A case–case study comparing the individual risk factors and symptomatology of Salmonella Heidelberg and Salmonella Typhimurium in Ontario in 2015, following implementation of the Ontario Investigation Tools

Salmonella Heidelberg and Salmonella Typhimurium are among the most common serotypes responsible for human salmonellosis in Ontario. Introduction of the Ontario Investigation Tools (OIT) in 2014 allowed for standardized case investigation and reporting. This study compared the risk factors and symptomatology for sporadic S. Heidelberg and S. Typhimurium cases reported in Ontario in 2015, following implementation of the OIT. Multilevel logistic regression models were applied to assess associations between serotype and individual‐level demographic characteristics, exposures and symptoms for sporadic confirmed cases of S. Heidelberg and S. Typhimurium in Ontario in 2015. There were 476 sporadic cases of S. Typhimurium (n = 278) and S. Heidelberg (n = 198) reported in Ontario in 2015. There were significant associations between the odds of the isolate from a case being one of these serotypes, and travel, consumption of sprouts (any type), contact with reptiles and development of malaise, fever or bloody diarrhoea. The S. Typhimurium and S. Heidelberg cases differed in both symptom presentation and risk factors for illness. Case–case comparisons of Salmonella serotypes have some advantages over case–control studies in that these are less susceptible to selection and recall bias while allowing for rapid comparison of cases to identify potential high‐risk exposures that are unique to one of the serotypes when compared to the other. Comparing cases of two different Salmonella serotypes can help to highlight risk factors that may be uniquely associated with one serotype, or more strongly associated with one serotype compared to another. This information may be useful for understanding relative source attribution between common serotypes of Salmonella.     

Brief Guide for Authors

正Journal of Arid Land(JAL)is an international journal(ISSN 1674-6767;CN 65-1278/K)for the natural sciences,sponsored by the Xinjiang Institute of Ecology and Geography,Chinese Academy of Sciences and Science Press.It is published by Science Press and Springer-Verlag Berlin Heidelberg bimonthly.JAL publishes original,innovative,and integrative research from arid and semiarid regions,ad     

Determination of DNA content of whole fish

ABSTRACT:   The DNA content of whole fish from 31 different North Atlantic fish species was determined. Sample preparation was performed on board the fishery research vessel 'Walter Herwig III' directly after catch and sorting. Up to three homogenates were prepared of each 10 specimens per species by mincing the whole fish. The homogenates were heated to destroy nuclease activity, and then stored at frozen temperature until being analyzed in the laboratory. Measurement of DNA content was carried out using the DNA specific fluorescent dye Hoechst 33258 (Serva Biochemica, Heidelberg, Germany). Matrix effects as light scattering and quenching could be estimated by use of standard addition of calf thymus DNA. DNA contents were referred to dry weight of sample material, and ranged from 570 µg to 3500 µg/g dry weight of homogenate. The coefficient of variation did not exceed 25% of mean for one species; coefficient of variation for all investigated species did not exceed 30% of mean, which was 1020 µg/g dry weight.