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.




Risk factors for foodborne illness

OzFoodNet sites identified some important risk factors for foodborne infections during 2001. Epidemiologists identified these by reviewing data on foodborne outbreaks and discussing the results of investigations. During 2001, OzFoodNet started a series of case control studies for common infections, which will further characterise risk factors for foodborne illness. The major risk factors for infection that OzFoodNet identified during 2001 are grouped in the following categories: imported foods; takeaway foods; seafood; and red meat and poultry.

Imported foods and Salmonella contamination

Like many other countries, Australia is importing increasing amounts of foods from overseas countries. In 2001, there were two major outbreaks in Australia associated with imported foods. The first of these was the outbreak of antibiotic resistant Salmonella Typhimurium Definitive Type 104 due to helva imported from Turkey.7 The second outbreak was an outbreak of Salmonella Stanley due to dried peanuts imported from China.8

While both of these outbreaks were small in terms of numbers of cases (50 overall) they have important implications for Australia and the food industry. When foods contaminated by microorganisms are imported they can pose a serious risk for primary industry and the processed food sector. Salmonella Typhimurium DT 104 has the potential to be a serious threat to primary industry due to its virulence and antibiotic resistant characteristics.10Salmonella Enteriditis phage type 4 is another agent that could prove devastating to the egg producing industry if it becomes established in Australia. It is vital that health and agriculture agencies are able to rapidly recognise outbreaks and identify the source.

Outbreaks due to imported foods have important resource implications for health and other regulatory authorities. Identifying the source of the food vehicle is difficult, as these foods often have a wide distribution and cases may be widely and thinly spread. Small numbers of cases of Salmonella Stanley were identified in every Australian jurisdiction except Tasmania and the Northern Territory. This type of investigation requires a coordinated response from all jurisdictions. Although a food vehicle may be identified, it may be difficult to control future product importation. For example, testing all food products containing peanuts coming into Australia is virtually impossible due to the huge range of products containing these nuts.

These outbreaks have shown that there is an obvious need to strengthen networks between Australian and international investigators. Health Canada was trying to identify a source for a similar outbreak of Salmonella Stanley in British Columbia during September 2001. The OzFoodNet posting to international electronic mailing lists about contaminated peanuts assisted them to identify the source of their outbreak.

The Victorian DHS was only able to confirm the source for the outbreak of Salmonella Definitive Type 104 in Victoria after Turkish helva was confirmed as the source of a similar outbreak in Sweden. These two international investigations involved intensive liaison with health authorities in Canada, China, Turkey, the United Kingdom, Sweden, Norway and other European countries.

While investigators find it difficult to identify imported food vehicles, it is even more difficult to identify the original source of contamination in the source country. Both of these investigations tracked a specific product back to a country of origin, but were unable to identify how the product became contaminated. This is a cause for concern, as it makes prevention effort almost impossible. The concept of product traceability is currently under discussion in international forums, such as the Codex Alimentarius Commission.

Health agencies are increasingly identifying outbreaks associated with foods that are distributed internationally.11,12,13Salmonella is frequently recognised as causing international outbreaks, but other agents have also been implicated.11 Imported foods are possibly responsible for many more cases of illness that currently go unrecognised by Australia's surveillance systems.

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Takeaway foods

The increasing consumption and volume of takeaway food served in Australia means that we are recognising more outbreaks associated with this sector. In 2001, there were 10 outbreaks associated with fast foods and one community-wide outbreak associated with products served by fast food restaurants. Many of these outbreaks were relatively small, but occurred repetitively.

In 2001, there were 3 small clusters of Salmonella and Campylobacter infections associated with takeaway kebabs. The vertical spits used to cook these products may not allow adequate internal cooking during busy periods. A recent survey of kebabs in Victoria showed that in 41.1 per cent of instances meat did not reach a surface temperature of 75 C, and 23 per cent of proprietors were cutting under-cooked meat off kebab spits.14

There were several small outbreaks associated with takeaway chickens, where the cause of contamination could not be determined.

