PhD Exit Seminar: Strengthening enteric disease surveillance and control in NSW through strategic use of public health data

Abstract

This thesis examines how public health data can be used to strengthen enteric disease surveillance and control in New South Wales (NSW), Australia. Enteric infections remain a major public health burden, and notifiable disease surveillance systems are central to monitoring trends, detecting outbreaks and guiding prevention. However, these systems often prioritise case counting and incident response, while the broader value of accumulated surveillance data, enhanced follow-up and supplementary data sources may be underused.

The thesis addresses this issue through three applied research areas. First, it re-examines long-term foodborne outbreak surveillance data in NSW to improve understanding of outbreak aetiology, implicated foods and prevention opportunities. By applying systematic classification approaches to historical outbreak data, this work demonstrates how existing surveillance records can generate new insights into the causes and sources of outbreaks, including those previously recorded with incomplete or unknown information.

Second, the thesis evaluates alternative methods for collecting exposure information from notified salmonellosis cases. In NSW, the high burden of salmonellosis limits routine case follow-up, which can delay or reduce the detection of dispersed outbreaks. A multi-year project comparing mailed letters, online surveys and SMS-based follow-up found that SMS offered an efficient and acceptable method for collecting timely exposure information. This work supports the use of scalable communication methods to increase surveillance coverage and improve outbreak detection.

Third, the thesis examines whether passive enteric disease notifications can be strengthened through linkage with supplementary public health data sources to identify risk factors and inform targeted prevention. One component uses retrospective data and links notifiable disease, perinatal and hospital admission data to describe the incidence, outcomes and demographic risk factors for salmonellosis and listeriosis during pregnancy. A second component occurred during an active outbreak and used supplementary immunity, vaccination and service data to assess hepatitis A susceptibility among men who have sex with men. Together, these analyses show how passive surveillance data can be combined with complementary datasets to provide deeper insights into enteric infections in vulnerable or priority populations.

Together, these studies show that public health data can be used more strategically to move enteric disease surveillance beyond passive notification and routine reporting. Re-analysis of existing data, improved case follow-up methods and linkage with complementary datasets can strengthen outbreak detection, identify prevention opportunities and support more targeted public health action. The thesis provides practical evidence for improving enteric disease surveillance systems in NSW and similar public health settings.

Speaker

Neil Franklin is an epidemiologist with NSW Health. For more than 16 years he has worked in the surveillance, investigation, policy and control of foodborne and enteric diseases, helping solve numerous foodborne outbreaks across Australia. Some of his favourite national outbreaks include Hepatitis A in frozen pomegranate, Shigellas on a Plane (associated with a chickpea salad) and Salmonella Saintpaul linked to Spring onions.  He is drawn to the detective work of epidemiology: connecting data, context, and observations to make sense of the bigger picture, then translating that picture into something meaningful for others.

His PhD builds on that approach, examining how routinely collected public health data can be brought together and used more effectively to answer applied epidemiological questions and support decision-making.