Megge Miller, Paul Roche, Keflemariam Yohannes, Jenean Spencer, Mark Bartlett, Julia Brotherton, Jenny Hutchinson, Martyn Kirk, Ann McDonald, Claire Vadjic

Results - Gastrointestinal diseases

Gastrointestinal diseases that were notified to NNDSS in 2003 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 decreased by 9 per cent, from 26,953 in 2002 to 24,655 in 2003 (Table 4). Compared with 2002, there was a decrease in the number of notifications of cryptosporidiosis (63%), hepatitis E (47%), salmonellosis (11%), shigellosis (12%), SLTEC/VTEC (8%) and typhoid (27%) in 2003. On the other hand, there were increases in the notifications of campylobacteriosis (4%), HUS (15%), hepatitis A (9%) and listeriosis (13%).

In this section reference will be made to the OzFoodNet 2003 annual report of foodborne diseases in Australia.³ This report was used as a resource for additional information on foodborne gastrointestinal disease outbreaks in Australia in 2003.

Botulism

One case of infant botulism in a female, less than 12 months old was reported to NNDSS in 2003. While no classic foodborne botulism has been reported in Australia since the commencement of notifications in 1992, there have been five cases of infant botulism reported between 1998 and 2003.

Campylobacteriosis

There were 15,372 notifications of campylobacteriosis in Australia in 2003. Campylobacteriosis is notifiable in all jurisdictions, except New South Wales. The national rate of notifications in 2003 was 116.5 cases per 100,000 population; a marginal increase compared with the rate reported in 2002 (112 cases per 100,000 population). South Australia continues to have the highest notification rate (173 cases per 100,000 population) for the second consecutive year (Table 3).

Monthly notifications of campylobacteriosis in 2003 were consistent with previous years (1998 to 2002), with the number of notifications peaking in the third quarter of the year (Figure 15). In 2003 four campylobacter related outbreaks were identified, two of which were associated with the consumption of un-pasteurised milk and close contact with animals. 3

Figure 15. Trends in notifications of campylobacteriosis, Australia, 1999 to 2003, by month of onset

The highest notification rate of campylobacteriosis was among children aged 0–4 years (Figure 16). In this age group notification rates were higher in males (263 cases per 100,000 population) than in females (202 cases per 100,000 population). The overall female to male ratio, as in previous years, was 1.2:1.

Figure 16. Notification rates of campylobacteriosis, Australia, 2003, by age group and sex

Cryptosporidiosis

In 2003, 1,219 cases of cryptosporidiosis were reported to NNDSS, a notification rate of six cases per 100,000 population and fall of 63 per cent on the 3,268 cases reported in 2002.

All states and territories reported decreases in cryptosporidiosis notifications. The Northern Territory and Western Australia had a notification rate above the national average at 47 and 22 cases per 100,000 population, respectively.

Children under the age of four continue to have the highest notification rate of cryptosporidiosis (49 cases per 100,000 population, (Figure 17). However, compared to 2002, the notification rate in this age group has dropped from 129 cases per 100,000 population.

Figure 17. Notification rates of cryptosporidiosis, Australia, 2003, by age group and sex

Hepatitis A

There were 418 cases of hepatitis A reported to NNDSS in 2003, a notification rate of two cases per 100,000 population. The notification rate of hepatitis A has been steadily decreasing for the last decade, but remained stable compared to 2002 (Figure 18).

Figure 18. Trends in notifications of hepatitis A, Australia, 1991 to 2003, by month of notification

Compared to 2002, hepatitis A notification rates decreased in all jurisdictions except in Tasmania, Victoria and Western Australia. The largest increase was recorded in Western Australia (1.6 to 4.4 cases per 100,000 population in 2002 and 2003, respectively). The Northern Territory continues to have the highest notification rate (20.2 cases per 100,000 population).

Males had a higher notification rate of hepatitis A (2.5 cases per 100,000 population) than females (1.7 cases per 100,000 population). The highest age specific rate of hepatitis A notifications among males was in the 0–4 year age group (3.9 cases per 100,000 population) and among females in the 15–19 year age group (2.8 cases per 100,000 population) (Figure 19).

Figure 19. Notification rates of hepatitis A, Australia, 2003, by age group and sex

Hepatitis A is commonly spread from person to person or from contaminated food or water. Among 101 cases of hepatitis A infection in 2003 (24% of all notifications) three frequently reported risk factors for hepatitis A infection were, overseas travel (51%), household or close contact with confirmed cases (23%) and childcare attendees, staff and their contacts (20%, Table 6).

