Enhancing foodborne disease surveillance across Australia in 2001: the OzFoodNet Working Group

In 2000, the OzFoodNet network was established to enhance surveillance of foodborne diseases across Australia. OzFoodNet consists of 7 sites and covers 68 per cent of Australia's population. This report is the first Annual report of the OzFoodNet Working Group, and was published in Communicable Diseases Intelligence Vol 26 No 3, September 2002. This report can be viewed in 5 HTML documents and is also available in PDF format.

Page last updated: 03 October 2002

A print friendly PDF version is available from this Communicable Diseases Intelligence issue's table of contents.

OzFoodNet projects

During 2001, OzFoodNet collaborators initiated several projects to investigate and understand foodborne disease, some of which were national in scope. This section briefly details the nature of these projects and the current status of this work.

National projects

During September, NCEPH collected the first month's data for the national gastroenteritis survey. Starting this study was a major achievement and required considerable collaboration. NCEPH also prepared a report into future directions for OzFoodNet, which outlined research gaps in Australia for foodborne disease.

OzFoodNet developed national case control studies for Campylobacter and Salmonella Enteritidis to identify risk factors for infection. During 2001, sites in Tasmania, Victoria and Western Australia started the Campylobacter study and the remaining sites made preparations. In 2001, OzFoodNet developed a proposal for a listeriosis case control study and piloted the methodology. At the December face-to-face meeting, this was changed to a case series in all but two sites. OzFoodNet sites in the Hunter and Queensland will run the original protocol as a case control study. The results of this case series will provide important information nationally on the underlying risk factors for infection and high-risk foods.

OzFoodNet will conduct a case control study of STEC/HUS in South Australia, which has the highest rates of STEC notification in Australia due to intensive screening. Investigators continued to revise the protocol for the national laboratory survey. This survey will determine the faecal testing practices of laboratories around Australia, and will provide important information that will assist interpretation of notification data.

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An outbreak register for Australia

Australia's lack of a systematic system of recording data on outbreaks of enteric disease has hampered our understanding of foodborne disease.24 Summary data from outbreaks can provide useful information for the development of policy.25

Before OzFoodNet commenced, the Hunter Health Area, New South Wales initiated a retrospective survey of outbreak information from all States and territories between the years 1995 to 2000. This data collection, coined OzBreaks, contains detailed information on 208 outbreaks. OzBreaks is currently being analysed in collaboration with OzFoodNet epidemiologists.

To improve the quality of this information, OzFoodNet developed a register to provide a prospective record of Australian disease outbreaks associated with food and water. The OzFoodNet working group agreed to collect outbreak information from 1 January 2001 onwards. The OzFoodNet data manager developed a database and form, based on those used by the World Health Organization European regional office and the USA Centers for Disease Control and Prevention.

OzFoodNet epidemiologists have conducted a trial of the new register and made recommendations for improvement. The CDNA has requested that OzFoodNet expand the register to include outbreaks of intestinal illness not related to food. To ensure that the system for surveillance of outbreaks works properly, OzFoodNet is communicating with international investigators and formally evaluating the register in July 2002.

Development of a national Campylobacter typing network

The Hunter Health Area, New South Wales site conducted a case control study of Campylobacter infections that commenced prior to OzFoodNet. One hundred and eighty isolates from this study have been typed by several phenotypic and genotypic methods. The OzFoodNet-Hunter epidemiologist along with microbiologists will evaluate the testing methods for their epidemiological usefulness, cost, speed, simplicity and concordance. The outcome of this evaluation will assist the identification of suitable testing methods for Campylobacter isolates collected as part of the national case-control study.

This evaluation is unique in that the assessment of the different typing schemes is epidemiological in nature. Comparison of typing is quite common in microbiological research, but often lacks epidemiological input. In this instance, the case control study data for the most common subtypes from a range of typing schemes will be analysed.26

Another benefit of this typing network is that it may provide an opportunity to develop into a network for typing organisms associated with other disease outbreaks. This method of sharing microbiological data has provided many countries with an increased capacity to control foodborne disease.27 Sharing pulsed field gel electrophoresis patterns using BioNumerics software is the basis of the successful PulseNet system.28

