Andrea Nesbitt

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.

Integrated surveillance and potential sources of Salmonella Enteritidis in human cases in Canada from 2003 to 2009

SUMMARY Salmonella Enteritidis has emerged as the most prevalent cause of human salmonellosis in Canada. Recent trends of S. Enteritidis subtypes and their potential sources were described by integrating Salmonella data from several Canadian surveillance and monitoring programmes. A threefold increase in S. Enteritidis cases from 2003 to 2009 was identified to be primarily associated with phage types 13, 8 and 13a. Other common phage types (4, 1, 6a) showed winter seasonality and were more likely to be associated with cases linked to international travel. Conversely, phage types 13, 8 and 13a had summer seasonal peaks and were associated with cases of domestically acquired infections. During agri-food surveillance, S. Enteritidis was detected in various commodities, most frequently in chicken (with PT13, PT8 and PT13a predominating). Antimicrobial resistance was low in human and non-human isolates. Continued integrated surveillance and collaborative prevention and control efforts are required to mitigate future illness.

Description and Burden of Travel‐Related Cases Caused by Enteropathogens Reported in a Canadian Community

BACKGROUND Risk of infections by enteropathogens among individuals traveling outside their country of residence is considered important. Such travel-related cases (TRC) have been poorly estimated and described in Canada. METHODS Data from an enhanced, passive surveillance system of diseases caused by enteropathogens within a Canadian community from June 2005 to May 2009 were used to describe TRC in terms of disease (pathogen, symptoms, hospitalization, duration, and timing of sickness relative to return); demographics (age and gender); and travel (destination, length, and accommodation); and to compare them with non-TRC. RESULTS Among 1,773 reported cases, 446 (25%) were classified as TRC with 9% of them being new immigrants. The main TRC diseases were campylobacteriosis, salmonellosis, and giardiasis. Disease onset occurred before return in 42% of TRC. Main destinations were Latin America/Caribbean and Asia. No differences by month and year were observed for onset, departure, and return dates. In addition to new immigrants, three subgroups of TRC based on travel destination, length of travel, type of accommodation, and age were identified and some diseases were more frequently observed in these subgroups. Generally, TRC did not differ from domestic cases in terms of age, gender, symptoms, hospitalization, and disease duration. Campylobacter coli and Salmonella enteritidis were significantly more frequent among TRC. CONCLUSIONS TRC of diseases caused by enteropathogens that are reportable in Canada represent a significant proportion of the burden of the total diseases. Subgroups of TRC exist and are associated with certain diseases. These results help inform the assessment of the actual risk related to travel for each subgroup of travelers and quantify the attribution of traveling abroad to the overall burden of these gastrointestinal diseases.

Water consumption habits of a south-western Ontario community

A cross-sectional telephone survey (n = 2,332) was performed to better understand the drinking water consumption patterns among residents in Waterloo Region, Ontario, Canada. We investigated the daily volume of water consumed (including tap and bottled) and factors related to that consumption. In addition, we investigated the daily volume of cold tap water consumed by those respondents who consumed no bottled water and the factors that influence this consumption. Among study respondents, 51% exclusively drank tap water, 34% exclusively drank bottled water and 14.5% drank both, with 10 to 75% of all cold water consumed in the previous day being bottled. The mean volume of water consumed in a day (including bottled and tap water) was 1.39 l. Among those who reported to exclusively consume tap water, the mean daily volume of tap water consumed was 1.45 l. The daily amount of cold water consumed in a day was lower for older respondents, more markedly for men than women. More educated respondents consumed more water during the day. Roughly 45% of households reported that they used a carbon filter to treat their water. Roughly 5% of respondents used advanced home treatment devices, including ultraviolet light, reverse osmosis, ozonation or distillation.

A Systematic Review and Meta-Analysis of the Campylobacter spp. Prevalence and Concentration in Household Pets and Petting Zoo Animals for Use in Exposure Assessments

Animal contact is a potential transmission route for campylobacteriosis, and both domestic household pet and petting zoo exposures have been identified as potential sources of exposure. Research has typically focussed on the prevalence, concentration, and transmission of zoonoses from farm animals to humans, yet there are gaps in our understanding of these factors among animals in contact with the public who don’t live on or visit farms. This study aims to quantify, through a systematic review and meta-analysis, the prevalence and concentration of Campylobacter carriage in household pets and petting zoo animals. Four databases were accessed for the systematic review (PubMed, CAB direct, ProQuest, and Web of Science) for papers published in English from 1992–2012, and studies were included if they examined the animal population of interest, assessed prevalence or concentration with fecal, hair coat, oral, or urine exposure routes (although only articles that examined fecal routes were found), and if the research was based in Canada, USA, Europe, Australia, and New Zealand. Studies were reviewed for qualitative synthesis and meta-analysis by two reviewers, compiled into a database, and relevant studies were used to create a weighted mean prevalence value. There were insufficient data to run a meta-analysis of concentration values, a noted study limitation. The mean prevalence of Campylobacter in petting zoo animals is 6.5% based on 7 studies, and in household pets the mean is 24.7% based on 34 studies. Our estimated concentration values were: 7.65x103cfu/g for petting zoo animals, and 2.9x105cfu/g for household pets. These results indicate that Campylobacter prevalence and concentration are lower in petting zoo animals compared with household pets and that both of these animal sources have a lower prevalence compared with farm animals that do not come into contact with the public. There is a lack of studies on Campylobacter in petting zoos and/or fair animals in Canada and abroad. Within this literature, knowledge gaps were identified, and include: a lack of concentration data reported in the literature for Campylobacter spp. in animal feces, a distinction between ill and diarrheic pets in the reported studies, noted differences in shedding and concentrations for various subtypes of Campylobacter, and consistent reporting between studies.

