Microbial water quality at contrasting recreational areas in a mixed-use watershed in eastern Canada.

Recreational water use is an important source of human enteric illness. Enhanced (episodic) surveillance of natural recreational waters as a supplement to beach monitoring can enrich our understanding of human health risks. From 2011 to 2013, water sampling was undertaken at recreational sites on a watershed in eastern Canada. This study compared the prevalence and associations of human enteric pathogens and fecal indicator organisms. Beach water samples had lower pathogen presence than those along the main river, due to different pollution sources and the hydrological disposition. Pathogen profiles identified from the beach sites suggested a more narrow range of sources, including birds, indicating that wild bird management could help reduce public health risks at these sites. The presence and concentration of indicator organisms did not differ significantly between beaches and the river. However, higher concentrations of generic Escherichia coli were observed when Salmonella and Cryptosporidium were present at beach sites, when Salmonella was present at the river recreational site, and when verotoxigenic E. coli were present among all sites sampled. In this watershed, generic E. coli concentrations were good indicators of potential contamination, pathogen load, and elevated human health risk, supporting their use for routine monitoring where enhanced pathogen testing is not possible.

Drinking and recreational water exposures among Canadians: Foodbook Study 2014-2015.

In Canada, over 400,000 enteric diseases related to drinking water occur each year, highlighting the importance of understanding sources of Canadians' drinking and recreational water exposures. To address this need, a population-based telephone survey of 10,942 Canadians was conducted between 2014 and 2015, assessing Canadian's drinking water sources and recreational water exposures using a seven-day recall method. Results were analyzed by province/territory, season, age group, gender, income, education, and urban/rural status. Store-bought bottled water was reported by nearly 20% of survey respondents as their primary drinking water source, while approximately 11% of respondents reported private well. The proportion of private well users was significantly greater than the national average in the Maritime Provinces where approximately 40-56% of respondents reported this as their primary drinking water source. As expected, Canadians' recreational water activities and exposures (e.g., swimming, pool, lake, and waterpark) peaked during summer and were most commonly reported among children aged 0-9 years. Waterborne disease in Canada requires a multi-faceted public health approach. Canadian baseline data on water exposures can inform policy and public health strategies (e.g., recreational water guidelines, private well water testing recommendations) and support research and risk assessment related to mitigating waterborne illness.

A Comparative Exposure Assessment of Campylobacter in Ontario, Canada.

To inform source attribution efforts, a comparative exposure assessment was developed to estimate the relative exposure to Campylobacter, the leading bacterial gastrointestinal disease in Canada, for 13 different transmission routes within Ontario, Canada, during the summer. Exposure was quantified with stochastic models at the population level, which incorporated measures of frequency, quantity ingested, prevalence, and concentration, using data from FoodNet Canada surveillance, the peer-reviewed and gray literature, other Ontario data, and data that were specifically collected for this study. Models were run with @Risk software using Monte Carlo simulations. The mean number of cells of Campylobacter ingested per Ontarian per day during the summer, ranked from highest to lowest is as follows: household pets, chicken, living on a farm, raw milk, visiting a farm, recreational water, beef, drinking water, pork, vegetables, seafood, petting zoos, and fruits. The study results identify knowledge gaps for some transmission routes, and indicate that some transmission routes for Campylobacter are underestimated in the current literature, such as household pets and raw milk. Many data gaps were identified for future data collection consideration, especially for the concentration of Campylobacter in all transmission routes.

Pooled Nucleic Acid Amplification Test for Screening of Stool Specimens for Shiga Toxin-Producing Escherichia coli.

