This article {extract} was published in Communicable Diseases Intelligence Vol 30 No 1 March 2006 and may be downloaded as a full version PDF from the Table of contents page.

Results, continued

Gastrointestinal diseases

In 2004, gastrointestinal diseases that were notified to NNDSS were: botulism, campylobacteriosis, cryptosporidiosis, haemolytic uraemic syndrome (HUS), hepatitis A, hepatitis E, listeriosis, salmonellosis, shigellosis, Shiga toxin-producing Escherichia coli /verotoxigenic E. coli (STEC/VTEC) infections and typhoid.

Notifications of gastrointestinal diseases increased by 2 per cent; from 24,676 in 2003 to 25,248 in 2004 (Table 4). Compared with 2003, there was a decrease in the number of notifications of campylobacteriosis (2%), hepatitis A (28%), listeriosis (7%) and STEC (15%) in 2004. On the other hand, increases were reported for cryptosporidiosis (28%), hepatitis E (107%), salmonellosis (8%), shigellosis (17%) and typhoid (43%). The reported changes in the number of notifications were within the expected range (i.e. within the five year mean and two standard deviations) except for hepatitis E which had an excess of 13 cases above the upper 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).

One case of infant botulism in a female, less than 12 months old was reported to NNDSS in 2004 (Table 2). Since the commencement of the surveillance of botulism in 1992 there have been six cases of infant botulism reported, but no classic foodborne botulism has been reported in Australia since NNDSS commenced collecting data on botulism 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 15,008 notifications of campylobacteriosis in Australia in 2004. Campylobacteriosis is notifiable in all jurisdictions, except New South Wales. The national rate of notifications in 2004 was 112 cases per 100,000 population; a marginal decrease compared with the rate reported in 2003 (116 cases per 100,000 population). All jurisdictions with the exception of Victoria reported decreases in notifications, with South Australia reporting the largest decrease (30%). Victoria reported a 12 per cent increase in notifications, and had the highest notification rate in 2004 (127 cases per 100,000 population).

Monthly notifications of campylobacteriosis in 2004, consistent with previous years (1999 to 2003), peaked in the third quarter of the year in late winter/early spring (Figure 15). In 2004, seven Campylobacter related outbreaks were identified, of which four were suspected to be foodborne.⁴ These suspected foodborne outbreaks occurred in an aged care facility, restaurant and food takeaway settings.

Figure 15. Trends in notifications of campylobacteriosis, Australia, 1999 to 2004, by month of onset

Children aged 0–4 years had the highest notification rate of campylobacteriosis ( Figure 16). In this age group notification rates were higher in males (243 cases per 100,000 population) than in females (175 cases per 100,000 population). The overall male to female ratio, as in previous years, was 1.2:1.

Figure 16. Notification rates of campylobacteriosis, Australia, 2004, 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 2004, a total of 1,573 cases of cryptosporidiosis were reported to NNDSS, a notification rate of 8 cases per 100,000 population, which represents an increase of 28 per cent on the 1,225 cases reported in 2003.

New South Wales, the Northern Territory, Queensland, and Victoria reported increases in cryptosporidiosis notifications, with the largest increase in Queensland (276%). The Northern Territory and Queensland had notification rates above the national average at 57 and 16 cases per 100,000 population, respectively.

Fifty per cent of cryptosporidiosis cases notified in 2004 were under the age of five years. Compared to 2003, the notification rate in this age group increased by 24 per cent in 2004. With a notification rate of 61 cases per 100,000 population, children under the age of four years continue to have the highest notification rate of cryptosporidiosis. Within this age group one-year-old males had the highest notification rate at 130 cases per 100,000 population ( Figure 17).

Figure 17. Notification rates of cryptosporidiosis, Australia, 2004, by age group and sex

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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 315 cases of hepatitis A reported to NNDSS in 2004, a notification rate of 2 cases per 100,000 population. The notifications of hepatitis A have steadily decreased over the last decade, but remained stable in the period 2002 through 2004 ( Figure 18).

Figure 18. Trends in notifications of hepatitis A, Australia, 1991 to 2004, by month of notification

Compared to 2003, hepatitis A notification rates decreased in all jurisdictions (ranging from 15% in South Australia to 92% in Tasmania) except in New South Wales where an increase of 9 per cent was reported. The Northern Territory had the highest notification rate (7 cases per 100,000 population) followed by New South Wales (3 cases per 100,000 population).

