Foodborne Disease OZFOODNET Surveillance Across Australia

Enhancing Foodborne Disease OZFOODNET Surveillance Across Australia

Annual Report 2003

Queensland OZFOODNET Communicable Diseases Unit Queensland Health

Queens and Government Queensland Health OzFoodNet - Enhancing Foodborne Disease Surveillance Across Australia

Annual Report 2003 Queensland Site

Site Epidemiologist - Russell Stafford

January - December 2003

Queensland OzFoodNet Site Communicable Diseases Unit Queensland Health

Located: Qld Health Scientific Services Level 1, Public Health Unit 39 Kessels Rd Coopers Plains QLD 4108 (07) 3000 9148

Contents Summary ...... 4 Introduction...... 6 Data Sources and Methods ...... 6 Incidence of Foodborne Disease 4th Quarter...... 7 Total Cases Reported ...... 7 Total Cases Reported ...... 9 Salmonella ...... 10 Incidence ...... 10 Trends ...... 11 Geographic Distribution...... 15 Campylobacter ...... 17 Incidence ...... 17 Trends ...... 18 Geographic Distribution...... 19 Listeria ...... 20 Incidence ...... 20 Trends ...... 20 Geographic Distribution...... 21 Shigella ...... 22 Incidence ...... 22 Trends ...... 23 Geographic Distribution...... 24 Yersinia ...... 25 Incidence ...... 25 Trends ...... 25 Geographic Distribution...... 26 Shiga-toxin Producing E.coli (STEC) / HUS ...... 27 Incidence ...... 27 Trends ...... 27 Geographic Distribution...... 28 Typhoid Fever / Paratyphoid Fever...... 29 Incidence ...... 29 Gastrointestinal Disease Outbreaks...... 30 Total 2003...... 30 Foodborne Disease Outbreaks...... 31 Significant foodborne illness outbreaks during 2003...... 33 Bacterial outbreaks...... 33 Viral outbreaks...... 34 Chemical outbreaks...... 35 Cluster Investigations ...... 36 OzFoodNet Projects – Applied Research in Queensland...... 37 Case Control Studies...... 37 Project Management...... 39 Project Objectives and Outcomes...... 39 Conclusions ...... 42 Publications/Presentations ...... 43

Acknowledgements...... 44 References ...... 45 Appendices ...... 46 Appendix 1. All reported gastroenteritis outbreaks in Queensland, by aetiology, 2003 ...... 46 Appendix 2. Annual notification numbers and rates per 100,000 population, for foodborne pathogens, Queensland, 2000 - 2003...... 48 Appendix 3. Salmonella and Campylobacter rates 1999 - 2003...... 49 Appendix 4. Maps of Queensland Health Zones and Statistical Divisions...... 50

Summary

This is the third Annual Report from the Queensland foodborne disease surveillance site, one of eight sentinel sites around Australia which comprise OzFoodNet. This report summarises the surveillance and applied epidemiological research activities conducted in Queensland between January and December 2003.

The following are key points from this report:

! There were 6,320 cases of foodborne illness due to the nine pathogens or conditions under surveillance notified to Queensland Health during 2003. This compares with 6,833 cases notified in 2002 and 6,340 cases notified in 2001.

! Campylobacter was the most frequently notified pathogen during 2003, followed by Salmonella. Together, these two pathogens contributed approximately 97% of all foodborne illness notifications for the year.

! There were 2,255 Salmonella notifications received during 2003, a decrease of 17.2% compared with the number notified in 2002. The 3,886 Campylobacter notifications received during 2003 was comparable to the number reported in 2002 (3905). The median age of notified Salmonella cases was 12.0 years; the median age of notified Campylobacter cases was 31.0 years.

! Children aged between 0 and 4 years accounted for 40.8% of the total number of Salmonella notifications received during 2003, but only 11.6% of the total number of Campylobacter notifications.

! The most commonly identified Salmonella serotypes during 2003 were Saintpaul (167 cases), Virchow PT8 (165 cases), Typhimurium PT135 (155 cases), Birkenhead (109 cases) and Chester (98 cases).

! The most notable change in the incidence of notified Salmonella infections between 2002 and 2003 has been the increase in S. Typhimurium PT197 (+190%). There were two reported outbreaks of S. Typhimurium PT197 infection during 2003 but these only accounted for 7 of the 90 notified cases. The majority of cases were notified from the Brisbane and Moreton Statistical Divisions (84.4%).

! A comparison of reported Salmonella infections among the three Queensland Health Zones during the 2003 period showed the highest notification rate was in the North Zone (108.6/100,000) with a decreasing trend from north to south. This trend has been a consistent feature of salmonellosis in Queensland during the past six years.

! Completeness of serotype and phage type information for Salmonella has improved during the past three years. Only 49 (2.2%) of the 2255 salmonellas notified during 2003 lacked serotype information. This compares with 2.5% in 2002 and 3.0% in 2001. Similarly, only 6 (0.6%) of the 977 Salmonella serotypes that are phage typed, lacked this information. This compares with 1.5% in 2002 and 5.0% in 2001.

! Campylobacter notification rates were consistently higher than Salmonella rates among children aged 5 years and older and for all adults, however, for children aged between 0 and 4 years notification rates were considerably higher for Salmonella infections.

! Notification rates for Campylobacter infection were 41.2% and 60.4% higher among male children aged 0 to 4 years and 15 to 19 years respectively than female children of the same age groups. Notification rates were similar for all other age groups.

! There were 6 sporadic cases of Shiga-toxin producing E.coli (STEC) and one case of Haemolytic Uraemic Syndrome (HUS) notified during 2003. The median age of STEC cases was 45.5 years with a range between 39 and 65 years. No food vehicles or sources of infection were identified following case investigations and there were no STEC outbreaks detected during 2003.

! During 2003, a total of 45 outbreaks of gastroenteritis affecting at least 727 people were reported to the Queensland OzFoodNet site. There were 65 (8.9%) people who were hospitalised and two deaths which were attributed to the gastroenteritis. Thirty (66.7%) outbreaks were attributed to foodborne transmission, affecting at least 311 people, of whom 28 (9.0%) were hospitalised.

! Ten of the 30 foodborne outbreaks had a bacterial aetiology, three were viral, ten were attributed to ciguatoxin, four to chemicals other than toxins and three had an unknown aetiology. There were no reported parasitic foodborne outbreaks. The most common bacterial pathogen responsible for foodborne outbreaks during 2003 was Salmonella, which was identified in eight (80.0%) outbreaks. Six of the 8 salmonellosis outbreaks were due to S. Typhimurium.

! Nine (30%) outbreaks were associated with meals served at restaurants, three (10) with catered functions and three (10%) with aged care facilities. There were twelve (40%) outbreaks associated with meals served within private residences, however, eight of the 12 outbreaks were caused by ciguatera poisoning due to consumption of purchased fish that was cooked in the home.

! A food vehicle was unable to be identified for 9 (30%) of the 30 outbreaks due to foodborne transmission. More importantly, a food vehicle was unable to be identified for 6 (60%) of the 10 foodborne outbreaks with a bacterial aetiology. Two of the 4 bacterial outbreaks with an identified food vehicle were determined using an analytic study during the investigation. Only one (10%) of the 10 bacterial outbreaks was confirmed as foodborne by microbiological evidence of the pathogen in food (Staphylococcus aureus and enterotoxin detected in pasta salad).

! Recruitment of subjects and data collection continued in Queensland during 2003 for two national prospective case control studies of sporadic infection due to Salmonella Enteritidis and Listeria monocytogenes and one state case control study of Salmonella Typhimurium phage type 170.

! Data analysis for the Queensland Salmonella Birkenhead case control study was completed in December 2003 and a report of the study findings will be published during 2004.

! Data analysis for the national Campylobacter case control study was conducted during 2003. A report of the study findings will be published during 2004.

! A poster describing the methods and preliminary findings of the Campylobacter case control study was presented at the 12th International Workshop on Campylobacter, Helicobacter and Related Organisms held in Aarhus, Denmark in September, 2003.

! An oral presentation describing the methods and preliminary findings of the Campylobacter case control study was presented at the 11th Australian Food Microbiology Conference of the Australian Institute of Food Science and Technology in Noosa in March, 2003.

Introduction OzFoodNet, established in 2000 by the Commonwealth Department of Health and Ageing, is a collaborative network of epidemiologists and microbiologists conducting enhanced surveillance, outbreak investigations and applied research into foodborne disease across six Australian States, the Northern Territory and the Australian Capital Territory. In 2003, the coverage of the network included the entire Australian population, which was estimated in September 2003 to be 19,941,300 persons1.

In 2003, two additional OzFoodNet bodies were established, an OzFoodNet Management Committee and an OzFoodNet Scientific Review Panel. The main task of the Management Committee is to provide strategic direction and oversight of the core work and research projects of OzFoodNet. The Scientific Review Panel will act as a consultancy body to assist with the development, conduct, and evaluation of OzFoodNet activities.

Partners of OzFoodNet include Food Standards Australia New Zealand (FSANZ), the National Centre for Epidemiology and Population Health (NCEPH), Dept of Agriculture, Fisheries and Forestry Australia (AFFA), the Communicable Diseases Network of Australia (CDNA) and the Public Health Laboratory Network (PHLN).

The aims of OzFoodNet are to: 1. Determine the frequency and burden of foodborne disease in Australia 2. Identify the causes and contributing factors to foodborne disease in Australia 3. Provide epidemiological information to inform prevention efforts 4. Describe the epidemiology of new and emerging foodborne pathogens

To address these objectives, OzFoodNet conducts enhanced surveillance, outbreak investigations and formal epidemiological studies in each of the sentinel sites. This report summarises the surveillance and applied epidemiological research activities conducted in Queensland during 2003.

Data Sources and Methods Incidence data are derived from statutorily notified cases of infection collated by the Communicable Diseases Unit, Queensland Health. All notified cases of foodborne illness include infections acquired overseas. Notifications received for Salmonella, Campylobacter, Listeria, Shiga-toxin producing E. coli (STEC), Shigella, Yersinia, Typhoid, Paratyphoid and Haemolytic Uraemic Syndrome (H.U.S.) between 1 January 2003 and 31 December 2003 were collated and analysed using Epi Info (V 6.04d), SPSS (V 10.0) and Microsoft Excel. All data in this report is based on date of receipt of notification. Crude notification rates were calculated using the Australian Bureau of Statistics (ABS) mid-year estimated resident population figures for 2002 as the denominator2.

Laboratory data were obtained from the Public Health Microbiology Laboratory, Queensland Health Scientific Services, and from the National Enteric Pathogen Surveillance Scheme located at the Microbiological Diagnostic Unit, Melbourne. Outbreak data were obtained from the OzFoodNet Gastrointestinal Illness Outbreak Register, Communicable Diseases Unit, Queensland Health.

