Descriptive study of enteric zoonoses in Ontario, Canada, from 2010 - 2012.

BACKGROUND: Contact with animals and their environment has long been recognized as an important source of enteric zoonoses. However, there are limited data available on the burden of illness associated with specific types of animals in Canada. This study describes the overall burden of enteric zoonoses in Ontario, Canada from 2010 to 2012. METHODS: Confirmed cases of seven enteric zoonotic diseases (campylobacteriosis, cryptosporidiosis, giardiasis, listeriosis, salmonellosis, verotoxin-producing E. coli (VTEC) infection, and yersiniosis) with episode dates from 2010 to 2012 were extracted from the integrated Public Health Information System (iPHIS). Reported exposures were categorized as animal contact, foodborne, waterborne and 'other', with animal contact grouped into nine sub-categories based on the type of animal or transmission setting. Overall incidence rates and proportions by animal exposure categories, age and sex-specific incidence rates and hospitalization and death proportions were calculated and sex proportions compared. RESULTS: Our study found that approximately 26% of the enteric pathogens assessed during the 2010 to 2012 period reported contact with animals and their environments as the mode of transmission. Of enteric disease cases reporting animal contact, farm exposures were reported for 51.3%, dog or cat exposures for 26.3%, and reptile or amphibian exposures for 8.9%. CONCLUSIONS: Contact with animals was reported more frequently during the period 2010 to 2012 in comparison to the period 1997 to 2003 when 6% or less of enteric cases were associated with animal contact. Public health professionals, stakeholders associated with animals and their related industries (e.g., pet treats, mobile zoos, abattoirs), and the public should recognize that animal contact is an important source of enteric illnesses in order to take measures to reduce the burden of illness from animal sources.

Multi-Province Listeriosis Outbreak Linked to Contaminated Deli Meat Consumed Primarily in Institutional Settings, Canada, 2008.

A multi-province outbreak of listeriosis occurred in Canada from June to November 2008. Fifty-seven persons were infected with 1 of 3 similar outbreak strains defined by pulsed-field gel electrophoresis, and 24 (42%) individuals died. Forty-one (72%) of 57 individuals were residents of long-term care facilities or hospital inpatients during their exposure period. Descriptive epidemiology, product traceback, and detection of the outbreak strains of Listeria monocytogenes in food samples and the plant environment confirmed delicatessen meat manufactured by one establishment and purchased primarily by institutions was the source of the outbreak. The food safety investigation identified a plant environment conducive to the introduction and proliferation of L. monocytogenes and persistently contaminated with Listeria spp. This outbreak demonstrated the need for improved listeriosis surveillance, strict control of L. monocytogenes in establishments producing ready-to-eat foods, and advice to vulnerable populations and institutions serving these populations regarding which high-risk foods to avoid.

A focus group study of enteric disease case investigation: successful techniques utilized and barriers experienced from the perspective of expert disease investigators.

BACKGROUND: In Ontario, Canada, enteric case investigators perform a number of functions when conducting telephone interviews including providing health education, collecting data for regulatory purposes ultimately to prevent further illness, enforcement, illness source attribution and outbreak detection. Information collected must be of high quality as it may be used to inform decisions about public health actions that could have significant consequences such as excluding a person from work, recalling a food item that is deemed to be a health hazard, and/or litigations. The purpose of this study was to describe, from the perspectives of expert investigators, barriers experienced and the techniques used to overcome these barriers during investigation of enteric disease cases. METHODS: Twenty eight expert enteric investigators participated in one of four focus groups via teleconference. Expert investigators were identified based on their ability to 1) consistently obtain high quality data from cases 2) achieve a high rate of completion of case investigation questionnaires, 3) identify the most likely source of the disease-causing agent, and 4) identify any possible links between cases. Qualitative data analysis was used to identify themes pertaining to successful techniques used and barriers experienced in interviewing enteric cases. RESULTS: Numerous barriers and strategies were identified under the following categories: case investigation preparation and case communication, establishing rapport, source identification, education to prevent disease transmission, exclusion, and linking cases. Unique challenges experienced by interviewers were how to collect accurate exposure data and educate cases in the face of misconceptions about enteric illness, as well as how to address tensions created by their enforcement role. Various strategies were used by interviewers to build rapport and to enhance the quality of data collected. CONCLUSIONS: To our knowledge, this is the first study to examine the perspectives of expert enteric disease case investigators on successful interview techniques and barriers experienced during enteric case investigation. A number of recommendations could improve the process of enteric case investigation in the Ontario context which include formal training and development of resource materials pertaining to interviewing, standardized interviewing tools, strategies to address cultural and language barriers, and the implementation of the single interviewer approach.

