This article {extract} was published in Communicable Diseases Intelligence Vol 31 No 1 March 2007 and may be downloaded as a full version PDF from the Table of contents page.

Results, continued

Gastrointestinal diseases

In 2005, gastrointestinal diseases that were notified to NNDSS were: botulism, campylobacteriosis, cryptosporidiosis, haemolytic uraemic syndrome (HUS), hepatitis A, hepatitis E, listeriosis, salmonellosis, shigellosis, Shiga-like toxin-producing Escherichia coli/verotoxigenic E. coli (SLTEC/VTEC) infections and typhoid.

Notifications of gastrointestinal diseases increased by 12%; from 26,173 in 2004 to 29,422 in 2005 (Table 4). Compared with 2004, there was a decrease in the number of notifications of listeriosis (13 notifications; 19%) and typhoid (24 notifications; 31%) in 2005. Variable increases were reported for all other gastrointestinal disease; botulism (200%), campylobacteriosis (6%), cryptosporidiosis (91%), haemolytic uraemic syndrome (25%), hepatitis A (2%), hepatitis E (11%), salmonellosis (8%), shigellosis (41%) and SLTEC/VTEC (78%). The number of notifications were within the historical range (i.e. within the 5-year mean and 2 standard deviations) except for hepatitis E which had an excess of 1 case, shigellosis which had an excess of 136 cases, and SLTEC/VTEC, which had an excess of 26 cases above the upper historical range. Listeriosis notifications were 6 cases below the lower historical range.

Botulism

Case definition – Botulism Only confirmed cases are reported. Confirmed case: Requires isolation of Clostridium botulinum OR detection of Clostridium botulinum toxin in blood or faeces AND a clinically compatible illness (e.g. diplopia, blurred vision, muscle weakness, paralysis, death).

Three cases of infant botulism in 2 males and a female were reported to NNDSS in 2005. All were aged less than 12 months. There have been 9 cases of infant botulism reported, but no classic foodborne botulism reported in Australia since botulism surveillance commenced in 1992.

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Campylobacteriosis

Case definition – Campylobacteriosis Only confirmed cases are reported. Confirmed case: Requires isolation or detection of Campylobacter species.

There were 16,468 notifications of campylobacteriosis in Australia in 2005. Campylobacteriosis is notifiable in all jurisdictions except New South Wales. The national rate of notifications in 2005 was 121 cases per 100,000 population; an increase of 4% compared with the rate reported in 2004 (116 cases per 100,000 population). All jurisdictions with the exception of Victoria reported increases in notifications, with Western Australia and Tasmania reporting the largest increases (25% and 23%). Victoria reported a 5% decrease in notifications after a 12% increase in 2004. Tasmania had the highest notification rate in 2005 (157 cases per 100,000 population) and Queensland had the lowest notification rate (111 cases per 100,000 population) (Table 3).

Monthly notifications of campylobacteriosis in 2005, consistent with previous years (2000 to 2004), peaked in the fourth quarter of the year in early summer (Figure 15). In 2005, 12 Campylobacter related outbreaks were identified of which 9 were suspected to be foodborne.⁴

Figure 15. Trends in notifications of campylobacteriosis, Australia, 2000 to 2005, by month of onset

Children aged 0–4 years had the highest notification rate of Campylobacter infection (Figure 16). In this age group, notification rates were higher in males (260 cases per 100,000 population) than in females (187 cases per 100,000 population). The overall male to female ratio, as in previous years, was 1.2:1.

Figure 16. Notification rate for campylobacteriosis, Australia, 2005, by age group and sex

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Cryptosporidiosis

Case definitions – Cryptosporidiosis Only confirmed cases are reported. Confirmed case: Requires detection of Cryptosporidium oocytes.

In 2005, a total of 3,209 cases of cryptosporidiosis were reported to NNDSS; an increase of 91% on the 1,684 cases reported in 2004. The national notification rate of 15.8 cases per 100,000 population represents an increase of 73% on the average notification rate for the previous 5 years.

All jurisdictions except the Northern Territory reported increases in cryptosporidiosis notifications, with increases ranging from 22% in Tasmania to 350% in the Australian Capital Territory. The Northern Territory and Queensland had a notification rate above the national average at 40 and 34 cases per 100,000 population, respectively.