Shiga toxin-producing Escherichia coli (STEC)-associated enteric illness is attributed to O157 and non-O157 serotypes; however, traditional culture-based methods underdetect non-O157 STEC. Labor and cost of consumables are major barriers to implementation of the CDC recommendation to test all stools for both O157 and non-O157 serotypes. We evaluated the feasibility of a pooled nucleic acid amplification test (NAAT) as an approach for screening stool specimens for STEC. For retrospective evaluation, 300 stool specimens were used to create pools of 10 samples each. The sensitivity was 83% for the preenrichment pooling strategy and 100% for the postenrichment pooling strategy compared with those for individual NAAT results. The difference in cycle threshold (CT) between individual and pooled NAAT results for specimens was significantly lower and more consistent for postenrichment pooling (stx1 mean = 3.90, stx2 mean = 4.28) than those for preenrichment pooling (excluding undetected specimens; stx1 mean = 9.34, stx2 mean = 8.96) (P ≤ 0.0013). Cost of consumables and labor time savings of 48 to 81% and 6 to 66%, respectively, were estimated for the testing of 90 specimens by the postenrichment pooled NAAT strategy on the basis of an expected 1 to 2% positivity rate. A 30-day prospective head-to-head clinical trial involving 512 specimens confirmed the sensitivity and labor savings associated with the postenrichment pooled NAAT strategy. The postenrichment pooled NAAT strategy described here is suitable for efficient large-scale surveillance of all STEC serotypes. Comprehensive detection of STEC will result in accurate estimation of STEC burden and, consequently, appropriate public health interventions.

Evaluation of Various Campylobacter-Specific Quantitative PCR (qPCR) Assays for Detection and Enumeration of Campylobacteraceae in Irrigation Water and Wastewater via a Miniaturized Most-Probable-Number-qPCR Assay.

UNLABELLED: Campylobacter spp. are the leading cause of bacterial gastroenteritis worldwide, and water is increasingly seen as a risk factor in transmission. Here we describe a most-probable-number (MPN)-quantitative PCR (qPCR) assay in which water samples are centrifuged and aliquoted into microtiter plates and the bacteria are enumerated by qPCR. We observed that commonly used Campylobacter molecular assays produced vastly different detection rates. In irrigation water samples, detection rates varied depending upon the PCR assay and culture method used, as follows: 0% by the de Boer Lv1-16S qPCR assay, 2.5% by the Van Dyke 16S and Jensen glyA qPCR assays, and 75% by the Linton 16S endpoint PCR when cultured at 37°C. Primer/probe specificity was the major confounder, with Arcobacter spp. routinely yielding false-positive results. The primers and PCR conditions described by Van Dyke et al. (M. I. Van Dyke, V. K. Morton, N. L. McLellan, and P. M. Huck, J Appl Microbiol 109:1053-1066, 2010, http://dx.doi.org/10.1111/j.1365-2672.2010.04730.x) proved to be the most sensitive and specific for Campylobacter detection in water. Campylobacter occurrence in irrigation water was found to be very low (<2 MPN/300 ml) when this Campylobacter-specific qPCR was used, with the most commonly detected species being C. jejuni, C. coli, and C. lari Campylobacters in raw sewage were present at ∼10(2)/100 ml, with incubation at 42°C required for reducing microbial growth competition from arcobacters. Overall, when Campylobacter prevalence and/or concentration in water is reported using molecular methods, considerable validation is recommended when adapting methods largely developed for clinical applications. Furthermore, combining MPN methods with molecular biology-based detection algorithms allows for the detection and quantification of Campylobacter spp. in environmental samples and is potentially suited to quantitative microbial risk assessment for improved public health disease prevention related to food and water exposures. IMPORTANCE: The results of this study demonstrate the importance of assay validation upon data interpretation of environmental monitoring for Campylobacter when using molecular biology-based assays. Previous studies describing Campylobacter prevalence in Canada utilized primers that we have determined to be nonspecific due to their cross-amplification of Arcobacter spp. As such, Campylobacter prevalence may have been vastly overestimated in other studies. Additionally, the development of a quantitative assay described in this study will allow accurate determination of Campylobacter concentrations in environmental water samples, allowing more informed decisions to be made about water usage based on quantitative microbial risk assessment.

Exploring the relationships between small non-community drinking water system characteristics and water system performance in Ontario, Canada.