Incidence of Foodborne Disease 4th Quarter

Total Cases Reported During the October to December 2003 reporting period, 1,506 cases of foodborne illness due to the nine pathogens or conditions under surveillance were notified to Queensland Health (Table 1). This compares with 1,696 cases notified for the corresponding period in 2002, a decrease of 11.2%. Campylobacter was the most frequently notified foodborne pathogen followed by Salmonella. The number of notifications of Salmonella received during the fourth quarter 2003 increased by 2.0%, while Campylobacter notifications decreased by 16.9%.

Table 1. Number of notified cases of foodborne pathogens in Queensland, Fourth Quarter 2002 and 2003 2003 2003 2002 2003 2002 Pathogen/

Condition Oct Nov Dec Oct-Dec Oct-Dec Total Total Salmonella 133 170 254 557 546 2255 2722 Listeria – materno-foetal 0 0 0 0 0 1 0 infection Listeria – other 1 1 1 3 2 10 20 Campylobacter 317 278 322 917 1104 3886 3905 Typhoid 1 1 0 2 1 5 11 Paratyphoid 1 0 0 1 0 7 0 Yersinia 6 5 9 20 14 94 73 Shigella 3 1 1 5 25 55 95 STEC* 1 0 0 1 3 6 6 HUS** 0 0 0 0 1 1 1 Total 463 456 587 1506 1696 6320 6833 * STEC : Shiga-toxin producing E. coli ** H.U.S : Haemolytic Uraemic Syndrome

There were three sporadic cases of invasive Listeriosis (all septicaemia) notified during the fourth quarter; an 88 year old male and two females aged 63 and 55 years. Both female patients died during their period of sepsis. The 55 year old female case was receiving treatment for metastatic breast carcinoma at the time of her illness. Her family refused to be interviewed about her food history, however, information received from her doctor indicated she had been consuming a variety of soft cheeses in the month prior to onset of her illness. No foods were tested to confirm the presence of Listeria in the cheeses. The 63 year old female had a primary underlying condition of ascites and liver disease (alcohol related) while the 88 year old male was receiving treatment for non-hodgkins lymphoma at the time of his infection. All infections were most likely community-acquired, however, no foods were collected for microbiological testing.

Two cases of Typhoid fever were reported in two males age 50 and 35 years respectively during this quarter. Both cases were travelling overseas during their incubation periods. The 50 year old case most likely acquired their infection in Bali (S. Typhi phage type D2), while the 35 year old case had a history of overseas travel to Western Samoa (S. Typhi phage type E1). A single case of Paratyphoid B Fever was notified in a 27 year-old male who had recently travelled to Morocco.

One case of STEC infection was notified during the fourth quarter of 2003 in a 39 year old female. Shiga-like toxin was detected in faeces using ELISA; the genes for stx1 and stx2 were detected by PCR (O157 serotype). No food vehicle or source of infection was identified. The infection appeared to be acquired in Queensland.

There were 558 Salmonella isolates notified during the fourth quarter, of which 543 (97.3%) were serotyped. The most commonly reported serovars were Typhimurium PT135 (13.8%), Virchow PT8 (9.8%), and Typhimurium PT197 (5.5%). Among the top five Salmonella infections during the quarter, Salmonella Typhimurium PT135 had the largest increase in numbers when compared to the same period in the previous year (Table 2). Of the 75 notified cases of Typhimurium PT135, 24 (Typhimurium PT135a) were laboratory-confirmed cases linked to an outbreak amongst residents and staff of a Brisbane nursing home most likely resulting from the consumption of eggnog at a Christmas function. Another outbreak of S. Typhimurium PT135 infection occurred during this period affecting at least 18 people attending a Gold Coast restaurant. Ten of the 18 cases were laboratory-confirmed. Eggs were also the suspected source of infection for this outbreak (refer to foodborne outbreaks section). Together, these two outbreaks accounted for 45.3% (34 cases) of all S. Typhimurium PT135 notifications received during the quarter.

Table 2. Top five Salmonella infections in Queensland, Fourth Quarter 2003, by date of receipt of notification. Serovar Oct – Dec 2003 Oct – Dec 2002 % Change* No. cases No. cases Typhimurium PT 135 75 32 +134.0 Virchow PT 8 53 41 +29.3 Typhimurium PT 197 30 15 +100.0 Saintpaul 29 28 +3.6 Chester 27 17 +59.0 % change in the number of cases reported in fourth quarter 2003 compared to fourth quarter 2002.

There were 5 cases of Shigella infection notified during the fourth quarter; 3 were confirmed as S. Sonnei and 1 case confirmed as S. flexneri. One case was not speciated. This compares to 25 cases of shigellosis notified for the same period in 2002, a decrease of 80%. The median age of cases was 52 years (range 48 – 70 years) and 4 of the 5 cases were female. There were no reported outbreaks during the quarter.

Yersiniosis notifications increased by 50% in comparison to the same period in 2002 with 20 cases notified during the fourth quarter 2003. Cases were widely distributed across Queensland. The median age of cases was 10.5 years (range <1 – 83 years), ratio of male to female cases was 1:0.82 (55.0%M, 45.0%F). There were no reported outbreaks of yersiniosis reported during the quarter.

Other notifications of known or possible foodborne illness received during this quarter included 22 cases of cryptosporidiosis and 25 cases of ciguatera poisoning. There were no reported outbreaks of cryptosporidiosis, however, there were 22 cases of ciguatera poisoning associated with three outbreaks. There were no cases of Vibrio cholerae infection reported during the quarter.

Incidence of Foodborne Disease 2003

Total Cases Reported In 2003, a total of 6,320 cases of illness due to the nine foodborne pathogens or conditions under surveillance were notified to Queensland Health (Table 3). This compares with 6,833 cases notified for the corresponding period in 2002. Campylobacter (61.5%) was the most frequently notified foodborne pathogen followed by Salmonella (35.7%). The number of notifications of Salmonella received during the 2003 period decreased by 17.2% in comparison to the same period in 2002. Campylobacter notifications for 2003 were comparable to 2002. Together, these two pathogens contributed approximately 97% of the total foodborne illness notifications received during the year for the nine foodborne pathogens or conditions under surveillance.

Table 3 Annual notification numbers and crude rates per 100,000 population, for foodborne pathogens, Queensland and Health Zones 2003. Pathogen Notifications & North Central South Queensland Queensland Rate/105 popn Zone Zone Zone 2003# 2002 Salmonella No. 648 786 803 2255 2722 Rate / 100,000 108.6 55.6 47.3 60.8 73.4 Listeria – materno No. 0 1 0 1 0 foetal Rate / 100,000 0.0 0.1 0.0 0.03 0.0 Listeria – Other No. 0 6 4 10 20 Rate / 100,000 0.0 0.4 0.2 0.27 0.54 Campylobacter No. 507 1582 1792 3886 3905 Rate / 100,000 85.0 112.0 105.6 104.8 105.3 Typhoid No. 0 1 2 5 11 Rate / 100,000 0.0 0.1 0.1 0.1 0.3 Paratyphoid No. 0 2 5 7 0 Rate / 100,000 0.0 0.1 0.3 0.2 0.0 Yersinia No. 21 33 40 94 73 Rate / 100,000 3.5 2.3 2.4 2.5 2.0 Shigella No. 10 21 24 55 95 Rate / 100,000 1.7 1.5 1.4 1.5 2.6 STEC* No. 0 3 3 6 6 Rate / 100,000 0.0 0.2 0.2 0.2 0.2 HUS** No. 1 0 0 1 1 Rate / 100,000 0.2 0.0 0.0 0.3 0.03 Total No. 1238 2534 2779 6320 6833 # Total number of notifications for Queensland (includes notifications that were not assigned a health zone). * STEC : Shiga-toxin producing E. coli ** H.U.S : Haemolytic Uraemic Syndrome

Notification rates for Salmonella during 2003 were highest in the North zone and were approximately twice those of the other two zones. Notification rates for Campylobacter were slightly lower in the North zone compared to the other two zones. There were no cases of Listeria or Shiga-toxin producing E. coli notified in the North zone during 2003, although the only notified case of Haemolytic Uraemic Syndrome (HUS) in the state during 2003 was from the North zone.

Annual notification numbers and crude rates per 100,000 population between the years 2000 and 2003 for all foodborne pathogens under surveillance are shown in Appendix 2.

Salmonella

Incidence There were 2,255 cases of salmonellosis reported in Queensland during 2003. This represented a decrease of 17.2% from the number reported during the same period in 2002. The crude annual notification rate decreased from 73.4 cases/100,000 population in 2002 to 60.8/100,000 in 2003. The ratio of male to female notifications was 1:1 (50.2%M, 49.8%F). The median age of cases was 12.0 years (range <1 to 98 years).

The highest age-specific notification rates of salmonellosis were in children aged 0 to 4 years (371.3/100,000) and 5 to 9 years (61.7/100,000) (Table 4). Notification rates were higher among male children aged 0 to 4 years than female children of the same age group. Notification rates for males and females were similar for all other age groups. Children aged between 0 and 4 years accounted for 40.8% of the total number of Salmonella notifications received during this period. Salmonella notification rates decreased substantially after the age of 9 years.

Table 4. Queensland notification numbers and annual rates per 100,000 population for Salmonella, by agegroup and sex, 2003 Age group Female Male Total (years) No. Rate/100,000 No. Rate/100,000 No. Rate/100,000 0-4 405 336.5 514 404.3 919 371.3 5-9 80 62.3 83 61.0 163 61.7 10-19 76 29.1 102 37.3 178 33.3 20-39 216 40.0 166 31.5 382 35.8 40-59 182 36.5 152 30.5 334 33.5 60+ 164 52.0 114 40.6 278 46.7 Total 1123 60.2 1131 61.4 2254 60.8

Among the 2,255 salmonellas notified in Queensland during 2003, a total of 2,206 (97.8%) were serotyped. The ten most frequently reported Salmonella infections during the reporting period are listed in Table 5. These ten serovars accounted for 46.8% of all salmonellas typed during 2003. Salmonella Saintpaul and S. Virchow phage type 8 (PT 8) continue to be the two most frequently reported Salmonella infections in Queensland, however, in comparison to the 2002 reporting period, S. Saintpaul and S. Virchow PT8 notifications decreased by 26.4% and 41.7% respectively.

Table 5. Top ten Salmonella infections in Queensland during 2003 and 2002 Serovar 2003 2002 % change*

No. cases % No. cases % Saintpaul 167 7.4 227 8.3 -26.4 Virchow Pt 8 165 7.3 283 10.4 -41.7 Typhimurium Pt 135 155 6.9 110 4.0 +40.9 Birkenhead 109 4.8 136 5.0 -19.9 Chester 98 4.3 84 3.1 +16.7 Typhimurium Pt 197 90 4.0 31 1.1 +190.3 Aberdeen 75 3.3 112 4.1 -33.0 Hvittingfoss 72 3.2 114 4.2 -36.8 Typhimurium Pt 170 70 3.1 136 5.0 -48.5 Muenchen 55 2.4 60 2.2 -8.3 * % change in the number of cases reported in total 2003 compared to total 2002.