Whole genome sequencing of increased number of azithromycin-resistant Shigella flexneri 1b isolates in Ontario.

Azithromycin (AZM) resistance among Shigella is a major public health concern. Here, we investigated the epidemiology of Shigella flexneri serotype 1b recovered during 2016-2018 in Ontario, to describe the prevalence and spread of AZM resistance. We found that 72.3% (47/65) of cases were AZM-resistant (AZMR), of which 95.7% (45/47) were among males (P < 0.001). Whole-genome based phylogenetic analysis showed three major clusters, and 56.9% of isolates grouped within a single closely-related cluster (0-10 ∆SNP). A single AZMR clonal population was persistent over 3 years and involved 67.9% (36/53) of all male cases, and none reported international travel. In 2018, a different AZMR cluster appeared among adult males not reporting travel. A proportion of isolates (10.7%) with reduced susceptibility to ciprofloxacin (CIP) due to S83L mutation in gyrA were AZM susceptible, and 71.4% reported international travel. Resistance to AZM was due to the acquisition of mph gene-bearing incFII plasmids having > 95% nucleotide similarity to pKSR100. Plasmid-borne resistance limiting treatment options to AZM, ceftriaxone (CRO) and CIP was noted in a single isolate. We characterized AZMR isolates circulating locally among males and found that genomic analysis can support targeted prevention and mitigation strategies against antimicrobial-resistance.

Intestinal toxemia botulism in 3 adults, Ontario, Canada, 2006-2008.

Five cases of intestinal toxemia botulism in adults were identified within an 18-month period in or near Toronto, Ontario, Canada. We describe findings for 3 of the 5 case-patients. Clinical samples contained Clostridium botulinum spores and botulinum neurotoxins (types A and B) for extended periods (range 41-61 days), indicative of intestinal toxemia botulism. Patients' clinical signs improved with supportive care and administration of botulinum antitoxin. Peanut butter from the residence of 1 case-patient yielded C. botulinum type A, which corresponded with type A spores found in the patient's feces. The food and clinical isolates from this case-patient could not be distinguished by pulsed-field gel electrophoresis. Two of the case-patients had Crohn disease and had undergone previous bowel surgery, which may have contributed to infection with C. botulinum. These cases reinforce the view that an underlying gastrointestinal condition is a risk factor for adult intestinal toxemia botulism.

A descriptive study of reportable gastrointestinal illnesses in Ontario, Canada, from 2007 to 2009.

BACKGROUND: Gastrointestinal illnesses (GI) continue to pose a substantial burden in terms of morbidity and economic impact in Canada. We describe the epidemiology of reportable GI in Ontario by characterizing the incidence of each reportable GI, as well as associated demographics, clinical outcomes, seasonality, risk settings, and likely sources of infection. METHODS: Reports on laboratory confirmed cases of amebiasis, botulism, campylobacteriosis, cryptosporidiosis, cyclosporiasis, giardiasis, hepatitis A, listeriosis, paratyphoid fever, salmonellosis, shigellosis, typhoid fever, illness due to verotoxin-producing Escherichia coli (VTEC-illness), and yersiniosis, from January 1, 2007 to December 31, 2009 were obtained from Ontario's passive reportable disease surveillance system. Cases were classified by history of relevant travel, association with outbreaks, and likely source of infection, obtained through follow-up of reported cases by local health authorities. RESULTS: There were 29,897 GI reported by health authorities in Ontario from 2007 to 2009. The most frequently reported diseases were campylobacteriosis (10,916 cases or 36.5% of all GI illnesses) and salmonellosis (7,514 cases, 25.1%). Overall, 26.9% of GI cases reported travel outside of Ontario during the relevant incubation period. Children four years of age and younger had the highest incidence rate for most GI, and significantly more (54.8%, p<0.001) cases occurred among males than females. The most commonly reported sources of infections were food (54.2%), animals (19.8%), and contact with ill persons (16.9%). Private homes (45.5%) and food premises (29.7%) were the most commonly reported exposure settings. Domestic cases of campylobacteriosis, cryptosporidiosis, giardiasis, salmonellosis, and VTEC-illness showed seasonal patterns with incidence peaking in the summer months. CONCLUSIONS: Reportable GI continues to be a burden in Ontario. Since more than one in four GI cases experienced in Ontario were acquired outside of the province, international travel is an important risk factor for most GI. Because private homes are the most commonly reported risk settings and the main suspect sources of infection are food, animal contact and ill persons, these findings support the continued need for public health food safety programs, public education on safe handling of food and animals, and proper hand hygiene practices.