Males, with a rate of 1.8 cases per 100,000 population had a higher notification rate of hepatitis A than females (1.3 cases per 100,000 population). The highest age specific rate of hepatitis A notifications among males and females was in the 5–9 year age group (3.8 cases per 100,000 population) and (2.8 cases per 100,000 population) respectively (Figure 19).

Figure 19. Notification rates of hepatitis A, Australia, 2004, by age group and sex

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In 2004, Indigenous Australians had the highest burden of hepatitis A. In 2004, Indigenous status of 90 per cent of cases was complete and 11 per cent of cases were Indigenous (Table 7).

Table 7. Hepatitis A notifications, Australia, 2004, by Indigenous status

State or territory	Indigenous	Non-Indigenous	Unknown	Total	% Indigenous (of total)
ACT	0	0	1	1	–
NSW	1	113	25	139	0.7
NT	5	8	0	13	38.5
Qld	0	20	2	22	–
SA	1	10	0	11	9.1
Tas	0	0	1	1	–
Vic	0	67	4	71	–
WA	28	28	1	57	49.1
Total	35	246	34	315	11.1

Hepatitis A is commonly spread from person to person or from contaminated food or water. Where information on risk factors was known (in 22% of all notifications), overseas travel and household contact with a case were the main risk factors for hepatitis A infection (Table 8).

Table 8. Risk exposures associated with hepatitis A virus infection, Australia, 2004, by state or territory

	State or territory
	ACT	NSW	NT	Qld	SA	Tas	Vic	WA	Aust
Total	1	139	13	22	11	1	71	57	315
Number of case with known risk factors*	0	57	6	11	6	0	41	21	142
Injecting drug use	–	0	0	0	1	0	4	–	7
Household/close contact of case	–	14	2	2	1	0	11	9	39
Overseas travel	–	41	1	12	3	0	28	9	94
Childcare	–	2	3	0	0	0	0	1	6
Homosexual contact	–	–	0	0	0	0	1	0	1
Sex worker	–	–	0	0	0	0	0	0	0
Other†	–	–	0	0	2	0	0	0	2

* Number of risk factors may not add up to the totals as exposures are not mutually exclusive hence more than one exposure per person is possible.

† Includes association with persons from country where hepatitis A is endemic and, living in areas where hepatitis A is endemic.

– Not assessed.

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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 28 cases of hepatitis E reported to NNDSS in 2004, an increase of 100 per cent on the number of cases reported in 2003. Twelve cases were reported in Victoria, eight in New South Wales, four in Queensland, three in Western Australia and one in Tasmania. The male to female ratio was 1.2:1. Cases were aged between 5 and 79 years (Figure 20). Data on countries visited were available for 26/94 cases with overseas travel and showed that 18 had travelled to India, two to Bangladesh and one each to China, Indonesia, Peru, Vietnam, Thailand and New Zealand.

Hepatitis E virus is transmitted enterically. In non-industrialised countries, where sanitation is poor water-borne transmission of hepatitis E occurs, while in industrialised countries zoonotic transmission (from pigs to humans) has been recorded. In Australia, locally acquired hepatitis E was reported in the early 1990s.⁵

Figure 20. Notification rates of hepatitis E, Australia, 2004, by age group and sex

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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 2004, 65 cases of listeriosis were reported to NNDSS, a notification rate of 0.3 cases per 100,000 population. Listeriosis notifications have been stable at this rate since 1998. In 2004, 71 per cent of listeriosis cases were aged over 50 years, with the highest notification rate in the 80–84 year age group in males and females ( Figure 21).

Figure 21. Notification rates of listeriosis, Australia, 2004, by age group and sex

In 2004, there were seven listeriosis cases of materno-foetal origin and one foetal death was reported.⁶ Health outcome for 29 cases was known, and of these, four cases all aged over 66 died. No common-source outbreaks of listeriosis were identified during 2004.⁶

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Salmonellosis (non-typhoidal)

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 7,607 salmonellosis cases were reported to NNDSS in 2004, a rate of 37.8 cases per 100,000 population and a 7 per cent increase from the rate reported in 2003 (35.4 cases per 100,000 population). During the five year period, 1998–2003, the highest national notification rate was 40 cases per 100,000 population in 2002.

