Food safety and animal production systems : controlling zoonoses at farm level

Small mammals as carriers of zoonotic bacteria on pig and cattle farms - Prevalence and risk of exposure in an integrative approach

To prevent foodborne infections from pigs and cattle, the whole food chain must act to minimize the contamination of products, including biosecurity measures which prevent infections via feed and the environment in production farms. Rodents and other small mammals can be reservoirs of and key vectors for transmitting zoonotic bacteria and viruses to farm animals, through direct contact but more often through environmental contamination. In line with One Health concept, we integrated results from a sampling study of small mammals in farm environments and data from a capture-recapture experiment into a probabilistic model which quantifies the degree of environmental exposure of zoonotic bacteria by small mammals to farm premises. We investigated more than 1200 small mammals trapped in and around 38 swine and cattle farm premises in Finland in 2017/2018. Regardless of the farm type, the most common species caught were the yellow-necked mouse (Apodemus flavicollis), bank vole (Clethrionomys glareolus), and house mouse (Mus musculus). Of 554 intestine samples (each pooled from 1 to 10 individuals), 33% were positive for Campylobacter jejuni. Yersinia enterocolitica was detected in 8% of the pooled samples, on 21/38 farm premises. Findings of Salmonella and the Shiga-toxin producing Escherichia coli (STEC) were rare: the pathogens were detected in only single samples from four and six farm premises, respectively. The prevalence of Campylobacter, Salmonella, Yersinia and STEC in small mammal populations was estimated as 26%/13%, 1%/0%, 2%/3%, 1%/1%, respectively, in 2017/2018. The exposure probability within the experimental period of four weeks on farms was 17-60% for Campylobacter and 0-3% for Salmonella. The quantitative model is readily applicable to similar integrative studies. Our results indicate that small mammals increase the risk of exposure to zoonotic bacteria in animal production farms, thus increasing risks also for livestock and human health.

Antimicrobial stewardship hindered by inadequate biosecurity and biosafety practices, and inappropriate antibiotics usage in poultry farms of Nepal-A pilot study

Nepal's poultry industry has experienced remarkable growth in the last decade, but farm biosafety and biosecurity measures are often overlooked by farmers. As a result, farms often suffer from sporadic and regular outbreaks of many diseases, impacting production and creating public health challenges. Poor management practices, including overuse of antibiotics for prophylaxis and therapeutics, can enhance the spread of poultry diseases by propagating antimicrobial resistance (AMR) that is threatening poultry and human health. We assessed biosafety, biosecurity risks and AMR stewardship in sixteen poultry farms located in four districts: Ramechhap, Nuwakot, Sindhupalchowk, and Kavre. Risk assessment and AMR stewardship evaluation questionnaires were administered to formulate biosafety and biosecurity compliance matrix (BBCM). Risk assessment checklist assessed facility operations, personnel and standard operating procedures, water supply, cleaning and maintenance, rodent/pest control and record keeping. Oral and cloacal samples from the poultry were collected, pooled, and screened for eight poultry pathogens using Polymerase Chain Reaction (PCR) tests. Based on BBCM, we identified the highest BBCM score of 67% obtained by Sindhupalchowk farm 4 and the lowest of 12% by Kavre farm 3. Most of the farms (61.6%) followed general poultry farming practices, only half had clean and well-maintained farms. Lowest scores were obtained for personnel safety standard (42.4%) and rodent control (3.1%). At least one of the screened pathogens were detected in all farms. Mycoplasma gallisepticum was the most common pathogen detected in all but three farms, followed by Mycoplasma synoviae. More than half of the farmers considered AMR a threat, over 26% of them used antibiotics as a preventive measure and 81% did not consider withdrawal period for antibiotics prior to processing of their meat products. Additionally, antibiotics classified as "Watch" and "Restrict" by the WHO were frequently used by the farmers to treat bacterial infections in their farms.

