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Asper D.J.,University of Saskatchewan | Karmali M.A.,Laboratory for Foodborne Zoonoses | Townsend H.,University of Saskatchewan | Rogan D.,Bioniche Life science | Potter A.A.,University of Saskatchewan
Clinical and Vaccine Immunology

Escherichia coli O157:H7 is an important zoonotic pathogen, causing hemolytic uremic syndrome (HUS). The colonization of cattle and human hosts is mediated through the action of effectors secreted via a type III secretion system (T3SS). The structural genes for the T3SS and many of the secreted effectors are located on a pathogenicity island called the locus of enterocyte effacement (LEE). We cloned and expressed the genes coding for 66 effectors and purified each to measure the cross-reactivity of type III secreted proteins from Shiga toxin-producing Escherichia coli (STEC) serotypes. These included 37 LEE-encoded proteins and 29 non-LEE effectors. The serological response against each protein was measured by Western blot analysis and enzym-elinked immunosorbent assay (ELISA) using sera from rabbits immunized with type III secreted proteins (T3SPs) from four STEC serotypes, experimentally infected cattle, and human sera from six HUS patients. Twenty proteins were recognized by at least one of the STEC T3SP-vaccinated rabbits by Western blotting. Several structural proteins (EspA, EspB, and EspD) and a number of effectors (Tir, NleA, and TccP) were recognized by O26-, O103-, O111-, and O157-specific sera. Sera from experimentally infected cattle and HUS patients were tested using an ELISA against each of the proteins. Tir, EspB, EspD, EspA, and NleA were recognized by the majority of the samples tested. A number of other proteins also were recognized by individual serum samples. Overall, proteins such as Tir, EspB, EspD, NleA, and EspA were highly immunogenic in vaccinated and naturally infected subjects and could be candidates for a cross-protective STEC vaccine. Copyright © 2011, American Society for Microbiology. All Rights Reserved. Source

Ravel A.,Laboratory for Foodborne Zoonoses | Davidson V.J.,University of Guelph | Ruzante J.M.,University of Maryland University College | Fazil A.,Public Health Agency of Canada
Foodborne Pathogens and Disease

The study used a structured expert elicitation survey to derive estimates of the foodborne attributable proportion for nine illnesses caused by enteric pathogens in Canada. It was based on a similar study conducted in the United States and focused on Campylobacter, Escherichia coli O157:H7, Listeria monocytogenes, nontyphoidal Salmonella enterica, Shigella spp., Vibrio spp., Yersinia enterocolitica, Cryptosporidium parvum, and Norwalk-like virus. For each pathogen, experts were asked to provide their best estimate and low and high limits for the proportion of foodborne illness relative to total cases. In addition, they provided background information with regard to food safety experience, including self-evaluated expertise for each pathogen on a 5-point scale. A snowball approach was used to identify 152 experts within Canada. The experts' background details were summarized using descriptive statistics. Factor analysis was used to determine whether the variability in best estimates was related to self-assessed level of expertise or other background information. Cluster analysis followed by beta function fitting was undertaken on best estimates from experts who self-evaluated their expertise 3 or higher. In parallel, Monte Carlo resampling was run using triangular distributions based on each expert's best estimate and its limits. Sixty-six experts encompassing various academic backgrounds, fields of expertise, and experiences relevant to food safety provided usable data. Considerable variation between experts in their estimated foodborne attributable proportions was observed over all diseases, without any relationship to the expert's background. Uncertainty about their estimate (measured by the low and high limits) varied between experts and between pathogens as well. Both cluster analysis and Monte Carlo resampling clearly indicated disagreement between experts for Campylobacter, E. coli O157, L. monocytogenes, Salmonella, Vibrio, and Y. enterocolitica. In the absence of more reliable estimates, the observed discrepancy between experts must be explored and understood before one can judge which opinion is the best. © Copyright 2010, Mary Ann Liebert, Inc. Source

Eguale T.,Addis Ababa Institute of Technology | Engidawork E.,Addis Ababa Institute of Technology | Gebreyes W.A.,Ohio State University | Asrat D.,Addis Ababa Institute of Technology | And 4 more authors.
BMC Microbiology

