to inadequate food systems safeguards to detect, trace and eliminate threats arising from zoonotic diseases. Such diseases are transmitted to humans through their interaction with animals in the food value chain including through the consumption of bush meat. Climate change has also facilitated the emergence of new zoonotic diseases. The lack of adequately enforced food-safety standards in managed agricultural production systems creates the necessary conditions for diseases to mutate into highly contagious strains. The lack of food safety measures in handling, packaging and sales of food increases risks of cross-species contamination. Finally, increasing anti-microbial resistance, combined with rapid urbanization and global interconnectedness allows diseases to spread rapidly among humans. Thus, part of the reconstruction efforts, post covid19, should include prioritizing proactive investments in food safety. The key to stave off another such pandemic lies in integrating one-health knowledge on zoonotic diseases along with food safety measures along the food value chain. Refocusing policy priorities from disease control to prevention will improve international coordination efforts in pandemic prevention. Implementing such proactive actions will cost a very small fraction of the reconstruction budgets. However, the expected benefits of the food-safety approach will include preventing global economic losses due to pandemics.

Malek R. Inventory and composting of yard waste in Serdang, Selangor, Malaysia

Composting of yard waste is one of the waste management approaches in the Malaysian Agricultural Research and Development Institute (MARDI) in Serdang, Selangor, Malaysia. The yard waste inventory was developed in the headquarters' area and a pilot-scale study was performed on the potential compost product. The total amount of yard waste generated from June 2017 to December 2017 was 16.75 tonnes with an average generation of 0.60 tonnes per week on the dry weight (d.w.) basis. The collected yard waste consisted of three major characteristics, namely dry leaves, fresh green leaves, and grass cuttings, and a waste estimation technique was applied to determine the composition of these three elements. The acquired information was used to formulate the initial compost mixture. The wastes were then mixed with an appropriate amount of livestock manure and other wastes to obtain the optimum initial C/N ratio, which was then found in the analysis to range between 25:1 and 42:1. Meanwhile, the C/N ratios obtained from the matured compost product were from 10:1 and 15:1. Moreover, most of the compost yield ranged between 50% and 70% (w w-1 d.w. basis), while the percentage of the seed germination in the compost was over 95%. The viability of the project was indicated from the economic analysis, with benefit to cost ratio (BCR) values of more than 1. The results also suggested that the large scale composting of yard waste in MARDI was feasible and its applicability is continuous. This technique also fulfilled the objective of producing quality compost, which was suitable for agricultural use.

Predicting Salmonella prevalence associated with meteorological factors in pastured poultry farms in southeastern United States

Consumer demand has increased for pastured poultry products as the drive for sustainable farming practices and ethical treatments of livestock have become popular in the press. It is necessary to identify the important meteorological factors associated with the prevalence of Salmonella in the pastured poultry settings since the presence of Salmonella in the environment could lead to contamination of the final product. The objective of this study was to develop a model to describe the relationship between meteorological factors and the presence of Salmonella on the pastured poultry farms. The random forest method was used to develop a model where 83 meteorological factors were included as the predicting variables. The soil model identified humidity as the most important variable associated with Salmonella prevalence, while high wind gust speed and average temperature were identified as important meteorological variables in the feces model. The developed models were robust in predicting the prevalence of Salmonella in pastured poultry farms with the area under receiver operating characteristic (ROC) curve values of 0.884 and 0.872 for the soil model and feces model, respectively. The predictive models developed in this study can provide users with practical and effective tools to make informed decisions with scientific evidence regarding the meteorological parameters that are important to monitor for increased on-farm Salmonella prevalence.

Seasonality in carriage of extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae in the general population: a pooled analysis of nationwide cross-sectional studies

Infections due to extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) are often preceded by asymptomatic carriage. Higher incidences in enteric infectious diseases during summer have been reported. Here, we assessed whether the presence of seasonality in intestinal ESBL-Escherichia coli/Klebsiella pneumoniae (ESBL-E/K) carriage in the general Dutch population exists. From 2014 to 2017, the faecal carriage of ESBL-E/K in healthy individuals was determined in three cross-sectional studies in the Netherlands, including 5985 subjects. Results were pooled to identify seasonal trends in prevalence (by month of sampling). Multivariate logistic regression analysis was used to calculate pooled odds ratios and 95% confidence intervals. Results were adjusted for age, sex, antibiotic use and travel. Overall prevalence of ESBL-E/K carriage was 4.3% (n = 260 ESBL-E/K-positive), with differences between months ranging from 2.6% to 7.4%. Compared to January, the monthly prevalence of ESBL-E carriage was highest in August (OR 1.88, 95% CI 1.02–3.49) and September (OR 2.25, 95% CI 1.30–3.89). The observed monthly differences in ESBL-E/K carriage rates suggest that there is seasonal variation in exposure to ESBL-E/K other than due to travelling and antibiotic use. This should be taken into account in designing future ESBL-E prevalence studies in temperate regions.