Longitudinal Study of Two Irish Dairy Herds: Low Numbers of Shiga Toxin-Producing Escherichia coli O157 and O26 Super-Shedders Identified

A 12-month longitudinal study was undertaken on two dairy herds to ascertain the Shiga-toxin producing Escherichia coli (STEC) O157 and O26 shedding status of the animals and its impact (if any) on raw milk. Cattle are a recognized reservoir for these organisms with associated public health and environmental implications. Animals shedding E. coli O157 at >10,000 CFU/g of feces have been deemed super-shedders. There is a gap in the knowledge regarding super-shedding of other STEC serogroups. A cohort of 40 lactating cows from herds previously identified as positive for STEC in a national surveillance project were sampled every second month between August, 2013 and July, 2014. Metadata on any potential super-shedders was documented including, e.g., age of the animal, number of lactations and days in lactation, nutritional condition, somatic cell count and content of protein in milk to assess if any were associated with risk factors for super-shedding. Recto-anal mucosal swabs (RAMS), raw milk, milk filters, and water samples were procured for each herd. The swabs were examined for E. coli O157 and O26 using a quantitative real time PCR method. Counts (CFU swab-1) were obtained from a standard calibration curve that related real-time PCR cycle threshold (Ct) values against the initial concentration of O157 or O26 in the samples. Results from Farm A: 305 animals were analyzed; 15 E. coli O157 (5%) were recovered, 13 were denoted STEC encoding either stx1 and/or stx2 virulence genes and 5 (2%) STEC O26 were recovered. One super-shedder was identified shedding STEC O26 (stx1&2). Farm B: 224 animals were analyzed; eight E. coli O157 (3.5%) were recovered (seven were STEC) and 9 (4%) STEC O26 were recovered. Three super-shedders were identified, one was shedding STEC O157 (stx2) and two STEC O26 (stx2). Three encoded the adhering and effacement gene (eae) and one isolate additionally encoded the haemolysin gene (hlyA). All four super-shedders were only super-shedding once during the 1-year sampling period. The results of this study show, low numbers of super-shedders in the herds examined, with high numbers of low and medium shedding. Although four super-shedding animals were identified, no STEC O157 or O26 were recovered from any of the raw milk, milk filter, or water samples. The authors conclude that this study highlights the need for further surveillance to assess the potential for environmental contamination and food chain security.

Suppression of Escherichia coli O157:H7 by Dung Beetles (Coleoptera: Scarabaeidae) using the lowbush blueberry agroecosystem as a model system

Wildlife as a source of microbial contamination is a food safety concern. Deer feces (scat) have been determined as a point source for Escherichia coli O157:H7 contamination of fresh produce. The ecological role of the scooped scarab (Onthophagus hecate (Panzer)), a generalist dung beetle species common in Maine blueberry fields, was explored as a biological control agent and alternatively as a pathogen vector between deer scat and food. A large-scale field survey of wildlife scat indicated that pathogenic E. coli O157:H7 was present, albeit at a low prevalence (1.9% of samples, n = 318), in the Maine lowbush blueberry agroecosystem. A manipulative field experiment verified that, should contact occur between deer scat and blueberry plants and fruit during the summer, contamination with E. coli O157:H7 can occur and persist for more than 72 h. For both the positive control and an experimental scat inoculation treatment, the levels of the bacterial population decreased over time, but at different rates (treatment x time interaction: F (1.9,18.8) = 358.486, P < 0.0001). The positive control inoculation, which resulted in a higher initial E. coli level on fruit, decayed at a faster rate than inoculation of fruit via scat in the experimental treatment. We conducted 2 laboratory studies to elucidate aspects of dung beetle feeding ecology as it relates to suppression of E. coli O157:H7 from deer scat to lowbush blueberry fruit. In both experiments, dung beetles buried the same amount of scat whether or not the scat was inoculated with the pathogen (F(1,6) = 0.001; P = 0.999 and (F (2,17) = 4.10, P = 0.147). Beetles feeding on E. coli inoculated deer scat were not found to vector the pathogen to fruit. In two studies, beetles lowered the amount of pathogenic E. coli persisting in soils compared to soils without beetles (F (2,9) = 7.757; P = 0.05 and F (2,17) = 8.0621, P = 0.004). Our study suggests that the dung beetle species, Onthophagus hecate, has the potential to contribute to the suppression of E. coli O157:H7 in agricultural landscapes.

