Results

Gastrointestinal diseases

In 2006, gastrointestinal diseases 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 in 2006 decreased to 27,924 from 29,424 in 2005 (Table 4a).

Compared with 2005, there was a decrease in the number of notifications of all gastrointestinal diseases except for listeriosis (an increase from 54 to 61 cases) and typhoid (an increase from 52 to 78 cases). Declines in the number of notifications in other diseases ranged from 1% in cryptosporidiosis to a 26% decline in shigellosis notifications (Table 4a).

The reported changes in the number of notifications were within the expected range (the 5-year mean plus or minus 2 standard deviations).

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).

In 2006, a single case of intestinal botulism that was not foodborne, was reported in 2006 in a 2-year-old child from Queensland. Intestinal botulism arises from the ingestion of Clostridium botulinum spores, which then germinate to produce and release toxin in the colon. Sources of intestinal botulism are poorly understood, but honey and dust have been suspected in the past.Cases of foodborne botulism are extremely rare. Since NNDSS commenced in 1991, there has only been 1 case of foodborne botulism, which was reported in 1999.

Campylobacteriosis

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

There were 15,398 notifications of campylobacteriosis in 2006, a 7% decline on the 16,488 notifications reported in 2005. Campylobacteriosis is notifiable in all jurisdictions except New South Wales. The national rate of notifications in 2006 was 111 cases per 100,000 population. The highest rate was reported in South Australia (161.7) and the lowest in Western Australia (94.4, Table 3).

There was an increase in campylobacteriosis notifications in spring and summer, consistent with previous years (Figure 15).

Top of pageFigure 15. Trends in notifications of campylobacteriosis, Australia, 2000 to 2006, by month of onset

Children aged 0–4 years had the highest notification rate of Campylobacter infection (218 cases per 100,000 population) with a secondary peak in the 20–24 years age group (148 cases per 100,000 population, Figure 16). In the 0–4 years age group notification rates were higher in males (245 cases per 100,000 population) than in females (188 cases per 100,000 population). The overall male to female ratio, as in previous years, was 1.15:1.

Figure 16. Notification rate of campylobacteriosis, Australia, 2006, 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. Laboratory definitive evidence: detection of Cryptosporidium oocytes.

In 2006, a total of 3,201 cases of cryptosporidiosis were reported to NNDSS (15.5 cases per 100,000 population), a similar number and rate to 2005 (3,211 cases, 15.8 cases per 100,000 population).

The highest rates of cryptosporidiosis were reported in the Northern Territory (34.8 cases per 100,000 population) and the Australian Capital Territory (24 cases per 100,000 population).

Of the 3,201 cases of cryptosporidiosis notified to NNDSS in 2006, 1,142 (35%) were under the age of 5 years. Within this age group, boys aged 1 year had the highest notification rate at 175 cases per 100,000 population (Figure 17).

Figure 17. Notification rate of cryptosporidiosis, Australia, 2006, by age group and sex

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There was a prolonged increase in cryptosporidiosis notifications from New South Wales, Queensland and Victoria from November 2005 to May 2006. Rates of cryptosporidiosis were also elevated in the Australian Capital Territory and the Northern Territory. Interviews with Victorian cryptosporidiosis cases notified between January and May 2006 identified 36 swimming pools as a probable source for 2 or more cases and 2 outbreaks at a special-needs school associated with person to person spread. Hyper-chlorination of the swimming pools and infection control procedures at the school brought these outbreaks under control.⁴

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.

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There were 280 notifications of hepatitis A in 2006 (1.4 cases per 100,000 population) a decrease of 14% on the 326 cases of hepatitis A reported to NNDSS in 2005. The number of notifications of hepatitis A decreased between 1998 and 2001 and have remained stable since 2002 (Figure 18).

Figure 18. Trends in notifications of hepatitis A, Australia, 1991 to 2006, by month of notification

Top of pageThe Northern Territory had the highest notification rate (14.5 cases per 100,000 population) followed by Western Australia (3.3 cases per 100 000 population) and New South Wales (1.4 cases per 100,000 population). Rates in all other jurisdictions were less than 1 case per 100,000 population (Table 3).

There were more notifications from males than females with a ratio of 1.2:1. Rates were highest in the 5–9 years age group (2.8 cases per 100,000 population, Figure 19).