Pizza was suspected as the vehicle for 5 outbreaks, one of which was due to S. Typhimurium 126 and the remainder of unknown aetiology. These outbreaks were small, due to the nature of consumption of these products, i.e. generally in small groups, making outbreak recognition difficult. OzFoodNet sites reported that pizzas have historically been the cause of toxin related outbreaks, particularly due to S. aureus. These bacterial toxins have been due to poor storage of raw ingredients immediately prior to pizza preparation. Pizza is a food that may also be undercooked, particularly during busy periods when cooking times are reduced.

Knowledge of safe times and temperatures for cooking food is essential for food businesses to ensure safe food. Although a validated food safety program can greatly assist businesses ensure that their food is safe, one of the major Salmonella outbreaks in 2001 was associated with a supplier with a certified safety program.

Seafood related illness

During 2001, there were 10 outbreaks associated with seafood that indicate potential risks for consumers. These included:
  • six outbreaks of ciguatera poisoning following reef fish consumption;
  • two outbreaks of oily diarrhoea associated with escolar consumption;
  • one outbreak of histamine poisoning after eating Mahi Mahi; and
  • one outbreak of Salmonella Mississippi suspected to be associated with oysters.
Ciguatera poisoning is a commonly reported illness, particularly in Queensland, where the majority of outbreaks occurred in 2001. Ciguatera poisoning may cause serious illness. In one outbreak, 11 out of 14 people were hospitalised as a result of their illness. In another outbreak, all 3 people consuming fish were affected and one person died. All outbreaks occurred in a home setting. The fish species implicated in these outbreaks included coral trout n=(2), Spanish mackerel n=(2), spotted mackerel n=(1), and barracuda n=(1). These species are recognised as a high risk for ciguatera poisoning. There is an obvious need to increase the education of amateur fishermen about species likely to cause ciguatera poisoning and the location of high-risk reefs and fishing locations.

During 2001, there were 2 outbreaks of diarrhoea associated with consumption of escolar (Lepidocybium flavobrunneum) or oilfish (Ruvettus pretiosus). There have been several outbreaks of this diarrhoeal syndrome around Australia in recent years, particularly in South Australia, Victoria and New South Wales. The outbreaks in 2001 affected 42 per cent (20/47) of people attending a conference in Newcastle and 33 per cent (5/15) of people attending a restaurant in Melbourne.

The marketing names used for these species are confusing, as they may be called butterfish, rudderfish, oilfish or escolar. Escolar and oilfish are the only two species that have the potential to cause illness. These fish have a very high content of indigestible wax ester, which causes oily diarrhoea, nausea and vomiting. The two other outbreaks associated with seafood in 2001, were a small outbreak of histamine poisoning (4 cases) and one of salmonellosis associated with oysters (6 cases). Histamine poisoning is not commonly reported in Australia, compared to other countries.15 The symptoms are short-lived and often affect small numbers of people. Salmonella outbreaks are not commonly associated with seafood, although oysters may be contaminated with human pathogens when grown in contaminated water.16

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Red meat and poultry

Twenty-seven per cent (23/86) of outbreaks reported by OzFoodNet sites were attributed to poultry or red meat products (Table 7). Many of these outbreaks were related to contamination post-cooking. There were 2 outbreaks of C. perfringens associated with cooked red meats, and four suspected toxin-related outbreaks associated with spit roast meats. The outbreak of Norwalk-like virus occurred at a large function where it was suspected that dishes or platters containing chicken became contaminated.