The objectives of this work were to investigate the relationships between characteristics of small non-community drinking water systems (SDWSs) and the performance of these systems with respect to Escherichia coli testing and risk ratings. Ontario-wide SDWS data were analysed using regression models with outcomes of (1) having an adverse E. coli test result in the 12 months prior to the last inspection and (2) the SDWS risk rating (high/medium vs. low risk) that is assigned by public health inspectors. Almost 34% (2,364/7,003) of SDWSs did not utilize treatment, more commonly for ground water than surface supplies (P < 0.001). The odds of having a positive E. coli test result were greater in systems using ground water with treatment (OR = 2.00; 95% CI 1.23-3.24) and surface water with treatment (OR = 1.97; 95% CI 1.05-3.71) compared to ground water with no treatment. The odds of having a water system rated high or medium compared to low risk was greater if the water system operated seasonally (OR = 1.36; 95% CI 1.17-1.59), had an adverse E. coli test result (OR = 1.66; 95% CI 1.09-2.53), and in specific facility types. This research helps to inform existing training opportunities available to SDWS operators in Ontario, and to better standardize the SDWS risk assessment process.

Non food-related risk factors of campylobacteriosis in Canada: a matched case-control study.

BACKGROUND: Campylobacteriosis is a prominent bacterial gastrointestinal infection worldwide with several transmission pathways. Its non-foodborne routes have been less documented and quantified. The study aimed to quantitatively explore the role of potential risk factors not directly associated with food for sporadic cases of C. jejuni infection in Canada. METHODS: This retrospective matched case-control study was built on an enhanced campylobacteriosis surveillance system and on a survey of healthy people and their behaviour with regards to potential risk factors for gastrointestinal infections that occurred in the same area in Canada. Eighty-five cases were individually matched by age and season to 170 controls. RESULTS: Through conditional logistic regression, risk factors were found only among water-related factors (drinking untreated water, using tap filter, drinking water from well and swimming in natural water), whereas drinking bottled water was protective. Among the 32 non-water related factors explored, 12 were surprisingly 'protective' factors without relevant explanation for that effect (for example gardening, attending a barbecue, eating food from a fast-food restaurant), suggesting that human infection by Campylobacter may be more frequently acquired at home than outside the home. CONCLUSIONS: This study confirms and quantifies the importance of the waterborne transmission of campylobacteriosis. People are encouraged to drink only treated water and to avoid the ingestion of natural water as much as possible while swimming or playing in water. Globally, general hygiene and proper food handling and cooking practices at home should continue to be encouraged.

Estimating the Relative Role of Various Subcategories of Food, Water, and Animal Contact Transmission of 28 Enteric Diseases in Canada.

OBJECTIVE: Enteric illness represents a significant burden of illness in Canada and internationally. Building on previous research, an expert elicitation was undertaken to explore the routes of transmission for 28 pathogens involved in enteric illness in Canada. This article considers the subcategories of foodborne, waterborne, and animal contact transmission. METHODS: As part of an expert elicitation, 31 experts were asked to provide estimates of source attribution for subcategories of foodborne (n = 15), waterborne (n = 10), and animal contact (n = 3) transmission. The results from an online survey were combined using triangular probability distributions, and median and 90% credible intervals were produced. The total proportion and estimated number of cases of enteric illness attributable to each type of food commodity, water source, and animal exposure route were calculated using results from the larger elicitation survey and from a recent Canadian foodborne burden of illness study (Thomas et al., 2013). RESULTS: Thirty experts provided foodborne subcategory estimates for 15/28 pathogens, waterborne subcategory estimates for 14/28 pathogens and animal contact subcategory estimates for 5/28. The elicitation identified raw produce, recreational water, and farm animal contact as important risk factors for enteric illness. These results also highlighted the complexity of transmission, with greater uncertainty for certain pathogens and routes of transmission. CONCLUSIONS: This study is the first of its kind to explore subcategories of foodborne, waterborne, and animal contact transmission across such a range of enteric pathogens. Despite inherent uncertainty, these estimates present an important quantitative synthesis of the roles of foodborne commodities, water sources, and pathways of animal contact in the transmission of enteric illness in Canada.

Systematic review of expert elicitation methods as a tool for source attribution of enteric illness.