Figure 19. Notification rate of hepatitis A, Australia, 2006, by age group and sex

In 2006, Indigenous Australians had higher notification rates of hepatitis A infections (6 cases per 10,000 population) compared with non-Indigenous Australians (1.3 cases per 100,000 population). In 2006, indigenous status was complete in 86% of hepatitis A notifications and 10% overall were Indigenous (Table 7).

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Table 7. Hepatitis A notifications, Australia, 2006, by indigenous status

State or territory	Indigenous		Non-Indigenous*		Total
	Notifications	Rate	Notifications	Rate	Notifications	Rate
Australian Capital Territory	0	0.0	1	0.3	1	0.3
New South Wales	2	1.5	93	1.4	95	1.4
Northern Territory	10	16.5	20	13.7	30	14.5
Queensland	0	0.0	31	0.8	31	0.8
South Australia	3	11.3	5	0.3	8	0.5
Tasmania	0	0.0	4	0.8	4	0.8
Victoria	0	0.0	44	0.9	44	0.9
Western Australia	13	19.4	54	2.7	67	3.3
Total	28	6.0	252	1.3	280	1.4

* Notifications in non-Indigenous persons include diagnoses in persons whose indigenous status was not reported.

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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 23 cases of hepatitis E in 2006, a decrease of 23% on the 30 cases reported to NNDSS in 2005. Ten cases were reported from New South Wales, 8 from Victoria, 2 each in the Australian Capital Territory and Queensland and 1 from Western Australia.

There were 13 male and 10 female cases (male to female ratio 1.3:1). Cases were aged 16–61 years. Eleven of the cases acquired their infections overseas.

Listeriosis

In 2006, 61 cases of listeriosis were notified to NNDSS, a 13% increase on the 54 cases reported to NNDSS in 2005.

In 2006, 50 (82%) listeriosis cases were aged over 50 years, with the highest notification rate in the 85 years or over age group in males and females (Figure 20). Six cases (4 women and 2 men) aged between 76 and 87 years died. Eight cases of materno-foetal listeriosis were reported to OzFoodNet in 2006.⁴ In 2 of these cases the infant died.

Figure 20. Notification rate of listeriosis, Australia, 2006, by age group and sex

Salmonellosis

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

There were 8,261 notification of salmonellosis (40.1 cases per 100,000 population) to NNDSS in 2006, a 2% decline from the 8,425 notifications reported in 2005.

The highest notification rates were reported in the Northern Territory (196 cases per 100,000 population), Queensland (67 cases per 100,000 population) and the Australian Capital Territory (41 cases per 100,000 population, Table 3 and Map 2).

Top of pageMap 2. Notification rates of salmonellosis, Australia, 2006, by Statistical Division of residence

The highest rate of notification was in children aged between 0–4 years: 30% of salmonellosis notifications were in this age group (Figure 21). The male to female ratio was 1:1.

Figure 21. Notification rate of salmonellosis, Australia, 2006, by age group and sex

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The 10 most frequently isolated serovars and phage types of Salmonella, which accounted for 39% of all isolates, are shown in Table 8. Nationally, S.Typhimurium 135 (including 135a), Saintpaul and Typhimurium 170/108 were the 3 most frequently isolated serovars/phage types.

In 2006, OzFoodNet reported 41 outbreaks of foodborne salmonellosis. S. Typhimurium species were responsible for 25 of the 41 (61%) Salmonella outbreaks. Eggs and foods made with eggs were implicated in 16 outbreaks of salmonellosis.⁴

Table 8. Top 10 isolates of Salmonella, Australia, 2006

Salmonella type (sero/phage type)	State or territory
	ACT	NSW	NT	Qld	SA	Tas.	Vic.	WA	Aust.
Salmonella Typhimurium 135*	11	195	20	169	79	39	143	53	709
Salmonella Saintpaul	14	100	31	264	13	6	74	57	559
Salmonella Typhimurium 170/108	11	212	0	54	58	14	99	5	453
Salmonella Typhimurium 9	7	76	1	62	58	14	109	11	338
Salmonella Virchow 8	2	27	13	207	0	1	9	4	263
Salmonella Birkenhead	1	101	0	150	0	0	4	0	256
Salmonella Typhimurium 44	6	41	1	29	16	3	109	6	211
Salmonella Infantis	2	59	15	17	36	1	25	10	165
Salmonella Chester	0	28	17	64	6	1	13	25	154
Salmonella Muenchen	0	27	16	67	6	0	6	31	153
Total	54	866	114	1,083	272	79	591	202	3,261

* Includes Salmonella Typhimurium 135a.