The most notable change in the incidence of Salmonella infection during 2003 was the increase in S. Typhimurium PT197 (+190.3%) notifications. There were two reported outbreaks of S. Typhimurium PT197 infection during 2003 but these only accounted for 7 of the 90 notified cases. The ratio of male to female notifications was 1:1 (51.1%M, 48.9%F). The median age of cases was 18.0 years (range <1 to 77 years). The majority of cases were notified from the Brisbane and Moreton Statistical Divisions (84.4%). Only three cases were notified from the North zone.

The increase in S. Typhimurium PT135 notifications in 2003 can be partly explained by the occurrence of two outbreaks in December due to this phage type. Thirty-four of the 155 notified cases were associated with these two outbreaks. One outbreak occurred in an aged care facility and a restaurant was the setting for the other outbreak. Eggs were the suspected source of infections for both outbreaks (see Foodborne Disease Outbreaks section in this report).

There were 75 cases of S. Enteritidis notified in Queensland during 2003. Forty (53%) were male; 35 female. Median age of cases was 29.0 years (range <1 to 89 yrs). Travel history for 17 of the 75 cases was unknown. Thirty-nine (67%) of the remaining 58 cases reported no overseas travel and were probably locally-acquired infections; 19 (33%) of 58 cases were probably overseas-acquired infections. Phage type 26 was the most commonly reported phage type among the local cases. Twenty-four (62%) of the 39 cases were PT 26. Other than 1 x PT21 and 1 x PT21b var, most of the remaining local cases had phage types that did not conform to a specific phage type (RDNC). Seven of the 12 RDNC phage types had identical patterns and were specified as RDNC 12. One case isolate was untypable. There were no identified outbreaks of S. Enteritidis during 2003.

Completeness of serotype and phage type information for Salmonella has improved during the past three years. Only 49 (2.2%) of the 2255 salmonellas notified during 2003 lacked serotype information. This compares with 2.5% in 2002 and 3.0% in 2001. Similarly, only 6 (0.6%) of the 977 Salmonella serotypes that are phage typed, lacked this information. This compares with 1.5% in 2002 and 5.0% in 2001.

Trends There has been a steady increase in Salmonella notifications throughout the 1990’s with 1998 recording the highest number during the decade. Notifications for Salmonella infections declined from 1998 to 2000 but then continued to increase again through 2001 and 2002. For 2003, notification numbers had declined slightly compared to 2002 (Figure 1). There is a distinct seasonal variation in Salmonella notifications with higher numbers reported during the warmer months of the year, especially around February and March (Figure 2).

Figure 1. Salmonella Annual Notification Rates in QLD between 1998 and 2003

30 Annual Notification Rate (per 100,000) 20

0 1998 1999 2000 2001 2002 2003 Year 11

Figure 2. Salmonella notifications, by month, January 2000 - December 2003

600

500

400

300 No. of notifications 200

100

-00 00 02 -03 -03 p- r v ar-00 Jul e ar-01 Jul-01 ar-02 ay-02 Jul-02 ay-03 Jul-03 Jan-00 M May-00 S Nov-00 Jan-01 M May-01 Sep-01 Nov-01 Jan-02 M M Sep-02 Nov- Jan-03 Ma M Sep-03 No

Six year time trends for the top four Salmonella infections (for 2003) are displayed in Figures 3 and 4. Figure 5 displays similar data for S. Typhimurium PT197 and S. Typhimurium PT170.

Salmonella Saintpaul and S. Virchow PT8 infections have shown relatively similar trends during the past six years. A large peak (66 cases) was observed in May 2000 for notified cases of S. Saintpaul. This peak suggests that a point source outbreak may have occurred around this time and is supported by the unusually high proportion of notified cases from the South Zone (42%) during this month. There were no confirmed outbreaks of this serovar reported in Queensland during 2000. A general decreasing trend in S. Virchow PT8 and S. Saintpaul notifications have been observed over the six year period (Figure 3).

Figure 3. Common Salmonella Serovars in Queensland 1998 - 2003

30 No. of Notifications

8 8 9 0 1 1 2 2 2 3 9 9 -98 9 -0 -00 0 0 -01 -01 0 0 0 0 -03 n- n- n n- n- n- a ar-98ay- Jul a Jul-99 ar-00ay-00Jul-00ep-00 a ar- ay Jul a Jul-02 ar-03ay-03Jul J M M Sep-98Nov-98J Mar-99May-99 Sep-99Nov-99Ja M M S Nov J M M Sep-01Nov-01J Mar-02May-02 Sep- Nov- Ja M M Sep-03Nov-03 Year

Saintpaul Virchow PT8

S. Typhimurium PT135 has also shown consistent seasonal patterns over the past six years (Figure 4), however, numbers peaked in December 2003 with 60 cases notified. Twenty-four (24) of the 60 notifications during this period were from an outbreak in an aged care facility in Brisbane and cases most likely acquired their infection through the consumption of eggnog. A further 10 laboratory confirmed cases reported during this period were due to another outbreak of S. Typhimurium PT135 associated with a restaurant on the Gold Coast. Again, eggs were the suspected source of infection. Further detail on these two outbreaks is presented in the Foodborne Disease Outbreak section of this report.

Notified cases of Salmonella Birkenhead during the past six years were highest in 1998 and 1999 and have declined in recent years (Figure 4). There were 241 cases reported in 1998 compared to 136 cases in 2002 and 109 cases in 2003. Despite this decreasing trend, this serovar is consistently among the top five Salmonella infections reported in Queensland. During 2002, the Queensland OzFoodNet site completed the data collection for the statewide case control study of risk factors associated with S. Birkenhead infection. Results from this study will be published in a separate report during 2004.

Figure 4. Common Salmonella Serovars in Queensland, 1998 - 2003

30 No. of Notifications

Typhimurium PT135 Birkenhead

There were only a few sporadic cases of Salmonella Typhimurium PT197 reported in Queensland between 1998 and 2001 (Figure 5). Notifications began to increase during 2002. S. Typhimurium PT197 notifications increased considerably in 2003, with a peak of 25 cases notified in January 2003. There were two reported outbreaks of S. Typhimurium PT197 infection during 2003 but these only accounted for 7 of the 90 notified cases. The majority of cases were notified from the Brisbane and Moreton Statistical Divisions (84.4%). Only three cases were notified from the North zone.

Similarly, there were only sporadic cases of Salmonella Typhimurium PT170 infection reported between 1998 and 2001, however, numbers increased dramatically during 2002 (Figure 5). 138 cases of S. Typhimurium PT170 infection were reported during 2002 with numbers peaking to 26 cases in October 2002. An outbreak of S. Typhimurium PT170 infection among attendees of a Sunshine Coast childcare centre was identified in the fourth quarter of 2002. Infection was linked to exposure to newborn chickens through a chicken hatching program. Trace back investigation identified S. Typhimurium PT170 and S. Typhimurium PT12 in two poultry breeder sheds operated by the hatchery, which supplied eggs for the hatching program. No further outbreaks of S. Typhimurium PT170 were confirmed during 2002. The number of notified cases decreased by about half to 70 cases during 2003. There were no reported outbreaks of this phage type during 2003. A case- control study was initiated in the first quarter 2003, to identify potential risk factors for this Salmonella phage type, however, due to the decrease in notifications during 2003, further data collection is required during 2004.

Figure 5. Common Salmonella Serovars in Queensland, 1998 - 2003

No. of Notifications of No. 10

Typhimurium PT197 Typhimurium PT170

Geographic Distribution A comparison of reported Salmonella infections among the three Queensland Health Zones during the 2003 period showed the highest notification rate was in the North Zone (108.6/100,000) with a decreasing trend from north to south (Table 3). This trend has been a consistent feature of salmonellosis in Queensland during the past six years (Figure 6).

Figure 6. Salmonella annual notification rates per 100,000 popn, by zone

200

180

160

140

120

100

80 Rate per 100,000

0 1997 1998 1999 2000 2001 2002 2003 Year

South Central North

The distribution of major Salmonella serovars across each of the three Queensland Health Zones is shown in Table 6. Salmonella Saintpaul was the most frequently reported serovar in the North Zone during the year, similar to 2002, while S. Typhimurium PT 135 was the most frequently notified serovar in the Central and Southern Zones during 2003.

In the North Zone, S. Saintpaul and S. Virchow PT8 have been the two most frequently reported serovars in this region in recent years. The top five salmonellas remain unchanged from 2002 except for S. Chester, which replaced S. Mgulani in the top five in this region. These top five serovars represented 39.3% of all salmonellas reported from this region in 2002.

The majority of S. Hvittingfoss cases reported in 2003 were predominantly from the North zone of Queensland (72.2%). Only 1 of the 72 notified cases were from the South zone. The significant feature of these infections is the high proportion of cases among very young children (median age = 1.0 years). There were no confirmed outbreaks of S. Hvittingfoss during 2003. In contrast, S. Typhimurium is reported predominantly from Central and South zones. Only 55 (9.1%) of the 603 S. Typhimurium cases notified in Queensland during 2003 were from the North zone.

In the Central Zone, S. Typhimurium PT135 emerged during 2003 to be the most common serovar for this region (58 cases). However, the outbreak of S. Typhimurium PT135 in December (24 laboratory-confirmed cases) associated with an aged care facility in Brisbane was a contributing factor to its high incidence in this zone in 2003. S. Virchow PT8, S. Saintpaul, S. Typhimurium PT170 and S. Birkenhead remained in the top five salmonellas for this zone as reported in 2002.

Notified cases of S. Virchow PT8 and S. Saintpaul were distributed throughout the Central zone, whereas, cases of S. Typhimurium PT170 and S. Birkenhead were reported predominantly from the Brisbane and Moreton Statistical Divisions. These top five serovars represented 28.9% of all salmonellas reported from the Central zone in 2003.

In the South Zone, the top five Salmonella serovars in 2003 remained unchanged from 2002 except for S. Typhimurium PT197 which replaced S. Typhimurium PT170 as the 4th most common Salmonella serovar notified in this zone. Fifty (96.2%) of the 52 notified cases were reported from the Brisbane and Moreton Statistical Divisions. Notified cases of S. Birkenhead (94.0%) and S. Virchow PT8 (94.4%) were also predominantly from these two statistical divisions. Notified cases of S. Saintpaul were distributed widely across the zone. These top five serovars represented 37.9% of all salmonellas reported from this zone in 2003.

Table 6. Top five Salmonella infections for each of the three Queensland Health Zones, 2003*

Northern Zone Central Zone Southern Zone Serovar No. % Serovar No. % Serovar No. % Saintpaul 77 11.9 Typhimurium PT 135 58 7.4 Typhimurium PT 135 80 10.0 Virchow PT8 53 8.2 Virchow PT8 56 7.1 Birkenhead 67 8.3 Hvittingfoss 52 8.0 Saintpaul 40 5.1 Virchow PT 8 54 6.7 Aberdeen 36 5.6 Typhimurium PT 170 37 4.7 Typhimurium PT 197 52 6.5 Chester 36 5.6 Birkenhead 36 4.6 Saintpaul 48 6.0 *Expressed as % of serotyped isolates for each Zone: 634 for Northern, 777 for Central and 796 for Southern

Annual notification numbers and crude rates for Salmonella, by health zone, for the period 1999 to 2003 are shown in Appendix 3.