Forty-four per cent of cryptosporidiosis cases notified in 2005 were under the age of 5 years. Compared to 2004, the notification rate in this age group increased by 72% in 2005. With a notification rate of 112 cases per 100,000 population, children under the age of 5 years continue to have the highest notification rate of cryptosporidiosis. Within this age group males aged 1 year had the highest notification rate at 229 cases per 100,000 population (Figure 17).

Figure 17. Notification rate for cryptosporidiosis, Australia, 2005, by age group and sex

Hepatitis A

Case definition – Hepatitis A Both confirmed cases and probable cases are reported. Confirmed case: Requires detection of anti-hepatitis A IgM, in the absence of recent vaccination, OR detection of hepatitis A virus by nucleic acid testing. Probable case: Requires clinical hepatitis (jaundice and/or bilirubin in urine) without a non-infectious cause AND contact between two people involving a plausible mode of transmission at a time when: (a) one of them is likely to be infectious (from two weeks before the onset of jaundice to a week after onset of jaundice), AND (b) the other has an illness that starts within 15 to 50 (average 28–30) days after this contact, AND at least one case in the chain of epidemiologically-linked cases (which may involve many cases) is laboratory confirmed.

There were 325 cases of hepatitis A reported to NNDSS in 2005; a notification rate of 2 cases per 100,000 population. The notifications of hepatitis A have steadily decreased for the last decade, but remained stable in the period 2004 to 2005 (Figure 18).

Figure 18. Trends in notifications of hepatitis A, Australia, 1991 to 2005, by month of notification

Compared to 2004, hepatitis A notification rates increased in 4 jurisdictions (ranging from 81% in Queensland to 351% in the Northern Territory) and decreased in 4 jurisdictions (ranging from 7% in Western Australia to 40% in New South Wales). The Northern Territory had the highest notification rate (32 cases per 100,000 population) followed by Western Australia (3 cases per 100,000 population).

The highest age-specific rate of hepatitis A notifications for both males and females was in the 5–9 year age group (3.2 cases and 3.4 cases per 100,000 population, respectively) (Figure 19). The overall male to female notification rate was 1:0.9.

Figure 19. Notification rate for hepatitis A, Australia, 2005, by age group and sex

Indigenous Australians had the highest burden of hepatitis A infection in 2005 with a rate of 9.9 cases per 100,000 population, compared with 0.6 cases per 100,000 population in the non-Indigenous population. In 2005 the Indigenous status of 86% of cases of hepatitis A was complete and 15% of cases were identified as Indigenous people compared with 11% in 2004.

Hepatitis A is commonly spread from person to person or from contaminated food or water. Information on risk factors was known in 67% of all notifications. Overseas travel and household contact with another case were the main risk factors for hepatitis A infection (Table 7).

Table 7. Risk exposure associated with hepatitis A virus infection, Australia, 2005

Total number of cases	325
Number of cases with known risk factors*
Injecting/recreational drug use	3
Household/close contact of case	52
Overseas travel	74
Childcare	9
Homosexual contact	9
Sex worker†	0
Other‡	2

* Exposures are not mutually exclusive hence more than one exposure per person is possible.

† Not available in New South Wales or Queensland.

‡ Includes association with persons from a country where hepatitis A is endemic and, living in an area where hepatitis A is endemic.

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Hepatitis E

Case definition – Hepatitis E Only confirmed cases are reported. Confirmed case: Requires detection of hepatitis E virus by nucleic acid testing OR, detection of hepatitis E virus in faeces by electron microscopy OR, detection of IgM or IgG to hepatitis E virus. If the person has not travelled outside Australia in the preceding 3 months, the antibody result must be confirmed by specific immunoblot.

There were 31 cases of hepatitis E reported to NNDSS in 2005, an increase of 11% on the number of cases reported in 2004. Twelve cases were reported in Victoria, 8 in Queensland, seven in New South Wales, 2 in Western Australia and 2 in the Australian Capital Territory. The male to female ratio was 2.1:1. Cases were aged between 10 and 74 years. Twenty-nine cases acquired their infections overseas: 17 had travelled to India, 3 to Vietnam, 3 throughout South East Asia and the remaining cases to other countries: mostly in Asia and South East Asia. One case in Victoria and 1 in Queensland were reported as locally acquired.

