Epidemiology and Communicable Disease Control in Western Australia

Abstract

This thesis presents my work as part of the requirements of the Master of Philosophy in Applied Epidemiology (MAE) from February 2020 to December 2021. I conducted four main research projects during my placement at the Communicable Disease Control Directorate (CDCD) at the Department of Health in Western Australia (WA). Epidemiology project: An epidemiological investigation into travel associated SARS-CoV-2 transmission on an international flight into Perth, Australia. Twenty passengers on the flight from Dubai, United Arab Emirates to Perth, Australia were positive to SARS-CoV-2. The risk of acquiring SARS-CoV-2 during air travel was investigated by conducting passenger interviews and using whole genome sequencing, systematic PCR testing and serology. Two primary cases were identified with 15 passengers classified as secondary cases. The three other positive passengers were not linked to the outbreak cluster. Risk of transmission increased for passengers seated within 2-rows of the primary cases, those that did not consistently wear a mask and those that were at Perth airport for greater than one hour. This investigation highlighted the need to consider pre- and post-flight points of infection during air travel. Establishing a surveillance system: Establishment of a data linkage vaccine safety surveillance system for thrombosis and thrombocytopenia syndrome in Western Australia. During the implementation of the COVID-19 immunisation program, a new side effect of thrombosis and thrombocytopenia syndrome (TTS) was linked to the Vaxzevria COVID-19 vaccine. Existing safety surveillance systems relied on patient or provider reports after an adverse event following immunisation. The authorisation to link the Australian Immunisation Register to the linked data repository increased surveillance capabilities to identify potential TTS cases. To reduce bias and confounding, and to test the validity of the system, exploratory analyses was conducted on the different surveillance attributes of the linked system. This event demonstrated the need to improve our existing vaccine safety surveillance systems to capture the situation more accurately in a timely manner. Outbreak Investigation: An outbreak of Salmonella Typhimurium at a prison in Western Australia, June 2020. Outbreaks of Salmonella Typhimurium have been linked with raw egg consumption within the prison justice system since 2015. Findings from this outbreak indicated that eating raw egg containing salads in the staff kitchen increased the risk of becoming ill with the pathogen. Investigations conducted on the farm and in the prison revealed that there were multiple areas identified for improvement to reduce future outbreaks. Data Analysis: The impact of COVID-19 on chlamydia in Western Australia 2020. This data analysis project found that there was a significant decrease in chlamydia notifications in April 2020, during the time of the most stringent COVID-19 restrictions. Reasons for the decrease were likely due to stay at home orders and reduced social spaces. There were minimal changes in the demographics of the notification rates. The testing rate also decreased in quarter 1 of 2020, suggesting that people were avoiding healthcare services. Once lockdown eased, testing rates increased but notification rates remained below average levels, indicating reduced chlamydia transmission. In my thesis I also describe an overview of my placement at the CDCD, publication, report to a general audience and teaching requirements conducted during the course of my MAE. All references and appendices are provided at the end of each respective chapter. Show more