Campylobacter

Incidence There were 3886 cases of Campylobacter enteritis reported in Queensland during 2003 which was comparable to the number reported in 2002. The crude annual notification rate decreased only slightly from 105.3 cases/100,000 population in 2002 to 104.8/100,000 in 2003 (Table 3). The ratio of male to female notifications was 1:0.8 (54.5%M, 45.4%F). The median age of cases was 31.0 years (range <1 to 95 years).

The highest age-specific notification rates for Campylobacter infection were in children aged 0 to 4 years (182.2/100,000) and young adults aged 20 to 39 years (126.0/100,000) (Table 7). This secondary peak among young adults aged 20 - 39 years was not seen with notified Salmonella infections. Notification rates were 41.2% and 60.4% higher among male children aged 0 to 4 years and 10 to 19 years respectively than female children of the same age groups. Male rates were only slightly higher than female rates for all other age groups.

Campylobacter notification rates were consistently higher than Salmonella rates among children aged 5 years and older and for all adults, however, for children aged between 0 and 4 years notification rates were considerably higher for Salmonella infections.

There were no confirmed outbreaks of Campylobacter enteritis reported during 2003.

Table 7. Notification numbers and rates per 100,000 population for Campylobacter, by age group and sex, 2003. Age group Female Male Total (years) No. Rate/100,000 No. Rate/100,000 No. Rate/100,000 0-4 181 150.4 270 212.4 451 182.2 5-9 94 73.3 120 88.2 214 80.9 10-19 153 58.6 257 94.0 410 76.7 20-39 630 116.8 714 135.4 1344 126.0 40-59 416 83.3 465 93.3 881 88.3 60+ 291 92.3 293 104.5 584 98.0 Total 1765 94.7 2119 115.0 3884 104.8

Trends Similar to Salmonella trends, Campylobacter notification rates have steadily increased during the 1990’s with 1998 recording the highest number of notifications to date (128.9/100,000 popn). There was a moderate fall in 1999 but rates have been relatively stable from 2000 through to 2003 (Figure 7). Seasonal trends over the past four years indicate that the number of Campylobacter notifications have been slightly higher during the warmer months (Figure 8).

Figure 7. Campylobacter Annual Notification Rates in QLD between 1998 and 2003

140

120

100

40 Annual Notification Rate (per 100,000)

0 1998 1999 2000 2001 2002 2003 Year

Figure 8. Campylobacter notifications, by month, January 2000 - December 2003

800

700

600

500

400

300 No. of notifications

200

100

0 1 1 2 3 00 00 0 0 02 0 03 03 0 03 - l- -01 - -02 - -02 - l- ul ul p- an ar- Ju ep-00 J ay J an ar- Ju e J M May-00 S Nov-00 Jan-01 Mar-0 May Sep-01 Nov-01 Jan-02 Mar- M Sep-02 Nov J M May-03 S Nov-03

Geographic Distribution A comparison of reported Campylobacter infections among the three Queensland Health zones showed the highest notification rate during 2003 was in the Central zone (112.0/100,000 popn) (Table 3). Notification rates were only slightly lower for the South Zone (105.6/100,000). The notification rates in Central and South zones were comparable to those in 2002, however, there was a 37.9% decrease in notification rates for the North zone in 2003 compared to the previous year (Figure 9).

Notification rates observed over the seven year period (1997 – 2003) show that in Central and South zones Campylobacter rates have been remarkably similar and yearly fluctuations are closely mirrored between the two zones. This trend suggests that the major source(s) of Campylobacter infection for these two zones maybe similar.

Notification rates of infection in the North Zone showed a similar trend to the other two zones but lower rates of infection from 1997 to 1999. However, between 2000 and 2003, the trends in the North Zone have differed markedly suggesting that the major source of Campylobacter infection in North Queensland during this period may have been different to the other two zones. An investigation of notified cases of Campylobacter infection from the Townsville and Cairns regions in August 2002, identified locally manufactured raw chicken contaminated with Campylobacter as a major contributing factor to the increase observed in 2002. A microbiological investigation demonstrated that the predominant Campylobacter strain (Fla type 7; PFGE type P1) among human cases from North Queensland was indistinguishable from the predominant Campylobacter strain detected in various raw chicken products whose source was a local North Queensland poultry abattoir. The Tropical PHU in conjunction with the Department of Primary Industries investigated the abattoir and made recommendations regarding hygiene aspects at the abattoir and disinfection processes along the production line. These interventions may partly explain the observed decrease in Campylobacter numbers in the North zone during 2003.

Figure 9. Campylobacter annual notification rates per 100,000 popn, by zone

160

140

120

100

Rate per 100,000 60

0 1997 1998 1999 2000 2001 2002 2003 Year

South Central North

Annual notification numbers and crude rates for Campylobacter, by health zone, for the period 1999 to 2003 are shown in Appendix 3.

Listeria

Incidence There were 11 cases of invasive Listeriosis (including one materno-foetal case) notified in Queensland during 2003. The crude annual notification rate was 0.3 cases / 100,000 population. All appeared to be sporadic cases. No outbreaks were identified and culture isolates from 7 of the 11 cases were tested by PFGE and all were genetically distinguishable from each other.

Ten of the eleven cases were older persons aged between 55 and 88 years; 7 were male. A pregnancy-related infection occurred in a 28 year-old who developed her infection at 21 weeks gestation. The foetus survived. Two deaths were attributed to Listeria infection, both females aged 63 and 55 years. The first case had an underlying condition of liver disease (alcohol related), while the second case was undergoing treatment for metastatic breast carcinoma.

The ratio of male to female notifications for non-pregnancy associated cases was 1:0.4 (70%M, 30%F). The median age was 73.5 years (range 55.0 – 88.0 years).

Trends Notifications of Listeria infection have been steadily increasing in Queensland in recent years with 4 cases reported in 1998, 11 cases in 1999, 13 cases in 2000, 19 cases in 2001 and 20 cases in 2002. However, there was a considerable decline in notified cases of Listeria in 2003 (n=11) to below the mean of the previous 4 years (n=16).

Figure 10. Listeria Trends in Qld, 1992 - 2003

10 No. of notifications

0 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 Year

Geographic Distribution Listeria cases were reported from the Central and Southern zones only, during 2003. There were 7 cases notified from the Central zone and 4 cases from the Southern zone. Of these 11 cases, 8 resided in the South East region of Queensland, specifically the Brisbane and Moreton Statistical Divisions.

This geographic clustering of cases in the Brisbane and Moreton Statistical Divisions was also seen in 2002 and 2001. Seventeen of the 18 cases notified in Queensland in 2002 and 17 of 19 cases notified in Queensland in 2001 were residents of this region.

Shigella

Incidence There were 55 cases of Shigella infection reported in Queensland during 2003, a decrease of 42% on the number notified in 2002 (95 cases). The total number of notifications for 2003 corresponded to a crude annual notification rate of 1.5 cases / 100,000 population (2.6 / 100,000 in 2002). The ratio of male to female notifications was 0.9:1.0 (45.5%M, 52.7%F). The median age of cases was 24.0 years (range <1 - 77 years). Of the 55 Shigella infections, 33 (60.0%) were S. Sonnei, 19 (34.5%) were S. flexneri, one was S. Dysenteriae and one was S. Boydii. There was one case reported as Shigella species only. There were no reported outbreaks of Shigellosis during 2003. The proportion of overseas acquired infections is unknown as most cases were not investigated.

The decrease in Shigella numbers has been predominantly in the North and Central zones of Queensland, with very little change in notification rates in the South zone. In the North zone, notified cases of Shigella sonnei infection declined from 27 in 2002 to only 6 cases in 2003, while Shigella flexneri numbers declined from 10 cases to 4 cases. In the Central zone, there was no change in rates between 2002 and 2003 for S. sonnei, however, S. flexneri infections decreased from 22 cases to 6 cases.

There are no recognised environmental or animal reservoirs for Shigella, except higher primates. Therefore, infected humans are the usual source of infection. Person to person is the usual mode of transmission in locally acquired infections in Australia, whereas, contaminated food or water are the common vehicles of transmission in overseas acquired infections. Foodborne outbreaks usually occur because of poor personal hygiene by an infected food handler or from the use of contaminated untreated water when washing fruit or vegetables. The last reported foodborne outbreak of shigellosis in Australia was in 1998 at a wake in Adelaide. Thirteen of 32 persons who attended the luncheon became ill with diarrhoea. Sliced ham contaminated by an infected foodhandler was implicated as the vehicle of transmission.

Trends Notifications for Shigella for the period 2000 – 2003 show a seasonal trend with higher numbers notified in the warmer months (Figure 11). Annual notifications have been steadily declining since 1998 (Figure 12).

Figure 11. Shigella Notifications, by Month, January 2000 - December 2003

15 No. of notifications

0 -00 -00 -01 -01 -01 -01 -02 -02 02 -03 -03 -03 -03 v y-02 l p- ay Jul-0 ep-00 Jul an-02 ar a Ju e Jul Jan-00 Mar M S Nov-00 Jan-01 Mar May Sep-01 No J M M S Nov-02 Jan-03 Mar May Sep-03 Nov Year

Figure 12. Shigella Annual Notification Rates in QLD between 1998 and 2003

4.5

3.5

2.5

1.5 Annual Notifcation Rate (per 100,000) 1

0.5

0 1998 1999 2000 2001 2002 2003 Year

Geographic Distribution A comparison of reported Shigella infections among the three Queensland Health Zones during 2003 showed that notification rates for S. Sonnei were slightly higher in the North and Central Zones compared to the South zone. Notification rates for S. Flexneri were higher in the North zone than in the other two zones.

Table 8. Shigella notification numbers and annual notification rates per 100,000 population in QLD, by health zone, 2003. Pathogen North Central South Qld No. Rate / No. Rate / No. Rate / No. Rate / 100,000 100,000 100,000 100,000 Shigella 4 0.7 6 0.4 8 0.5 18 0.5 flexneri Shigella 6 1.0 14 1.0 13 0.8 33 0.9 sonnei Shigella 0 0.0 0 0.0 1 0.1 1 0.03 boydii Shigella 0 0.0 0 0.0 1 0.1 1 0.03 dysenteriae

Yersinia

Incidence There were 94 cases of Yersinia infection reported in Queensland during 2003 which represented a crude annual notification rate of 2.5 cases / 100,000 population. This compares with 73 notified cases in 2002, an increase of 28.8%. The ratio of male to female notifications was approximately 1:1 (51.1%M, 48.9%F). The median age of cases was 8.0 years (range <1 to 90 years). Of the 94 notified cases, 43.6% were aged 0 to 4 years. There were no reported outbreaks during 2003.

Yersinia entercolitica is the primary species associated with foodborne illness. Most cases of infection are sporadically acquired but outbreaks have been reported in the literature. Not all strains of Yersinia enterocolitica are pathogenic; only a small number of bioserotypes are pathogenic. The predominant pathogenic strain in Australia is biotype 4 and serotype 0:3. The main reservoir of this strain is pigs and human infections are usually associated with the handling and/or consumption of pig products, although it has been isolated from beef and poultry.