The Northern Territory and Queensland had notification rates 5 and 1.6 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 2004, the Kimberley Statistical Division of Western Australia had the highest notification rate at 309 cases per 100,000 population. The same Statistical Division had a notification rate of 323 cases per 100,000 population in 2003.

Map 2. Notification rates of salmonellosis, Australia, 2004, by Statistical Division of residence

As in previous years, reports of salmonellosis peaked during summer (January to March) ( Figure 22). Thirty-five per cent of salmonellosis cases in 2004 had dates of onset during the first quarter of the year.

Figure 22. Trends in notifications of salmonellosis, Australia, 1999 to 2004, by month of onset

As in 2003, the highest rate of notification was in children aged between 0–4 years: 32 per cent of salmonellosis notifications were in this age group (Figure 23).

Figure 23. Notification rates of salmonellosis, Australia, 2004, by age group and sex

The National Enteric Pathogens Surveillance Scheme reported serovars for 7,771 isolates in 2004.⁷ The 10 most frequently isolated serovars and phage types of Salmonella, which accounted for 43 per cent of all isolates, are shown in Table 9. Nationally, Salmonella Typhimurium 135, Salmonella Typhimurium 170 and S. Saintpaul were the three most frequently isolated serovars/phage types. In 2003, S. Saintpaul was ranked fourth among the most notified serovars. S. Typhimurium 12 was for the first time, in the top 10 serovars in 2004, replacing Salmonella Typhimurium 290.

In 2004, there was little change to the distribution of Salmonella serovars reported in 2003. The most commonly reported serovars in Queensland, Tasmania, and the Northern Territory were S. Virchow 8 (9% of salmonellosis notifications), S. Mississippi (52% of salmonellosis notifications) and S. Ball (15% of salmonellosis notifications), respectively. Typhimurium was the most commonly reported serovar in the rest of the jurisdictions. Typhimurium 170 accounted for 55 per cent of cases in the Australian Capital Territory, 17 per cent in New South Wales, 11 per cent in Victoria, and 13 per cent in South Australia. In Western Australia, Typhimurium 135 was the most commonly notified phage type, making 12 per cent of salmonellosis notifications.

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Table 9. Top 10 human isolates of Salmonella, Australia, 2004

Organism	State or territory
	ACT	NSW	NT	Qld	SA	Tas	Vic	WA	Aust	Total (%)
S. Typhimurium 170	33	357	2	50	0	4	129	2	577	7.4
S. Typhimurium 135	5	189	3	180	18	1	92	75	563	7.2
S. Saintpaul	1	41	49	226	13	2	20	42	394	5.1
S. Typhimurium 9	6	119	0	43	44	4	130	14	360	4.6
S. Virchow 8	4	43	1	248	9	2	26	0	333	4.3
S. Typhimurium 197	9	48	0	147	2	0	61	1	268	3.4
S. Birkenhead	1	80	1	167	1	1	11	1	263	3.4
S. Typhimurium 12	3	172	0	30	8	0	18	2	233	3.0
S. Chester	2	34	12	87	20	1	11	23	190	2.4
S. Infantis	6	59	7	11	21	1	43	10	158	2.0
Sub Total	70	1,142	75	1,189	136	16	541	170	3,339	43.0
Other isolates	37	1,005	296	1,559	392	104	598	441	4,432	57.0
Total	107	2,147	371	2,748	528	120	1139	611	7,771	100

Source: National Enteric Pathogens Surveillance System.

Outbreaks and clusters of salmonellosis

In 2004, OzFoodNet reported 118 foodborne disease outbreaks of which 29 were attributable to S. Typhimurium infection. These outbreaks affected 599 persons and resulted in 74 hospitalisations. Of the six significant foodborne outbreaks (affecting 50 or more persons each) in 2004, two were due to Typhimurium: phage types 12 in New South Wales and phage type 9 in Victoria. The outbreak that occurred in New South Wales was a community-wide outbreak. In this outbreak, investigators found that the consumption of home prepared chicken was the main risk factor for S. Typhimurium 12 infection. The outbreak in Victoria was associated with the consumption of food from a pizza restaurant. S. Typhimurium 9 was isolated from several foods, suggesting that there had been cross contamination of foods.⁸

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Shigellosis

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

In 2004, a total of 518 cases of shigellosis were reported to NNDSS, a notification rate of 2.6 cases per 100,000 population. This rate was 18 per cent higher than the rate reported in 2003 (2.2 cases per 100,000 population), but it was within the five year average (Table 4). The Northern Territory continued to have the highest notification rate at 59.5 cases per 100,000 population, but this was a decrease by 10 per cent in notification rates compared to 2003. Nationally, notifications of the disease remained stable over the last five years ( Figure 24). The male to female ratio remained at 0.8:1.