Projects in single sites

OzFoodNet epidemiologists or collaborators have developed several other studies within their jurisdictions. These include:
  • a molecular typing project in Western Australia looking at automated ribotyping of bacterial foodborne pathogens, and development of a typing library using BioNumerics software;
  • a pilot study looking at enhancing Environmental Health Officer reports of foodborne disease outbreaks in Victoria;
  • case control studies for locally important Salmonella infections, including the following serovars and phage types:
  • S. Birkenhead in Queensland and northern New South Wales;
  • S. Mississippi in Tasmania;
  • S. Typhimurium 126 in South Australia; and
  • S. Typhimurium 135 in New South Wales, Victoria and Western Australia.
Two sites, Queensland and Victoria, attempted to establish sentinel surveillance for gastroenteritis in general practice. Despite intensive liaison with divisions of general practice, both sites found it difficult to recruit recorders for the scheme. OzFoodNet has decided not to proceed with sentinel GP surveillance at this stage, particularly when other groups such as the Royal Australian College of General Practice already collect such data. OzFoodNet is funded by the Commonwealth Department of Health and Ageing.

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Conclusion and recommendations

OzFoodNet is much more than a data gathering exercise. OzFoodNet has demonstrated its capacity to investigate and respond to outbreaks at the national level and can potentially provide an early-warning capacity for bioterrorism events associated with food.

In time, OzFoodNet will be able to assess the efficacy of current and proposed food hygiene standards and their enforcement by jurisdictions. OzFoodNet represents a significant investment in applied research into foodborne disease. It is important for the results of this work to become incorporated into policy formulation. The results of analytical studies initiated in 2001 will provide a useful insight into the occurrences of foodborne disease in Australia.

Recommendations regarding common risk factors

As a result of recurring outbreaks associated with commonly eaten foods, OzFoodNet recommends that Australian regulatory authorities:
  1. consider developing guidelines for the safe preparation of takeaway kebabs and pizza;
  2. educate amateur fishermen about the dangers of eating reef fish from areas affected by ciguatera poisoning;
  3. provide effective guidelines to aged care facilities aimed at preventing foodborne disease outbreaks; and
  4. monitor, with OzFoodNet, the incidence of escolar-associated outbreaks, following national efforts to prevent these outbreaks.

Recommendations regarding improving foodborne disease surveillance

To improve national surveillance of foodborne disease, OzFoodNet recommends that:
  1. Health and food safety agencies should continue to improve international liaison regarding food safety alerts and disease outbreaks about widely distributed foods.
  2. Health, food safety agencies and agricultural agencies should consider developing a long-term survey of retail meats across Australia to determine the prevalence of specific Salmonella types and Campylobacter to aid communicable disease investigations.
  3. Health, food safety, industry and agricultural agencies should develop closer links to share information about the occurrence of foodborne pathogens.
  4. OzFoodNet should develop short guidelines on investigating national clusters to outline responsibilities and expectations of all parties.
  5. The Commonwealth Department of Health and Ageing in conjunction with CDNA should consider building on the Campylobacter typing network coordinated by OzFoodNet-Hunter to enable rapid sharing of molecular typing data on bacterial pathogens.
  6. OzFoodNet epidemiologists should develop standard reporting practices for pregnancy-associated listeriosis.
  7. State and territory health departments should continue to conduct rigorous checks on the quality of surveillance data maintained on surveillance databases.
  8. State and territory health departments should consider using completeness and timeliness of Salmonella reporting as a potential performance indicator of surveillance and capacity to control disease.
  9. OzFoodNet should review the under-reporting of haemolytic uraemic syndrome to state and territory health departments.

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This report is based on the work of epidemiologists in each of the seven OzFoodNet sites during 2001: Rosie Ashbolt, Rod Givney, Joy Gregory, Geoff Millard, Nittita Prasopa-Plaizier, Jane Raupach, Russell Stafford, Lynn Meuleners, Eleanor Sullivan and Leanne Unicomb.

It also represents the work of Gillian Hall, Nola Tomaska and Rebecca Hundy from the National Centre for Epidemiology and Population Health, and Craig Williams from OzFoodNet. Project officers, interviewers and research assistants at each of the sites contributed to this report, including: Robert Bell, Meredith Caelli, Dot Little, Vanessa Madden, and Virginia Rendis.

During 2001, there were many people who made substantial contributions to the work of OzFoodNet, particularly: Mary Beers, David Coleman, Scott Crerar, Craig Dalton, Rob Hall, Geoff Hogg, Kerry-Ann O'Grady and Tony Watson.

OzFoodNet benefited from the interaction with international counterparts including: Fred Angulo, John Cowden, Kathryn Dore, Victoria Edge, Ian Fisher, Beth Imhoff, William Keene, Malinda Kennedy, Deon Mahoney, Shannon Majowicz, James Flint, Frank Rogers, Paul Sockett, Robert Tauxe, Thomas Van Gilder and Maty de Witt.

