A temporal study of Salmonella serovars in animals and humans in Alberta
This thesis is an investigation of the temporal relationship between ' Salmonella' serovars in animals and humans. Passive laboratory-based surveillance data from 1990 to 2001 were obtained from Alberta Agriculture Food and Rural Development, and Alberta Health and Wellness. Nine hundred and sixty-one isolates from chickens, 418 from cattle, 108 from pigs, and 9,188 from humans were analyzed to identify common serovars, trends, and the presence of temporal clusters. 'Salmonella' Typhimurium, Hadar, Heidelberg, and Thompson were in the top five serovars from human and non-human sources. Trends of 'Salmonella' Typhimurium, Heidelberg, and Hadar showed similar patterns. Clusters were observed in 7 of 15, 5 of 5, and 23 of 32 serovars from chickens, cattle, and humans, respectively. Clusters of 'Salmonella' Heidelberg and Typhimurium var. Copenhagen occurred concurrently in chickens and humans. Inferences made from clustering patterns, and limitations and benefits of passive surveillance systems are discussed.