23 December 2011
Nesbitt, A. et al. (2011) Epidemiology and Infection
In Canada, human salmonellosis is notifiable, with about 5000 cases reported annually, second only to campylobacteriosis in causing bacterial gastroenteritis.
S. Enteritidis has become the most common serotype of human salmonellosis in Canada, surpassing S. Typhimurium and representing about 33% of all human Salmonella isolates reported in 2009.
Recent trends of S. Enteritidis subtypes and their potential sources were described by integrating Salmonella data from several Canadian surveillance and monitoring programmes.
A threefold increase in S. Enteritidis cases from 2003 to 2009 was identified to be primarily associated with phage types 13, 8 and 13a. Other common phage types (4, 1, 6a) showed winter seasonality and were more likely to be associated with cases linked to international travel.
Conversely, phage types 13, 8 and 13a had summer seasonal peaks and were associated with cases of domestically acquired infections. The various agri-food data examined in this study showed that the broiler chicken commodity was more often contaminated with S. Enteritidis than other livestock commodities that were regularly sampled. PT8, PT13 and PT13a were the most common strains in broiler samples, similar to human cases. The data showed an overall increase in recovery of S. Enteriditis from broiler chicken between 2005 and 2009, which paralleled that observed in humans.
Outbreak investigations involving PT8 and PT13 have implicated chicken and eggs as the source of human infection.
Antimicrobial resistance levels in S. Enteritidis sourced from healthy animals on farms and at slaughter, and from retail meats remained low over the study period.