Regeneration of recombinant antigen microarrays for the automated monitoring of antibodies against zoonotic pathogens in swine sera

The ability to regenerate immobilized proteins like recombinant antigens (rAgs) on surfaces is an unsolved problem for flow-based immunoassays on microarray analysis systems. The regeneration on microarray chip surfaces is achieved by changing the protein structures and desorption of antibodies. Afterwards, reactivation of immobilized protein antigens is necessary for reconstitution processes. Any backfolding should be managed in a way that antibodies are able to detect the protein antigens in the next measurement cycle. The regeneration of rAg microarrays was examined for the first time on the MCR3 flow-based chemiluminescence (CL) microarray analysis platform. The aim was to reuse rAg microarray chips in order to reduce the screening effort and costs. An antibody capturing format was used to detect antibodies against zoonotic pathogens in sera of slaughtered pigs. Different denaturation and reactivation buffers were tested. Acidic glycine-SDS buffer (pH 2.5) and 8 M guanidinium hydrochloride showed the best results in respect of denaturation efficiencies. The highest CL signals after regeneration were achieved with a carbonate buffer containing 10 mM DTT and 0.1% BSA for reactivation. Antibodies against Yersinia spp. and hepatitis E virus (HEV) were detected in swine sera on one immunochip over 4 days and 25 measurement cycles. Each cycle took 10 min for detection and regeneration. By using the rAg microarray chip, a fast and automated screening of antibodies against pathogens in sera of slaughtered pigs would be possible for zoonosis monitoring.

Infections at the animal/human interface: shifting the paradigm from emergency response to prevention at source

The majority of emerging infectious diseases have their source in animals, and emergence occurs at the human/animal interface, when infections in animals breech the species barrier to infect humans, the population in which they are often first identified. The response is frequently characterized by a series of emergency activities to contain and manage the infection in human populations, and at the same time to identify the source of the infection in nature. If infection is found to have a source in animals, and if animals cause a continuous threat of human infection, culling is often recommended with severe economic impact. Currently, efforts are being undertaken for closer interaction at the animal/human interface through joint surveillance and risk assessment between the animal and human medicine sectors, and research is underway in geographic areas where emergence at the animal/human interface has occurred in the past. The goal of this research is to identify infectious organisms in tropical and other wild animals, to genetically sequence these organisms, and to attempt to predict which organisms have the potential to emerge in human populations. It may be more cost-effective to learn from past emergence events, and to shift the paradigm from disease surveillance, detection, and response in humans; to prevention of emergence at the source by understanding and mitigating the factors, or determinants, that influence animal infection. These determinants are clearly understood from the study of previous emergence events and include human-induced changes in natural environments, urban areas, and agricultural systems; raising and processing animal-based foods; and the roles of global trade, migration, and climate change. Better understanding of these factors learned from epidemiological investigation of past and present emergence events, and modeling and study of the cost-effectiveness of interventions that could result in their mitigation, could provide evidence necessary to better address the political and economic barriers to prevention of infections in animals. Such economically convincing arguments for change and mitigation are required because of the basic difference in animal health-driven by the need for profit; and human health-driven by the need to save lives.

Phenotypic and genetic parameters of antibody and delayed-type hypersensitivity responses of lactating Holstein cows

Breeding dairy cattle using diverse phenotypic markers has been suggested as a feasible approach to improve health and decrease the deleterious consequences of infectious diseases. Studies conducted in pigs have demonstrated the value of antibody (AMIR)- and cell (CMIR)-mediated immune responses as quantitative traits for improving immune responsiveness by selecting livestock using estimated breeding values (EBV) for immune response (IR) traits. Studies of cattle have tested the possibility of using IR traits as phenotypic markers to classify cows as high (HR), average (AR) and low (LR) responders. Information is scarce or unavailable about either genetic parameters of AMIR and CMIR or their phenotypic and genetic associations with production, conformation, fertility or health traits in lactating dairy cattle. The objectives of the current study were to evaluate phenotypic and genetic parameters of both AMIR and CMIR as quantitative immunological traits (n=6) in comparison with production, fertility and health traits in dairy cattle for their use in a selection index intended to improve bovine health. Results of this study showed significant AMIR and CMIR responses. Most phenotypic correlations between IR traits and production, health or fertility traits were not significant. The highest heritabilities (h(2)) were observed for delayed-type hypersensitivity (DTH) to killed Candida albicans whole cell (CaWC) at 48 h (0.54) and AMIR day 14 (0.42). The highest genetic correlations were observed between AMIR 14 and AMIR 21 (0.99) and between DTH to CaWC 24h and DTH to CaWC 48 h (0.93). Two important and significant sire EBV correlations were noted between AMIR and fat % (0.18), and between CMIR and protein % (-0.15). In conclusion, this study demonstrated that both AMIR and CMIR are heritable traits in cattle and could be considered for their inclusion in a selection index intended to improve health.