One Health and EcoHealth in Ontario: a qualitative study exploring how holistic and integrative approaches are shaping public health practice in Ontario.

BACKGROUND: There is a growing recognition that many public health issues are complex and can be best understood by examining the relationship between human health and the health of the ecosystems in which people live. Two approaches, One Health and Ecosystem Approaches to Health (EcoHealth), can help us to better understand these intricate and complex connections, and appear to hold great promise for tackling many modern public health dilemmas. Although both One Health and EcoHealth have garnered recognition from numerous health bodies in Canada and abroad, there is still a need to better understand how these approaches are shaping the practice of public health in Ontario.The purpose of this study was to characterize how public health actors in Ontario are influenced by the holistic principles which underlie One Health and EcoHealth, and to identify important lessons from their experiences. METHODS: Ten semi-structured interviews were conducted with ten participants from the public health sphere in Ontario. Participants encompassed diverse perspectives including infectious disease, food systems, urban agriculture, and environmental health. Interviews were recorded, transcribed and analyzed using qualitative content analysis to identify major themes and patterns. RESULTS: Four major themes emerged from the interviews: the importance of connecting human health with the environment; the role of governance in promoting these ideas; the value of partnerships and collaborations in public health practice; and the challenge of operationalizing holistic approaches to public health. Overall study participants were found to be heavily influenced by concepts couched in EcoHealth and One Health literature, despite a lack of familiarity with these fields. CONCLUSIONS: Although One Health and EcoHealth are lesser known approaches in the public health sphere, their holistic and systems-based principles were found to influence the thoughts, values and experiences of public health actors interviewed in this study. This study also highlights the critical role of governance and partnerships in facilitating a holistic approach to health. Further research on governance and partnership models, as well as systems-based organizational working practices, is needed to close the gap between One Health and EcoHealth theory and public health practice.

Evaluating risk factors for endemic human Salmonella Enteritidis infections with different phage types in Ontario, Canada using multinomial logistic regression and a case-case study approach.

BACKGROUND: Identifying risk factors for Salmonella Enteritidis (SE) infections in Ontario will assist public health authorities to design effective control and prevention programs to reduce the burden of SE infections. Our research objective was to identify risk factors for acquiring SE infections with various phage types (PT) in Ontario, Canada. We hypothesized that certain PTs (e.g., PT8 and PT13a) have specific risk factors for infection. METHODS: Our study included endemic SE cases with various PTs whose isolates were submitted to the Public Health Laboratory-Toronto from January 20th to August 12th, 2011. Cases were interviewed using a standardized questionnaire that included questions pertaining to demographics, travel history, clinical symptoms, contact with animals, and food exposures. A multinomial logistic regression method using the Generalized Linear Latent and Mixed Model procedure and a case-case study design were used to identify risk factors for acquiring SE infections with various PTs in Ontario, Canada. In the multinomial logistic regression model, the outcome variable had three categories representing human infections caused by SE PT8, PT13a, and all other SE PTs (i.e., non-PT8/non-PT13a) as a referent category to which the other two categories were compared. RESULTS: In the multivariable model, SE PT8 was positively associated with contact with dogs (OR=2.17, 95% CI 1.01-4.68) and negatively associated with pepper consumption (OR=0.35, 95% CI 0.13-0.94), after adjusting for age categories and gender, and using exposure periods and health regions as random effects to account for clustering. CONCLUSIONS: Our study findings offer interesting hypotheses about the role of phage type-specific risk factors. Multinomial logistic regression analysis and the case-case study approach are novel methodologies to evaluate associations among SE infections with different PTs and various risk factors.