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Shigellosis

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

In 2006 there were 543 cases of shigellosis reported to NNDSS, a decrease of 26% on the 729 cases reported in 2005. The 2006 notification rate was 2.6 cases per 100,000 population. The Northern Territory had the highest notification rate (61 cases per 100,000 population).

Children under the age of 5 years represented 25% of shigellosis notifications (136 cases, 10.7 per 100,000 population, Figure 22). The male to female rate ratio was 0.9:1.

Figure 22. Notification rate of shigellosis, Australia, 2006, by age group and sex

The highest burden of shigellosis continues to be in Indigenous populations. In 2006, of the notifications of shigellosis where indigenous status of cases was complete (71% of all cases) 38% were identified as Indigenous. In the Northern Territory (where in 97% of notifications the indigenous status of cases was complete), 91% of shigellosis cases were Indigenous and in South Australia (97% complete), 46% were Indigenous.

Shigella flexneri and Shigella sonnei infections accounted for 58.2% and 34.8% of shigellosis, respectively in 2006 (Table 9). Ninety-three per cent of Shigella flexneri infections were further typed, of which (104, 35%) were type 4a and 55 (18%) were type 2A. Eighty-three per cent (158) of Shigella sonnei infections were further typed, of which 50% were type A.

Top of pageTable 9. Shigella infections, Australia, 2006, by serogroups and state or territory

Organism	State or territory									Per cent
	ACT	NSW	NT	Qld	SA	Tas.	Vic.	WA	Aust.
S. boydii	0	3	0	2	0	0	2	0	7	1.3
S. dysenteriae	0	1	0	2	0	0	1	2	6	1.1
S. flexneri	0	35	109	23	25	2	26	96	316	58.2
S. sonnei	0	34	13	59	11	1	46	25	189	34.8
Sub total	0	73	122	86	36	3	75	123	518	95.4
Unknown	2	2	3	11	1	0	1	5	25	4.6
Total	2	75	125	97	37	3	76	128	543	100.0

Person to person transmission and acquisition of infection overseas are the major modes of Shigella infections. OzFoodNet did not identify any Shigella outbreaks associated with food in 2006.⁴

Shiga 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 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 STEC/VTEC is isolated in the context of haemolytic uraemic syndrome (HUS), it should be notified as STEC/VTEC and HUS.

There were 70 cases of STEC/VTEC notified to NNDSS in 2006 a reduction of 19% on the 86 cases reported in 2005.

As in previous years, South Australia routinely tested bloody stools by polymerase chain reaction (PCR) for genes coding for Shiga toxin. Consequently, 36 of the 70 cases (51%) were notified in South Australia, which also had the highest notification rate (2.3 cases per 100,000 population). There were no cases reported from the Australian Capital Territory or Tasmania.

Cases occurred in all age groups, with 11 (15%) cases in children aged less than 5 years. There were more cases reported among men (male to female ratio 1.4:1).

Typing information was available on only 18 cases. These included 7 cases of 0157, 4 of 011 and 3 of026.

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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 2006, 13 cases of HUS were reported to NNDSS (a 35% decrease on the 20 cases reported in 2005). Cases were reported mainly from New South Wales (11 cases) with single cases reported from South Australia and Victoria.

Of the 13 cases of HUS notified in 2006, 6 were males and 7 females. The median age for both sexes was 5 years with an age range of 1 to 60 years. STEC was isolated in 3 cases of HUS and the serotype of 1 (an 055) was identified. In New South Wales, all cases of HUS were interviewed but no common risk factors or links between cases were identified.⁴

Typhoid

There were 78 cases of typhoid reported in 2006, an increase of 50% on the 52 notifications in 2005. Nationally, the male to female ratio was 1.05:1, with the highest number of notifications in the 20–29 years age range (Figure 23).

Figure 23. Number of notifications of typhoid, Australia, 2006, by age group and sex

OzFoodNet reported 74 cases of typhoid in 2006. Sixty-eight cases (93%) reported overseas travel; one-third of these travelled in India.⁴

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