Crohn's disease and the mycobacterioses: a quarter century later. Causation or simple association?

It has been more than 25 years since Mycobacterium paratuberculosis was first proposed as an etiologic agent in Crohn's disease based on the isolation of this organism from several patients. Since that time, a great deal of information has been accumulated that clearly establishes an association between M. paratuberculosis and Crohn's disease. However, data are conflicting and difficult to interpret and the field has become divided into committed advocates and confirmed skeptics. This review is an attempt to provide a thorough and objective summary of current knowledge from both basic and clinical research from the views and interpretations of both the antagonists and proponents. The reader is left to draw his or her own conclusions related to the validity of the issues and claims made by the opposing views and data interpretations. Whether M. paratuberculosis is a causative agent in some cases or simply represents an incidental association remains a controversial topic, but current evidence suggests that the notion should not be so readily dismissed. Remaining questions that need to be addressed in defining the role of M. paratuberculosis in Crohn's disease and future implications are discussed.

Escherichia coli O157:H7 in beef cattle: on farm contamination and pre-slaughter control methods

This paper addresses food safety in beef cattle production, with particular emphasis on factors that affect the prevalence of Escherichia coli O157:H7 in beef cattle and on control methods that have been investigated. Product recalls and foodborne diseases due to this organism continue to occur even though control measures have been under investigation for over 20 years. Most meatborne outbreaks are due to improper food handling practices and consumption of undercooked meat. However, the majority of pathogenic bacteria that can spread at slaughter by cross-contamination can be traced back to the farm rather than originating from the slaughter plant. This would ideally require the adoption of rigorous on-farm intervention strategies to mitigate risks at the farm level. On-farm strategies to control and reduce E. coli O157:H7 at the farm level will reduce the risk of carcass contamination at slaughter and processing facilities although they will not eliminate E. coli O157:H7. The most successful strategy for reducing the risk of contamination of beef and beef products will involve the implementation of both pre- and post-harvest measures.

Knowledge and attitudes toward food safety and use of good production practices among Canadian broiler chicken producers

Provincial broiler-chicken marketing boards in Canada have recently implemented an on-farm food safety program called Safe, Safer, Safest. The purpose of this study was to measure broiler chicken producers' attitudes toward the program and food safety topics and use of highly recommended good production practices (GPP). Mailed and Web-based questionnaires were administered to all producers registered in British Columbia, Ontario, and Quebec in 2008. The response percentage was 33.2% (642 of 1,932). Nearly 70% of respondents rated the program as effective in producing safe chicken, and 49.1% rated the program requirements as easy to implement. Most respondents (92.9%) reported that they do not raise other poultry or keep birds as pets, and 79.8% reported that they clean and disinfect their barns between each flock cycle. Less than 50% of respondents reported that visitors wash their hands or change their clothes before entering barns, 38.4% reported that catching crews wear clean clothes and boots, and 35.8% reported that a crew other than from the hatchery places chicks. Respondents who rated the program requirements as effective or easy to implement were more likely to report the use of five of six highly recommended GPP. Only 21.1% of respondents indicated that Campylobacter can be transmitted from contaminated chicken meat to humans, and 26.6% believed that antimicrobial use in their industry is linked to antimicrobial resistance in humans. Continuing education of producers should focus on improving their awareness of these issues, while mandatory GPP should include those that are known to be effective in controlling Campylobacter and Salmonella in broiler chicken flocks.