Many others assisted with OzFoodNet projects or provided advice during 2001 including: Ross Andrews, John Bates, Jim Black, Phillip Byrd, Scott Cameron, Mark Crome, Greg Dorricot, Gary Dowse, James Flint, Margaret Hellard, Dianne Lightfoot, Tim Inglis, Ed Kraa, Jan Lanser, Angela Merianos, Eddie O'Brien, Heather O'Donnell, Andy Pointon, Brent Robertson, Paul Roche, Martha Sinclair, Ingrid Tribe, Thomas Van Gilder, Mark Veitch, members of the Communicable Disease Network Australia and the Public Health Laboratory Network, and many others.

Population health data on gastroenteritis was collected by: Loretta Vaughan and Adrian Serraglio from the Health Surveillance and Evaluation Section, Public Health (DHS Victoria); the Epidemiology Services Unit, Health Information Centre (Queensland Health Department); and Anne Taylor from Centre for Population Studies in Epidemiology (DHS South Australia) and Harrison Health Research for national level data.

We have really appreciated the managerial assistance from staff of the Department of Health and Ageing, Food Standards Australia New Zealand, and the National Public Health Partnership.

We also acknowledge the hard work of various public health professionals around Australia who interviewed patients and investigated outbreaks. The high quality of their work is the foundation of this report.

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1. Food policy in the National Centre for Disease Control. Commun Dis Intell 2000;24:95.

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3. Centers for Disease Control and Prevention. Preliminary FoodNet data on the Incidence of foodborne illnesses - selected sites, United States, 2000. MMWR Morb Mortal Wkly Rep 2002;51:325-329.

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5. Nylen G, Dunstan F, Palmer SR, Andersson, Y, Bager F, Cowden J, et al. The seasonal distribution of campylobacter infection in nine European countries and New Zealand. Epidemiol Infect 2002;128:383-390.

6. Nassar N, Sullivan E. Australia's mothers and babies 1999. Australian Institute of Health and Welfare, National Perinatal Statistics Unit, Perinatal Statistics Series Number 11, Sydney; 2001.

7. O'Grady K, Powling J, Tan A, Vulcanis M, Lightfoot D, Gregory J, et al. Salmonella Typhimurium DT104 - Australia, Europe. ProMed Mail, 22 August 2001. Available from: http://www.promedmail.org. Accessed 12 November 2001.

8. Kirk M, Tan A, Genobile D, et al. An international outbreak of Salmonella Stanley associated with dried peanuts - the importance of thorough local investigation and widespread communication. International Conference on Emerging Infectious Diseases Latebreaker Poster Session, Atlanta: Georgia; 2002.

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10. Crerar SK, Nicholls TJ, Barton MD. Multi-resistant Salmonella Typhimurium DT104 - implications for animal industries and the veterinary profession. Aust Vet J 1999;77:170-171.

11. Katz D, Kumar S, Malecki J, Lowdermilk M, Koumans EH, Hopkins R. Cyclosporiasis associated with imported raspberries, Florida, 1996. Public Health Rep 1999;114:427-438.

12. Taormina PJ, Beuchat LR, Slutsker L. Infections associated with eating seed sprouts: an international concern. Emerg Infect Dis 1999;5:626-634.

13. Kaferstein FK, Motarjemi Y, Bettcher DW. Foodborne disease control: a transnational challenge. Emerg Infect Dis 1997;3:503-510.

14. A survey of Victorian kebab takeaway stores - draft report. Victorian Department of Human Services. Melbourne, 2002.

15. Becker K, Southwick K, Reardon J, Berg R, MacCormack JN. Histamine poisoning associated with eating tuna burgers. JAMA 2001;285:1327-1330.

16. Wilson IG, Moore JE. Presence of Salmonella spp. and Campylobacter spp. in shellfish. Epidemiol Infect 1996;116:147-53.

17. Mead PS, Slutsker L, Dietz V, McCaig LF, Bresee JS, Shapiro C, Griffin PM, et al. Food-related illness and death in the United States. Emerg Infect Dis 1999;5:607-625.

18. McKay I. Food Safety Standards Costs and Benefits. Australia New Zealand Food Authority. Canberra; 1999.

19. Hellard ME, Sinclair MI, Forbes AB, Fairley CK. A randomized, blinded, controlled trial investigating the gastrointestinal health effects of drinking water quality. Environ Health Perspect 2001;109:773-778.