Table 7. Outbreaks associated with poultry or red meat/meat products, 2001, by agent and vehicle

Agent category
Poultry Red meat/meat products Suspected poultry Suspected red meat/meat products Total
C.   perfringens
-
2
-
-
2
Norwalk virus
-
-
1
1
2
Campylobacteriosis
2
-
-
-
2
Salmonella Typhimurium
1
3
-
1
5
Salmonella Virchow
1
-
-
-
1
Suspected salmonellosis
-
-
-
1
1
Suspected toxin
-
-
-
4
4
Unknown
-
-
6
-
6
Total
4
5
7
7
23


Salmonella was responsible for 7 outbreaks associated with these foods, five of which were due to Salmonella Typhimurium serovar. The South Australian Department of Human Services investigated a large outbreak of Salmonella Typhimurium phage type 126. The department investigation demonstrated a strong association between illness and consuming locally produced chicken meat. They also identified concurrent epidemics of this Salmonella in local chicken flocks. Industry instituted a range of interventions, which was likely to have resulted in a subsequent decrease in the number of human cases.

During 2001, OzFoodNet sites investigated 38 clusters of Salmonella infections affecting 235 people. These included serovars commonly isolated from animal sources, such as Typhimurium, Virchow, and Bovismorbificans. Eleven of these clusters were various phage types of S.Typhimurium and accounted for 158 notified cases. Many of these clusters appeared to have links to red meat and/or poultry, either through human-animal contact or contaminated food.

Some of the reasons that investigators suspected that these clusters were related to these sources were:
  • reports of isolation of these organisms from non-human sources in the NEPSS database;
  • sporadic cases where the source of infection was known, e.g. a farmer infected with a certain type of Salmonella coincident with an outbreak in an animal herd;
  • mixed infections with other organisms, such as Campylobacter, that are commonly associated with the suspected source;
  • previous experience with outbreaks and sporadic cases of the specific Salmonella infection; and
  • surveys of foods.
Identifying the source of these human infections is very difficult since poultry and red meats are very commonly consumed. While it is very difficult to identify sources, it is vital that public health agencies can compare data on Salmonella isolates from different sources to generate hypotheses.

State and territory health departments routinely consult NEPPS data on isolates from non-human sources to assist with investigations, although the underlying sampling distribution is unknown. It is often very difficult to obtain data from industry that are relevant to the investigation. To overcome these problems, jurisdictions could consider developing a long-term survey of Salmonella and Campylobacter in red meat and poultry at the retail level to monitor trends. If the sampling plan is well devised and the survey is conducted over a long period of time, investigators may be able to correlate these data with human infections. It is also vital for health agencies to improve liaison with industry and departments of agriculture.

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Burden of disease

Foodborne disease imposes a substantial burden on the community and healthcare system.17 One of the primary aims of OzFoodNet is to determine the incidence of foodborne disease in Australia. In 1999, the Australia New Zealand Food Authority estimated that there were approximately 4.2 million cases of foodborne disease each year, costing in excess of A$2.6 billion.18

NCEPH is conducting a National Gastroenteritis Survey on behalf of OzFoodNet to determine the incidence of gastroenteritis, which will be used to estimate the burden of foodborne disease. Two sites, Queensland and Victoria, also collected data about gastroenteritis through their state-based computer-assisted telephone interview (CATI) systems during 2001. This section reports on the progress of the National Gastroenteritis Survey and the preliminary results from the two state-based surveys.

Early estimates from the data collected in these three surveys indicate that the incidence of gastroenteritis is approximately one episode per person per year.19 If we consider that roughly 35 per cent of gastrointestinal disease may be due to food, then there may be as many as 7 million cases of foodborne disease in Australia each year.17 This is considerably higher than previous estimates.18

The National Gastroenteritis Survey

NCEPH started the OzFoodNet National Gastroenteritis Survey in September 2001. The main aim of this cross-sectional survey is to determine the incidence of gastroenteritis in Australia and to contribute to more reliable estimates of foodborne disease. The survey will also allow OzFoodNet to:
  • identify regional or seasonal trends in gastroenteritis;
  • determine the health seeking behaviours of persons with gastroenteritis; and
  • determine the faecal testing patterns of medical practitioners who treat patients with gastroenteritis.
The National Gastroenteritis Survey uses the CATI technique to record people's experience of gastroenteritis in the previous month. The survey will run from September 2001 to August 2002 and will enrol approximately 6,000 people from all Australian states and territories. The results will be analysed by varying case definitions of gastroenteritis. This will range from the broadest possible, such as any acute episode of vomiting or diarrhoea in the last 4 weeks through to more stringent criteria, such as three or more loose stools or two episodes of vomiting in any 24-hour period. To ensure that the data are relevant to foodborne disease, OzFoodNet will exclude people attributing symptoms to non-infectious causes.

