Infectious Disease Surveillance and One Health

Linking sporadic Salmonella Typhimurium DT9 to a recurrent outbreak source

Project Summary

Human Salmonella infections are acquired from a variety of sources, with eggs being increasingly implicated. Identifying these sources of infection, and understanding their relative importance enables targeted public health interventions to reduce disease. Salmonellosis is a significant and growing public health problem in Victoria. The incidence of notified cases has risen steadily, with close to 4000 cases notified in Victoria in 2014. However, notified cases of disease are thought to be an underestimate with the true incidence of disease in the community estimated to be at least 7-fold higher.

Public health investigation of Salmonella is usually limited to outbreaks and sometimes clusters of disease. This is largely due to difficulties associated with following up the large numbers of individual cases seen annually.  Much of our understanding of foodborne disease causation therefore comes from studying outbreaks, meaning that information on sporadic cases of salmonellosis is limited, particularly with regard to the potential burden of sporadic disease that might be associated with ongoing contamination at a single producers.

This project therefore aims to use whole genome sequencing to identify genetically related isolates and then quantify the number of cases and relative proportion of sporadic versus outbreak cases attributable to these isolates, which all originate at a single egg farm in Victoria, over a five year period. This will provide important information on the potential burden of sporadic salmonellosis in the population.

Project Partners

Department of Health and Human Services (DHHS), Victoria, Australia

Australian National University (ANU), Canberra, Australia