The epidemiology of travel-related Salmonella Enteritidis in Ontario, Canada, 2010-2011.

BACKGROUND: Increases in the number of salmonellosis cases due to Salmonella Enteritidis (SE) in 2010 and 2011 prompted a public health investigation in Ontario, Canada. In this report, we describe the current epidemiology of travel-related (TR) SE, compare demographics, symptoms and phage types (PTs) of TR and domestically-acquired (DA) cases, and estimate the odds of acquiring SE by region of the world visited. METHODS: All incident cases of culture confirmed SE in Ontario obtained from isolates and specimens submitted to public health laboratories were included in this study. Demographic and illness characteristics of TR and DA cases were compared. A national travel survey was used to provide estimates for the number of travellers to various destinations to approximate rates of SE in travellers. Multivariate logistic regression was used to estimate the odds of acquiring SE when travelling to various world regions. RESULTS: Overall, 51.9% of SE cases were TR during the study period. This ranged from 35.7% TR cases in the summer travel period to 65.1% TR cases in the winter travel period. Compared to DA cases, TR cases were older and were less likely to seek hospital care. For Ontario travellers, the adjusted odds of acquiring SE was the highest for the Caribbean (OR 37.29, 95% CI 17.87-77.82) when compared to Europe. Certain PTs were more commonly associated with travel (e.g., 1, 4, 5b, 7a, Atypical) than with domestic infection. Of the TR cases, 88.9% were associated with travel to the Caribbean and Mexico region, of whom 90.1% reported staying on a resort. Within this region, there were distinct associations between PTs and countries. CONCLUSIONS: There is a large burden of TR illness from SE in Ontario. Accurate classification of cases by travel history is important to better understand the source of infections. The findings emphasize the need to make travellers, especially to the Caribbean, and health professionals who provide advice to travellers, aware of this risk. The findings may be generalized to other jurisdictions with travel behaviours in their residents similar to Ontario residents.

Nuggets of Wisdom: Salmonella Enteritidis Outbreaks and the Case for New Rules on Uncooked Frozen Processed Chicken.

In 2014 and 2015, three Canadian Salmonella serotype Enteritidis outbreak investigations implicated uncooked, frozen, processed chicken products produced at the same establishment, namely establishment A. In November 2014, a sustained increase in the number of reported domestically acquired Salmonella Enteritidis cases in Ontario led to the first outbreak investigation, which implicated uncooked, frozen, processed chicken products produced at establishment A. In June 2015, the identification of pulsed-field gel electrophoresis patterns that had not been previously reported in Canada led to a national Salmonella Enteritidis investigation. Of 51 cases reported nationally, 35 were from Ontario. Uncooked, frozen, processed chicken products produced at establishment A were identified as the source of the outbreak, and public health action was taken as a result of this second investigation. In September 2015, a sustained increase in the number of domestically acquired Salmonella Enteritidis PT13a cases in Ontario led to a third outbreak investigation, which identified a total of 36 PT13a cases. Uncooked, frozen, processed chicken products produced at establishment A were again identified as the source of the outbreak. Outbreaks have been linked to uncooked, frozen, processed chicken products since the late 1990s. Information collected during the three outbreak investigations, and from other jurisdictions, suggests that the breaded and prebrowned appearance of the product, as well as factors related to product packaging and marketing, result in consumer misperception that this raw product is cooked. This misperception may result in mishandling and improper cooking. The three outbreaks described in this article highlight the potential ongoing risks to consumers from these products and support interventions to prevent contamination at the source level and infection at the consumer level.

Estimating the under-reporting rate for infectious gastrointestinal illness in Ontario.