The preliminary data available in December 2001 covered the 4 months between September and December 2001 from 2,417 interviews of people across Australia. The unweighted results showed that approximately 12 per cent of respondents experienced symptoms of gastroenteritis in the previous 4 weeks. Preliminary analysis of the data suggests that there is variation by region, age and a medical history of chronic illness.20 In the 4-month period there was modest variation across the jurisdictions with the highest level being recorded in the Northern Territory (Table 8). The Northern Territory recorded nearly twice the incidence of gastroenteritis of most other jurisdictions.

Table 8. Proportion of respondents with symptoms of gastroenteritis,* September to December 2001, by State and Territory

State
Proportion with gastroenteritis (%)
New South Wales
10
Northern Territory
21
Queensland
11
South Australia
12
Tasmania
11
Victoria
11
Western Australia
10
Total
12

* Unweighted and all-inclusive definition of gastroenteritis
† Includes the Australian Capital Territory, and an over sample in the Hunter Area Health Service


There was considerable difference in incidence by age, with younger children in the 0-4 year age group having the highest level of gastroenteritis. Approximately 20 per cent of this age group experienced gastroenteritis in the past 4 weeks compared with 5 per cent of older adults.

About 20 per cent of people with gastroenteritis visited their doctor or casualty department for treatment, but only about 3 per cent had a stool sample taken for testing. About a third took some form of medication, mostly painkillers. About a third of working people missed a day or more of work when they had gastroenteritis.

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Victorian Population Health Survey

The Victorian Department of Human Services surveyed 7,494 persons aged 18 years or older as part of the Victorian Population Health Survey conducted between August and November 2001.

The survey used a CATI methodology to collect data about a range of health topics and demographic information. In the survey there were seven questions relating to gastroenteritis. The case definition for an episode of gastroenteritis was three or more loose stools, or two or more episodes of vomiting in a 24-hour period. Survey respondents were asked if they had experienced gastroenteritis in the previous 4 weeks. Persons with chronic conditions in which diarrhoea or vomiting were predominant symptoms were excluded from analysis.

The survey found that 10.1 per cent of adults had either diarrhoea or vomiting in the past 4 weeks when people with chronic gastrointestinal symptoms were excluded (Table 9). Twenty-one per cent of these people sought medical assistance for their illness, and 3.4 per cent had a faecal specimen tested.

Table 9. Self-reported gastroenteritis reported in the previous 4 weeks for adults over 18 years, Victorian Population Health Survey, August to December 2001

  Adults (n=7,494)
n %
Gastroenteritis
760
10.1
Days off work/school/study/home duties
172
22.6*
Consulted doctor/nurse/medical person
157
20.7*
Stool tested
26
3.4*
Hospitalised
20
2.6*

* The denominator for proportions reporting days off work, consultation to doctor, stool testing and hospitalisation is the number of survey respondents reporting gastroenteritis (n = 760).


Queensland Health 2001 Omnibus Survey

The Queensland Department of Health surveyed a total of 3,081 persons aged 18 years or older as part of the Queensland Health 2001 Omnibus Survey conducted between March and May in 2001. The Survey also collected data on children aged 7 months to 4 years from a nested survey of 386 parents or caregivers.

The survey used a CATI methodology to collect data about a range of health topics and demographic information. In the survey, there were 17 questions relating to gastroenteritis in adults and 13 addressed to carers of young children. The case definition for an episode of diarrhoea was three or more loose stools in a 24-hour period. Respondents were asked about episodes of diarrhoea during the preceding month. Persons with chronic conditions in which diarrhoea is a symptom were excluded from analysis.

