An Infectious Interest: Epidemiology of Communicable Diseases in Australia
Date
2019
Authors
Vette, Kaitlyn
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While placed in the Communicable Disease Epidemiology and Surveillance Section in the Office of Health Protection at the Australian Government Department of Health, I focused on five projects. Using the World Health Organization's (WHO) Pandemic Influenza Severity Assessment (PISA), I established parameters and thresholds to measure the transmissibility, seriousness and impact of circulating influenza in Australia. I found that when these measures were applied to the 2017 influenza season, they aligned with the characterisation of the season by the National Influenza Surveillance Committee based on expert opinion and historical ranges. My implementation of PISA is now being used nationally to make evidence-based, reproducible assessments of the influenza season in real-time. To gain international experience with PISA, I am interning with WHO's Global Influenza Programme following thesis submission. I conducted an evaluation of the Australian Paediatric Surveillance Unit's surveillance of acute flaccid paralysis using the United States Centers for Disease Control and Prevention's Guidelines for Evaluating Public Health Surveillance Systems. I found the surveillance system to have high stability, acceptability, representativeness and predictive value positive. To increase the usefulness of the system, I recommended that timeliness should be enhanced by reducing the complexity of the system, and that facilitation of increased stool sampling to exclude poliovirus infection should be improved. I used data from the National Enhanced Listeriosis Surveillance System to describe and analyse predisposing risk factors and outcomes amongst nationally notified listeriosis cases in Australia from 2010-17. When compared to the population without each risk factor, I found the risk of listeriosis was 658 times higher in organ transplant recipients, 174 times higher in those with non-haematological cancers, and a range of 1.5-38 times higher in those with other chronic conditions, cases >45 years, pregnant women and those with international backgrounds. The study also highlighted a higher rate of meningitis and death amongst cases without identified susceptibility risk factors compared to cases with any risk factors. In 2017-18, an unusual Salmonella Typhimurium (STm) multiple-locus variable-number tandem repeats analysis (MLVA) profile (3-25-13-12-523) appeared in the Australian Capital Territory. I undertook a retrospective case-case analysis to generate a hypothesis about the infectious source. As part of this I compared two case-control selection methods; one using MLVA-differentiated STm case-controls, and the other using case-controls selected from other Salmonella serovars. When cases were compared to STm case-controls, significantly higher egg consumption was detected in cases through multivariate analysis. No significant exposures were found when cases were compared to non-STm case-controls. This study provided a hypothesis for the source of infections and demonstrated that MLVA may be useful in expanding case- control selection to include those from the same Salmonella serovar. I was also involved in communicable disease surveillance and response for the Gold Coast Commonwealth Games. I established a system of international disease surveillance and reporting, and participated in local monitoring and response through placement at the Gold Coast Public Health Unit. Each of these projects has informed disease surveillance, prevention and control in Australia and has contributed to the understanding of the diseases' epidemiology.
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