During the winter of 2000 to 2001, an outbreak due to Salmonella Enteritidis (SE) phage type 30 (PT30), a rare strain, was detected in Canada. The ensuing investigation involved Canadian and American public health and food regulatory agencies and an academic research laboratory. Enhanced laboratory surveillance, including phage typing and pulsed-field gel electrophoresis, was used to identify cases. Case questionnaires were administered to collect information about food and environmental exposures. A case-control study with 16 matched case-control pairs was conducted to test the hypothesis of an association between raw whole almond consumption and infection. Almond samples were collected from case homes, retail outlets, and the implicated processor, and environmental samples were collected from processing equipment and associated farms for microbiological testing. One hundred sixty-eight laboratory-confirmed cases of SE PT30 infection (157 in Canada, 11 in the United States) were identified between October 2000 and July 2001. The case-control study identified raw whole almonds as the source of infection (odds ration, 21.1; 95% confidence interval, 3.6 to infinity). SE PT30 was detected in raw whole natural almonds collected from home, retail, distribution, and warehouse sources and from environmental swabs of processing equipment and associated farmers' orchards. The frequent and prolonged recovery of this specific organism from a large agricultural area was an unexpected finding and may indicate significant diffuse contamination on these farms. Identification of almonds as the source of a foodborne outbreak is a previously undocumented finding, leading to a North American recall of this product and a review of current industry practices.

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.

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 populationbased interventions.MeSH terms: Gastroenteritis; infectious disease reporting; surveillance; Ontario; Canada La traduction du résumé se trouve à la fin de l'article.

BackgroundGastrointestinal 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.MethodsReports 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.ResultsThere 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.ConclusionsReportable 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.