This article {extract} was published in Communicable Diseases Intelligence Vol 34 No 3 September 2010 and may be downloaded as a full version PDF from the Table of contents page.
Results, continued
Gastrointestinal diseases
In 2008, 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 (STEC) infections and typhoid.
Overall notifications of gastrointestinal diseases in 2008 decreased 10% from 30,325 in 2007 to 27,308 in 2008. However, notifications of hepatitis E, HUS, shigellosis and typhoid were notably increased compared with the 5-year mean (exceeded the mean by more than 2 standard deviations).
OzFoodNet, Australia's enhanced foodborne disease surveillance network, monitors the incidence of diseases caused by pathogens commonly transmitted by food using population-based passive and enhanced surveillance for notifiable gastrointestinal diseases and for outbreaks of gastroenteritis and enteric disease. In 2008, OzFoodNet aggregated and analysed data from the NNDSS supplemented by enhanced surveillance data from OzFoodNet sites on the following 9 diseases or conditions, a proportion of which may be transmitted by food: non-typhoidal salmonellosis; campylobacteriosis infections (except in New South Wales); listeriosis; shigellosis; typhoid; STEC infections; botulism; HUS; and hepatitis A. The data and results from these analyses are summarised in the following sections but are reported in more detail elsewhere. 18
Botulism
Foodborne botulism arises from the consumption of a food that is contaminated with pre-formed Clostridium botulinum toxin.
No cases of botulism were reported to NNDSS in 2008, compared with 1 case in 2007.
Campylobacteriosis
Campylobacteriosis is notifiable in all Australian jurisdictions, except New South Wales.
In 2008, there were 15,535 notifications of campylobacteriosis, a 9% decrease compared with the 16,996 notifications reported in 2007. The national rate of campylobacteriosis notifications in 2008 was 107.5 per 100,000 population. The lowest and highest rates of Campylobacter notification were in Western Australia (84.2 per 100,000 population) and in South Australia (124.2 per 100,000 population) respectively. The highest age specific notification rates of Campylobacter were amongst males and females aged 0–4 years. Amongst children aged under 5 years, the highest notification rate was in boys aged 1 year (336.9 per 100,000 population) (Figure 14).
Figure 14: Notification rate for campylobacteriosis, Australia, 2008, by age group and sex, and inset: age and sex in children aged under 5 years
Cryptosporidiosis
In 2008, 2,005 notifications of cryptosporidiosis were reported to the NNDSS, with a national notification rate of 9.4 per 100,000 population, a 29% decrease over the number of notifications reported in 2007.
The highest notification rates of cryptosporidiosis were reported in the Northern Territory (46.4 per 100,000 population) and Queensland (16.2 per 100,000 population).
Fifty-three per cent of all cryptosporidiosis notifications in 2008 were in children aged under 10 years, the majority of which were male (54%) (Figure 15). Overall, the number of cryptosporidiosis notifications were similar between males (49%) and females (51%), however, the number of notifications was higher among females (54%) (Figure 15), while in the 20–39 year age range (62%) than in males of the same age.
Figure 15: Notification rate for cryptosporidiosis, Australia, 2008, by age group and sex, and inset: age and sex in children aged under 5 years
Haemolytic uraemic syndrome
During 2008, there were 31 cases of HUS notified to NNDSS, with a rate of 0.1 per 100,000 population, which is the same as the mean annual notification rate between 2003 and 2007. Over half of these notifications were reported from New South Wales (17 notifications). The median age of notifications was 14 years, with a range of 0–83 years. Similar to previous years, the highest notification rate was in children aged 0–4 years, with 11 of the 31 notifications in this age group (0.8 notifications per 100,000 population). 18
Cases of HUS may be due to causes other than Shiga toxin-producing E. coli, including other non-foodborne pathogens and genetic predisposition. In 2008, an antecedent STEC infection was reported for 52% (16/31) of notifications. In 2008, 1 case of HUS was known to be due to a non-bacterial cause, 2 cases resulted from Streptococcus pneumoniae infection, and in the remaining 11 cases no aetiology was reported.
Hepatitis A
Notifications of hepatitis A declined in 2008, with 276 notifications compared with a mean of 306 per year between 2003 and 2007 (Table 11 and Figure 16).
