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The Epidemiology of Human Salmonella Enteritidis Infections in Ontario, Canada, 2007-2009

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Title: The Epidemiology of Human Salmonella Enteritidis Infections in Ontario, Canada, 2007-2009
Author: Varga, Csaba
Department: Department of Population Medicine
Program: Population Medicine
Advisor: Guerin, Michele
Abstract: In this thesis, 1,932 Salmonella Enteritidis infections reported to Ontario’s surveillance system from 2007 to 2009 were evaluated. Annual age-and sex-adjusted incidence rates were calculated across Ontario’s public health units. Poisson regression was used to estimate incidence rate ratios of cases among years, seasons, age groups, and sexes. A scan statistic was used to identify spatial clusters of high infection rates within the Greater Toronto Area. Negative binomial regression was used to identify area-level associations between infection rates and socioeconomic status indicators. In Toronto, global and local clustering of infections were evaluated. Across Ontario’s health regions, cases with major phage types were classified by their incidence rates, clinical symptoms, and exposure settings. A scan statistic was applied to detect phage type-specific spatial, temporal, and space-time clusters. The annual age-and-sex-adjusted incidence rates per 100,000 person-years were 4.4 in 2007, and 5.2 in both 2008 and 2009. Higher incidence of infections was observed in the years 2008 and 2009, in the spring, and in children. Within three public health units of the Greater Toronto Area, a high rate spatial cluster was identified in downtown Toronto. Areas with high average number of children at home per family, areas with high and areas with low average median family income, and areas with a medium proportion of visible minority population had the highest infection rates. In Toronto, the global cluster analysis showed significant maximum spatial clustering of high infection rates at 3.3 km. The local cluster analysis identified distinct areas with high infection rates, mainly in downtown Toronto. The major phage types in Ontario were 8, 13a, 13, 1, 5b, and 4. Diarrhea, abdominal pain, and fever were the most common symptoms. International travel and unknown exposure settings were the most frequently reported settings for PT 5b, 4, and 1 cases. Unknown, private home, food premise, and international travel were the most frequently reported exposure settings for PT 8, 13, and 13a cases. A number of PT-specific spatial, temporal and space-time clusters were identified. The study results will aid public health authorities to design effective disease prevention and control programs, and early detection systems.
URI: http://hdl.handle.net/10214/8646
Date: 2014-12
Rights: Attribution-NoDerivs 2.5 Canada


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Attribution-NoDerivs 2.5 Canada Except where otherwise noted, this item's license is described as Attribution-NoDerivs 2.5 Canada