The Role of Pathogenic E. coli in Fresh Vegetables: Behavior, Contamination Factors, and Preventive Measures

Many raw vegetables, such as tomato, chili, onion, lettuce, arugula, spinach, and cilantro, are incorporated into fresh dishes including ready-to-eat salads and sauces. The consumption of these foods confers a high nutritional value to the human diet. However, the number of foodborne outbreaks associated with fresh produce has been increasing, with Escherichia coli being the most common pathogen associated with them. In humans, pathogenic E. coli strains cause diarrhea, hemorrhagic colitis, hemolytic uremic syndrome, and other indications. Vegetables can be contaminated with E. coli at any point from pre- to postharvest. This bacterium is able to survive in many environmental conditions due to a variety of mechanisms, such as adhesion to surfaces and internalization in fresh products, thereby limiting the usefulness of conventional processing and chemical sanitizing methods used by the food industry. The aim of this review is to provide a general description of the behavior and importance of pathogenic E. coli in ready-to-eat vegetable dishes. This information can contribute to the development of effective control measures for enhancing food safety.

Preharvest Transmission Routes of Fresh Produce Associated Bacterial Pathogens with Outbreak Potentials: A Review

Disease outbreaks caused by the ingestion of contaminated vegetables and fruits pose a significant problem to human health. The sources of contamination of these food products at the preharvest level of agricultural production, most importantly, agricultural soil and irrigation water, serve as potential reservoirs of some clinically significant foodborne pathogenic bacteria. These clinically important bacteria include: Klebsiella spp., Salmonella spp., Citrobacter spp., Shigella spp., Enterobacter spp., Listeria monocytogenes and pathogenic E. coli (and E. coli O157:H7) all of which have the potential to cause disease outbreaks. Most of these pathogens acquire antimicrobial resistance (AR) determinants due to AR selective pressure within the agroecosystem and become resistant against most available treatment options, further aggravating risks to human and environmental health, and food safety. This review critically outlines the following issues with regards to fresh produce; the global burden of fresh produce-related foodborne diseases, contamination between the continuum of farm to table, preharvest transmission routes, AR profiles, and possible interventions to minimize the preharvest contamination of fresh produce. This review reveals that the primary production niches of the agro-ecosystem play a significant role in the transmission of fresh produce associated pathogens as well as their resistant variants, thus detrimental to food safety and public health.

Climate Change Impacts on Waterborne Diseases: Moving Toward Designing Interventions

PURPOSE

Climate change threatens progress achieved in global reductions of infectious disease rates over recent decades. This review summarizes literature on potential impacts of climate change on waterborne diseases, organized around a framework of questions that can be addressed depending on available data.

RECENT FINDINGS

A growing body of evidence suggests that climate change may alter the incidence of waterborne diseases, and diarrheal diseases in particular. Much of the existing work examines historical relationships between weather and diarrhea incidence, with a limited number of studies projecting future disease rates. Some studies take social and ecological factors into account in considerations of historical relationships, but few have done so in projecting future conditions. The field is at a point of transition, toward incorporating social and ecological factors into understanding the relationships between climatic factors and diarrheal diseases and using this information for future projections. The integration of these components helps identify vulnerable populations and prioritize adaptation strategies.

How will climate change impact microbial foodborne disease in Canada?

Foodborne disease is a major concern in Canada and represents a significant climate change-related threat to public health. Climate variables, including temperature and precipitation patterns, extreme weather events and ocean warming and acidification, are known to exert significant, complicated and interrelated effects along the entire length of the food chain. Foodborne diseases are caused by a range of bacteria, fungi, parasites and viruses, and the prevalence of these diseases is modified by climate change through alterations in the abundance, growth, range and survival of many pathogens, as well as through alterations in human behaviours and in transmission factors such as wildlife vectors. As climate change continues and/or intensifies, it will increase the risk of an adverse effect on food safety in Canada ranging from increased public health burden to the emergence of risks not currently seen in our food chain. Clinical and public health practitioners need to be aware of the existing and emerging risks to respond accordingly.