Expert elicitation is a useful tool to explore sources of uncertainty and to answer questions where data are expensive or difficult to collect. It has been used across a variety of disciplines and represents an important method for estimating source attribution for enteric illness. A systematic review was undertaken to explore published expert elicitation studies, identify key considerations, and to make recommendations for designing an expert elicitation in the context of enteric illness source attribution. Fifty-nine studies were reviewed. Five key themes were identified: the expert panel including composition and recruitment; the pre-elicitation material, which clarifies the research question and provides training in uncertainty and probability; the choice of elicitation tool and method (e.g., questionnaires, surveys, and interviews); research design; and analysis of elicited data. Careful consideration of these themes is critical in designing and implementing an expert elicitation in order to reduce bias and produce the best possible results. While there are various epidemiological and microbiological methods available to explore source attribution of enteric illness, expert elicitation provides an opportunity to identify gaps in our understanding and where such studies are not feasible or available, represents the only possible method for synthesizing knowledge about transmission.

Expert elicitation as a means to attribute 28 enteric pathogens to foodborne, waterborne, animal contact, and person-to-person transmission routes in Canada.

Enteric illness contributes to a significant burden of illness in Canada and globally. Understanding its sources is a critical step in identifying and preventing health risks. Expert elicitation is a powerful tool, used previously, to obtain information about enteric illness source attribution where information is difficult or expensive to obtain. Thirty-one experts estimated transmission of 28 pathogens via major transmission routes (foodborne, waterborne, animal contact, person-to-person, and other) at the point of consumption. The elicitation consisted of a (snowball) recruitment phase; administration of a pre-survey to collect background information, an introductory webinar, an elicitation survey, a 1-day discussion, survey readministration, and a feedback exercise, and surveys were administered online. Experts were prompted to quantify changes in contamination at the point of entry into the kitchen versus point of consumption. Estimates were combined via triangular probability distributions, and medians and 90% credible-interval estimates were produced. Transmission was attributed primarily to food for Bacillus cereus, Clostridium perfringens, Cyclospora cayetanensis, Trichinella spp., all three Vibrio spp. categories explored, and Yersinia enterocolitica. Multisource pathogens (e.g., transmitted commonly through both water and food) such as Campylobacter spp., four Escherichia coli categories, Listeria monocytogenes, Salmonella spp., and Staphylococcus aureus were also estimated as mostly foodborne. Water was the primary pathway for Giardia spp. and Cryptosporidium spp., and person-to-person transmission dominated for six enteric viruses and Shigella spp. Consideration of the point of attribution highlighted the importance of food handling and cross-contamination in the transmission pathway. This study provides source attribution estimates of enteric illness for Canada, considering all possible transmission routes. Further research is necessary to improve our understanding of poorly characterized pathogens such as sapovirus and E. coli subgroups in Canada.

Estimates of foodborne illness-related hospitalizations and deaths in Canada for 30 specified pathogens and unspecified agents.

Foodborne illness estimates help to set food safety priorities and create public health policies. The Public Health Agency of Canada estimates that 4 million episodes of foodborne illness occur each year in Canada due to 30 known pathogens and unspecified agents. The main objective of this study was to estimate the number of domestically acquired foodborne illness-related hospitalizations and deaths. Using the estimates of foodborne illness for Canada along with data from the Canadian Hospitalization Morbidity Database (for years 2000-2010) and relevant international literature, the number of hospitalizations and deaths for 30 pathogens and unspecified agents were calculated. Analysis accounted for under-reporting and underdiagnosis. Estimates of the proportion foodborne and the proportion travel-related were incorporated for each pathogen. Monte Carlo simulations were performed to account for uncertainty generating mean estimates and 90% probability intervals. It is estimated that each year there are 4000 hospitalizations (range 3200-4800) and 105 (range 75-139) deaths associated with domestically acquired foodborne illness related to 30 known pathogens and 7600 (range 5900-9650) hospitalizations and 133 (range 77-192) deaths associated with unspecified agents, for a total estimate of 11,600 (range 9250-14,150) hospitalizations and 238 (range 155-323) deaths associated with domestically acquired foodborne illness in Canada. Key pathogens associated with these hospitalizations or deaths include norovirus, nontyphoidal Salmonella spp., Campylobacter spp., VTEC O157 and Listeria monocytogenes. This is the first time Canada has established pathogen-specific estimates of domestically acquired foodborne illness-related hospitalizations and deaths. This information illustrates the substantial burden of foodborne illness in Canada.

