OzFoodNet: enhancing foodborne disease surveillance across Australia: Quarterly report, April to June 2001

This article published in Communicable Diseases Intelligence Volume 25, No 4, November 2001 contains the quarterly report on foodborne disease surveillance in Australia

Page last updated: 17 December 2001

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

Martyn Kirk for the OzFoodNet Working Group1


OzFoodNet is a collaborative network conducting applied research into foodborne disease. It was established by the Commonwealth Department of Health and Ageing, formerly the Department of Health and Aged Care.1 During the second quarter of 2001, OzFoodNet prepared several protocols for national studies investigating the burden and causes of foodborne disease. OzFoodNet epidemiologists assisted with investigations into several outbreaks of foodborne illness, including a major outbreak of Salmonella Bovismorbificans 32 associated with iceberg lettuce, and Australia's first outbreak of multi-drug resistant Salmonella Typhimurium Definitive Type (DT) 104.

This second quarterly report of OzFoodNet summarises the reporting of foodborne disease in the six States of Australia during the second quarter of 2001.2 During this time, the Australian Capital Territory and the Northern Territory participated as observers in OzFoodNet, and we have not included data from these jurisdictions unless specified.

Notifications in the second quarter

In this report we have used the date that the health department received notifications, unless specified otherwise.

During the quarter, OzFoodNet sites reported 3,551 notifications of campylobacteriosis (excluding New South Wales). The median ages of cases ranged between 24-32 years. All States reported that the male to female ratio of cases was approximately 1:1 except South Australia (1.4:1). The Tasmanian Health Department reported a large increase in the rate of Campylobacter infections in the northern part of Tasmania, although no source was identified. The South Australian Department of Human Services investigated one point source outbreak of Campylobacter infection associated with a restaurant meal.

OzFoodNet sites reported a total of 1,672 cases of salmonellosis during the second quarter and identified the source of 10 Salmonella outbreaks. The median ages of reported cases in all States ranged from 15-24 years old, except for Queensland where the median age was 9 years. OzFoodNet sites reported that Salmonella Typhimurium (phage types 64, 135 and 126), Virchow (8 and 36var1) and Enteriditis were the most common serovars (Table 1). The majority of these Salmonella Enteriditis infections were acquired overseas.

The following table displays Notifications of new and relapsed cases of tuberculosis, and rates per 100,000 population, Australia, 1986 to 1999, by year. If you are not able to access these data please e-mail cdi.editor@health.gov.au.

Top of pageTable 1. Top five Salmonella infections reported to OzFoodNet sites, April to June 2001, by date of receipt

OzFoodNet site
Top five Salmonella infections, by type
Number of cases
2nd quarter 2001 2nd quarter 2000 YTD 2001 Total 2000 Ratio1
Queensland Virchow 8 59 66 123 126 0.89
Saintpaul 40 90 106 132 0.44
Bovismorbificans 32 36 0 36 1 -
Birkenhead 33 21 96 55 1.57
Typhimurium 126 27 1 35 2 27.0
Hunter Typhimurium 64 4 3 7 14 1.33
Typhimurium 44 2 0 5 0 -
Typhimurium 170 2 0 3 1 -
Typhimurium 135 1 3 7 10 0.33
Enteriditis 1 1 1 1 1.00
New South Wales Typhimurium 135 34 34 25 138 1.00
Typhimurium 9 29 47 30 115 0.61
Birkenhead 18 17 12 77 1.05
Typhimurium 64 17 21 55 53 0.81
Stanley 10 5 11 56 2.00
South Australia Typhimurium 126 29 1 74 4 29.00
Typhimurium 9 14 7 36 28 2.00
Typhimurium 64 9 4 22 20 2.25
Typhimurium 108 5 3 6 9 1.70
Virchow 5 2 15 1 2.50
Tasmania Mississippi 31 19 86 69 1.60
Typhimurium 9 5 4 9 21 1.30
Enteriditis 4 2 3 2 5 0.67
Enteriditis 1 2 1 2 1 2.00
Typhimurium 135 2 1 2 5 2.00
Western Australia Typhimurium 135 5 59 49 68 0.08
Typhimurium 22 3 2 5 2 1.50
Typhimurium 4 3 7 18 13 0.43
Typhimurium 8 3 0 4 1 -
Bovismorbificans 2 0 7 0 -
Victoria Typhimurium 9 33 55 89 186 0.60
Typhimurium 135 20 21 63 71 0.95
Typhimurium 4 17 2 54 37 8.50
Virchow 36var1 11 10 20 19 1.10
Virchow 34 8 18 24 60 0.44

1. Ratio of number of cases reported in second quarter 2001 to second quarter 2000

The Tasmanian OzFoodNet Site reported that Salmonella Mississippi - an endemic serovar in this State - was the most common Salmonella infection for the quarter. Tasmania reported one household cluster of S. Mississippi, although no source was identified. Both Queensland and New South Wales OzFoodNet sites reported that Salmonella Birkenhead was common, which relate to an endemic focus of this serovar in southeast Queensland and northern New South Wales. During the quarter, State and Territory Health Departments commenced investigations into a variety of Salmonella serovars, including: Bovismorbificans (phage types 32 and 14), Muenchen, Typhimurium (phage types 126, 135 and 104) and Virchow (phage type 8).

State health departments received 11 notifications of listeriosis during the second quarter of 2001, which compared to 22 for the same quarter in 2000. Median ages for cases ranged from 38.5 to 70 years. South Australia reported one foetal infection in an infant of 34 weeks gestation. The mother had previously consumed soft cheese. There is little seasonality to notifications of Listeria infection (Figure). Despite the small numbers of cases of listeriosis notified to individual jurisdictions, there is potential for cross-border or national outbreaks.