Knowledge of zoonoses among those affiliated with the ontario Swine industry: a questionnaire administered to selected producers, allied personnel, and veterinarians

Zoonoses are diseases caused by infectious agents that are transmitted from animals to humans. Some zoonoses have been associated with the pig and pork industry. To ensure the safety of pigs and pork and to improve public health it is essential to understand the level of knowledge of those affiliated with the swine industry. The purpose of our study was to assess the knowledge of and attitude toward zoonotic and other microbial hazards among targeted groups of stakeholders associated with the Ontario swine industry. A postal questionnaire was sent to 409 individuals representing producers, veterinarians, and allied industry personnel. The questionnaire included seven dichotomous and Likert-scale type questions on microbial hazards, addressing topics on familiarity, concern, presence, antimicrobial resistance, and knowledge transfer. The overall response rate was 53% (218/409). More respondents were concerned about the zoonotic potential of Salmonella spp. (53-94%) and swine influenza virus (64-75%) than other hazards. The group of veterinarians were more familiar (>89%) with all microbial hazards than other occupation groups. Additionally, antimicrobial resistance was reported as a problem by more (60%) veterinarians than producers (20%). Educational efforts should focus on preferred methods of knowledge transfer (e.g., producer meetings, magazine) to update swine industry personnel about zoonoses in an attempt to improve food safety and public health.

Factors in foodborne disease control: a brief overview of issues in changing zoonotic disease transmission and the roles of public health and veterinary professionals

Worldwide, foodborne illness remains a constant public health issue, despite improvements in husbandry, food processing, preservation, and preparation. Both veterinary medicine and public health have roles to play in the surveillance, prevention and control of this on-going issue. The objectives of this summary are to describe foodborne hazards of the 21st century, highlighting a few of the recent emerging pathogens, and identify some key areas of focus for prevention and control of foodborne illness. The roles of both public health and the veterinary profession in control will also be discussed.

Prevalence and risk factors for bacterial food-borne zoonotic hazards in slaughter pigs: a review

The Hygiene Package and Regulation EC-2160/2003 require information flow from farm to slaughterhouse to enhance European consumers protection in a 'farm to fork' approach. This obligation especially concerns food-borne zoonotic hazards transmitted to humans through pork consumption, such as thermophilic Campylobacter spp., Listeria monocytogenes, Salmonella enterica and Yersinia enterocolitica. Prevalence estimates of these four hazards are affected by the sampling strategy and diagnostic procedure. Individual prevalence estimates for pig carriage (from digestive contents or lymph nodes collected at slaughterhouse) were higher than individual prevalence estimates for pig shedding (from faeces). Among risk factors described in the literature, poor pen cleaning and disinfection after pig departure to slaughterhouse and poor bio-security measures are of major significance. Moreover, whereas wet feed increases the risk of pig infection by L. monocytogenes, dry feed is a risk factor for Salm. enterica. Mixing batches of pigs, notably in fattening herds, represents a risk for the transmission of Salm. enterica and Y. enterocolitica. Whereas small herds are more infected by thermophilic campylobacters and Y. enterocolitica, higher prevalence of Salmonella is observed in large herds due to a more frequent mixing of batches. Antibiotic treatment during the finishing period increases the risk of transmission of Salm. enterica. The forenamed elements should be taken into account to characterize farms in a risk assessment approach and to improve zoonotic hazard management in the pork food chain.

Research priorities for coordinating management of food safety and water quality

Efforts to exclude disease organisms from farms growing irrigated lettuce and leafy vegetables on California's central coast are conflicting with traditionally accepted strategies to protect surface water quality. To begin resolving this dilemma, over 100 officials, researchers, and industry representatives gathered in April 2007 to set research priorities that could lead to effective co-management of both food safety and water quality. Following the meeting, research priorities were refined and ordered by way of a Delphi process completed by 35 meeting participants. Although water quality and food safety experts conceptualized the issues differently, there were no deep disagreements with respect to research needs. Top priority was given to investigating the fate of pathogens potentially present on farms. Intermediate priorities included characterizing the influence of specific farm management practices on food safety and improving our understanding of vector processes. A scientific subdiscipline focusing on competing risks is needed to characterize and resolve conflicts between human and environmental health.