Top of page

Table 6. Risk exposures associated with hepatitis A virus infection, Australia, 2003, by state or territory*

	State or territory
	ACT	NT	Qld	SA	Tas	Vic
Total	5	40	48	13	14	89
Injecting drug use	–	0	0	1	0	0
– User	–	–	0	–	–	–
– Contact with	–	–	9	–	–	–
Household /close contact of case	–	4	9	–	0	10
Overseas travel	3	9	13	1	2	23
Childcare	–	3	9	–	0	8
– Attendee	–	–	3	–	–	–
– Staff	–	–	1	–	–	–
– Household contact	–	–	5	–	–	–
Homosexual contact	–	0	1	–	0	0
Sex worker	–	0	–	–	0	0
Interstate travel	–	–	–	–	–	2
Occupational exposure	–	–	–	–	–	1
Outbreak (source unknown)	–	–	–	–	–	4
Unknown	2	24	26	12	3	42

* New South Wales and Western Australia did not report risk exposures associated with hepatitis A. The number of cases notified were 124 in New South Wales and 85 in Western Australia. Exposures are not mutually exclusive hence more than one exposure per person is possible.

– Risk factor not sought.

Hepatitis E

There were 10 cases of hepatitis E reported to NNDSS in 2003. Six cases were reported in New South Wales and two cases each in the Australian Capital Territory and Victoria. There were four males and six females, all aged between 15 and 60 years. Data on travel history were available for three cases and showed that all had travelled overseas.

Listeriosis

In 2003, 69 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 2003, 75 per cent of listeriosis cases were aged over 60 years, with the highest notification rate in the 80–84 year age group in males and the 75–79 age group in females (Figure 20).

Figure 20. Notification rates of listeriosis, Australia, 2003, by age group and sex

In 2003, 12 per cent (8/69) of listeriosis cases were of materno-foetal origin and one death in a neonate was reported. OzFoodNet reported that in 2003, there were 16 deaths in non-pregnancy related listeriosis cases. No common-source outbreaks of listeriosis were investigated during 2003.³

Salmonellosis (non-typhoidal)

A total of 7,011 salmonellosis cases were reported to NNDSS in 2003, a rate of 35.3 cases per 100,000 population and a 12 per cent decrease from the rate reported in 2002 (40 cases per 100,000 population). During the five year period 1998 to 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 notification rates of salmonellosis were reported in the northern part of the country (Map 2), with outside Darwin having the highest notification, the Kimberly Statistical Division of Western Australia having the highest notification rate at 230 cases per 100,000 population.

Map 2. Notification rates of salmonellosis, Australia, 2003, by Statistical Division of residence

As in previous years, reports of salmonellosis peaked during summer (January to March). Thirty-nine per cent of salmonellosis cases in 2003 had dates of onset during this period (Figure 21).

Figure 21. Trends in notifications of salmonellosis, Australia, 1999 to 2003, by month of onset

Similar to previous years, the highest rate was in children aged between 0–4 years: 32 per cent of salmonellosis notifications were in this age group (Figure 22). However, in 2003, the notification rate in children aged 0–4 years, dropped 14 per cent from 211 cases per 100,000 population in 2002 to 182 cases per 100,000 population in 2003.

Top of page

Figure 22. Notification rates of salmonellosis, Australia, 2003, by age group and sex

The National Enteric Pathogens Surveillance Scheme reported serovars for 6,808 isolates,⁴ representing 97 per cent of notified cases of salmonellosis (n=7,011) in 2003. The 10 most frequently isolated serovars and phage types of Salmonella, which accounted for 44 per cent of all isolates, are shown in Table 7. Nationally, as in the previous year, the three most commonly reported Salmonella serovar or phage types were Salmonella Typhimurium 135, Salmonella Typhimurium 170 and Salmonella Typhimurium 9. Three Salmonella types: S. Infantis, Salmonella Typhimurium 197 and Salmonella Typhimurium 290 were not among the top 10 serovars reported in 2002. These have replaced S. Hvittingfoss, S. Muenchen, and S.Typhimurium 126 from top 10 serovars reported in 2002.

The distribution of Salmonella serovars varied across jurisdictions. The most commonly reported serovars in Queensland, Tasmania, and the Northern Territory were S. Virchow (8% of salmonellosis notifications), S. Mississippi (49% of salmonellosis notifications) and S. Ball (13% of salmonellosis notifications), respectively. Salmonella Typhimurium was the most commonly reported serovar in the rest of the jurisdictions. Salmonella Typhimurium 135 accounted for 33 per cent of cases in the Australian Capital Territory, 18 per cent in Victoria, and 12 per cent in Western Australia. In New South Wales the most commonly notified phage type was Salmonella Typhimurium 170 (12% of salmonellosis notifications) and in South Australia the most common notified phage type was Salmonella Typhimurium 9.