The Victorian Infectious Diseases Reference Laboratory detected a large increase in hepatitis E positive samples in the first quarter of 2005, which coincided with outbreaks of hepatitis E in India.⁵

Listeriosis

Case definitions – Listeriosis Only confirmed cases are reported. Where a mother and foetus/neonate are both confirmed, both cases are reported. Confirmed case: Requires isolation or detection of Listeria monocytogenes from a site that is normally sterile, including foetal gastrointestinal contents.

In 2005, 54 cases of listeriosis were reported to NNDSS, a notification rate of 0.3 cases per 100,000 population. This represents a decrease of 20% compared to the 5-year average. Eighty-five per cent of listeriosis cases were aged over 50 years, with the highest notification rate in the over 85 year age group in both males and females (Figure 20). Of 19 cases where the outcome of the infection was known, 3 cases died.

Figure 20. Notification rate for listeriosis, Australia, 2005, by age group and sex

In 2005, there were 4 listeriosis cases of materno-foetal origin and 1 foetal death reported. An outbreak of listeriosis linked to the consumption of cold meats in South Australia, occurred in 2005. The Australian Capital Territory also reported a cluster of 3 cases but no common source was identified.⁴

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Salmonellosis (NEC)

Case definitions: – Salmonellosis Only confirmed cases are reported. Confirmed case: Requires isolation or detection of Salmonella species (excluding S. typhi which is notified separately under typhoid).

A total of 8,441 salmonellosis cases were reported to NNDSS in 2005, a rate of 41.5 cases per 100,000 population and a 6.6% increase from the rate reported in 2004 (39.0 cases per 100,000 population). The national notification rate for 2005 showed an increase of 14.1% over the mean rate for the previous 5 years.

The Northern Territory, Queensland and Tasmania had notification rates 4.7, 1.6 and 1.5 times the national notification rate, respectively (Table 3). The highest rates of notification of salmonellosis were reported in the northern part of the country (Map 2). In 2005, the Northern Territory, excluding Darwin, had the highest notification rate at 275 cases per 100,000 population. This Statistical Division had a notification rate of 288 cases per 100,000 population in 2004.

Map 2. Notification rate for salmonellosis, Australia, 2005, by Statistical Division of residence

Traditionally, the incidence of Salmonella infections fluctuates seasonally, peaking in March. In 2005, several outbreaks caused Salmonella notifications to peak in January (Figure 21). Thirty-three per cent of salmonellosis cases in 2005 had dates of onset during the summer months.

Figure 21. Trends in notifications of salmonellosis, Australia, 2000 to 2005, by month of onset

As in 2004, the highest rate of notification was in children aged between 0–4 years (195 cases per 100,000 population): 29% of salmonellosis notifications were in this age group (Figure 22).

Figure 22. Notification rate for salmonellosis, Australia, 2005, by age group and sex

The National Enteric Pathogens Surveillance Scheme reported serovars for 8,241 isolates in 2005.6 The 10 most frequently isolated serovars and phage types of Salmonella, which accounted for 45% of all isolates, are shown in Table 8. Salmonella Typhimurium 135, Salmonella Typhimurium 197 and Salmonella Typhimurium 170 were the 3 most frequently isolated serovars/phage types. Several outbreaks were associated with these 3 phage types, the largest, which affected 268 people in Victoria, was caused by phage type 197. Salmonella Typhimurium 44 appeared in the top 10 serovars for the first time in 2005.

Salmonella Saintpaul was the most commonly reported serovar in Queensland and in the Northern Territory (11% and 12% of salmonellosis notifications). In all other jurisdictions Salmonella Typhimurium was the most commonly reported serovar. Salmonella Typhimurium 135 accounted for 59% of cases in Tasmania, 13% in the Australian Capital Territory and 9% in Western Australia. Salmonella Typhimurium 170 was the most commonly notified phage type in New South Wales and the Australian Capital Territory making up 15% and 13% of salmonellosis notifications respectively. In Victoria, Salmonella Typhimurium 197 was the most common phage type (19%) and in South Australia Salmonella Typhimurium 9 accounted for 10% of notifications (Table 8).