20. Bytzer P, Talley NJ, Leemon M, Young LJ, Jones MP, Horowitz M. Prevalence of gastrointestinal symptoms associated with diabetes mellitus: a population-based survey of 15,000 adults. Arch Intern Med 2001;161:1989-1996.

21. Bytzer P, Howell S, Leemon M, Young LJ, Jones MP, Talley NJ. Low socioeconomic class is a risk factor for upper and lower gastrointestinal symptoms: a population based study in 15,000 Australian adults. Gut 2001;49:66-72.

22. Lindenmayer P. Networking for health protection: the Communicable Diseases Network Australia. Commun Dis Intell 2001;25:266-269.

23. Kirk MD, Dalton CB, Beers M, Cameron AS, Murray C. Timeliness of Salmonella notifications in South Australia. Aust N Z J Public Health 1999;23:198-200.

24. Crerar SK, Dalton CB, Longbottom HM, Kraa E. Foodborne disease: current trends and future surveillance needs in Australia. Med J Aust 1996;165:672-675.

25. O'Brien SJ, Elson R, Gillespie IA, Adak GK, Cowden JM. Surveillance of foodborne outbreaks of infectious intestinal disease in England and Wales 1992-1999: contributing to evidence-based food policy? Public Health 2002;116:75-80.

26. Neimann J, Nielsen EM, Engberg J, et. al. Clinical symptoms, seasonal variation, history of foreign travel, environmental risk factors for infection and antibiotic resistance of isolates associated with enteritis of different Campylobacter species and serotypes in Denmark. J Med Micro in press.

27. Terajima J, Experience with PFGE/two settings 'Japan's experience with PFGE and the Internet'. APEC Emerging Infections Program. Network of Networks Meeting, Seattle, 28-30 January 2002. Available from: www.apec.org/infectious/NoN/Terajima_APEC.pdf. Accessed on 30 May 2002.

28. Multistate outbreak of listeriosis - United States, 2000. MMWR Morb Mortal Wkly Rep 2000;49:1129-1130.

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Appendix 1. Notification summary of infections potentially due to food for OzFoodNet sites, 2001, by date of onset

    ACT NSW Hunter Qld SA Tas Vic WA Total
Campylobacter n
Salmonella n
Yersinia n
Typhoid n
Shigella n
Listeria n

NN Not notifiable
Rate= Rate per 100,000 population

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Appendix 2. Outbreak summary for OzFoodNet sites, 2001