The survey found that 13.6 per cent of adults and 18.9 per cent of children had acute diarrhoea in the preceding month (Table 10). Persons aged 18-39 years were almost twice as likely as those aged 40 years and older to report acute diarrhoea in the preceding month.

There was no significant difference for incidence of acute diarrhoea between persons living in a capital city or other major urban areas and persons living in rural and remote areas. There was no significant difference in the incidence of acute diarrhoea between lower and higher socio-economic groups as measured by the Australian Bureau of Statistics Socio-economic Indices for Areas, which is different to reports in the literature.21

Parents of young children with diarrhoea were more than twice as likely to seek medical care compared with adults (RR 2.5; 95% CI 1.8-3.5), although doctors requested stool specimens from similar proportions of presenting adults and young children.

Table 10. Acute diarrhoea reported in the previous month, comparing adults and children aged between 7 months and 4 years, Queensland Health Omnibus Survey, March to May 2001

  Adults (n=3,081) Children (n=386)
n % n %
Acute diarrhoea
418
13.6
73
18.9
Consulted doctor
77
18.4*
34
46.6*
Stool collected
11
2.6*
6
8.2*

* The denominator for proportions reporting consultation to doctor and stool testing is the number of survey respondents reporting gastroenteritis (n = 418 for adults and n= 73 for children).


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Improving surveillance

OzFoodNet aims to improve the investigation and reporting of foodborne disease throughout Australia. During 2001, OzFoodNet reviewed and evaluated surveillance of foodborne disease in different jurisdictions. These discussions highlighted that surveillance in different jurisdictions varies in sensitivity to detect and investigate outbreaks. OzFoodNet aims to ensure that each jurisdiction enhances the sensitivity of their surveillance system in a way that is sustainable in the longer term.

Communicating nationally

OzFoodNet has developed into the major forum vehicle for discussing foodborne disease incidence at the national level in Australia. OzFoodNet contributes to CDNA, which is Australia's peak body for surveillance and response to communicable diseases. CDNA meets each fortnight by teleconference to discuss issues about communicable diseases that are of national importance.22 OzFoodNet is able to investigate clusters of foodborne disease that occur in more than one Australian jurisdiction.

During 2001, OzFoodNet started circulating a short summary report of outbreaks and clusters occurring at each site. These reports are circulated each fortnight and detail:
  • the occurrence of point source outbreaks occurring in the site;
  • results from current and previous investigations;
  • any increases in enteric pathogens; and
  • the current incidence of important foodborne diseases, such as: listeriosis, STEC and Salmonella Enteritidis infections.
OzFoodNet holds monthly teleconferences to update members about the occurrence of clusters of disease and discuss the progress of joint projects. If cluster investigations involve more than one jurisdiction more frequent teleconferences are conducted.

National outbreak coordination

In July 2001, CDNA requested that OzFoodNet coordinate the investigation into an outbreak of S. Stanley that was occurring in people with Asian surnames in several Australian jurisdictions. OzFoodNet convened teleconferences to discuss state and territory investigations of cases. All jurisdictions agreed to pool de-identified data into a spreadsheet for descriptive analysis and hypothesis generation.

This outbreak investigation was unusual in that very few cases were notified in each jurisdiction. Some jurisdictions only had one or 2 cases notified. It demonstrated the need for centralising data and coordinating investigations nationally. OzFoodNet also coordinated summaries of several smaller clusters of Salmonella infections occurring across different jurisdictions.

National case definitions

All contributors using the same case definitions and applying them consistently improve public health surveillance. During 2001, the CDNA revised the case definitions for national surveillance of communicable diseases. This review, which included input from OzFoodNet included several diseases potentially transmitted via food.

Case series of listeriosis

The FSANZ requested that OzFoodNet compile data on human listeriosis for a risk assessment on Listeria in seafood. OzFoodNet obtained data from all states and territories on cases of listeriosis reported between 1998 and 2000.