Meeting Report: Key Outcomes from a Collaborative Summit on Agricultural Water Standards for Fresh Produce

On February 27 to 28, 2018, the Produce Safety Alliance convened a national water summit in Covington, KY to discuss the requirements of the United States Food and Drug Administration's (FDA) Food Safety Modernization Act Standards for the Growing, Harvesting, Packing, and Holding of Produce for Human Consumption (Produce Safety Rule [PSR]). The goals of the meeting were to better understand the challenges growers face in implementing the requirements in Subpart E-Agricultural Water and work collaboratively to develop practical solutions to meet fruit and vegetable production needs while protecting public health. To meet these goals, the summit engaged a diverse group of stakeholders including growers, researchers, extension educators, produce industry members, and regulatory personnel. Key outcomes included defining implementation barriers due to diversity in water sources, distribution systems, commodity types, climates, farm size, and production activities. There was an articulated need for science-based solutions, such as the use of agricultural water system assessments and sharing of federal, state, and regional water quality data, to ensure qualitative and quantitative standards reduce microbial risks. These identified challenges and needs resulted in significant debate about whether reopening the PSR-Subpart E for modification or attempting to address concerns through guidance would provide the best mechanism for alleviating concerns. In addition, training, outreach, and technical assistance were identified as vital priorities once the concerns are formally addressed by FDA. The water summit highlighted the critical need for transparency of FDA's progress on reevaluating the Subpart E requirements to help guide growers' decisions regarding the use of agricultural water.

Interrelationships between Multiple Climatic Factors and Incidence of Foodborne Diseases

Climatic factors can affect the incidence of foodborne diseases (FBDs). Moreover, microbial network inference is useful for predicting the interrelationships between the incidence of FBDs and climatic factors. However, the interrelationships between FBD pathogens and most climatic factors are unknown. Using principal component analysis (PCA) and partial correlation coefficient matrices (PCCMs), we determined the intra-ecosystem interrelationship network of the multiple combined effects of 5 climatic factors (temperature, relative humidity, rainfall, insolation, and cloudiness) and the monthly incidences of 12 bacterial FBDs. Many FBD pathogens are interrelated with multiple combined factors. Salmonellosis has strong positive interrelationships with Vibrio parahaemolyticus and enterohemorrhagic Escherichia coli, and the interrelationships between Staphylococcus aureus/enteropathogenic E. coli/enterotoxigenic E. coli exhibits a typical triangular pattern with the combined effects of all 5 climatic factors. Meanwhile, campylobacteriosis and Clostridium perfringens infections are negatively interrelated with insolation and cloudiness. Enteroinvasive E. coli, Bacillus cereus, Listeria spp., and Yersinia enterocolitica are significantly interrelated with any climatic factor combination. The interrelationships or higher-order interrelationships among these climatic factors play an important role in the incidence of FBDs, although the underlying mechanisms remain unclear. Our results will serve as a foundation for more sophisticated models of future FBD patterns with regard to climate change.

The Hurdle Approach-A Holistic Concept for Controlling Food Safety Risks Associated With Pathogenic Bacterial Contamination of Leafy Green Vegetables. A Review

Consumers appreciate leafy green vegetables such as baby leaves for their convenience and wholesomeness and for adding a variety of tastes and colors to their plate. In Western cuisine, leafy green vegetables are usually eaten fresh and raw, with no step in the long chain from seed to consumption where potentially harmful microorganisms could be completely eliminated, e.g., through heating. A concerning trend in recent years is disease outbreaks caused by various leafy vegetable crops and one of the most important foodborne pathogens in this context is Shiga toxin-producing Escherichia coli (STEC). Other pathogens such as Salmonella, Shigella, Yersinia enterocolitica and Listeria monocytogenes should also be considered in disease risk analysis, as they have been implicated in outbreaks associated with leafy greens. These pathogens may enter the horticultural value network during primary production in field or greenhouse via irrigation, at harvest, during processing and distribution or in the home kitchen/restaurant. The hurdle approach involves combining several mitigating approaches, each of which is insufficient on its own, to control or even eliminate pathogens in food products. Since the food chain system for leafy green vegetables contains no absolute kill step for pathogens, use of hurdles at critical points could enable control of pathogens that pose a human health risk. Hurdles should be combined so as to decrease the risk due to pathogenic microbes and also to improve microbial stability, shelf-life, nutritional properties and sensory quality of leafy vegetables. The hurdle toolbox includes different options, such as physical, physiochemical and microbial hurdles. The goal for leafy green vegetables is multi-target preservation through intelligently applied hurdles. This review describes hurdles that could be used for leafy green vegetables and their biological basis, and identifies prospective hurdles that need attention in future research.