Trends Notifications for Yersinia in Queensland for the period 2000 – 2003 showed, in general, a seasonal trend towards higher numbers in the warmer months, particularly in the month of January (Figure 13). Annual notifications of Yersinia infection steadily declined between 1993, when there were 315 notified cases, and 2001 when there were 53 notified cases. However, the number of notified cases has increased again during the past two years with 73 cases in 2002 and 94 cases in 2003.

Figure 13. Yersinia Notifications, by Month, January 2000 - December 2003 30

15 No. of notifications 10

1 3 3 00 0 01 02 02 03 0 0 -00 -00 - -00 - - - -02 -02 l- -03 -03 - ar ay Jul ep-00 Jul an Ju ar ay Jul Jan-00 M M S Nov Jan-01 Mar May-01 Sep-01 Nov-01 J Mar May Sep-02 Nov-02 Jan-03 M M Sep- Nov- Year

Annual notification rates for yersiniosis infection over the past six years are shown in Figure 14. The reason for the decline in rates during the 1990’s is unknown.

Figure 14. Yersinnia Annual Notification Rates in QLD between 1998 and 2003

3.5

2.5

1.5

Annual Notification Rate (per 100,000) 1

0.5

0 1998 1999 2000 2001 2002 2003 Year

Geographic Distribution Thirty-five of the 94 notified Yersinia cases were reported from the Brisbane area. The distribution of Yersinia cases was, however, widespread across the State with 33 cases reported from the Central Zone, 21 from the North Zone and 40 cases reported from the South Zone. Notification rates for Yersinia infection were comparable between the Central and Southern Zones (2.3 and 2.4 per 100,000 respectively). Although the least number of notifications were received from the Northern Zone over the reporting period, notification rates from this zone were higher in comparison to the Central and Southern Zones (Table 3).

Shiga-toxin Producing E.coli (STEC) / HUS

Incidence There were 6 sporadic cases of Shiga-toxin producing E. coli (STEC) and one case of Haemolytic Uraemic Syndrome (HUS) notified to the Communicable Diseases Unit during 2003. The same number of STEC and HUS notifications were received in 2002. The single notified case of HUS occurred in a 41 year old female from Northern Queensland. No aetiological agent or source of infection was identified. The crude annual notification rate for STEC in Queensland in 2003 was 0.2 / 100,000.

The ratio of male to female STEC notifications during 2003 was 1:1 (50%M, 50%F). Cases were aged 39 – 65 years with a median age of 45.5 years. No food vehicles or sources of infection were identified following case investigations and there were no STEC outbreaks detected during 2003.

All 6 cases were confirmed by an ELISA test for shiga-toxins. Molecular testing using PCR detected the stx1 and/or stx2 genes in 3 of the 6 cases where the organism was isolated. Two cases were E. coli O157, one was E. coli O130 while the remaining STEC cases were not typed (Table 9). There were no O157:H7 strains detected. The two E. coli O157 strains were H-, while the E. coli O130 strain was H11.

Table 9. Frequency of STEC serotypes in Qld, 2003. Serotype No. of Cases

O130 1 O157 2 Not typed 3 Total 6

Trends The number of STEC notifications in Queensland during the past six years has been relatively constant with a median of 6 cases. There were 3 cases reported in 1998, 6 cases in 1999, 2000, 2002 and 2003 and 13 cases in 2001 (Figure 15).

Figure 15. STEC Nofications by Year, 1998 - 2003

6 No. of Notifications

0 1998 1999 2000 2001 2002 2003 Year

Changing laboratory protocols for the screening of faeces for STEC and the use of various diagnostic laboratory tests for detection of the various serotypes, toxins and virulence markers will have impacted considerably on the number of STEC cases detected and notified to Queensland Health in recent years.

For example, the number of faecal specimens submitted to the Public Health Microbiology Reference Laboratory for shiga-toxin testing has increased significantly during the past three years. There were 192 faecal specimens submitted for shiga-toxin testing in Queensland during 2003 of which 6 (3.1%) were positive. In 2002, 241 faecal specimens were submitted for shiga-toxin testing with 6 (2.5%) positive and for 2001, 238 specimens were submitted with 13 (5.5%) positive. Between 1998 and 2000 there were 37, 81 and 97 faecal specimens submitted respectively.

Geographic Distribution Five of the 6 cases of STEC infection notified in 2003 resided in the Brisbane and Moreton Statistical Divisions. During the past six years, STEC notifications have primarily been reported from the Central and Southern Zones only. During this period, notifications from the North zone were received in 1998 and 1999 only (Figure 16).

Figure 16. STEC Notifications by Zone, 1998 - 2003

No . 5 of No tifi 4 ca tio ns 3

0 1998 1999 2000 2001 2002 2003 Year

Central North South

Typhoid Fever / Paratyphoid Fever

Incidence There were 5 cases of Typhoid Fever (crude annual notification rate: 0.1 /100,000), 6 cases of Paratyphoid Fever (A) and 1 case of Paratyphoid Fever (B) notified in Queensland during 2003. This compares with 11 cases of Typhoid Fever and no cases of Paratyphoid Fever (A) or (B) reported in 2002. The median age of typhoid cases was 24.0 years (range 13.0 – 50.0 Years). The median age of Paratyphoid Fever (A) cases was 27.0 years (range 0.6 – 54 years). The single case of Paratyphoid Fever (B) occurred in a 27.0 year old male from Brisbane. This case had a recent history of overseas travel to Morocco prior to onset of symptoms.

All five Typhoid infections were acquired overseas with 1 case from the Philippines, 1 case from India, 1 case from Afghanistan, and the remaining two cases were acquired in Bali and Samoa respectively. Phage type information is given in Table 10.

The six cases of Paratyphoid Fever (A) were all acquired overseas as shown in Table 11.

Table 10. Frequency of Typhoid phage types in QLD 2003 Country of Travel No. Cases Phage Type

Philippines 1 Degraded India 1 Untypable Afghanistan 1 E1a Bali 1 D2 Samoa 1 E1

Table 11. Frequency of Paratyphoid Fever (A) phage-types in QLD 2003. Country of Travel No. Cases Phage Type

Thailand 2 13 Pakistan 1 13 Nepal 1 RDNC Cambodia 1 RDNC India 1 1a

Gastrointestinal Disease Outbreaks

Total 2003 During 2003, a total of 45 outbreaks of gastrointestinal illness affecting at least 727 people were reported to the Queensland OzFoodNet site. There were 65 (8.9%) people who were hospitalised and two deaths which were attributed to the gastroenteritis. Thirty (66.7%) of the 45 outbreaks were confirmed or suspected to be caused by foodborne transmission. There were 16 Norovirus outbreaks reported during 2003, 11 were suspected person to person transmission, 3 were suspected foodborne transmission and 2 outbreaks were thought to be a combination of both foodborne and person to person transmission. There were three outbreaks with an unknown aetiology which affected at least 18 people. All three outbreaks were foodborne or suspected foodborne transmission. The aetiological agents associated with the 45 outbreaks are shown in Table 12.

Of the 45 outbreaks, 30 (66.7%) were due to foodborne or suspected foodborne transmission affecting at least 311 people of whom 28 were hospitalised. Non-foodborne gastroenteritis outbreaks resulted in at least 416 cases and 37 hospitalisations.

Appendix 1 provides details of all 45 gastroenteritis outbreaks in Queensland during 2003 by aetiology.

Table 12. Gastrointestinal illness outbreaks in Queensland, by aetiology, 2003. Etiology / agent No. of Cases Hospitalised Deaths Outbreaks Bacterial Salmonella 8 108 23 2 Clostridium perfringens 1 19 0 0 Staphylococcus aureus 1 16 0 0 Viral Norovirus 16 449 34 0 Rotavirus 1 3 2 0 Chemical Ciguatoxin 10 47 5 0 Wax esters (Escolar) 1 20 0 0 Scombroid 2 5 0 0 Sorbic acid 1 23 0 0 Unknown / Other Unknown aetiological 3 18 0 0 agent Mixed pathogens 1 19 1 0 TOTAL 45 727 65 2

Foodborne Disease Outbreaks There were 30 confirmed or suspected foodborne disease outbreaks recorded in Queensland during 2003 affecting at least 311 people, of whom 28 (9.0%) were hospitalised (Table 13). There were two reported deaths that were attributed to foodborne illness. Both deaths occurred in elderly residents from an aged care facility following an outbreak of salmonellosis. Outbreaks during the summer months (Dec, Jan, Feb) accounted for almost half (47%) of the total number of foodborne illness outbreaks for 2003.

Ten outbreaks had a bacterial aetiology, 10 were caused by seafood toxins, 2 were caused by histamine poisoning, one outbreak was associated with wax esters (Escolar fish poisoning) and one outbreak was associated with high levels of sorbic acid (food preservative) in cheese (symptoms included allergic reactions around mouth, but no gastroenteritis). There were 3 norovirus outbreaks and 3 outbreaks with an unknown etiology which were suspected to be due to foodborne transmission. There were no reported parasitic foodborne outbreaks. Of the 10 outbreaks with a bacterial aetiology, 8 were caused by salmonellosis and two were associated with toxin-producing organisms (Staphylococcus aureus and Clostridium perfringens).

The most common agent responsible for foodborne outbreaks during 2003 was ciguatoxin (10 outbreaks) followed by Salmonella (8 outbreaks). Most of the ciguatera outbreaks had small case numbers, whereas, the average number of cases for Salmonella outbreaks was 14. Six of the eight Salmonella outbreaks were due to S. Typhimurium.

Nine (30%) outbreaks were associated with meals served at restaurants, three (10) with catered functions and three (10%) with aged care facilities. There were twelve (40%) outbreaks associated with meals served within private residences, however, eight of the 12 outbreaks were caused by ciguatera poisoning due to consumption of purchased fish that was cooked in the home. Three of the 12 private residence outbreaks had a bacterial aetiology, two were Salmonella outbreaks and the other was caused by Clostridium perfringens.

Two (20%) of the 10 bacterial outbreaks and two of the 3 viral outbreaks were investigated epidemiologically using analytic studies (three retrospective cohort studies and one case control study). All four analytic studies identified a significant statistical association with a specific food vehicle. The Queensland OzFoodNet site assisted the respective public health units and performed the epidemiological analysis of data for all four analytic studies that were conducted in Queensland in 2003.

A food vehicle was unable to be identified for 9 (30%) of the 30 outbreaks due to foodborne transmission. More importantly, a food vehicle was unable to be identified for 6 (60%) of the 10 foodborne outbreaks with a bacterial aetiology. Two of the 4 bacterial outbreaks with an identified food vehicle were determined using an analytic study during the investigation. Only one (10%) of the 10 bacterial outbreaks was confirmed as foodborne by microbiological evidence of the pathogen in food (Staphylococcus aureus and enterotoxin detected in pasta salad).

