Applied Epidemiology in Communicable Diseases, Victoria, 2016 - 2017

Abstract

This thesis presents the projects and activities I have undertaken throughout 2016-2017 to fulfil the requirements of the Master of Philosophy - Applied Epidemiology (MAE). My placement was shared between OzFoodNet Victoria (within the Victorian Department of Health and Human Services) and the Microbiological Diagnostic Unit Public Health Laboratory (MDU). This shared placement provided me with the unique opportunity to experience the different day-to-day workings of a state health department and a public health reference laboratory, while also experiencing the multitude of ways in which these two organisations work together to protect the health of the Victorian public.

In my placement at MDU I completed an evaluation of the Victorian Hospital Pathogens Surveillance Scheme (VHPSS). This scheme has been running since 1988 and collects information on invasive bacterial and fungal infections and their antimicrobial sensitivities in the Victorian population. My evaluation highlighted the value of the VHPSS in collecting information on pathogens not captured by any other surveillance system in Victoria, and made a number of recommendations to improve the function and focus of the scheme, especially in the context of increasing concerns surrounding antimicrobial resistance nationally and globally.

In my placement with OzFoodNet Victoria I was involved in the investigation of multiple clusters and outbreaks of enteric disease. In particular, I coordinated the investigation of an outbreak of Salmonella Typhimurium at a Melbourne café which was linked to the consumption of hollandaise sauce. This outbreak highlighted the dangers of improper food handling in preparing and storing partially-cooked egg products, and the limited knowledge many people have about the risks of consuming these foods.

Following another Salmonella outbreak, I conducted an epidemiological study on the proportion of outbreak cases who developed symptoms of transient or chronic sequelae following their infection. In particular, this study collected information on symptoms of post-infectious irritable bowel syndrome (PI-IBS) and reactive arthritis (ReA). This study found that in the six months following their Salmonella infection, 18% of study participants experienced new gastrointestinal symptoms consistent with PI-IBS, and 11% of participants experienced new joint symptoms consistent with ReA. Many of these participants were still experiencing these symptoms a year after their Salmonella infection, indicating the development of chronic disease.

I also conducted analyses on data from the Victorian Food Frequency Survey. This survey collected information on the consumption of approximately 250 food items in 4008 well Victorian people, so that their food consumption frequencies could be compared to information from Salmonella case interviews (and interviews for cases of other enteric pathogens such as Campylobacter and Shiga-toxin producing Escherichia coli) to assist in generating hypotheses to try and identify sources of infection. I translated this data into an accessible format for use in outbreak investigations, and examined the demographic consumption patterns of various high-risk food items to determine who might be most at risk of infection.

These projects, alongside the teaching activities and scientific communications presented in this thesis, fulfil the requirements of the MAE program and will contribute to the public health of Victorians.