Background: Salmonellae are major worldwide zoonotic pathogens infecting a wide range of vertebrate species including humans. Consumption of contaminated dairy products and contact with dairy cattle represent a common source of non-typhoidal Salmonella infection in humans. Despite a large number of small-scale dairy farms in Addis Ababa and its surrounding districts, little is known about the status of Salmonella in these farms. Results: Salmonella was recovered from the feces of at least one animal in 7.6 % (10/132) of the dairy farms. Out of 1203 fecal samples examined, 30 were positive for Salmonella resulting in a weighted animal level prevalence of 2.3 %. Detection of diarrhea in an animal and in a farm was significantly associated with animal level (p = 0.012) and herd level (p < 0.001) prevalence of Salmonella. Animal level prevalence of Salmonella was significantly associated with age (p = 0.023) and study location; it was highest among those under 6 months of age and in farms from Adaa district and Addis Ababa (p < 0.001). Nine different serotypes were identified using standard serological agglutination tests. The most frequently recovered serotypes were Salmonella Typhimurium (23.3 %), S. Saintpaul (20 %), S. Kentucky (16.7 %) and S. Virchow (16.7 %). All isolates were resistant or intermediately resistant to at least one of the 18 drugs tested. Twenty-six (86.7 %), 19 (63.3 %), 18 (60 %), 16 (53.3 %) of the isolates were resistant to streptomycin, nitrofurantoin, sulfisoxazole and tetracycline, respectively. Resistance to 2 drugs was detected in 27 (90 %) of the isolates. Resistance to 3 or more drugs was detected in 21 (70 %) of the isolates, while resistance to 7 or more drugs was detected in 11 (36.7 %) of the isolates. The rate of occurrence of multi-drug resistance (MDR) in Salmonella strains isolated from dairy farms in Addis Ababa was significantly higher than those isolated from farms outside of Addis Ababa (p = 0.009). MDR was more common in S. Kentucky, S. Virchow and S. Saintpaul. Conclusion: Isolation of Salmonella serotypes commonly known for causing human salmonellosis that are associated with an MDR phenotype in dairy farms in close proximity with human population is a major public health concern. These findings imply the need for a strict pathogen reduction strategy. © 2016 Eguale et al. Source

Anany H.,University of Guelph | Anany H.,Ain Shams University | Lingohr E.J.,Laboratory for Foodborne Zoonoses | Villegas A.,Laboratory for Foodborne Zoonoses | And 4 more authors.
Virology Journal

Background: Lytic bacteriophages have been applied successfully to control the growth of various foodborne pathogens. Sequencing of their genomes is considered as an important preliminary step to ensure their safety prior to food applications. Results: The lytic bacteriophage, SboM-AG3, targets the important foodborne pathogen, Shigella. It is morphologically similar to phage ViI of Salmonella enterica serovar Typhi and a series of phages of Acinetobacter calcoaceticus and Rhizobium meliloti. The complete genome of SboM-AG3 was determined to be 158 kb and was terminally redundant and circularly permuted. Two hundred and sixteen open reading frames (ORFs) were identified and annotated, most of which displayed homology to proteins of Salmonella phage ViI. The genome also included four genes specifying tRNAs. Conclusions: This is the first time that a Vi-specific phage for Shigella has been described. There is no evidence for the presence of virulence and lysogeny-associated genes. In conclusion, the genome analysis of SboM-AG3 indicates that this phage can be safely used for biocontrol purposes. © 2011 Anany et al; licensee BioMed Central Ltd. Source

Thomas M.K.,Public Health Agency of Canada | Murray R.,Public Health Agency of Canada | Flockhart L.,Public Health Agency of Canada | Pintar K.,Laboratory for Foodborne Zoonoses | And 4 more authors.
Foodborne Pathogens and Disease

Estimates of foodborne illness are important for setting food safety priorities and making public health policies. The objective of this analysis is to estimate domestically acquired, foodborne illness in Canada, while identifying data gaps and areas for further research. Estimates of illness due to 30 pathogens and unspecified agents were based on data from the 2000-2010 time period from Canadian surveillance systems, relevant international literature, and the Canadian census population for 2006. The modeling approach required accounting for under-reporting and underdiagnosis and to estimate the proportion of illness domestically acquired and through foodborne transmission. To account for uncertainty, Monte Carlo simulations were performed to generate a mean estimate and 90% credible interval. It is estimated that each year there are 1.6 million (1.2-2.0 million) and 2.4 million (1.8-3.0 million) episodes of domestically acquired foodborne illness related to 30 known pathogens and unspecified agents, respectively, for a total estimate of 4.0 million (3.1-5.0 million) episodes of domestically acquired foodborne illness in Canada. Norovirus, Clostridium perfringens, Campylobacter spp., and nontyphoidal Salmonella spp. are the leading pathogens and account for approximately 90% of the pathogen-specific total. Approximately one in eight Canadians experience an episode of domestically acquired foodborne illness each year in Canada. These estimates cannot be compared with prior crude estimates in Canada to assess illness trends as different methodologies were used. © Copyright 2013, Mary Ann Liebert, Inc. 2013. Source

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