Figure. Notifications of listeriosis, Australia, 1998 to June 2001, by States and Territories, and month of onset

Figure. Notifications of listeriosis, Australia, 1998 to June 2001, by States and Territories, and month of onset

OzFoodNet sites reported 10 cases of shiga toxin producing E. coli infections during the quarter, with South Australia and Queensland each reporting four cases. Investigators did not identify any sources and all cases appeared sporadic. The median ages ranged from 14 to 71 years.

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Foodborne disease outbreaks

During the second quarter of 2001, OzFoodNet sites reported 16 outbreaks that were potentially related to food (Table 2). These outbreaks affected approximately 224 people, of which 24 were hospitalised and one died. The Victorian Department of Human Services identified helva imported from Turkey, as the source of the first Australian outbreak of multi-drug resistant Salmonella Typhimurium DT 104.* This serovar is a significant problem for countries in the northern hemisphere, due to its propensity to affect many different types of animals, and the antibiotic resistance of the serovar.3 The Queensland Department of Health identified iceberg lettuce that was contaminated during processing as the source of an outbreak of Salmonella Bovismorbificans 32 that affected people across Queensland.

The following table displays Notifications of new and relapsed cases of tuberculosis, and rates per 100,000 population, Australia, 1986 to 1999, by year. If you are not able to access these data please e-mail cdi.editor@health.gov.au.

Table 2. Outbreaks reported by OzFoodNet sites, April to June 2001

Month of outbreak
Agent responsible
Number exposed
Number affected
Responsible vehicles
Hunter June Take-away pizza shop Unknown Unknown 4 Pizza
May Kebab shop Unknown Unknown 2 Suspected chicken kebab
May Supermarket Unknown Unknown 3 Suspected BBQ chicken
May Take-away pizza shop Unknown Unknown 8 Pizza
Qld June Caterer Suspected Norwalk 14 10 Unknown
June Home Ciguatera 3 3 Barracuda (Sphyraena jello)
June Hotel S. Montevideo Unknown 8 Unknown
May Take away restaurant S. Bovismorbificans 32 Unknown 36 Commercially processed iceberg lettuce
SA June Cafe S. Zanzibar Unknown 2 Suspected chicken dish
June (investigations still continuing) Community S. Typhimurium 126 Unknown 44 to end of June; 72 to 10th August 2001 Chicken products
May Restaurant Campylobacter jejuni 13 10 Unknown
Tas April Household S. Mississippi 7 7 Unknown
April Household S. Typhimurium 9 6 6 Suspected duck eggs
Vic April School Camp S. Typhimurium 9 55 29 Unknown
June Community S. Typhimurium DT104 Unknown 23 (20 Vic; 2 NSW;1 Qld) Turkish Helva
WA June Restaurant S. Typhimurium 64 ~40 29 Fried ice cream

Applied research

The OzFoodNet collaboration has achieved some important goals during the first six months of 2001, which included:
  • development of a National survey of diarrhoeal disease through the National Centre for Epidemiology and Population Health;
  • development of protocols for four national case control studies to examine risk factors for campylobacteriosis, listeriosis, Salmonella Enteriditis, and shiga-toxin producing E. coli;
  • development of a national outbreak register for foodborne disease;
  • communicating about clusters of foodborne diseases, through a fortnightly cluster report;
  • comparing molecular typing methods for Campylobacter;
  • development of a national survey of pathology laboratories;
  • assisting with the investigation of several important clusters and outbreaks of foodborne disease that have crossed jurisdictional boundaries;
  • communication with international agencies involved in similar international work; and
  • formation of an important forum for discussing issues relating to foodborne disease.
There are many important areas of foodborne disease surveillance, which OzFoodNet cannot adequately address in this first phase of work. Some examples of this further work include: estimating the cost of foodborne disease, determining the fraction of foodborne disease that is notified to health authorities, novel means of detecting outbreaks, risk factors for other foodborne pathogens, etc. OzFoodNet is currently developing a paper on the potential future of ongoing collaborative work to improve our understanding of foodborne disease.

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Author affiliations

1. Corresponding author: Mr Martyn Kirk, Coordinating Epidemiologist, OzFoodNet, c/o National Public Health Partnership, Level 12, 589 Collins Street, Melbourne Victoria, 3000 Telephone +61 3 9616 1522, E-mail Martyn.Kirk@dhs.vic.gov.au

The full membership of the OzFoodNet Working Group is listed at the end of this report.

The OzFoodNet Working Group is (in alphabetical order): Rosie Ashbolt (Tas), Meredith Caelli (Hunter PHU), Scott Crerar (ANZFA), Craig Dalton (Hunter PHU), Rod Givney (SA), Joy Gregory (Vic), Gillian Hall (NCEPH), Brigid Hardy (AFFA), Geoff Hogg (MDU), Rebecca Hundy (SA), Martyn Kirk (ANZFA), Vanessa Madden (Tas), Ian McKay (DHA), Lynn Meuleners (WA), Geoff Millard (ACT), David Peacock (NT), Nittita Prasopa-Plaizier (Vic), Paul Roche (DHA), Russell Stafford (Qld), Nola Tomaska (NCEPH), Leanne Unicomb (Hunter PHU), Craig Williams (ANZFA)

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1. Kirk M for the OzFoodNet Working Party. OzFoodNet: Enhancing Foodborne Disease Across Australia: Quarterly Report January - March 2001 Commun Dis Intell 2001;25: 103-106.

2. 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, www.promedmail.org (Accessed 12 November 2001).

3. Crerar SK, Nicholls TJ, Barton MD. Multi-resistant Salmonella Typhimurium DT104 - implications for animal industries and the veterinary profession. Aust Vet J1999;77:170-1.

This article was published in Communicable Diseases Intelligence Volume 25, No 4, November 2001.

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