Table 8. Top 10 isolates of Salmonella, Australia, 2005, by state or territory

Organism	State or territory									Total %
	ACT	NSW	NT	Qld	SA	Tas	Vic	WA	Aust
S. Typhimurium 135	14	188	1	135	23	175	198	68	802	16.6
S. Typhimurium 197	1	113	0	140	5	2	280	4	545	11.3
S. Typhimurium 170*	14	328	0	48	3	6	64	9	472	9.8
S. Saintpaul	3	42	48	271	13	2	24	33	436	9.0
S. Typhimurium 9	11	155	5	33	57	10	124	11	406	8.4
S. Virchow 8	2	28	10	182	6	1	7	12	248	5.1
S. Typhimurium 44	6	67	0	59	28	6	53	9	228	4.7
S. Birkenhead	0	85	0	128	0	0	6	1	220	4.5
S. Chester	1	30	14	87	14	1	10	29	186	3.8
S. Hvittingfoss	5	23	5	129	1	0	19	3	185	3.8
Sub-total	57	1,059	83	1,212	150	203	785	179	3,728	77.0
Other isolates	6	217	35	370	90	63	134	197	1,112	23.0

Source: National Enteric Pathogenic Surveillance System.

* Reported as Salmonella Typhimurium phage type 108 in some states and territories.

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Outbreaks and clusters of salmonellosis

In 2005, OzFoodNet reported 104 clusters and outbreaks of salmonellosis of which 61% (63/104) were attributable to S. Typhimurium infection. Thirty-three foodborne outbreaks of salmonellosis were reported. These outbreaks affected 1,200 persons and resulted in 150 hospitalisations and 4 deaths.

Of the 5 significant foodborne outbreaks (affecting 50 or more persons each) in 2005, 4 were due to Salmonella Typhimurium: 1 outbreak of STM197 in Victoria; 2 of STM135 in Tasmania and one outbreak of STM64 in South Australia. The STM197 outbreak in Victoria was associated with dips served at a Turkish restaurant. The 2 STM135 outbreaks in Tasmania were associated with cakes prepared at a bakery and raw egg sauces in a restaurant. A single egg-farm supplied eggs to both premises. The STM64 outbreak in South Australia was associated with consumption of bread rolls from a restaurant. The fifth significant Salmonella outbreak occurred in Western Australia and was due to Salmonella Oranienburg associated with the consumption of alfalfa sprouts.⁴

Shigellosis

Case definitions – Shigellosis Only confirmed cases are reported. Confirmed case: Isolation or detection of Shigella species.

In 2005, a total of 732 cases of shigellosis were reported to NNDSS, a notification rate of 3.6 cases per 100,000 population. This rate was 39% higher than the rate reported in 2004 (2.6 cases per 100,000 population), and 40% higher than the 5-year average (Table 4). Notification rates for 2005 increased compared to 2004 in all jurisdictions except South Australia. The Northern Territory continued to have the highest notification rate at 96.7 cases per 100,000 population, an increase by 66.6% in notification rates compared to 2004. Nationally, notification rates of the disease had been declining for the period 1999 to 2003, then increased in 2004 and again in 2005 (Figure 23).

Figure 23. Trends in notifications of shigellosis, Australia, 2000 to 2005, by month of onset

The male to female rate ratio remained at 0.9:1. Children under the age of 4 years represented 31% of shigellosis notifications (Figure 24). This age group had a notification rate of 17.8 cases per 100,000 population, which was an increase of 40% compared to the rate reported in 2004 (12.7 cases per 100,000 population).

The highest rate of shigellosis continues to be in Indigenous populations with a rate of 64 cases per 100,000 population compared to 0.5 cases per 100,000 population in the non-Indigenous population. In 2005, of the notifications of shigellosis where Indigenous status of cases was complete (73% of all cases) 59% were identified as Indigenous. In the Northern Territory (where Indigenous status was complete for 100% of notifications) 82% of shigellosis cases were Indigenous.

Figure 24. Notification rate for shigellosis, Australia, 2005, by age group and sex

Shigella flexneri and Shigella sonnei infections accounted for 44% and 52% of shigellosis, respectively in 2005 (Table 9). Eighty-nine per cent of Shigella flexneri infections were further typed, of which 27% were type 4a mannitol negative and 27% were type 2a. Eighty-three per cent of Shigella sonnei infections were further typed, of which 54% were type A.