Table 13. Foodborne illness outbreaks reported in Queensland during 2003. No. Month Etiology No. Cases Vehicle Setting Study Evidence1 exposed type Bacterial 1 Jan S. Anatum 70 2 Unknown Aged Care Case D series 2 Jan S. Typhimurium 9 5 Unknown Restaurant Case D PT197 series 3 Feb Staphylococcus 120 16 Pasta Salad Caterer Case M,D aureus series 4 Feb S. Muenchen Unknown 2 Unknown Aged Care Case D series 5 May Clostridium 53 19 Curried Prawns Private Cohort S perfringens Residence 6 May S. Typhimurium Unknown 21 Roast Pork / Restaurant Case S PTu307 Apple sauce Control 7 Sept S. Typhimurium Unknown 7 Unknown Private Case D PTu307 Residence series 8 Dec S. Typhimurium 12 6 Unknown Private Case D PT197 Residence series 9 Dec S. Typhimurium 71 47 Suspected raw Aged care Case D PT135a egg series 10 Dec S. Typhimurium Unknown 18 Unknown Restaurant Case D PT135 series Chemical Case 11 Jan Ciguatoxin 4 2 Coral Trout Other D series Private Case 12 Jan Ciguatoxin 3 3 Mackerel Steaks D Residence series Private Case 13 Feb Ciguatoxin Unknown 7 Coral Trout D Residence series Private Case 14 Mar Ciguatoxin 3 3 Queen fish D Residence series Case 15 Mar Scrombroid Unknown 3 Dolphin Fish Restaurant D,L series Private Case 16 2 2 Tuna Patties D Mar Scrombroid Residence series Cod Fish Heads Private Case 17 May Ciguatoxin 2 2 D (soup) Residence series Giant Trevally Private Case 18 5 3 D May Ciguatoxin Fish Residence series Case 19 May Sorbic Acid 135 23 Cheese Childcare L series Barracuda Private No 20 Aug Ciguatoxin 5 5 (Sphyraena D residence data spp.) 21 Nov Ciguatoxin 3 3 Red Emperor Private Case D (Fish head soup) Residence series 22 Oct Ciguatoxin 15 15 Spanish Restaurant Case D Mackerel series 23 Dec Ciguatoxin Unknown 4 Unknown Private Case D Residence series 24 Dec Wax esters 30 20 Escolar Fish Restaurant Case D (Escolar) series Viral 25 July Norovirus 70 31 Trifle Function Cohort S 26 Sept Norovirus 100 13 Unknown Function Cohort S 27 Sept Norovirus 38 11 Unknown BBQ/Picnic Case D Series Unknown Case 28 Jan Unknown Unknown 6 Unknown Restaurant D series Case 29 Feb Unknown 10 7 Beef Burgundy Restaurant D series Case 30 Oct Unknown Unknown 5 Unknown Restaurant D series D = Descriptive evidence implicating the suspected vehicle or suggesting foodborne transmission; S = Statistical association between illness and one or more foods; M = Microbiological confirmation of agent in the suspect vehicle and cases; L = laboratory confirmed chemical agent in food.

Significant foodborne illness outbreaks during 2003

There were 11 foodborne outbreaks affecting 10 or more people reported during 2003. Five of the 11 outbreaks had a bacterial aetiology, three were viral, two were chemical and one had an unknown aetiology.

Bacterial outbreaks Staphylococcus aureus infection was identified among 16 of 120 production crew members working in a rural area of North Queensland in February 2003. Moderate numbers of Staphylococcus aureus were detected in faecal samples provided, though no enterotoxin was detected in stools or vomitus samples. Enterotoxin was detected in a ham and pasta salad and vegetable pasta salad that had been prepared by a commercial caterer for the production crew. Both pasta salad samples had >2.5 x 106 orgs/gm detected. Contamination was most likely due to inadequate storage and temperature abuse.

The investigation in May of an outbreak of gastrointestinal illness among attendees of a wedding function in the Mackay region, found a significant association between illness and eating curried prawns. There were no leftover curried prawns from the function for microbiological testing to confirm the epidemiological findings, however, two faecal specimens were positive for moderate numbers of Clostridium perfringens spores and vegetative cells (104 – 105/ g of faeces), although this was not considered diagnostic by the laboratory. Clostridium perfringens vegetative cell counts in healthy adults are normally ≤ 103/ g of faeces. The nature of the symptoms (predominantly diarrhoea and cramps, with no vomiting), the median incubation period (13 hrs), and the median duration of illness (19 hrs) were all consistent with C. perfringens food poisoning. It is likely that the curried sauce ingredient was the food item which was contaminated with the organism as C. perfringens was not detected in the individual prawns following microbiological culture.

An extensive investigation failed to identify the source of infection for an outbreak of Salmonella Typhimurium U307 linked to two clubs at the Sunshine Coast. There were 15 laboratory-confirmed and six probable cases identified during the investigation of this outbreak (15xQld, 4xNSW, 1xVic, 1xNT). Reported onset dates of illness were between 26/03/2003 and 15/04/2003. Nineteen of the 21 cases were linked to the same club. Two cases reportedly ate at another nearby club. Eighteen of the 21 cases were female; median age of cases was 47 yrs (range 2-75 yrs). The case control study identified roast pork (OR 12.0, 95%CI 1.6, 91.1) as a potential vehicle of infection, however, the epidemic curve indicated transmission of infection occurred intermittently over a two week period. Microbiological testing of foods and condiment samples, environmental swabs and faecal specimens from 36 foodhandlers were negative for Salmonella.

A point source outbreak of Salmonella Typhimurium PT135a occurred among 71 residents of an aged care facility in Brisbane in December. The setting was a Christmas function that was held at the facility. There were a total of 47 cases which included 44 residents, 2 visitors and 1 staff member. Twenty-four (24) cases were laboratory confirmed. Sixteen cases required hospitalisation. The likely food vehicle for the outbreak was egg nog but this could not be confirmed by an epidemiological study due to the age and mental status of the patients. Food samples from the facility including eggs were culture negative for Salmonella. There was no leftover egg nog for testing. Environmental samples taken from the poultry farm that supplied the eggs (drag swabs, eggs and boot covers worn through sheds) were negative for S. Typhimurium PT135a, however, S. Mbandaka, S. Singapore and S. Infantis were cultured from these samples.

An investigation of an outbreak of Salmonella Typhimurium PT135 among patrons who attended a Gold Coast restaurant in December 2003 failed to identify the food vehicle responsible for transmission of infection. There were 18 reported cases (10 laboratory confirmed) and 3 required hospitalisation. Hollandaise sauce, however, was a suspected vehicle of transmission as it included the use of raw eggs as an ingredient. The observed technique for preparing hollandaise sauce involved running the raw yolk through the fingers, adding butter and other ingredients before blending and serving uncooked at room temperature. The sauce is stored at room temperature to prevent separation of ingredients. Eggs used by the restaurant were sourced directly from a local farm. It is likely that surface contaminated eggs were used to prepare this sauce and that a combination of handling contaminated eggs and using the above technique for separation of egg yolk would explain the transmission of Salmonella. All environmental samples taken from the restaurant were culture negative. No analytic epidemiological investigation was conducted.

Viral outbreaks The investigation of an outbreak of gastrointestinal illness among attendees of a catered function held in July identified norovirus as the likely aetiological agent. A list of 57 persons of the 70 people who attended the function was provided for follow-up. Forty-four of the 57 attendees were interviewed. Thirty-one of the 44 subjects were ill with vomiting and/or diarrhoea. The median age of cases was 58 years (range 40-74 years). The median incubation period was 35.0 hours (range 16-46 hours) while the median duration of illness was 36.0 hours (range 8-61 hours). Fourteen of 15 stool specimens were positive for norovirus by PCR testing.

Epidemiological analysis of the data implicated trifle as the likely vehicle of transmission (RR 1.7, 95%CI 1.0, 2.8). Twenty of the 24 persons who reportedly ate the trifle developed gastroenteritis (AR=83.3%). Though the association between trifle and illness was weak, the association was highly plausible given that the trifle dish was prepared by an ill food handler at a private residence prior to the function and, in addition, a kitchen hand had reportedly vomited in the kitchen area during the preparation of desserts (between the main and sweets courses). The onset of illness among the 31 cases occurred within a narrow time frame (16- 45 hrs after the function) and the attack rate among all guests was high. These results suggested a point source outbreak and given the setting (and that foods were the common exposures), it is likely that most of the cases acquired their infection by foodborne transmission. Trifle consumption explained about 70% of case illnesses (8 cases did not eat trifle), however, transmission of infection by other contaminated foods, fomite to person transmission or person to person transmission may also have occurred.

Norovirus was identified as the likely aetiological agent responsible for a point source outbreak of gastroenteritis among attendees of a wedding function held in September. Approximately 100 guests attended the function, however, only 24 were contacted as part of the investigation. Thirteen of the 24 subjects interviewed met the case definition of developing diarrhoea and/or vomiting within 48 hours of the function. The median age of cases was 25 years (range 19-63 years). The median incubation period for the cases was 36.0 hours (range 16-49 hours) and the median duration of illness was 30.0 hours (range 13- 48 hours). Norovirus was detected in stool samples from two cases. There were no leftover food items from the wedding function for microbiological testing.

Univariate analyses of the data showed that persons who had eaten fish balls were significantly more likely to develop illness compared to those persons who did not eat this food (attack rate {AR} 63.6% vs 36.3%, relative risk {RR} 2.8, 95%CI 1.2, 6.7). A number of other food items had elevated relative risk values (beef and samosa), though these food items were not statistically significant. Only a small proportion of attendees were interviewed during the investigation, therefore, the epidemiological results should be interpreted with caution. Norovirus spreads through aerosols as well as the faecal oral route and has a very low infective dose, as low as 100 organisms. If fishballs was a vehicle, it is likely that the fishballs were contaminated by an infected foodhandler through handling of the fishballs after cooking. Foodborne transmission was likely to be the predominant mode of transmission of infection as anecdotal evidence from the persons interviewed indicated there were no people physically ill during the wedding function.

Chemical outbreaks An outbreak of ciguatera poisoning occurred in October among a group of fishermen who consumed a Spanish Mackerel fish caught from their chartered boat and cooked on the same night at a restaurant in the resort where the group was accomodated. Fifteen male adults including the chef developed symptoms of nausea, vomiting, diarrhoea, cramps, reverse temperature sensation, skin tingling and numbness after consuming the fish. The median incubation period was six hours.

There were two outbreaks of ciguatera poisoning during 2003 following the consumption of fish soups but not the fish flesh. Both soups were prepared using the fish heads of reef fish purchased from takeaway seafood stores.

In December, 20 of 80 Gold Coast Hospital staff developed diarrhoea tinged with oily yellow- orange droplets after consuming escolar fish at a Christmas party held at a restaurant on the Gold Coast. These symptoms are characteristic of escolar and can occur following consumption of ocean fish with a high wax ester content in their flesh. Onset times ranged between 3 – 36 hours after eating the meal and the duration illness averaged 2 – 3 days. The exact number of people who ate the fish was unknown.

