The OzFoodNet story: 2000 to present day

OzFoodNet is a network of epidemiologists whose primary interest is foodborne disease. The network is now over 10 years old and in this time, there have been many research studies and outbreak investigations undertaken by the network. A considerable body of published work exists that details the achievements and workings of the OzFoodNet network and the OzFoodNet sites. Lessons have been learnt from outbreak investigations, with improved surveillance systems developed for pathogens such as Listeria monocytogenes. The work of OzFoodNet plays an important part in informing food safety policy and regulations.

OzFoodNet is a collaborative program to enhance the surveillance of foodborne disease. The program was established in 2000 by the then Australian Government Department of Health and Aged Care and state and territory health departments. One of the events that led to the formation of OzFoodNet was an outbreak in 1995 of Shiga-like toxin producing Escherichia coli (STEC) causing haemolytic uremic syndrome (HUS) associated with mettwurst sausage^1,2. Within months of the outbreak, Australian governments were seeking to develop new national food safety standards. However, there were challenges in the development of these standards due to the lack of comprehensive data on the incidence and causes of foodborne illness³. With no state or national foodborne disease surveillance system, public health practitioners and policy makers could only rely on case reports, infrequent outbreak reports, irregular and ad hoc summaries of foodborne disease, and overseas surveillance data to formulate food safety standards⁴. One project concluded that there was value in a population based systematic and enhanced surveillance system to better understand the epidemiology of foodborne disease. Given this finding, an 18 month trial of enhanced foodborne disease surveillance commenced in the Hunter region of NSW⁵. The trial was a proof of principle and a national work program on food safety coordinated by the Australian Government Department of Health and Ageing (DoHA) built upon this initiative in the Hunter with the formation of OzFoodNet: A national system to enhance foodborne disease surveillance³.

OzFoodNet is a network of epidemiologists based in each state and territory health department and DoHA. At each site there are 1 to 3 epidemiologists, with some sites also having a supportive surveillance or administrative staff member. The network includes other organisations, including Food Standards Australia New Zealand (FSANZ), Australian Government Department of Agriculture, Fisheries and Forestry, the Public Health Laboratory Network and the National Centre for Epidemiology and Population Health (NCEPH) (Figure 1). OzFoodNet is a member of the Communicable Diseases Network Australia, a sub-committee of the Australian Health Protection Principal Committee.

OzFoodNet is a network for detecting and responding to nationally important foodborne diseases, monitoring the burden of these illnesses, and identifying the sources of specific foodborne outbreaks through enhanced communication and cooperation amongst jurisdictions. The network was modelled on the Centre for Disease Control (CDC) FoodNet model of active surveillance⁶ and has evolved into a mature network. Many of the epidemiologists are long standing members of the network and some have been with OzFoodNet from its inception. The OzFoodNet network is funded through DoHA by the Australian Government.

Regular communication within the network and with the relevant stakeholders and partners has been one of the key factors in the network’s ability to function effectively. Prior to the formation of OzFoodNet, no such data sharing and communication existed between states. Through rapid communication using list servers, a fortnightly enteric disease surveillance report, regular monthly teleconferences, and face to face meetings held several times a year at different OzFoodNet sites – network members have been able to communicate in a regular and timely fashion, sharing information, data, ideas and co-operating in outbreak investigations. There is a high level of trust within the network which is one of OzFoodNet’s strengths.

OzFoodNet is also partner of the WHO Global Foodborne Infections Network, which is a capacity-building program that promotes integrated, laboratory based surveillance and intersectoral collaboration among human health, veterinary and food-related disciplines⁷. Some OzFoodNet epidemiologists have participated as trainers in courses covering both the Western Pacific Region and South-East Asia region, where they are able to share their knowledge and experience in a training environment but also build relationships with international colleagues and networks interested in foodborne disease.

In the early years of the network there was a strong emphasis on research and in developing a better understanding of foodborne disease. Several studies examined the risk factors for campylobacteriosis^{8 9}; studies into particular Salmonella types from certain areas of Australia, such as S. Mississippi in Tasmania¹⁰ and also research into the identification of risk factors for sporadic listeriosis cases¹¹.

OzFoodNet and NCEPH have estimated that there were 5.4 million cases of foodborne infectious gastroenteritis annually in Australia circa 2000³. The burden of foodborne disease in Australia is substantial, costing approximately $1.2 billion dollars annually, mainly resulting from lost productivity when people with gastroenteritis stayed home from work, or having other people staying home to look after them. Currently, an NCEPH work program is underway to provide revised estimates of foodborne disease incidence in Australia, circa 2010. Funding to revise these estimates has been provided by DoHA, Food Standards Australia New Zealand (FSANZ) and the New South Wales Food Authority.