Table 11: Notifications of hepatitis A, Australia, 2008, by state or territory
State or territory |
Number of cases | Number acquired overseas | Per cent acquired overseas |
|---|---|---|---|
| ACT | 5 |
3 |
60 |
| NSW | 69 |
53 |
77 |
| NT | 3 |
2 |
67 |
| Qld | 71 |
30 |
42 |
| SA | 20 |
13 |
65 |
| Tas | 1 |
0 |
0 |
| Vic | 85 |
46 |
54 |
| WA | 22 |
7 |
32 |
| Total | 276 |
154 |
56 |
In 2008, the median age of notifications was 24 years (range 1–97 years) of which 57% (158/276) of notifications were male.
Overseas travel was the most frequently reported risk factor for infection with hepatitis A in 2008, with 56% (154/276) of notifications reporting overseas travel (Table 11). The most commonly reported overseas travel destinations were India (29), Indonesia (11) and Pakistan (8).
Indigenous status was known for 89% of notifications in 2008. The proportion of cases of hepatitis A amongst Indigenous persons declined from a mean of 14% (167/1,193) of notifications for the years 2003–2006 to 1.2% (3/245) of notifications in 2008 (Table 12). This marked decrease in the number and proportion of cases that were Indigenous is likely to be due in part to targeted vaccination programs for Indigenous children commencing in Queensland in 1999, and the provision of free hepatitis A vaccine for all Indigenous children in South Australia, Western Australia and the Northern Territory from 2006 (Figure 16).19
Table 12: Hepatitis A notifications, Australia, 2003 to 2008, by indigenous status
Year |
Indigenous | Non-Indigenous | Unknown | |||
|---|---|---|---|---|---|---|
| n | % | n | % | n | % | |
| 2003 | 53 |
12 |
325 |
76 |
53 |
12 |
| 2004 | 37 |
12 |
251 |
79 |
31 |
10 |
| 2005 | 48 |
15 |
232 |
71 |
46 |
14 |
| 2006 | 28 |
10 |
218 |
78 |
35 |
12 |
| 2007 | 0 |
0 |
146 |
88 |
19 |
12 |
| 2008 | 3 |
1 |
243 |
88 |
30 |
11 |
Figure 16: Trends in notifications of hepatitis A, Australia, 1991 to 2008, by month of diagnosis
Hepatitis E
In 2008, there were 44 notifications of hepatitis E, compared with 18 notifications in 2007 and a mean of 22 cases per year between 2003 and 2007. Fourteen cases were reported from both New South Wales and Victoria, 7 cases from Queensland, 6 cases from Western Australia and three from the Northern Territory.
In 2008, 68% (30/44) of cases were known to have been acquired overseas. The median age of cases was 28 years (range 12–78 years), possibly reflecting higher rates of overseas travel in younger adults.
Listeriosis
In 2008, 68 cases of Listeria monocytogenes infection were reported to the NNDSS, a crude notification rate of 0.3 per 100,000 population including 12 deaths. The 2008 notification rate was consistent with the 5-year historical mean annual notification rate (0.3 per 100,000 population). Similar to previous years, 22% of cases (15/68) were pregnancy-associated infections, occurring in pregnant women or newborn babies. In 2008, 47% (25/53) of the non-pregnancy related cases were female. Forty-nine per cent (33/68) of notifications were in people aged 60 years or more. The highest age specific notification rate was in people aged 85 years or more (1.9 per 100,000 population, 7 cases). Seven per cent (1/15) of pregnancy related cases and 21% (11/53) of non-pregnancy associated cases in 2008 were fatal.18
Salmonellosis (non-typhoidal)
In 2008, there were 8,310 cases of Salmonella infection corresponding to a notification rate of 38.8 per 100,000 population and similar to the 5-year mean of 8,210 cases per year. Notification rates amongst jurisdictions ranged from 31.1 per 100,000 population in Victoria to 226.1 per 100,000 population in the Northern Territory. Approximately half (49%) of Salmonella notifications were in males. The highest age specific rate of Salmonella infection was 169.3 per 100,000 population in children aged from 0–4 years, with the highest rates in those aged 2 years or over (Figure 17).
Figure 17: Notification rate for Salmonella infection, Australia, 2008, by age and sex
In 2008, the most commonly notified Salmonella serotype was S. Typhimurium, which was responsible for approximately 42% of all notified infections. S. Typhimurium phage types 135, 44, 170/108 and 9 were commonly reported, representing four of the top 5 Salmonella infections nationally.18
In 2008, OzFoodNet reported 35 outbreaks of foodborne salmonellosis affecting 486 people. Individual notifications of salmonellosis are very rarely attributed to a food vehicle.