Table 9. Shigella infections, Australia, 2005, by serogroups and state or territory

Organism	State or territory								Total	Per cent
	ACT	NSW	NT	Qld	SA	Tas	Vic	WA
S. boydii	0	4	1	0	0	0	2	1	8	1.1
S. dysenteriae	0	2	0	1	0	0	0	0	3	0.4
S. flexneri	1	29	128	20	32	3	21	91	325	45.5
S. sonnei	6	97	64	55	16	2	77	61	378	52.9
Sub-total	7	132	193	76	48	5	100	153	714	100.0
Unknown	0	3	3	4	0	0	5	3	18	–
Total	7	135	196	80	48	5	105	156	732	–

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Shiga-like toxin-producing Escherichia coli/verotoxigenic Escherichia coli

Case definitions – Shiga-like toxin-producing/verotoxin-producing Escherichia coli (SLTEC/VTEC) Only confirmed cases are reported. Confirmed case: Requires isolation of Shiga-toxigenic/verotoxigenic Escherichia coli from faeces, OR, isolation of Shiga toxin or verotoxin from a clinical isolate of E. coli OR, identification of the gene associated with the production of Shiga toxin or vero toxin in E. coli by nucleic acid testing on isolate or raw bloody diarrhoea. Note: Where SLTEC/VTEC is isolated in the context of haemolytic uraemic syndrome (HUS), it should be notified as SLTEC/VTEC and HUS.

There were 87 cases of SLTEC/VTEC reported to NNDSS in 2005 compared with 49 cases in 2004. With a notification rate of 0.4 cases per 100,000 population, the rate of SLTEC/VTEC notifications represented an increase of 70% compared to the average for the previous 5 years. The increase in notifications was due to an increase in screening for SLTEC/VTEC by Western Australia, Victoria and parts of New South Wales. As in previous years, South Australia continued to routinely test bloody stools by polymerase chain reaction for genes coding for Shiga-like toxin. Forty-six per cent of all cases were notified in South Australia (2.6 cases per 100,000 population). The Australian Capital Territory and the Northern Territory did not report any cases of SLTEC/VTEC. OzFoodNet reported that among typed E. coli (49% of all notifications) 39% were subtypeO157, 26% were subtype O11 and 16% were O26.⁴

Haemolytic uraemic syndrome

Case definitions – Haemolytic uraemic syndrome (HUS) Only confirmed cases are reported. Confirmed case: Requires acute microangiopathic anaemia on peripheral blood smear (schistocytes, burr cells or helmet cells) AND AT LEAST ONE OF THE FOLLOWING: acute renal impairment (haematuria, proteinuria or elevated creatinine level), OR, thrombocytopaenia, particularly during the first seven days of illness. Note: Where SLTEC/VTEC is isolated in the context of HUS, it should be notified as both SLTEC/VTEC and HUS.

In 2005, 20 cases of HUS were reported to NNDSS; a rate of 0.1 cases per 100,000 population, an increase of 23% on the rate in 2004 (15 cases). Eleven cases occurred in New South Wales. No HUS cases were notified in the Australian Capital Territory or the Northern Territory. Among the 20 cases of HUS notified in 2005, 55% were males. The median age among males was 13 years (range 1–68 years) and among females was 25 years (range 2–81 years). SLTEC was isolated in 9 cases of HUS. Toxigenic E. coli was identified in 9 of the 20 cases. The serotypes of these 9 were O111 (2), O157:H (2), OR:H– (1), O111:H– (1), O49 (1), and unknown (2).

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Typhoid

Case definitions – Typhoid fever Only confirmed cases are reported. Confirmed case: Requires isolation or detection of Salmonella typhi.

In 2005, there were 52 notifications of typhoid; a rate of 0.26 cases per 100,000 population, representing an decrease of 23% compared to the average notification rate for the previous 5 years. All jurisdictions reported a decrease in notification rates except Western Australia, which reported a 67% increase. Nationally, the male to female ratio was 1:0.7, with the highest notification rates in males aged 20–24 and 15–19 years (1.6 and 1.0 cases per 100,000 population respectively) and in females aged 5–9 and 15–29 years (0.6 cases per 100,000 population) (Figure 25).

The National Enteric Pathogen Surveillance Scheme identified 50 Salmonella Typhi isolates in 2005, 42 of which were from Australian residents. Of the 42 Australian residents, 9 had no travel history recorded, 1 had not travelled, 1 had carrier contact, 1 was a carrier and the remaining 30 cases had travelled outside Australia including in South East Asia, Africa, Europe, Pacific Islands, and South America.⁶

Figure 25. Notification rate for typhoid, Australia, 2005, by age group and sex