Study of chemical composition and nutritional values of vegetable wastes in Bangladesh

The present study was conducted with the objectives of determining the chemical composition and nutritional value of vegetable waste (VW) of households and the marketplace for their suitability as ruminant feed. The crude protein, total digestible nutrients and extent of rumen degradability of dry matter (DM) of VW of households were 140.0 g kg-1, 0.668 and 0.855, respectively; while those of the marketplace were 169.0 g kg-1, 0.633 and 0.80, respectively. The levels of chromium and lead in each respectively, was 13.27 and 1.53 ng kg-1DM; and 31.01 and 5.71 ng kg-1DM. The total aflatoxins in VW of households was 3.08 µg kg-1DM, and undetectable in VW from the marketplace. Considering the chemical composition and safety parameters studied, VW could preliminary be considered as animal feed. The feeding of processed marketplace VW (VWP) at 275 g kg-1DM of a diet or 0.76% of live weight (LW) to growing bulls, replacing 50% of a concentrate mixture as supplement to a Napier silage diet for a period of 34 days reduced the total DM intake (0.0276 vs 0.0343 LW) without any significant (P > 0.05) changes in DM or protein digestibility. Blood urea levels (19.5 vs 23.67 mg dl-1), and serum creatinine levels (1.37 vs 1.08 mg dl-1) differed significantly (P > 0.05) between the two groups but were within normal physiological ranges. Therefore, it may be concluded that the level of incorporation of VWP would be less than 50% replacement of the concentrate in the diet. Further research is required to determine optimum inclusion levels in ruminant diets.

Impact of relative humidity, inoculum carrier and size, and native microbiota on Salmonella ser. Typhimurium survival in baby lettuce

The effects of relative humidity (RH), fluctuating climate conditions, inoculum size and carrier on the survival of Salmonella enterica serovar Typhimurium on baby lettuce in environmental test chambers were studied. Buffered peptone water (BPW), distilled water (DW), and irrigation water (IW) were compared as inoculum carriers. Additionally, survival of Salmonella in suspensions prepared using filtered and unfiltered IW was assessed. Salmonella Typhimurium survived better on baby lettuce plants at high RH independently of the inoculum size. When lettuce plants were grown under fluctuating environmental conditions, Salmonella survival was similar under both RH conditions. Regarding the inoculum carrier, the inoculated microorganism survived better on lettuce plants when BPW was used as carrier both at high and low RH. Survival rate of Salmonella in IW was affected by the presence of native microbiota. Native microbiota present in IW did not affect survival of Salmonella or the levels of mesophilic bacteria on the baby lettuce leaves. The information obtained in the present study contributes to the knowledge on the effect of environmental conditions on pathogenic bacteria survival on growing edible plants. These results are useful when selecting the methodology to carry out experimental studies on the survival of microbial pathogens under different pre-harvest conditions.

Development and evaluation of the bacterial fate and transport module for the Agricultural Policy/Environmental eXtender (APEX) model

The Agricultural Policy/Environmental eXtender (APEX) is a watershed-scale water quality model that includes detailed representation of agricultural management. The objective of this work was to develop a process-based model for simulating the fate and transport of manure-borne bacteria on land and in streams with the APEX model. The bacteria model utilizes manure erosion rates to estimate the amount of edge-of-field bacteria export. Bacteria survival in manure is simulated as a two-stage process separately for each manure application event. In-stream microbial fate and transport processes include bacteria release from streambeds due to sediment resuspension during high flow events, active release from the streambed sediment during low flow periods, bacteria settling with sediment, and survival. Default parameter values were selected from published databases and evaluated based on field observations. The APEX model with the newly developed microbial fate and transport module was applied to simulate fate and transport of the fecal indicator bacterium Escherichia coli in the Toenepi watershed, New Zealand that was monitored for seven years. The stream network of the watershed ran through grazing lands with daily bovine waste deposition. Results show that the APEX with the bacteria module reproduced well the monitored pattern of E. coli concentrations at the watershed outlet. The APEX with the microbial fate and transport module will be utilized for predicting microbial quality of water as affected by various agricultural practices, evaluating monitoring protocols, and supporting the selection of management practices based on regulations that rely on fecal indicator bacteria concentrations.