Loss of virulence genes in Escherichia coli populations during manure storage on a commercial swine farm

Confined livestock production farms typically store their wastes prior to land application. Here, we employed three complementary approaches to evaluate changes in the population structure and stability of virulence genes in Escherichia coli during manure storage on a commercial farm that housed healthy swine. Isolates were genotyped by repetitive extragenic palindromic PCR using the BOXA1R primer and evaluated for the presence of selected virulence genes by PCR. Isolates obtained from the manure holding tank (n = 392) carried estB, fedA, stx(2e), astA, paa, aida-I, and sepA at lower frequencies than isolates obtained from fresh feces (n = 412). Fresh fecal material from the barn was added into diffusion chambers and immersed in the manure holding tank for 7 weeks. The fecal E. coli population was initially dominated by a single genotype, all isolates of which carried fedA and aida-I. After 7 weeks, a genotype that did not carry any virulence genes dominated the surviving population. In a second experiment, 48 fecal isolates of E. coli that varied in their genotypes and virulence gene complement were incubated in diffusion chambers in the manure holding tank for 3 weeks. Over 95% of the inoculum population carried at least one virulence gene, whereas after 3 weeks 90% of the recovered isolates carried no virulence genes. Taken together, these results indicate that during commercial manure storage, there was a significant reduction in the carriage of these virulence genes by E. coli. We propose that loss of virulence genes from enteric pathogens in the farm and in natural environments may, if generalized, contribute to the attenuation of a public health risk from contamination with agricultural wastes.

Effectiveness of simulated interventions in reducing the estimated prevalence ofE. coliO157:H7 in lactating cows in dairy herds

A transmission model developed to investigate the dynamics of Escherichia coli O157:H7 bacteria in a typical Dutch dairy herd was used to assess the effectiveness of vaccination, diet modification, probiotics (colicin) and hygienic measures as to water troughs and bedding, when they are applied single or in combination, in reducing the prevalence of infected animals. The aim was to rank interventions based on their effectiveness in reducing the baseline prevalence of infected animals in the lactating group. The baseline prevalence of the lactating group and the within-herd prevalence were estimated by the model to be 5.02% and 13.96% respectively. The results show that all four interventions, if applied to all four animal groups or only to young stock, are the most effective and will reduce the baseline prevalence by 84% to 99%. In general, combinations of hygiene (applied in all groups) and one other intervention had the highest effectiveness in reducing prevalence in the lactating group. Vaccination and diet modification show a slightly higher effectiveness than colicin and hygiene.

Methodological Quality Assessment of Review Articles Evaluating Interventions to Improve Microbial Food Safety

Review articles are a means of summarizing the potentially vast volume of research on a topic. However, the methodological quality of review articles varies, and reviews on the same topic may reach different conclusions. We evaluated 65 review articles published between 2000 and 2005 that addressed the effectiveness of microbial food safety interventions, using criteria for methodological soundness developed in the medical field. Overall, the methodological quality of the review articles was poor, with none of the reviews providing information on the method of locating primary research studies or the inclusion/exclusion criteria for selecting primary studies. None of the reviews included a critical appraisal of the methodological quality of the primary studies. Less than half of the reviews stated a focused research question, explored possible reasons for differences in the results of primary studies, discussed the generalizability of results, or proposed directions for future research. There is a need to improve the methodological quality of review articles on microbial food safety interventions if they are to be of use in policy and decision making.

Genetic diversity of Anaplasma marginale strains from cattle farms in the province of Palermo, Sicily

Bovine anaplasmosis, caused by the tick-borne rickettsia Anaplasma marginale, is endemic in Sicily and results in economic loss to the cattle industry. This study was designed to characterize strains of A. marginale at the molecular level from cattle in the Province of Palermo, Sicily. Seropositivity of cattle >or=1 year old for A. marginale in the study area ranged from 62% to 100%. The observed prevalence of A. marginale infections in cattle herds ranged from 25% to 100%. Two predominant A. marginale msp4 genotypes were found. A positive correlation was found between the prevalence of infection and the presence of Rhipicephalus (Boophilus) annulatus. Phylogenetic analysis of msp4 sequences of European strains of A. marginale did not provide phylogeographical information. These results suggest that development of farm husbandry systems and vaccines for genetically heterogeneous populations of A. marginale are needed for control of anaplasmosis in this region of Sicily.