BACKGROUND: In Ontario, infectious gastrointestinal illness (IGI) reporting can be represented by a linear model of several sequential steps required for a case to be captured in the provincial reportable disease surveillance system. Since reportable enteric data are known to represent only a small fraction of the total IGI in the community, the objective of this study was to estimate the under-reporting rate for IGI in Ontario. METHODS: A distribution of plausible values for the under-reporting rate was estimated by specifying input distributions for the proportions reported at each step in the reporting chain, and multiplying these distributions together using simulation methods. Input distributions (type of distribution and parameters) for the proportion of cases reported at each step of the reporting chain were determined using data from the Public Health Agency of Canada's National Studies on Acute Gastrointestinal Illness (NSAGI) initiative. RESULTS: For each case of enteric illness reported to the province of Ontario, the estimated number of cases of IGI in the community ranged from 105 to 1,389, with a median of 285, and a mean and standard deviation of 313 and 128, respectively. CONCLUSIONS: Each case of enteric illness reported to the province of Ontario represents an estimated several hundred cases of IGI in the community. Thus, reportable disease data should be used with caution when estimating the burden of such illness. Program planners and public health personnel may want to consider this fact when developing population-based interventions.

Investigation of clusters of giardiasis using GIS and a spatial scan statistic.

BACKGROUND: Giardia lamblia is the most frequently identified human intestinal parasite in Canada with prevalence estimates of 4-10%. However, infection rates vary by geographical area and localized 'pockets' of high or low infection rates are thought to exist. Water-borne transmission is one of the major routes of infection. Sources of contamination of drinking water include humans, domestic and wild animals. A previous study in southern Ontario, Canada, indicated a bivariate association between giardiasis rates and livestock density and/or manure use on agricultural land; however these variables were not significant when the variable 'rural' was added to the model. In that study, urban areas were defined as those with a minimum of 1,000 persons and a population density of at least 400 persons per Km2; all other areas were considered rural. This paper investigates the presence of local giardiasis clusters and considers the extent to which livestock density and manure application on agricultural land might explain the 'rural' effect. A spatial scan statistic was used to identify spatial clusters and geographical correlation analysis was used to explore associations of giardiasis rates with manure application on agricultural land and livestock density. RESULTS: Significant (P < 0.05) high rate spatial clusters were identified in a number of areas. Results also showed significant (P < 0.05) associations between giardiasis rates and both livestock density and manure application on agricultural land. However, the associations were observed in only two regions. CONCLUSIONS: There is evidence that giardiasis clusters in space in southern Ontario. However, there is no strong evidence to suggest that either livestock density or manure application on agricultural land plays an important role in the epidemiology of giardiasis in the study area. Therefore these factors do not seem to explain the higher rates of giardiasis reported in rural areas. The spatial scan statistics methodology used in this study has an important potential use in disease surveillance for confirming or refuting cluster alarms.

Geographical and temporal distribution of human giardiasis in Ontario, Canada.

BACKGROUND: Giardia is the most frequently identified intestinal parasite in North America. Although information on geographical distribution of giardiasis is critical in identifying communities at high risk, little has been done in this area. Therefore, the objective of this study was to investigate the geographical and temporal distribution of human giardiasis in Ontario in order to identify possible high risk areas and seasons. Two spatial scales of analyses and two disease measures were used with a view to identifying the best of each in assessing geographical patterns of giardiasis in Ontario. Global Moran's I and Moran Local Indicators of Spatial Associations were used to test for evidence of global and local spatial clustering, respectively. RESULTS: There were seasonal patterns with summer peaks and a significant (P < 0.001) decreasing temporal trend. Significant (P < 0.05) global spatial clustering of high rates was observed at the Census Sub-division spatial scale but not at the Census Division scale. The Census Sub-division scale was a better scale of analyses but required spatial empirical Bayesian smoothing of the rates. A number of areas with significant local clustering of giardiasis rates were identified. CONCLUSIONS: The study identified spatial and temporal patterns in giardiasis distribution. This information is important in guiding decisions on disease control strategies. The study also showed that there is benefit in performing spatial analyses at more than one spatial scale to assess geographical patterns in disease distribution and that smoothing of disease rates for mapping in small areas enhances visualization of spatial patterns.

Enteric illness in Ontario, Canada, from 1997 to 2001.