Experience, training and confidence among small, non-community drinking water system operators in Ontario, Canada.

The water operator plays an important role in water safety; however, little published research exists that has examined this role. The purpose of this study was to develop a greater understanding of the experience, existing knowledge, confidence and future training needs of the small, non-community drinking water operator in Ontario in order to help guide future outreach and training opportunities. A cross-sectional telephone survey of 332 small, non-community drinking water operators in Ontario was conducted in July and August 2011. Survey questions pertained to respondents' experience as operators, formal training, perceived importance of water safety issues, confidence in handling water safety issues, and future training needs. Approximately 16% (54/330) of respondents had one year or less experience as a water operator, and 60% (199/332) reported that being a water operator was not a chosen profession. Only 37% (124/332) of operators reported completing operator training. Respondents reported a preference for online training courses or on-site training (compared with a classroom setting). Low training rates, inexperience, and in certain situations, low confidence, among many small water system operators highlight a need to provide continued support to the development of ongoing training opportunities in this population.

Spatiotemporal analysis of Cryptosporidium species/genotypes and relationships with other zoonotic pathogens in surface water from mixed-use watersheds.

Nearly 690 raw surface water samples were collected during a 6-year period from multiple watersheds in the South Nation River basin, Ontario, Canada. Cryptosporidium oocysts in water samples were enumerated, sequenced, and genotyped by detailed phylogenetic analysis. The resulting species and genotypes were assigned to broad, known host and human infection risk classes. Wildlife/unknown, livestock, avian, and human host classes occurred in 21, 13, 3, and <1% of sampled surface waters, respectively. Cryptosporidium andersoni was the most commonly detected livestock species, while muskrat I and II genotypes were the most dominant wildlife genotypes. The presence of Giardia spp., Salmonella spp., Campylobacter spp., and Escherichia coli O157:H7 was evaluated in all water samples. The greatest significant odds ratios (odds of pathogen presence when host class is present/odds of pathogen presence when host class is absent) for Giardia spp., Campylobacter spp., and Salmonella spp. in water were associated, respectively, with livestock (odds ratio of 3.1), avian (4.3), and livestock (9.3) host classes. Classification and regression tree analyses (CART) were used to group generalized host and human infection risk classes on the basis of a broad range of environmental and land use variables while tracking cooccurrence of zoonotic pathogens in these groupings. The occurrence of livestock-associated Cryptosporidium was most strongly related to agricultural water pollution in the fall (conditions also associated with elevated odds ratios of other zoonotic pathogens occurring in water in relation to all sampling conditions), whereas wildlife/unknown sources of Cryptosporidium were geospatially associated with smaller watercourses where urban/rural development was relatively lower. Conditions that support wildlife may not necessarily increase overall human infection risks associated with Cryptosporidium since most Cryptosporidium genotypes classed as wildlife in this study (e.g., muskrat I and II genotype) do not pose significant infection risks to humans. Consequently, from a human health perspective, land use practices in agricultural watersheds that create opportunities for wildlife to flourish should not be rejected solely on the basis of their potential to increase relative proportions of wildlife fecal contamination in surface water. The present study suggests that mitigating livestock fecal pollution in surface water in this region would likely reduce human infection risks associated with Cryptosporidium and other zoonotic pathogens.

Investigating public perceptions and knowledge translation priorities to improve water safety for residents with private water supplies: a cross-sectional study in Newfoundland and Labrador.