Assessing multiple foodborne, waterborne and environmental exposures of healthy people to potential enteric pathogen sources: effect of age, gender, season, and recall period

SUMMARY Information is lacking in Canada on the frequency of exposures of healthy people to enteric pathogen sources (i.e. water, food, animal contact) at the community level. This information is critical to develop more robust risk assessments and prioritize control measures. A 12-month-long cross-sectional telephone survey of 1200 healthy individuals in a sentinel community was performed. Survey respondents were divided into three recall period groups (3, 7, 14 days). The occurrence of 46 exposures (including water, animal contact, environmental contact and high-risk foods) was assessed per recall period. Effect of age, gender, and season on exposures was modelled and frequencies of exposure were extrapolated. Thirty-five exposures had similar occurrences across recall periods. Age was significant for 23 exposures, season for 18, and gender for three. Exposures that vary by age and season (i.e. bottled water, swimming, etc.) warrant consideration when investigating and analysing cases of enteric 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.

Epidemiological and clinical description of the top three reportable parasitic diseases in a Canadian community.

SUMMARY This study provides a comprehensive epidemio-clinical picture of sporadic, domestically acquired cases of amoebiasis, cryptosporidiosis and giardiasis in one Canadian community based on patient symptom, outcome and exposure data from an enhanced surveillance system. It yields valuable data for estimating the burden of those diseases including the proportion of bloody diarrhoea, hospitalization, and disease duration. Age differences were observed by incidence rate and for some clinical information and exposures to risk factors. For each of the three diseases, the animal/environment-to-person route was the most common possible main transmission route according to the exposure reported, whereas the person-to-person route was the least common. Exposure was higher for the 10–24 years age group of giardiasis cases for swimming in recreational waters (79%) and attending a barbeque (50%). Therefore, comparisons between groups of cases or extrapolation of results when estimating the burden of illness should be adjusted for age.

Campylobacter spp. Prevalence and Levels in Raw Milk: A Systematic Review and Meta-Analysis

Campylobacteriosis is the leading bacterial gastrointestinal disease internationally, contributing significantly to the enteric illness burden. Cases have been associated with the consumption of raw milk, a behavior that has garnered attention recently. Estimates of the prevalence and levels of Campylobacter spp. in raw milk are lacking, which hinders risk assessment attempts. This article is a systematic review and meta-analysis of reported prevalence and levels of zoonotic Campylobacter spp. in the raw milk of cows, goats, and sheep in Canada, the United States, Europe, Australia, and New Zealand. The relevant literature was reviewed, and trained reviewers examined the results for inclusion of articles in the meta-analysis. Relevant data (prevalence and/or level of Campylobacter in raw milk, country of origin, animal species, sample source, Campylobacter species identified, etc.) were extracted, and a meta-analysis was performed in Stata v. 12 (Metaprop command). The weighted mean prevalence of Campylobacter spp. in raw milk samples was 1.18%. Subgroup analyses were conducted to examine how prevalence varied by study characteristics, with the highest prevalence values in studies from the United Kingdom (by country, 6.4%), about cows (by animal species, 1.3%), and including samples taken from inline filters (by sample source, 1.75%) and in studies that included species that are not pathogenic to humans (by Campylobacter species, 1.14%). Two articles each included a single Campylobacter level, 0.16 ± 0.3 and approximately 0.047 most probable number per ml. Despite a relatively low prevalence, consumption of raw milk is inherently risky because no treatment has been used to inactivate pathogens. This potential risk further supports maintaining regulations to limit the sales of raw milk.

Using environmental health officers’ opinions to inform the source attribution of enteric disease: further analysis of the “most likely source of infection”

BackgroundPolicies and programs are needed to mitigate the burden of enteric disease in Canada. Source attribution, a goal of FoodNet Canada, can inform such strategies and can be accomplished with the information provided by expert opinion. This includes environmental health officers’ (EHOs) opinions on the “most likely source of infection” (MLSI) of confirmed cases of enteric disease that are investigated by the Fraser Health Authority in British Columbia, FoodNet Canada’s second sentinel site.MethodsExposure data from the MLSI were categorized into ten groups and summarized for five enteric disease groups using endemic cases in the first analysis, and a combination of endemic and international travel cases for the second analysis. An exploratory analysis was also conducted on risk setting information in the MLSI. The final analysis involved using a logistic regression model (Wald test) to describe the inherent biases in the data.ResultsExposure proportions, by disease group, were similar to those of an analysis of MLSI data from FoodNet Canada’s Ontario sentinel site. Food exposure represented the greatest proportion of overall enteric disease (32.0%), as well as for salmonellosis (45.0%), verotoxigenic E. coli (VTEC) infection (38.1%), and campylobacteriosis (30.0%) cases. The majority of parasitic diseases (41.2%) were attributed to water exposure. Food safety practices and consuming unpasteurized products were more frequently reported for campylobacteriosis (19.7% and 5.4%, respectively) compared to other enteric diseases. More VTEC infection was attributed to domestic travel (4.8%) than the other enteric diseases. Among endemic and international travel-related cases combined, VTEC infection was attributed more to endemic food exposure (35.5%) than international travel (16.1%), but similar proportions of campylobacteriosis were attributed to endemic food exposure (25.1%) and international travel (25.1%). Variations existed in the exposure and risk setting information that EHOs included in the MLSI, and in their propensity to enter food sources over other types of exposures.ConclusionsResults from the MLSI analysis for exposure, risk setting, and EHO bias, are valid contributions for informing source attribution. Important considerations from this work, including strategies to standardize and improve the quality of MLSI data, will enhance source attribution hypotheses.