The data required considerable checking and interpretation, but yielded important insights into surveillance for listeriosis. An example of this was the inconsistencies in recording materno-foetal infections between states and territories. States and territories reported 49 listeriosis cases in pregnant women that corresponded to 37 distinct infections. For each pregnancy-associated infection, jurisdictions recorded either the mother or the baby as a single case, or they recorded both the mother and the baby on the dataset (Figure 14). This means that the numbers of listeriosis cases occurring in each jurisdiction are not comparable. The review also highlighted many information gaps on routine surveillance databases, such as information on risk factors and Indigenous status.

Figure 14. Notifications of listeriosis in pregnant women, 1998 to 2000, by method of State and Territory dataset entry (n=49 cases)

Figure 14. Notifications of listeriosis in pregnant women, 1998 to 2000, by method of State and Territory dataset entry (n =49 cases)

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Timeliness and completeness of Salmonella reporting

Effective surveillance of Salmonella relies on data that are transmitted in a timely fashion and recorded systematically.23 In 2001, OzFoodNet epidemiologists evaluated surveillance for foodborne diseases. These evaluations highlighted some deficiencies inherent in the system, which became obvious during multi-jurisdictional investigations.

OzFoodNet epidemiologists worked with local data providers and reference laboratories to improve the timeliness of surveillance data. Some examples of improvements are listed below.
  • By changing the way data were reported from the reference laboratory, the OzFoodNet-Hunter site was able to decrease the median time delay between specimen collection to receipt of a serovar result from 21 days to 17 days.
  • The OzFoodNet-Tasmania site was able to improve the timeliness of Salmonella reports by recording sero-groupings, as the predominant serovar. Mississippi is the only one belonging to the E/G group. S.Mississippi accounted for 59 per cent (96/166) of notifications in Tasmania during 2001. While not providing definitive results, this change will allow the Tasmanian Department of Health and Community Services to identify potential outbreaks of Salmonella Mississippi, and non-Mississippi serovars.
  • The OzFoodNet-Western Australia site was able to liaise with the local reference laboratory to increase the frequency of sending Salmonella isolates requiring phage typing to reference laboratories in South Australia and Victoria. Minimising the time taken for batching isolates is vital for outbreak detection and control.
Despite these examples of improvements to Salmonella timeliness, there are still many gains yet to be made in this area. Timeliness should improve considerably with the introduction of electronic reporting from laboratories to health departments.

It is equally important for health agencies to accurately record reports of Salmonella on surveillance databases. The quality of datasets around the country can influence detection of clusters for investigation (Box 2).

Box 2. A pseudo outbreak due to data entry error

At a routine teleconference, an epidemiologist identified a recent increase in Salmonella Typhimurium phage type 4 in a neighbouring geographic region (Region A) of their state (Figure 15). An epidemiologist in another state reported a concurrent increase of S. Typhimurium 4 at the same time. Upon further investigation, the increase in the first state was found to be entirely due to a data entry error. This national discussion about this pseudo-outbreak again highlighted the importance of rigorous quality assurance in surveillance data collection.


Figure 15. Pseudo outbreak of Salmonella Typhimurium 4 due to data entry error in the neighbouring region to an OzFoodNet site

Figure 15. Pseudo outbreak of Salmonella Typhimurium 4 due to data entry error in the neighbouring region to an OzFoodNet site
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There was a marked improvement in completeness of Salmonella typing information on surveillance databases in jurisdiction between 2000 and 2001 (Table 11). There was a 5.3 per cent increase in salmonellosis cases on notification databases with appropriate typing data, up from 88.0 per cent in 2000 to 93.3 per cent in 2001. Importantly, the rates of completeness particularly improved in the states of Western Australia and New South Wales in these 2 years. Western Australia reported the largest improvement of 23.1 per cent from 2000 to 2001, which was due to the health department receiving voluntary laboratory notifications of communicable diseases at this time. South Australia had the highest rate of completeness with appropriate information for 99.8 per cent of all cases in 2001.