Cluster Investigations A cluster is defined as an increase in infections that are epidemiologically related in time, place or person where investigations are unable to implicate a vehicle or determine a mode of transmission responsible for the increase. An example is a temporal or geographic increase in the number of cases of a specific Salmonella serovar or phage type.

During 2003, the Queensland OzFoodNet site conducted a minimum of 10 cluster investigations within the state and participated in several national cluster investigations. There were a total of 56 reported cases associated with the state investigations and all related to clusters of Salmonella. These figures do not include identified outbreaks documented previously in this report or cluster investigations conducted solely by the Public Health Units.

Clusters of interest included:

! Four cases of S. Reading were identified in February 2003. Cases were clustered by age. No common exposures were identified among the cases however, it was likely that most, if not all of the infections were acquired by zoonotic transmission. All four cases had contact with farm animals including calves, pigs and chickens in the week prior to the onset of illness. No cases reported eating any potentially high risk foods. Three of the four cases live or work in a farm environment, while the fourth case visited a petting zoo in the week prior to illness. One case also reported removing rats nests from a farm shed prior to illness.

! A cluster of 9 cases of Salmonella Typhimurium PT170a (STM170a) occurred in south- east Queensland with specimen collection dates between 07/07/2003 and 16/7/2003. Four of the cases were children aged less than 10 years old and five were adults aged 24 years or older. NEPSS reported that this phage type had not been reported in either human or non-human sources in Australia before. No overseas travel was reported among the cases. All isolates were resistant to sulphonamides and trimethoprim (unlike STM170 strains which have been sensitive to these two antibiotics to-date). Sulfas and trimethoprim are registered for use in the veterinary industry. All nine isolates had identical plasmid profiles providing further evidence of a common source.

! An investigation of an apparent cluster of Salmonella Enteritidis PT 21b amongst eight people in southern Queensland took place in early September. Further investigation, revealed that all of the positive specimens came from the same pathology laboratory and all specimens except one were collected on the same day. Two of the 8 cases had a history of overseas travel, which was not consistent with a single outbreak source. Hypothesis-generating interviews did not suggest any common exposures among the cases. Following discussions with the pathology laboratory, further investigation identified a laboratory error among all but one case. Results of the investigation determined that there was a single case of S. Enteritidis PT 21b who acquired their infection whilst travelling through Malaysia.

OzFoodNet Projects - Applied Research in Queensland

Current status of applied epidemiological research into foodborne disease (Queensland OzFoodNet site):

Case Control Studies

1. Salmonella Birkenhead case control study:

Data collection for the Queensland Salmonella Birkenhead case control study was completed in December 2002. The Salmonella Birkenhead study was co-ordinated and managed by the Queensland OzFoodNet site, however, the Northern Rivers Public Health Unit (New South Wales) also contributed data towards this study. At the completion of data collection, 111 cases and 234 controls had been enrolled and interviewed for this study. There were 81 cases and 178 controls from Queensland and 30 cases and 56 controls from New South Wales. Data analysis has been completed and the study report is currently being written.

2. Campylobacter case control study:

Data collection for the multicentre national Campylobacter case control study was completed in August 2002. Nationally, a total of 881 cases and 833 controls participated in the study of persons aged 5 years and older and 138 cases and 134 controls participated in the study of children aged between 0 and 4 years. Epidemiological data analysis has been completed and the study report is currently being written.

Laboratory typing of case isolates by Flagellin typing (flaA typing) and antibiotic sensitivity testing is currently being undertaken across several public health laboratories in Australia. It is proposed that the epidemiological case control data will be re-analysed by subgroup analysis following completion of typing.

3. Salmonella Enteritidis case control study:

The multicentre national Salmonella Enteritidis case control study was initiated in November 2001 and completion of data collection will occur in December 2004. It is anticipated that between 50 and 75 cases and 150 to 225 controls will be recruited for this study. This is a study of risk factors associated with locally-acquired infections, however, descriptive data including source of infection is also being collected on overseas-acquired infections. The majority of locally-acquired infections in Australia occur in Queensland. At the completion of 2003, 52 locally-acquired cases and 80 controls had been enrolled and interviewed from Queensland.

4. Listeria monocytogenes case control study:

The multicentre Listeria monocytogenes case control study commenced in the second quarter of 2002 and is expected to run for a period of 2-3 years. It is anticipated that between 50 and 100 cases and 100 to 200 controls will be recruited for this study. At the completion of 2003, 7 cases and 8 controls had been enrolled and interviewed from Queensland.

5. Salmonella Typhimurium phage type 170 case control study:

A statewide prospective case control study of sporadic infection due to Salmonella Typhimurium phage type 170 was commenced in February 2003 by the Queensland OzFoodNet site. The study was in response to a significant increase in the incidence of notified cases of this infection across the Eastern States of Australia during 2002. At the completion of 2003, 18 cases and 32 controls had been enrolled and interviewed from Queensland. It is anticipated that data collection will continue until the end of 2004.

Project Management

Project Objectives and Outcomes

The primary objectives of OzFoodNet are to (1) determine the frequency and burden of foodborne disease in Australia, (2) identify the causes and contributing factors to foodborne disease in Australia, (3) provide epidemiological information to inform prevention efforts and (4) describe the epidemiology of new and emerging foodborne pathogens.

To address these objectives, the following strategies were proposed -

1. Enhanced surveillance of sporadic and outbreak-associated diarrhoeal disease by :

! Conducting investigation of foodborne disease outbreaks using analytic epidemiological studies;

! Enhancing surveillance and investigation of foodborne pathogen clusters;

! Testing for a wider range of pathogens using reference laboratories and use of advanced subtyping methods to support epidemiological analysis;

! Evaluating laboratory practices for detection of foodborne pathogens and timeliness of referral of pathogens to reference laboratories for further identification or typing;

! Surveillance for antimicrobial resistance among foodborne pathogens;

! Ongoing analysis of foodborne pathogen notification, hospital separation and mortality data;

! Analysis of data on foodborne pathogens from non-human sources (National Enteric Pathogen Surveillance Scheme).

2. Identify risk factors for sporadic infection with common foodborne pathogens by conducting national and statewide epidemiological studies

3. Conduct population cross-sectional surveys to determine the burden of acute diarrhoeal illness in the community and to provide information to enable the calculation of more reliable estimates of the incidence of foodborne illness in Australia

Each of the above strategies are being addressed by the Queensland OzFoodNet site, in collaboration with other OzFoodNet sites, through a variety of project activities. The outcomes of these activities during 2003 are itemised below.

1. Enhanced surveillance of sporadic and outbreak-associated diarrhoeal disease

! Queensland OzFoodNet site administers daily and weekly surveillance programs for specific foodborne pathogens.

! The Queensland Notifiable Conditions System (NOCS) generates automated outbreak detection alerts for foodborne pathogens.

! Queensland OzFoodNet site is evaluating a systematic approach to the investigation of clusters of cases of Salmonella infection detected during routine surveillance. One of the project objectives is to evaluate the likelihood (Positive Predictive Value) of a true outbreak of Salmonella infection occurring based on a set of criteria which are applied to the surveillance data.

! Queensland OzFoodNet site maintains a close working relationship with the Public Health Microbiology Reference Laboratory (Queensland Health) and is informed daily of any potential foodborne illness clusters detected through serotyping, phagetyping or genotyping.

! Queensland OzFoodNet Cluster Reports were submitted to the National Co- ordinating Epidemiologist each fortnight throughout the year. State reports were collated and a National Fortnightly Cluster Report was provided for each State OzFoodNet site. Both state and national reports were distributed to Public Health Physicians and selected public health personnel in Queensland Health.

! Queensland OzFoodNet Quarterly Reports were submitted to the National Co-ordinating Epidemiologist for collation of data and a National OzFoodNet Surveillance Report was published in the Communicable Diseases Intelligence each quarter. The Queensland OzFoodNet Quarterly Reports were distributed to the Communicable Diseases Unit, the Food Services section of the Environmental Health Unit and all Public Health Units in Queensland.

! The Queensland OzFoodNet site participated in national monthly teleconferences and quarterly face to face meetings to enhance foodborne disease surveillance across Australia.

! Clusters of foodborne pathogens that were investigated at a state level during 2003 included infections due to Salmonella Typhimurium phage type 135a, Salmonella Typhimurium phage type U307, Salmonella Typhimurium phage type 170a, Salmonella Enteritidis phage type 21b, Salmonella Saintpaul, Salmonella Chester, Salmonella Reading, Salmonella Hvittingfoss and Salmonella Anatum.

! During 2003, forty-five outbreaks of gastroenteritis in Queensland were investigated and documented in the Queensland Foodborne Illness/Gastroenteritis Outbreak Register. Thirty (67%) outbreaks were attributed to foodborne transmission. Selected information from these outbreaks were forwarded to the National OzFoodNet Outbreak Register.

! Antimicrobial susceptibility testing was conducted on all Salmonella isolates referred to the Queensland Public Health Microbiology Reference Laboratory for the following serovars (all phage types) – Typhimurium, Enteritidis, Bovismorbificans, Virchow, Typhi, Paratyphi, Heidelberg and Hadar. Antimicrobial testing was provided either by the University of Melbourne Microbiological Diagnostic Unit (MDU) or the Institute of Medical and Veterinary Science (IMVS, South Australia).

2. Identify risk factors for sporadic infection with common foodborne pathogens by conducting National and Statewide Epidemiological studies

! The Queensland OzFoodNet site completed the data cleaning and conducted the data analysis for the national Campylobacter case control study. Data analysis was also completed for the Salmonella Birkenhead case control study. The study reports for both these case control studies will be completed during 2004. Data collection for the Salmonella Enteritidis, Listeria monocytogenes and the Salmonella Typhimurium phage type 170 case control studies is still proceeding.

! All Salmonella Enteritidis isolates in Queensland are forwarded to IMVS, South Australia for phage typing and antimicrobial susceptibility testing.

! Listeria isolates from all cases notified in Queensland during the case control study period are forwarded to the Public Health Microbiology Laboratory on behalf of the Queensland OzFoodNet site for storage and subsequent subtyping and antibiotic susceptibility testing.

3. Conduct National and State cross-sectional surveys to identify the burden of acute diarrhoeal illness in the community and to provide information to enable the calculation of more reliable estimates of the incidence of foodborne illness in Australia

! The OzFoodNet National Gastroenteritis Survey was completed in August 2002 after 12 months of data collection. Data analysis was completed during 2003 and the final National Gastroenteritis Report will be released in 2004.

Conclusions This report summarises the surveillance and applied epidemiological research activities of the Queensland OzFoodNet site during 2003 and highlights the benefits of enhanced foodborne disease surveillance both at a state level and nationally. OzFoodNet has lowered the threshold for detecting potential outbreaks of foodborne illness by building on existing surveillance mechanisms. OzFoodNet has built capacity to collect, interpret and disseminate timely data in ways that support public health action, improved the communication links within and between jurisdictions and improved the quality of data by standardising reporting.