Enteric illness is a common problem worldwide. In Ontario (population of 11.4 million, 2001 Census of Canada), laboratory-confirmed cases of "reportable" enteric diseases are reported to local health units. Public health staff members investigate these illnesses and subsequently report details to the Ministry of Health and Long-Term Care through an electronic reporting system. From 1997 to 2001, 44,451 sporadic cases of illness attributable to eight enteric pathogens (Campylobacter, Salmonella, verotoxin-producing Escherichia coli, Yersinia, Shigella, hepatitis A, Listeria, and Clostridium botulinum) were reported. This number was less than the 56,690 cases reported from 1992 to 1996. Campylobacter accounted for the highest annual average incidence rate at 42.3 cases per 100,000 persons, with Salmonella following at 22.6, verotoxin-producing E. coli at 3.7, Yersinia at 3.0, Shigella at 2.7, hepatitis A at 2.3, and Listeria at 0.3. The 4 months from June to September accounted for almost half (46.5%) of all cases. For 74.0% of the outbreaks associated with these eight enteric pathogens, foodborne contamination was identified as the mode of transmission. Poultry and other meat items accounted for 68.4% of the food items when food was identified as the vehicle. Admittedly, the "foods" and "modes of transmission" identified may have been subject to investigator bias based on previous knowledge. The most common risk setting, which was reported in approximately half of the cases, was private homes; travel-associated illness and restaurants were the second and third most frequently reported risk settings at 24.6 and 14.1%, respectively. Findings from this study suggest that public health efforts should be directed toward safe food handling in the home during the summer months.

A descriptive study of human Salmonella serotype typhimurium infections reported in Ontario from 1990 to 1998.

BACKGROUND: Salmonella infections cause gastrointestinal and systemic diseases worldwide and are the leading causes of food-borne illnesses in North America (1-4). Salmonella serotype typhimurium (ST), in particular, is increasingly becoming a major public health concern because of its ability to acquire multiple resistant genes (5,6). OBJECTIVE: To describe demographic, temporal and geographical distributions, and reported risk factors of nonoutbreak cases of ST reported to a surveillance system in Ontario. METHODOLOGY: Descriptive analyses were performed on data on salmonellosis cases reported in Ontario between 1990 and 1998. Direct age- and sex-standardized rates were computed, and temporal trend analyses were performed using simple linear regression and a general additive model with a locally weighted regression (LOESS) smoother. RESULTS: The mean annual rates of infections with all Salmonella serotypes and with ST were 27 cases per 100,000 persons and 3.7 cases per 100,000 persons, respectively. Males and children under five years of age had significantly higher rates of both ST and ST definitive type 104 (DT104) infections. There was also evidence of temporal clustering of all strains of Salmonella, with significantly more cases being reported during the summer. Significantly higher rates of ST DT104 were observed in urban areas compared with rural areas, suggesting potential differences in the geographical distribution of risk factors. CONCLUSIONS: Information on demographic, temporal and geographical distributions, and risk factors is critical in planning disease control strategies. Further prospective analytical observation studies are needed to gain a better understanding of the epidemiology of ST and ST DT104 in Ontario, which will better guide disease control decisions.

Increased burden of illness associated with antimicrobial-resistant Salmonella enterica serotype typhimurium infections.

This study investigated the burden of illness associated with 440 cases of Salmonella enterica serotype Typhimurium infection identified in Canada between December 1999 and November 2000. We categorized case subjects' infections by definitive phage type 104 (DT104) and antimicrobial-resistance patterns. These variables were then investigated as risk factors for hospitalization. Hospitalization was more likely to occur among case subjects whose infections were resistant to at least ampicillin, chloramphenicol and/or kanamycin, streptomycin, sulphamethoxazole, and tetracycline (R-type AK/CSSuT; odds ratio [OR], 2.3; P=.003), compared with case subjects with AK/CSSuT-susceptible infections, and among case subjects with non-DT104 R-type AKSSuT infections (OR, 3.6; P=.005), compared with case subjects with non-DT104 AKSSuT-susceptible infections. In contrast, hospitalization rates did not differ between case subjects with DT104 infections and case subjects with non-DT104 infections or between case subjects with DT104 R-type ACSSuT infections and case subjects with DT104 ACSSuT-susceptible infections. We estimated that 57% of the hospitalizations among AK/CSSuT case subjects and 72% of the hospitalizations among non-DT104 AKSSuT case subjects were attributable to the resistance patterns of the infections.