Much of the work of OzFoodNet in recent years has been focused on foodborne outbreak investigations including between four to six multijurisdictional outbreaks annually. Working as a collaborative network involving states and territories and other Australian Government agencies has resulted in the detection and investigation of a number of notable and instructive multijurisdictional outbreaks of foodborne disease (Table 1). These have included national outbreaks of Salmonella Saintpaul associated with rockmelons,¹² S. Litchfield associated with papaya¹³, a Listeria monocytogenes outbreak associated with chicken meat sandwiches and wraps on a domestic airline¹⁴ , an outbreak of Hepatitis A associated with semi-dried tomatoes^15,16, and outbreaks of norovirus due to imported oyster meat¹⁷. At times, foodborne outbreaks have crossed international borders, with a Shigella sonnei outbreak in Australia and Denmark associated with imported baby corn from Thailand¹⁸.

Table 1. Summary of selected significant multijurisdictional outbreak investigations undertaken by OzFoodNet.

Figure 1. The recent 39^th OzFoodNet Face to Face meeting held in Melbourne in February included a large number of OzFoodNet stakeholders as well as the network’s epidemiologists.

Multi-jurisdictional outbreak investigations coordinated by OzFoodNet are critical to maintaining a safe food supply for Australia. These investigations also assist in the development of national policies and regulation to prevent foodborne disease. OzFoodNet maintains a national Outbreak Register which is a detailed repository of data concerning outbreaks of enteric-related disease in Australia from 2001 to the present. Regulatory agencies rely on these data in order to inform risk assessment and standards development. Information from the OzFoodNet Outbreak Register has been used to inform food policy and contribute to food standards that are developed by FSANZ

Vehicles for Salmonella outbreaks have been varied – from eggs and egg products, poultry and meat products, and dishes such as sandwiches and condiments/sauces¹⁹. Egg-associated outbreaks have been documented frequently over the last several years^20–22 with enhanced data collection around egg-associated outbreaks being one of the network’s current areas of focus²³. In 2010, egg-associated outbreaks compromised 14% of all outbreaks investigated and 36% of all Salmonella outbreaks²⁴. The outbreak data in relation to eggs has been one of the resources used to inform the development of the Primary Production and Processing Standard for Eggs and Egg Products (Standard 4.2.5 by FSANZ).

The network has developed a national approach to surveillance for some foodborne pathogens of particular interest so that consistent and comparable information is collected when needed and to detect potential outbreaks.

Following a national outbreak of Listeria in 2009¹², OzFoodNet undertook to improve Listeria surveillance and outbreak detection though the establishment of an enhanced Listeria surveillance system. This system uses a variety of molecular typing techniques which have been developed in recent years and been used to detect clusters of cases based on the molecular types. Information is stored on a web based database enabling real time data entry and analysis. The food histories of cases are analysed when clusters are detected to identify potential sources of infection.

A recent application of this enhanced surveillance system occurred in late 2012, when OzFoodNet began investigating an outbreak of a particular Listeria monocytogenes subtype. Epidemiological analysis of the case data in this enhanced surveillance system was able to quickly identify a possible association between cases and the consumption of soft cheese that led to a national recall of the suspected products thought to be associated with the outbreak (http://www.foodstandards.gov.au/.../jindicheesepotential5792.cfm).

One of the strengths of the OzFoodNet work has been the ability to detect and investigate promptly potential multi-jurisdictional outbreaks of foodborne disease. Much of the work of OzFoodNet relies on the laboratories that provide typing information on a variety of isolates such as Salmonella and Listeria monocytogenes. There have been changes and improvements in molecular characterisation techniques such as multiple-locus variable number tandem repeat Analysis (MLVA) over the past few years. Due to these developments, multijurisdictional outbreaks or cluster investigations by OzFoodNet now involve detailed case definitions concerning S. Typhimurium phage types, MLVA types and pulse field gel electrophoresis (PFGE) patterns to include all jurisdictions and the differences in Salmonella typing methods that exist across Australia. The different characterisation techniques in each jurisdiction have been implemented and utilised based on the need to capture timely surveillance data for the jurisdiction. These evolving techniques provide greater discrimination of organisms which often aids outbreak investigations. However, their development has resulted in some challenges for surveillance between Australian states and territories.

OzFoodNet has successfully conducted surveillance and responded to outbreaks of foodborne illness since its commencement in 2000. This success has been based on continued funding support by DoHA and on the building and maintenance of strong working relationships that have fostered collaboration between many different partners, including public health units, health departments, laboratories, reference laboratories, food safety agencies, and primary industry departments.

We thank the many epidemiologists, Masters of Applied Epidemiology scholars, DoHA graduate trainees, project officers, interviewers and research assistants at each of the OzFoodNet sites. We would like to acknowledge the work of various public health professionals and laboratory staff around Australia who interviewed patients, tested specimens, typed isolates and investigated outbreaks. We would particularly acknowledge jurisdictional laboratories, the Microbiological Diagnostic Unit Public Health Laboratory, the South Australia Pathology’s Australian Salmonella Reference Centre, Queensland Health Scientific Services, PathWest and the National Enteric Pathogen Surveillance Scheme for their help and guidance with foodborne disease surveillance. The quality of their work was the foundation for OzFoodNet.

Further information on the network is available from the OzFoodNet website, www.ozfoodnet.gov.au.