BACKGROUND: The first objective of this study was to investigate the public perceptions of private water and alternative sources with respect to safety, quality, testing and treatment in Newfoundland and Labrador (NL), Canada. The second objective was to provide public health practitioners with recommendations for improving knowledge translation (KT) efforts in NL, based on assessments of respondents' perceived information needs and preferred KT methods. METHODS: A cross-sectional telephone survey of 618 households with private water supplies was conducted in March-April, 2007. Questions pertained to respondents' perceptions of their tap water, water concerns, alternative water use, well characteristics, and water testing behaviours. RESULTS: Approximately 94% of households were supplied by private wells (50% drilled and 50% dug wells), while 6% obtained water from roadside ponds, rivers or springs (RPRS). While 85% rated their water quality highly, 55% nevertheless had concerns about its overall safety. Approximately 11% of respondents never tested their water, and of the 89% that had, 80% tested at frequencies below provincial recommendations for bacterial testing. More than one-third of respondents reported treating their water in the home, and 78% employed active carbon filtration methods. Respondents wanted more information on testing options and advice on effective treatment methods. Targeted advertising through television, flyers/brochures and/or radio is recommended as a first step to increase awareness. More active KT methods involving key stakeholders may be most effective in improving testing and treatment behaviour. CONCLUSIONS: The results presented here can assist public health practitioners in tailoring current KT initiatives to influence well owner stewardship behaviour.

Harnessing the theoretical foundations of the exponential and beta-Poisson dose-response models to quantify parameter uncertainty using Markov Chain Monte Carlo.

Dose-response models are the essential link between exposure assessment and computed risk values in quantitative microbial risk assessment, yet the uncertainty that is inherent to computed risks because the dose-response model parameters are estimated using limited epidemiological data is rarely quantified. Second-order risk characterization approaches incorporating uncertainty in dose-response model parameters can provide more complete information to decisionmakers by separating variability and uncertainty to quantify the uncertainty in computed risks. Therefore, the objective of this work is to develop procedures to sample from posterior distributions describing uncertainty in the parameters of exponential and beta-Poisson dose-response models using Bayes's theorem and Markov Chain Monte Carlo (in OpenBUGS). The theoretical origins of the beta-Poisson dose-response model are used to identify a decomposed version of the model that enables Bayesian analysis without the need to evaluate Kummer confluent hypergeometric functions. Herein, it is also established that the beta distribution in the beta-Poisson dose-response model cannot address variation among individual pathogens, criteria to validate use of the conventional approximation to the beta-Poisson model are proposed, and simple algorithms to evaluate actual beta-Poisson probabilities of infection are investigated. The developed MCMC procedures are applied to analysis of a case study data set, and it is demonstrated that an important region of the posterior distribution of the beta-Poisson dose-response model parameters is attributable to the absence of low-dose data. This region includes beta-Poisson models for which the conventional approximation is especially invalid and in which many beta distributions have an extreme shape with questionable plausibility.

Estimates of the burden of foodborne illness in Canada for 30 specified pathogens and unspecified agents, circa 2006.

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.

A Canadian application of one health: integration of Salmonella data from various Canadian surveillance programs (2005-2010).

Most bacterial pathogens associated with human enteric illness have zoonotic origins and can be transmitted directly from animals to people or indirectly through food and water. This multitude of potential exposure routes and sources makes the epidemiology of these infectious agents complex. To better understand these illnesses and identify solutions to reduce human disease, an integrative approach like One Health is needed. This article considers the issue of Salmonella in Canada and interprets data collected by several Canadian surveillance and research programs. We describe recovery of Salmonella from various samples collected along the exposure pathway and compare the serovars detected in the different components under surveillance (animal, food, environment, and human). We then present three examples to illustrate how an approach that interprets multiple sources of surveillance data together is able to address issues that transcend multiple departments and jurisdictions. First, differences observed in recovery of Salmonella from different cuts of fresh chicken collected by different programs emphasize the importance of considering the surveillance objectives and how they may influence the information that is generated. Second, the high number of Salmonella Enteritidis cases in Canada is used to illustrate the importance of ongoing, concurrent surveillance of human cases and exposure sources to information domestic control and prevention strategies. Finally, changing patterns in the occurrence of ceftiofur-resistant Salmonella Heidelberg in retail meats and humans demonstrates how integrated surveillance can identify an issue in an exposure source and link it to a trend in human disease. Taken together, surveillance models that encompass different scales can leverage infrastructure, costs, and benefits and generate a multidimensional picture that can better inform disease prevention and control programs.