Month of outbreak
Setting category
Agent responsible
Number affected
Responsible vehicles
Australia July Nationwide S. Stanley 27   D+M Imported dried peanuts
ACT December Conference/ function Suspected toxin 22 0 D Suspected spit roast meal
December Conference/ function Suspected toxin 110 0 D Suspected spit roast meal
December Conference/ function Suspected toxin 68 0 D Suspected spit roast meal
December Conference/ function Suspected toxin 31 0 D Suspected spit roast meal
September Conference/ function Suspected viral 61 0 D Suspected salad at barbecue
December Restaurant Suspected toxin 19 0 D Suspected Turkish banquet
Hunter October Conference/ function Escolar wax esters 20 0 D+M Escolar
June Takeaway Unknown 4 0 D Pizza
May Takeaway Unknown 8 0 D Pizza
May Takeaway Unknown 4 0 D Pizza
October Takeaway S. Typhimurium 126 2 1 D Chicken pizza
April Restaurant Unknown 6 0 D Suspected seafood sauce
July Restaurant Unknown 10 0 D Suspected honey chicken
July Takeaway Unknown 2 0 D Suspected takeaway chicken
May Takeaway Unknown 2 0 D Suspected chicken kebab
May Takeaway Unknown 3 0 D Suspected BBQ chicken
November Restaurant Campylobacter 2 0 D Unknown
Qld January Camp Unknown 87 0 D Drinking water
January Home Ciguatera poisoning 14 11 D Spanish Mackerel
January Home Ciguatera poisoning 2 0 D Spotted Mackerel
June Home Ciguatera poisoning 3 3 D Barracuda (Sphyraena jello)
November Home Ciguatera poisoning 4 0 D Coral Trout
November Home Ciguatera poisoning 9 0 D Spanish Mackerel
February Restaurant Histamine fish poisoning 4 0 D Mahi Mahi
August Community Cryptosporidiosis 8 3 A+M Unpasteurised pets milk (cow)
July Conference/ function Norwalk virus 56 0 A Salads, steak sandwiches
March Conference/ function S. Virchow PT 8 2 0 D Chicken
July Restaurant Campylobacter 2 0 D+M Duck liver
March Takeaway C. jejuni 3 0 D Chicken kebabs
January Restaurant C. perfringens 9 0 A+M Reef & beef meal
July Restaurant C. perfringens 8 0 A Beef curry
May Community S. Bovismorbificans 32 36 6 A+M Chicken salad in pita bread
February Aged care S. Heidelberg PT 1 12 6 D Suspected eggs
February Aged care Unknown 19 0 D Unknown
March Aged care S. Muenchen 3 0 D Unknown
February Conference/ function Unknown 6 0 D Unknown
June Conference/ function Suspected viral 10 1 D Unknown
December Hotel Unknown 6 0 D Unknown
June Hotel S. Montevideo 8 1 D Unknown
July Restaurant C. perfringens 7 0 D Unknown
SA December Home S. Typhimurium 135a 11 4 A+M Tiramisu dessert
December Restaurant S. Typhimurium 64var 28 0 A+M Mango pudding
March Takeaway S. Typhimurium 126 9 3 A Custard tart with strawberries and a jelly glaze
March Aged care S. Typhimurium 135 17 3 A+M Raw egg (mince & potato pie & rice pudding)
May Community S. Typhimurium 126 88   A+M Chicken
June Home S. Typhimurium 135a 2 0 D+M Homemade italian sausage
January Restaurant S. Typhimurium 29 8 1 D Unknown
June Restaurant S. Zanzibar 2 0 D Unknown
May Restaurant C. jejuni 10 1 D Unknown
Tas April Home S. Typhimurium 9 6 1 D Suspected duck egg whites
April Home S. Mississippi 7 0 D Unknown
February Home Unknown 9 0 D Unknown
Vic June Community S. Typhimurium 104 23 7 A+M Turkish Helva
March Home Ciguatera poisoning 16 0 D Coral trout
August Restaurant Wax ester (butterfish diarrhoea) 5 0 D+M Butterfish
December Home S. Virchow 34 11 2 M Barbequed chicken or beef
March Hotel Unknown 15 0 A Combination cheese platter, mushroom risotto, Thai prawns
February Restaurant Unknown 5 0 D Suspected pizza
July Hotel S. Typhimurium 99 22 2 A Lamb's fry
August Restaurant S. Typhimurium 99 95 1 A Eye fillet meal
October Conference/function Campylobacter 50 0 A Tomato and cucumber salad
December Community S. Mississippi 6 0 D Suspected oysters
August Camp Suspected Campylobacter (1 +ve) 12 0 D Suspected unpasteurised milk
January Home S. Typhimurium 170 14 3 D Unknown
February Restaurant Norwalk virus 65 0 A Suspected sausages
May Takeaway Unknown (1 positive Salmonella) 3 1 D Suspected kebabs
November Aged care Campylobacter 49 1 D Unknown
April Camp S. Typhimurium 9 30 1 D Unknown
December Conference/function Unknown (suspected toxin) 269 0 D Suspected soup or roast beef
December Hotel C. perfringens 9 0 D Suspected potato and bacon soup
December Restaurant Unknown (suspected toxin) 33 1 D Unknown
February Restaurant Norwalk virus 31 0 D Unknown
January Restaurant Norwalk virus 9 0 D Unknown
March Restaurant Norwalk virus 16 0 D Unknown
September Restaurant Unknown (suspected toxin) 7 0 D Unknown
WA October Conference/function Unknown 50 1 A Cranachan (dessert)
June Restaurant S. Typhimurium 64 36 4 A+M Fried ice cream
March Camp S. Typhimurium 135 var 29 0 D Suspected bore water supply
December Conference/function Norwalk virus 56 0 A Suspected chicken
July Restaurant Unknown 6 0 D Possible undercooked turkey
November Takeaway Unknown 10 0 D Suspected chicken
February Camp S. Wandsworth 50 0 D Unknown
October Camp Norwalk virus 11 1 D Unknown
December Conference/function Unknown 4 0 D Unknown
September Restaurant Unknown 7 0 D Unknown

* D Descriptive evidence implicating the suspected vehicle or suggesting food or waterborne transmission.
A Statistical association between illness and one or more foods determined from a formal epidemiological study.
M Microbiological confirmation of agent in the suspect vehicle and cases

This article was published in Communicable Diseases Intelligence Volume 26, No 3, September 2002

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