It is likely that the majority of salmonellas isolated at primary laboratories are typed due to a well-developed system of referral. The overall improvements observed in 2001 can be partly attributed to the interaction of OzFoodNet epidemiologists with surveillance systems. While there was an improvement in this area from 2000 to 2001, it is an area that OzFoodNet epidemiologists need to monitor and improve in the future.

Table 11. Completeness of Salmonella typing data on State and Territory surveillance databases, 2000 and 2001

Information required
Per cent of notifications with appropriate typing information, by notification date
ACT NSW Qld SA
2000 (n=100) 2001 (n=76) 2000 (n=1,341) 2001 (n=1,670) 2000 (n=1,818) 2001 (n=2,169) 2000 (n=452) 2001 (n=613)
Salmonella serotype
96.0
98.7
92.8
94.1
97.2
97.0
99.6
99.8
S. Bovismorbificans phage type
-
100
50.0
39.4
100
100
100
100
S. Enteritidis phage type
100
100
78.2
80.8
94.8
90.2
100
100
S. Hadar phage type
0.0
100
52.9
38.9
100
73.3
100
100
S. Heidelberg phage type
100
100
18.2
84.6
90.6
91.8
-
-
S. Typhimurium phage type
100
100
88.1
95.7
93.1
95.8
100
100
S. Virchow phage type
100
100
38.2
67.2
97.4
95.0
100
100
Salmonella with information
95.0
98.7
80.5
87.8
95.0
94.7
99.6
99.8


Table 11. Completeness of Salmonella typing data on State and Territory surveillance databases, 2000 and 2001, continued

Information required
Per cent of notifications with appropriate typing information, by notification date
Tas Vic WA OzFoodNet sites
2000 (n=127) 2001 (n=166) 2000 (n=1,009) 2001 (n=1,091) 2000 (n=936) 2001 (n=898) 2000 (n=5,783) 2001 (n=6,683)
Salmonella serotype
96.9
98.2
97.7
97.7
92.2
95.2
95.5
96.5
S. Bovismorbificans phage type
100
100
96.3
96.7
62.5
57.1
76.4
83.2
S. Enteritidis phage type
100
100
100
100
34.5
85.5
78.3
89.4
S. Hadar phage type
-
-
81.8
100
80.0
85.7
75.8
77.8
S. Heidelberg phage type
0.0
-
75.0
100
0.0
0.0
68.6
88.6
S. Typhimurium phage type
97.0
96.4
99.8
99.7
55.2
87.8
87.7
96.4
S. Virchow phage type
100
-
99.1
100
80.0
66.7
90.7
92.5
Salmonella with information
95.3
97.6
97.1
97.4
68.1
89.4
88.0
93.3


Increasing OzFoodNet coverage

During 2001, the Northern Territory participated in OzFoodNet as observers. The Food Branch of the New South Wales Health Department also participated in several teleconferences and attended face-to-face meetings.

The Australian Capital Territory joined OzFoodNet as a fully funded member in August 2001. The OzFoodNet epidemiologist in the Australian Capital Territory is also assisting NCEPH with the estimation of the burden of foodborne disease in Australia. At the time of writing, contracts had recently been finalised which will see OzFoodNet coverage to include all of New South Wales and the Northern Territory.

Efficient surveillance of infectious diseases relies upon good liaison between health agencies and public health laboratories. OzFoodNet has continued to work collaboratively with laboratories in each jurisdiction and the PHLN and is undertaking several studies with strong laboratory involvement, which has associated benefits for surveillance.

International developments

In 2001, OzFoodNet established collaborative links with international agencies conducting surveillance and research into foodborne diseases. Several countries have conducted similar studies to OzFoodNet, which will yield important insights into the incidence and control of foodborne disease. These collaborations have included agencies, such as the USA Centers for Disease Control and Prevention, the Food Safety Authority of Ireland, Health Canada, the Institute of Environmental Science and Research New Zealand, the United Kingdom Public Health Laboratory Service, and the World Health Organization.


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

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