Table 7. Top ten isolates of Salmonella, Australia, 2003

Organism	Number of human isolates, by state or territory
	ACT	NSW	NT	Qld	SA	Tas	Vic	WA	Aust	Total %
S. Typhimurium 135	27	174	16	155	17	6	229	70	694	10
S. Typhimurium 170	4	232	0	66	1	5	129	4	441	7
S. Typhimurium 9	4	139	6	45	29	7	168	20	418	6
S. Saintpaul	2	41	26	163	13	5	18	30	298	4
S. Chester	1	43	17	94	23	0	7	34	219	3
S. Virchow 8	0	32	3	166	0	1	5	1	208	3
S. Infantis	3	95	5	16	18	3	50	11	201	3
S. Birkenhead	0	68	0	103	0	0	1	3	175	3
S. Typhimurium 197	0	63	0	86	1	0	17	3	170	3
S. Typhimurium 290	6	33	0	9	2	5	85	6	146	2
Other	35	927	274	1,205	327	110	551	409	3,838	56
Total	82	1,847	347	2,108	431	142	1,260	591	6,808

Source: National Enteric Pathogens Surveillance Scheme.

Outbreaks and clusters of salmonellosis

In 2003, OzFoodNet investigated 99 foodborne disease outbreaks of which 25 were attributable to S. Typhimurium infection. These outbreaks affected 672 persons with 78 hospitalisations and five deaths. Of the five significant foodborne outbreaks (affecting 50 or more persons each) in 2003, three were due to Salmonella Typhimurium. Of these, one occurred in a restaurant and was associated with dishes containing eggs, another was associated with the consumption of Vietnamese rolls from a bakery and the third was associated with pigeon meat. There were several others due to other serotypes of Salmonella.³

Shigellosis

In 2003, 440 cases of shigellosis were reported to NNDSS, a notification rate of 2.2 cases per 100,000 population and a marginal decrease from the 2.5 cases per 100,000 population reported in 2002 (Table 4). The Northern Territory continues to have the highest notification rate at 66 cases per 100,000 population, which represents an increase of 27 per cent in notification rates compared to 2002. However, nationally, notifications of the disease continue to decline (Figure 23).

Figure 23. Trends in notifications of shigellosis, Australia, 1991 to 2003, by month of onset

Children under the age of four continue to represent 33 per cent of shigellosis notifications. In 2003, this age group had the highest notification rate at 11 cases per 100,000 population (Figure 24), but compared to 2002 rates (14.1 cases per 100,000 population) notification rates in this age group have decreased by 17 per cent.

Indigenous people carry the highest burden of shigellosis. In 2003, of the total national notifications of shigellosis, 67 per cent of cases with known Indigenous status (indigenous status was unknown in 33% of cases) were identified as Indigenous. In the Northern Territory (where in 98% of notifications the Indigenous status is known), 81 per cent of shigellosis cases notified were Indigenous.

Top of page

Figure 24. Notification rates of shigellosis, Australia, 2003, by age group and sex

Shiga-like toxin producing/verotoxigenic Escherichia coli (SLTEC/VTEC)

There were 49 cases of SLTEC/VTEC reported to NNDSS in 2003. With a notification rate of 0.2 cases per 100,000 population, the rate of SLTEC/VTEC notifications remained stable relative to the previous year. Seventy-six per cent of cases were notified in South Australia (2.4 cases per 100,000 population), where bloody stools are routinely tested by polymerase chain reaction for genes coding for shiga toxin. No cases were notified from the Australian Capital Territory, New South Wales, the Northern Territory or Tasmania. OzFoodNet reported that among typed E. coli, 25 per cent were subtype O157 and 15 per cent were subtype O111.³

Haemolytic uraemic syndrome

In 2003, 15 cases of HUS were reported to NNDSS, a rate of 0.1 case per 100,000 population, comparable to the 13 cases reported in 2002. No HUS cases were notified in the Australian Capital Territory or Tasmania. Among the 15 cases of HUS notified in 2003, five were males. The median age among males was 9 years (range 0–80 years) and among females the median age was 7 years (range 1–51 years). OzFoodNet reported that STEC was isolated in three cases of HUS of which one was E. coli O157.³

Typhoid

The notification rate of typhoid has been relatively stable for the last five years. In 2003, there were 51 notifications of typhoid, a rate of 0.3 cases per 100,000 population. In 2002, 70 cases were notified. The male to female ratio was 1:1, with the highest notification rates in males aged 20–24 years and 85+ years (1.0 cases per 100,000 population) and in females aged 0–4 years (0.8 cases per 100,000 population) (Figure 25). The National Enteric Pathogen Surveillance Scheme identified 49 Salmonella Typhi isolates, 46 of which were from Australian residents and three cases from overseas visitors, including students. Of the 46 Australian residents, 29 had travelled to South and South East Asia and the Middle East, but 17 had no travel history recorded.⁴

Figure 25. Notification rates of typhoid, Australia, 2003, by age group and sex

 

This article {extract} was published in Communicable Diseases Intelligence Vol 29 No 1 March 2005 and may be downloaded as a full version PDF from the Table of contents page.