Applied Epidemiology in South Australia 2014 - 2015
Creators: name: Stewart, Jeffrey
Publisher: name: The Australian National University
Year: 2015
Subjects: Blood Borne Viruses (BBV)
Communicable Disease Control Branch
CDCB
Disease Surveillance and Investigation Section
DSIS
Master of Philosophy in Applied Epidemiology
MAE
Sexually Transmitted Infections
STI
Salmonella Typhimurium phage type 9
STM 9

description: The South Australian Communicable Disease Control Branch at SA Health is responsible for public health and protection of South Australians through the surveillance and detection of communicable diseases. I was placed within the Branch between 2014 and 2015 as a Masters of Philosophy in Applied Epidemiology (MAE) scholar. In this thesis I present work undertaken during my placement to fulfil the requirements of the MAE. Three of my projects all involved the investigation of Salmonella Typhimurium phage type 9 (STM 9) notifications in South Australia. Notifications of STM 9 have been increasing in South Australia over the past ten years and in 2014 represent a third of all Salmonella notifications in the state. I conducted a data analysis of STM 9 notifications in South Australia between 2005 and 2014. A descriptive and analytical review of notifications was conducted to define trends and changes in the surveillance data and to provide insight into the increase in case numbers. The analysis compared sporadic and outbreak cases and detailed the descriptive characteristics of different multiple-locus variable-number tandem-repeat analysis patterns reported for this phage type. The analysis identified higher notification rates in people living in areas of higher socio-economic advantage and a particular increase in case numbers since 2012. It also identified a large proportion of outbreaks associated with eggs. I conducted a case control study to identify risk factors for sporadic STM 9 notifications in South Australia. This project involved interviewing sporadic STM 9 cases who were frequency matched with controls by age category. The questionnaire explored food, environmental and behavioural exposures. The interim analysis included in this thesis includes 332 participants (40 participants short of the required sample size) and identifies defrosting meat by submerging in water as a potential risk factor and consuming caged eggs as a potential protective behaviour. I investigated an outbreak of STM 9 in a group of school children staying at a campsite in New South Wales while visiting Canberra on a school excursion. The investigation was able to alert other jurisdictions to the potential problem, which resulted in the identification of another affected school group from New South Wales. The cohort study with the South Australian school group was unable to identify a specific source of the outbreak. The environmental investigation conducted at the campsite did not identify any problems and food and environmental samples obtained were all negative for Salmonella. For my remaining project I undertook an evaluation of the South Australian infectious syphilis surveillance system. The evaluation used the Centers for Disease Control and Prevention guidelines to assess ten surveillance system attributes. The impact of three proposed probable case definitions were also assessed. I was able to identify that the system, although highly sensitive, had variable data quality and inconsistencies due to the lack of a systematically applied case definition. Improvements in feedback to external stakeholders were recommended. The probable case definition requiring single high rapid plasma regain cut off greater than or equal to 16, and not requiring a case to have risk factors, had the highest sensitivity.