Figure 24. Trends in notifications of shigellosis, Australia, 1999 to 2004, by month of onset

Children under the age of four years represented 31 per cent of shigellosis notifications (Figure 25). This age group had a notification rate of 13 cases per 100,000 population, which is five times the national rate and an increase of 18 per cent compared to the rate reported in 2003 (11 cases per 100,000 population).

Figure 25. Notification rates of shigellosis, Australia, 2004, by age group and sex

Indigenous populations continue to have the highest burden of shigellosis. In 2004, of the notifications of shigellosis where Indigenous status of cases was complete (64% of all cases) 37 per cent were identified as Indigenous. In the Northern Territory (where 98% of notifications had the Indigenous status of the case recorded), 82 per cent of shigellosis cases were Indigenous people.

Shigella flexneri and Shigella sonnei infections accounted for about 50 per cent and 48 per cent of shigellosis, respectively in 2004 (Table 10).

Table 10. Shigella infections, Australia, 2004, by serogroup and state or territory

Organism	State or territory
	ACT	NSW	NT	Qld	SA	Tas	Vic	WA	Total	Per cent
S. boydii		2		1	1		2	1	7	1.9
S. dysenteriae		1		1				1	3	0.8
S. flexneri		32		16	39	2	28	67	184	49.5
S. sonnei	2	59		30	13	1	37	36	178	47.8
Sub Total	2	94	0	48	53	3	67	105	372	100.0
Unknown	0	2	119	13	1	0	3	8	146	–
Total	2	96	119	61	54	3	70	113	518	–

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Shiga-like toxin-producing/verotoxigenic Escherichia coli

Case definitions – Shiga toxin-producing/verotoxin-producing Escherichia coli (STEC/VTEC) Only confirmed cases are reported. Confirmed case: Requires isolation of Shigatoxigenic/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 STEC/VTEC is isolated in the context of haemolytic uraemic syndrome (HUS), it should be notified as STEC/VTEC and HUS.

There were 44 cases of SLTEC/VTEC reported to NNDSS in 2004. With a notification rate of 0.2 cases per 100,000 population, the rate of SLTEC/VTEC notifications remained stable compared to 2003. Seventy-three per cent of cases were notified in South Australia (1.8 cases per 100,000 population), where bloody stools are routinely tested by polymerase chain reaction (PCR) for genes coding for Shiga toxin. New South Wales, Queensland, and Victoria were the only other jurisdictions that notified SLTEC/VTEC. OzFoodNet reported that among typed E. coli (67% of all notifications) 15 per cent were subtype O157, 16 per cent were subtype O11 and 13 per cent were O26.⁶

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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 STEC/VTEC is isolated in the context of HUS, it should be notified as both STEC/VTEC and HUS.

In 2004, 15 cases of HUS were reported to NNDSS, a rate of 0.1 cases per 100,000 population, the same rate as in 2003. No HUS cases were notified in the Australian Capital Territory, Tasmania, the Northern Territory or Western Australia. Among the 15 cases of HUS notified in 2004, six were males. The median age among males was 19 years (range 2–54 years) and among females was 34 years (range 0–82 years). STEC was isolated in three cases of HUS.

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Typhoid

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

In 2004, there were 73 notifications of typhoid, a rate of 0.4 cases per 100,000 population, representing an increase of 43 per cent compared to 2003. The largest increase, compared to 2003, occurred in New South Wales (increase of 143%). Nationally, the male to female ratio was 1:1, with the highest notification rates in males aged 0–4 years (0.9 cases per 100,000 population) and in females aged 15–19 years (1.2 cases per 100,000 population) (Figure 26). The National Enteric Pathogen Surveillance Scheme identified 71 SalmonellaTyphi isolates, 68 of which were from Australian residents. Of the 68 Australian residents, 17 had no travel history recorded, two had not travelled, and the remaining 49 cases had travelled outside Australia in South East Asia, Africa, Europe, Pacific Islands, and South America.⁷

Figure 26. Notification rates of typhoid, Australia, 2004, by age group and sex