Combined influence of multiple climatic factors on the incidence of bacterial foodborne diseases

Information regarding the relationship between the incidence of foodborne diseases (FBD) and climatic factors is useful in designing preventive strategies for FBD based on anticipated future climate change. To better predict the effect of climate change on foodborne pathogens, the present study investigated the combined influence of multiple climatic factors on bacterial FBD incidence in South Korea. During 2011-2015, the relationships between 8 climatic factors and the incidences of 13 bacterial FBD, were determined based on inpatient stays, on a monthly basis using the Pearson correlation analyses, multicollinearity tests, principal component analysis (PCA), and the seasonal autoregressive integrated moving average (SARIMA) modeling. Of the 8 climatic variables, the combination of temperature, relative humidity, precipitation, insolation, and cloudiness was significantly associated with salmonellosis (P<0.01), vibriosis (P<0.05), and enterohemorrhagic Escherichia coli O157:H7 infection (P<0.01). The combined effects of snowfall, wind speed, duration of sunshine, and cloudiness were not significant for these 3 FBD. Other FBD, including campylobacteriosis, were not significantly associated with any combination of climatic factors. These findings indicate that the relationships between multiple climatic factors and bacterial FBD incidence can be valuable for the development of prediction models for future patterns of diseases in response to changes in climate.

Using Microsimulation to Estimate the Future Health and Economic Costs of Salmonellosis under Climate Change in Central Queensland, Australia

BACKGROUND

The incidence of salmonellosis, a costly foodborne disease, is rising in Australia. Salmonellosis increases during high temperatures and rainfall, and future incidence is likely to rise under climate change. Allocating funding to preventative strategies would be best informed by accurate estimates of salmonellosis costs under climate change and by knowing which population subgroups will be most affected.

OBJECTIVE

We used microsimulation models to estimate the health and economic costs of salmonellosis in Central Queensland under climate change between 2016 and 2036 to inform preventative strategies.

METHODS

We projected the entire population of Central Queensland to 2036 by simulating births, deaths, and migration, and salmonellosis and two resultant conditions, reactive arthritis and postinfectious irritable bowel syndrome. We estimated salmonellosis risks and costs under baseline conditions and under projected climate conditions for Queensland under the A1FI emissions scenario using composite projections from 6 global climate models (warm with reduced rainfall). We estimated the resulting costs based on direct medical expenditures combined with the value of lost quality-adjusted life years (QALYs) based on willingness-to-pay.

RESULTS

Estimated costs of salmonellosis between 2016 and 2036 increased from 456.0 QALYs (95% CI: 440.3, 473.1) and AUD29,900,000 million (95% CI: AUD28,900,000, AUD31,600,000), assuming no climate change, to 485.9 QALYs (95% CI: 469.6, 503.5) and AUD31,900,000 (95% CI: AUD30,800,000, AUD33,000,000) under the climate change scenario.

CONCLUSION

We applied a microsimulation approach to estimate the costs of salmonellosis and its sequelae in Queensland during 2016-2036 under baseline conditions and according to climate change projections. This novel application of microsimulation models demonstrates the models' potential utility to researchers for examining complex interactions between weather and disease to estimate future costs. https://doi.org/10.1289/EHP1370.

Identifying and modeling meteorological risk factors associated with pre-harvest contamination of Listeria species in a mixed produce and dairy farm

This study sought to investigate the prevalence of Listeria species (including L. monocytogenes) in a mixed produce and dairy farm and to identify specific meteorological factors affecting Listeria spp. presence. Environmental samples were collected monthly from locations within the mixed farm over 14months and were analyzed for Listeria spp. Meteorological factors were evaluated for their association with the presence of Listeria spp. by using logistic regression (LR) and random forest (RF). The developed LR model identified wind speed and precipitation as significant risk factors (P<0.05), indicating higher wind speed at day 2 prior to sampling and higher average precipitation over the previous 25days before sampling increased the probability of isolation of Listeria spp. from the mixed farm. Results from RF revealed that average wind speed at day 2 prior to sampling and average precipitation in the previous 25days before sampling were the most important factors influencing the presence of Listeria spp., which supported the findings from LR. These findings indicate that the occurrence of Listeria spp. was influenced by wind speed and precipitation, suggesting run-off and wind-driven dust might be possible routes of pathogen transmission in mixed farms. The developed LR and RF models, with robust predictive performances as measured by the area under the receiver operating characteristic curves, can be used to predict Listeria spp. contamination risk in a mixed farm under different weather conditions and can help with the evaluation of farm management practices and the development of control strategies aimed at reducing pre-harvest microbial contamination in a mixed farming system.