With respect to the applied epidemiological research currently being conducted by OzFoodNet, the national gastroenteritis population survey will identify the burden of acute gastroenteritis in the community and provide data which will enable the calculation of more accurate estimates of the incidence foodborne illness. It will also provide a baseline for which future surveys can be compared. This type of surveillance will contribute to the monitoring of the effects of food safety policies and interventions on foodborne disease incidence. The collation and analysis of data from the foodborne outbreak register and the results of case control studies will contribute significantly to the identification of risk factors and causes of foodborne disease in Australia.

The outcomes from OzFoodNet will be improved investigation and control efforts and the incorporation of results into policy formulation to improve food safety in Australia.

Publications/Presentations

1. Stafford RJ, Ashbolt R, Unicomb L, Kirk M and the OzFoodnet Working Group. A multicentre prospective case control study of sporadic Campylobacter infection in Australia. Poster presented at the 12th International Workshop on Campylobacter, Helicobacter and Related Organisms held in Aarhus, Denmark in September, 2003.

2. Stafford RJ, Ashbolt R, Unicomb L and the OzFoodnet Working Group. A case control study of risk factors for Campylobacter infection in Australia. Oral presentation at the 11th Australian Food Microbiology Conference of the Australian Institute of Food Science and Technology in Noosa in March, 2003.

Acknowledgements John Bates, Helen Smith, Gino Micalizzi, Denise Murphy, Trudy Graham and other staff (Public Health Microbiology Laboratory, Queensland Health Scientific Services); Dr Linda Selvey, Dr Margaret Young, Dr Robyn Pugh, Craig Davis, Cristine Chirico, David Gould (Communicable Diseases Unit, Queensland Health); Kerry Bell, Gary Bielby (Food Services, Environmental Health Unit, Queensland Health); Dr Brad McCall (Brisbane Southside Public Health Unit).

Epidemiologists and staff of other OzFoodNet sites: Martyn Kirk (National Co-ordinating Epidemiologist, OzFoodNet); Janet Li (OzFoodNet Data Manager); Rosie Ashbolt (Tasmania); Dr Rod Givney, Dr Jane Raupach, Barry Combs and Lillian Mwanri (South Australia); Joy Gregory, Karin Lalor (Victoria); Minda Sarna (Western Australia); Dr Craig Dalton, Leanne Unicomb, Dr Tony Merritt, Dot Little (Hunter Public Health Unit); Jennie Musto and Leonie Neville (NSW); Geoff Millard (ACT); and Dr Gillian Hall from the National Centre for Epidemiology and Population Health.

Dr Ian McKay, Catherine Gay, Craig Shadbolt, Dr Paul Roche, Kate Hutchison (Commonwealth Department Health and Ageing); Dr Geoff Hogg, Dr Mark Veitch, Joan Powling, Di Lightfoot, Mary Valcanis (National Enteric Pathogen Surveillance Scheme, MDU, Melbourne); Dianne Davos (Salmonella Reference Laboratory, IMVS, South Australia).

Public Health Medical Officers, Public Health Nurses, Epidemiologists and Environmental Health Officers of all Public Health Units in Queensland who contributed information to OzFoodNet.

References

Australian Bureau of Statistics. 3101.0 Australian Demographic Statistics, September 2003. Canberra 2004.

Australian Bureau of Statistics. Age and Sex distribution of the Estimated Resident Population, Queensland. Canberra: ABS, 2002.

Appendices

Appendix 1. All reported gastroenteritis outbreaks in Queensland, by aetiology, 2003

1(A) Bacterial Gastroenteritis Outbreaks in Queensland, 2003 No. Month Etiology No. Cases Vehicle Setting Study Evidence* exposed type 1 Jan S. Anatum 70 2 Unknown Aged Care Case D series 2 Jan S. Typhimurium 9 5 Unknown Restaurant Case D PT197 series 3 Feb Staphylococcus 120 16 Pasta Salad Caterer Case M,D aureus series 4 Feb S. Muenchen Unknown 2 Unknown Aged Care Case D series 5 May Clostridium 53 19 Curried Prawns Private Cohort S perfringens Residence 6 May S. Typhimurium Unknown 21 Roast Pork / Restaurant Case S PT U307 Apple sauce Control 7 Sept S. Typhimurium Unknown 7 Unknown Private Case D PT U307 Residence series 8 Dec S. Typhimurium 12 6 Unknown Private Case D PT197 Residence series 9 Dec S. Typhimurium 71 47 Suspected raw Nursing Case D PT135a egg Home series 10 Dec S. Typhimurium Unknown 18 Unknown Restaurant Case D PT135 series * D = Descriptive evidence implicating the suspected vehicle or suggesting foodborne transmission; S = Statistical association between illness and one or more foods; M = Microbiological confirmation of agent in the suspect vehicle and cases.

1(B) Chemical Gastroenteritis Outbreaks in Queensland, 2003 No. Month Etiology No. Cases Vehicle Setting Study Evidence* exposed type Case 1 Jan Ciguatoxin 4 2 Coral Trout Other D series Private Case 2 Jan Ciguatoxin 3 3 Mackerel Steaks D Residence series Private Case 3 Feb Ciguatoxin Unknown 7 Coral Trout D Residence series Private Case 4 Mar Ciguatoxin 3 3 Queen fish D Residence series Case 5 Mar Scrombroid Unknown 3 Dolphin Fish Restaurant D, L series Private Case 6 2 2 Tuna Patties D Mar Scrombroid Residence series Cod Fish Heads Private Case 7 May Ciguatoxin 2 2 D (soup) Residence series Giant Trevally Private Case 8 5 3 D May Ciguatoxin Fish Residence series Case 9 May Sorbic Acid 135 23 Cheese Childcare L series Barracuda Private 10 Aug Ciguatoxin 5 5 (Sphyraena No data D residence spp.) 11 Nov Ciguatoxin 3 3 Red Emperor Private Case D (fish head soup) Residence series 12 Oct Ciguatoxin 15 15 Spanish Restaurant Case D Mackerel series 13 Dec Ciguatoxin Unknown 4 Unknown Private Case D Residence series 14 Dec Wax esters 30 20 Escolar Fish Restaurant Case D (Escolar) series * D = Descriptive evidence implicating the suspected vehicle or suggesting foodborne transmission; S = Statistical association between illness and one or more foods; M = Microbiological confirmation of agent in the suspect vehicle and cases; L = laboratory confirmed chemical agent in food.

1(C) Viral gastroenteritis outbreaks in Queensland, 2003 No. Month Etiology No. Cases Vehicle Setting Study Evidence1 exposed type Case 1 Jan Norovirus Unknown 16 Unknown Restaurant D series Private Case 2 Feb Norovirus 18 15 Unknown D Residence series Case 3 Mar Norovirus Unknown 13 Unknown Other D series Person To Case 4 April Norovirus Unknown 55 Hospital D Person series Person To Case 5 May Norovirus Unknown 25 Community D Person series 6 May Norovirus Unknown 10 Unknown Unknown Cohort D Person To Case 7 May Norovirus Unknown 65 Hospital D Person series 8 July Norovirus 70 31 Trifle Function Cohort S Case 9 July Norovirus 20 Unknown Hospital D Series Case 10 July Norovirus 16 Unknown Resort D Series Aug Norovirus 64 20 Person To Hospital Case 11 D Person series 12 Sept Norovirus 100 13 Unknown Function Cohort S Case 13 Sept Norovirus 38 11 Unknown BBQ/Picnic D Series Case 14 Oct Norovirus 196 51 Unknown Aged Care D Series Case 15 Oct Norovirus 64 15 Unknown Hospital D Series Case 16 Oct Rotavirus 80 3 Unknown Childcare D series Case 17 Nov Norovirus 72 29 Unknown Restaurant C Series * D = Descriptive evidence implicating the suspected vehicle or suggesting foodborne transmission; S = Statistical association between illness and one or more foods; M = Microbiological confirmation of agent in the suspect vehicle and cases.

1(D) Gastroenteritis outbreaks of unknown aetiology in Queensland, 2003 No. Month Etiology No. Cases Vehicle Setting Study Evidence* exposed type Case 1 Jan Unknown Unknown 6 Unknown Restaurant D series Case 2 Feb Unknown 10 7 Beef Burgundy Restaurant D series Case 3 Oct Unknown Unknown 5 Unknown Restaurant D series Mixed pathogens incl Salmonella, Case 4 Nov 152 19 Unknown Childcare D norovirus and series rotavirus * D = Descriptive evidence implicating the suspected vehicle or suggesting foodborne transmission; S = Statistical association between illness and one or more foods; M = Microbiological confirmation of agent in the suspect vehicle and cases.

Appendix 2. Annual notification numbers and rates per 100,000 population, for foodborne pathogens, Queensland, 2000 - 2003

Pathogen/Condition 2000 2001 2002 2003 No. Rate/100,000 No. Rate/100,000 No. Rate/100,000 No. Rate/100,000 Salmonella 1820 51.0 2169 59.7 2722 73.4 2255 60.8 Listeria 13 0.4 19 0.5 20 0.5 11 0.3 Campylobacter 3682 103.2 3969 109.2 3905 105.3 3886 104.8 Typhoid 2 0.1 8 0.2 11 0.3 5 0.1 Paratyphoid 3 0.1 1 0.03 0 0.0 7 0.2 Yersinia 59 1.7 53 1.5 73 2.0 94 2.5 Shigella 107 3.0 107 2.9 95 2.6 55 1.5 STEC* 6 0.2 13 0.4 6 0.2 6 0.2 HUS** 2 0.1 1 0.03 1 0.03 1 0.03 Total 5694 6340 6833 6320 * STEC : Shiga-toxin producing E. coli ** H.U.S : Haemolytic Uraemic Syndrome

48 Appendix 3. Salmonella and Campylobacter rates 1999 - 2003 (A) Annual notification numbers for Salmonella and Campylobacter, by Qld health zones, 1999-2003

Salmonella Campylobacter

1999 2000 2001 2002 2003 1999 2000 2001 2002 2003

North zone 663 554 559 803 648 436 749 551 806 507

Central zone 864 661 801 1034 786 1281 1347 1587 1453 1582

South zone 763 605 807 873 803 1502 1585 1829 1618 1792

QLD 2292 1820 2169 2722 2255 3222 3682 3969 3905 3886

(B) Annual rates per 100,000 population for Salmonella and Campylobacter, by Qld health zones, 1999-2003

Salmonella Campylobacter

1999 2000 2001 2002 2003 1999 2000 2001 2002 2003

North zone 113.7 93.8 95.0 136.4 108.6 74.8 126.9 93.6 136.9 85.0

Central zone 64.6 48.6 57.8 74.7 55.6 95.8 99.1 114.6 104.9 112.0

South zone 47.9 37.4 48.6 52.5 47.3 94.3 98.0 110.1 97.4 105.6

QLD 65.3 51.0 59.7 74.9 60.8 91.7 103.2 109.2 107.4 104.8

Appendix 4. Maps of Queensland Health Zones and Statistical Divisions.

Health Zones – Queensland Statistical Divisions – Queensland