Shigellosis
In 2008, there were 828 cases of shigellosis reported to the NNDSS compared with 602 in 2007. The 2008 notification rate was 3.9 per 100,000 population, which was higher than the mean annual notification rate of 2.8 notifications per 100,000 between 2003 and 2007. As in previous years, the highest notification rate was in the Northern Territory, with 79.6 per 100,000 population compared with an average rate of 71.9 per 100,000 population per year between the years 2003 and 2007.18
The highest age specific notification rates were amongst males and females aged 0–4 years, with age specific rates of 12.5 and 13.9 notifications per 100,000 population, respectively (Figure 18). Overall in 2008, 50% of all shigellosis notifications were male.
Figure 18: Notification rate for shigellosis, Australia, 2008, by age and sex
Notification rates were higher amongst men aged between 30 and 44 years than in females of the same age, which may in part be explained by the outbreak of shigellosis amongst men who reported sex with other men as a risk factor in 2008.18
Rates of shigellosis in Australia are higher amongst Indigenous people than in non-Indigenous people. In 2008, there were 318 notifications of shigellosis amongst Indigenous people (38% of notifications), with an age standardised rate of 58.9 per 100,000 population. Indigenous status information in 2008 was 81% complete. Shigellosis is one of the 18 priority diseases for which the NSC has agreed to improve Indigenous status reporting.
The most common biotypes of shigellosis in 2008 were Shigella sonnei biotype a (28%) and Shigella sonnei biotype g (22%). These 2 biotypes were also the most common in 2007, but different to 2006 when the most common biotype was Shigella flexneri 4a mannitol negative.18
Shiga toxin-producing Escherichia coli
In 2008, there were 106 cases of STEC, corresponding to a rate of 0.5 notifications per 100,000 population. This was similar to the mean annual notification rate of 0.4 notifications per 100,00 population between 2003 and 2007.18
In 2008, 51.9% of cases were female and the median age of cases was 24 years (range 0–89 years). The highest age specific notification rate for STEC was amongst people over the age of 85 years. Other peaks were observed in the 0–4 and 10–14 year age groups (Figure 19).
Figure 19: Notifications of Shiga toxin-producing Escherichia coli, Australia, 2008, by age group
South Australia reported 36% (39/106) of all STEC notifications, followed by Queensland (35%, 37/106), New South Wales (18%, 19/106) and Victoria (10%, 11/106). There were no cases notified in the Australian Capital Territory, the Northern Territory, Tasmania or Western Australia in 2008.
Rates of STEC infection are strongly influenced by jurisdictional practices regarding the screening of stool specimens.20 In particular, South Australia routinely tests all bloody stools by polymerase chain reaction (PCR) for gene coding for Shiga toxins and other virulence factors, contributing to the higher rates of detection of infection for this State. Queensland conducts routine culture on bloody stools. If there is no growth in culture, PCR is not performed, instead, enzyme-linked immunosorbent assay for Shiga toxin is conducted on the specimen. In New South Wales, some routine screening for STEC genes in stools containing microscopic blood is conducted in the Hunter–New England region, but not elsewhere. In Western Australia, 2 pathology laboratories routinely screen bloody stools with either sorbitol Maconkey agar culture or tissue culture. Other jurisdictions do not routinely screen for STEC.
Typhoid
There were 105 cases of Salmonella Typhi infection (typhoid) notified during 2008. This equated to a notification rate of 0.5 per 100,000 population, slightly higher than the annual rate of 0.3 per 100,000 between 2003 and 2007. Cases were reported from all Australian states and territories except for the Australian Capital Territory and Tasmania.
Overseas travel was the primary risk factor for typhoid in Australia in 2008 with 92% (97/105) of notifications known to have been acquired overseas. India was the most frequently reported country for overseas acquired cases, with 49% (48/97) of notifications, followed by Bangladesh, Indonesia, and Pakistan, each of which were reported as a travel destination for 9% (9/97) of overseas-acquired notifications. The highest typhoid notification rates were in the 20–24 year age group (1.4 per 100,000 population) and the 25–29 year age group (1.1 per 100,000 population) (Figure 20), reflecting higher rates of overseas travel in these age groups.
Figure 20: Notifications of typhoid, Australia, 2008, by age group
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Communicable Diseases Surveillance
This issue - Vol 34 No 3, September 2010
NNDSS Annual report 2008
Communicable Diseases Intelligence