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The aim of this study was to determine serological prevalence for Salmonella in 90 Alberta finishing swine farms over a 5-month period; to evaluate the correlation between the detection of Salmonella by bacteriological culture and serology; and to identify risk factors for Salmonella seroprevalence. Participating farms were visited 3 times. A total of 30 blood and 15 fecal samples were collected from finishing pigs on each farm. VetScreen Salmonella covalent mix-ELISA (Svanovir) and conventional culture were performed. The apparent Salmonella seroprevalences at the sample and farm level were 13.2% (95% confidence interval [CI], 10.5-15.5%) and 83.3% (95% CI, 74-90.4%), respectively. Most of the farms had within-farm seroprevalence ofor=20%, indicating that pigs on these farms had a low exposure to Salmonella. The Salmonella farm status changed frequently across 3 visits. The correlation between fecal prevalence and seroprevalence at the farm and farm visit level was 0.71 (P0.0001) and 0.47 (P0.0001), respectively. The use of meal feed and the reported use of antimicrobials through water were associated with a lower farm seroprevalence for Salmonella. Longitudinal sampling and testing are required to properly evaluate Salmonella on-farm status. The interpretation of existing serological and culture tests for Salmonella in swine should take into consideration their imperfect sensitivity, what these tests actually measure (previous exposure vs. current shedding), and the Salmonella serovar distribution within the targeted population. Further work is necessary to demonstrate the effectiveness of on-farm interventions against Salmonella in swine.

This study used integrated surveillance data to assess the seasonality in retail chicken contamination and of human activities and their role on the seasonality of human endemic salmonellosis. From June 2005 to May 2008, reported cases of salmonellosis were followed-up comprehensively using a standardized questionnaire, and 616 retail chicken breasts were systematically tested for Salmonella, in one Canadian community. Poisson regression was used to model seasonality of human cases, Salmonella in retail chicken, and to assess the relationship between these and selected meteorological variables. The case-case approach was used to compare the activities of salmonellosis cases that occurred during the summer peak to the other cases. There were 216 human endemic salmonellosis cases (incidence rate: 14.7 cases/100,000 person-years), predominantly of Typhimurium and Enteritidis serotypes (28.4% and 20.8%, respectively). The monthly distribution of cases was associated with ambient temperature (p0.001) with a significant seasonal peak in June (p = 0.03) and July (p = 0.0005), but it was not associated with precipitation (p = 0.38). Several activities reported by cases tended to be more frequent during summer. Particularly, attending a barbeque and gardening within the 3 days before the disease onset were two significant risk factors for salmonellosis in June or July compared with the salmonellosis cases that occurred in the other months. Out of all chicken samples, 185 (30%) tested positive for Salmonella spp., Kentucky being the dominant serotype (44.3% of positive samples). The monthly proportion of positive chicken samples showed no seasonal variations (p = 0.30) and was not associated with the monthly count of human cases (p = 0.99). In conclusion, even though evidence generally supports chicken as a primary vehicle of Salmonella to humans, the contamination of retail chicken was not driving the seasonality in human salmonellosis. Attending a barbeque or gardening during the hotter months of the year should be further assessed for their risk.