Detection and characterization of Giardia duodenalis and Cryptosporidium spp. on swine farms in Ontario, Canada.

As part of the C-EnterNet surveillance program of the Public Health Agency of Canada, 122 pooled swine manure samples from 10 farms in Ontario, Canada were collected and tested for Giardia and Cryptosporidium. Giardia duodenalis cysts and Cryptosporidium spp. oocysts were detected using immunofluorescence microscopy. Nested-polymerase chain reaction protocols were performed to amplify the small subunit rRNA gene and the ß-giardin gene for G. duodenalis, and the small subunit rRNA gene and the heat shock protein-70 gene for Cryptosporidium spp. The DNA amplicons were sequenced to determine genotypes and species. A mixed multivariable method was used to compare the presence of Giardia and Cryptosporidium in different stages of production. Both Giardia cysts and Cryptosporidium oocysts were present on all tested farms, with 50.8% of the samples positive for G. duodenalis and 44.3% positive for Cryptosporidium spp. by microscopy, and 66.4% and 55.7%, respectively, positive by polymerase chain reaction (PCR). No significant agreement was observed between microscopy and PCR method to detect Giardia and Cryptosporidium (p<0.05). The prevalence of Giardia in manure pits and finisher pigs did not differ (p>0.05), however, it was less frequent (odds ratio, OR=0.21 [0.07, 0.63]) among sows. Cryptosporidium was more likely (OR=3.6 [1.3, 9.9]) to be detected in manure pits and weaners (OR=3.3 [1.1, 10.0]) compared to finisher pigs, and it was less frequent (OR=0.06 [0.007, 0.55]) in sows than in finishers (p<0.05). DNA sequencing demonstrated that 92.1% of the Giardia isolates were Assemblage B and 7.9% were Assemblage E. The most prevalent Cryptosporidium were Cryptosporidium parvum (55.4%), and Cryptosporidium sp. pig genotype II (37.5%). These findings indicate that the occurrence of zoonotic isolates of G. duodenalis and Cryptosporidium is very high on swine farms in southern Ontario, and that there is a potential for transmission between swine and humans by means of cyst and oocyst contaminated water or foods.

Antimicrobial resistance of Salmonella and generic Escherichia coli isolated from surface water samples used for recreation and a source of drinking water in southwestern Ontario, Canada.

Antimicrobial resistance (AMR) in the aquatic environment represents an important means of introduction and dissemination of resistance genes, and presence of resistant pathogens in surface waters may pose a public health concern to recreational and drinking water users. The purpose of this study was to explore antimicrobial resistance patterns in water samples collected from the Grand River watershed (southwestern Ontario, Canada) to describe the composition, trends and potential risks of AMR in the aquatic environment. As part of FoodNet Canada and the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS), stream water samples were collected bi-weekly from sampling sites within the Grand River watershed in the Waterloo, Ontario sentinel site and tested for the presence and antimicrobial susceptibility of Salmonella spp. (2005-2013) and generic Escherichia coli (2012-2013). Of all samples tested, 16% of Salmonella and 22% of E. coli isolates were resistant to at least one antimicrobial, including three Salmonella isolates and two E. coli isolates that were resistant to Category I antimicrobials, which are classified as very high importance for the treatment of serious bacterial infections in humans. The greatest proportion of resistant E. coli isolates were observed from the river site upstream of the drinking water intake, while the greatest proportion of resistant Salmonella isolates were from sites upstream in the watershed, and at one recreational water site. Salmonella resistance trends remained fairly stable between 2007 and 2013, with the exception of streptomycin and tetracycline which increased in 2010 and 2013. Continued surveillance of antimicrobial resistance patterns and exploration of risk factor data will allow for a better understanding of resistance transmission in the aquatic environment.