Antibacterial and antioxidant properties of grape stem extract applied as disinfectant in fresh leafy vegetables

In the present study total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity and antimicrobial properties of grape (Vitis vinifera var. Red Globe) stem extract is reported. Also, the identification of main phenolic compounds was carried out by UPLC-PAD analysis. TPC and TFC of extract were 37.25 g GAE kg^-1 and 98.07 g QE kg^-1, respectively. Extract showed an antioxidant capacity of 132.60 and 317 g TE kg^-1 for DPPH and ABTS radical scavenging capacity, respectively. The main phenolic compounds identified were rutin, gallic acid, chlorogenic acid, caffeic acid, catechin and ferulic acid. Extract inhibited the growth of Listeria monocytogenes, Staphylococcus aureus, Salmonella enterica subsp. enterica serovar Typhimurium, and Escherichia coli O157: H7 at MIC range 16-18 g L^-1. Extract affected the different phases of bacterial growth. In addition, application of Extract (25 g L^-1) as a sanitizer was effective to reduce the populations of all bacteria inoculated in lettuce (0.859-1.884 log reduction) and spinach (0.843-2.605 log reduction). This study emphasizes the potential of grape processing byproducts as an emergent and attractive source of bioactive compounds with antioxidant properties and antimicrobial activity against important foodborne pathogens. The study demonstrated that stem extract could be used to control the presence of human pathogenic bacteria in fresh leafy vegetables.

Microbial quality of irrigation water used in leafy green production in Southern Brazil and its relationship with produce safety

Irrigation water has been recognized as an important microbial risk factor for fruits and vegetables in many production areas, but there is still a lack of information about how the microbiological quality of different irrigation water sources and climatic conditions influence the safety of vegetables produced in Brazil. This study evaluated the distribution of generic E. coli and the prevalence of E. coli O157:H7 in two different water sources (ponds and streams bordering farmlands and urban areas) used for irrigation and on commercially produced lettuces in Southern Brazil. We also evaluated the effect of agricultural factors and meteorological conditions in the potential contamination of water and produce samples. A longitudinal study was conducted on four farms during a year (July 2014 to August 2015). The results showed generic E. coli prevalence of 84.8% and 38.3% in irrigation water samples and on lettuces, respectively, indicating irrigation water as an important source of contamination of lettuces. No significant differences were detected in the counts of E. coli between the two different surface water sources. The climatic conditions, particularly rainfall and environmental temperature, have influenced the high concentration of E. coli. The highest loads of E. coli in irrigation water and on lettuces were found during the warmest time of the year. E. coli O157:H7 was detected by qualitative polymerase chain reaction (qPCR) in 13 water samples but only 4 were confirmed by isolation in culture media.

Quantitative contamination assessment of Escherichia coli in baby spinach primary production in Spain: Effects of weather conditions and agricultural practices

A quantitative microbial contamination model of Escherichia coli during primary production of baby spinach was developed. The model included only systematic contamination routes (e.g. soil and irrigation water) and it was used to evaluate the potential impact of weather conditions, agricultural practices as well as bacterial fitness in soil on the E. coli levels present in the crop at harvest. The model can be used to estimate E. coli contamination of baby spinach via irrigation water, via soil splashing due to irrigation water or rain events, and also including the inactivation of E. coli on plants due to solar radiation during a variable time of culturing before harvest. Seasonality, solar radiation and rainfall were predicted to have an important impact on the E. coli contamination. Winter conditions increased E. coli prevalence and levels when compared to spring conditions. As regards agricultural practices, both water quality and irrigation system slightly influenced E. coli levels on baby spinach. The good microbiological quality of the irrigation water (average E. coli counts in positive water samples below 1 log/100mL) could have influenced the differences observed among the tested agricultural practices (water treatment and irrigation system). This quantitative microbial contamination model represents a preliminary framework that assesses the potential impact of different factors and intervention strategies affecting E. coli concentrations at field level. Taking into account that E. coli strains may serve as a surrogate organism for enteric bacterial pathogens, obtained results on E. coli levels on baby spinach may be indicative of the potential behaviour of these pathogens under defined conditions.