Results - continued

Bloodborne viruses

In 2012, the bloodborne viruses reported to the NNDSS were hepatitis B, C, and D. Both hepatitis B and C cases were notified to the NNDSS as either ‘newly acquired’, where evidence was available that the infection was acquired in the 24 months prior to diagnosis; or ‘greater than 2 years or unspecified’ period of infection. These categories were reported from all states and territories except Queensland where all cases of hepatitis C, including newly acquired, were reported as being ‘greater than 2 years or unspecified’. The determination of a case as ‘newly acquired’ is heavily reliant on public health follow-up, with the method and intensity of follow-up varying by jurisdiction and over time.

In interpreting these data it is important to note that changes in the number of notified cases over time may not solely reflect changes in disease prevalence or incidence. National testing policies developed by the Australian Society for HIV Medicine^17,18 and screening programs, including the preferential testing of high risk populations such as prisoners, injecting drug users and persons from countries with a high prevalence of hepatitis B or C, may contribute to these changes.

Information on exposure factors relating to the most likely source(s) of or risk factors for infection for hepatitis B and C was reported in a subset of diagnoses of newly acquired infections. The collection of enhanced data is also dependent on the level of public health follow-up, which is variable by jurisdiction and over time.

Notifications of HIV and AIDS were reported directly to The Kirby Institute, which maintains the National HIV Registry. Information on national HIV and AIDS surveillance can be obtained from The Kirby Institute web site (http://www.kirby.unsw.edu.au/).

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Hepatitis B

Hepatitis B virus causes inflammation in the liver.¹⁹ Notifications of acute hepatitis B are classified as ‘newly acquired’ and chronic infections as ‘unspecified’.

Epidemiological situation in 2012

In 2012, there were 6,702 notified cases of hepatitis B (both newly acquired and unspecified), equating to a rate of 29.5 cases per 100,000 (Figure 3). The Northern Territory reported the highest hepatitis B rate in 2012 (87.2 per 100,000), followed by Victoria (33.9 per 100,000), Western Australia (33.8 per 100,000) and New South Wales (31.9 per 100,000) (Table 1).

Between 2002 and 2012, unspecified hepatitis B rates decreased by 13.3% from 33.0 to 28.7 per 100,000, while newly acquired hepatitis B rates decreased from 2.0 to 0.8 per 100,000 (Figure 3). The continued decline in hepatitis B notifications may be attributed to the hepatitis B vaccination program, which was introduced nationally for infants in 2000, and the adolescent hepatitis B vaccination program, which was introduced in 1997.²⁰ In 2012, approximately 94% of children 12–24 months of age were assessed as being fully immunised against hepatitis B.²¹

Figure 3: Notification rate for newly acquired hepatitis B* and unspecified hepatitis B,^† Australia, 2002 to 2012, by year

* Data for newly acquired hepatitis B for the Northern Territory (2002–2004) includes some unspecified hepatitis B cases

† Data for unspecified hepatitis B for all states and territories, excluding the Northern Territory between 2002 and 2004

Text version of Figure 3 (TXT 1 KB)

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Newly acquired hepatitis B

Epidemiological situation in 2012

In 2012, 193 newly acquired hepatitis B notifications (0.8 per 100,000) were reported to the NNDSS, a 1.0% decrease compared with the 195 cases (0.9 per 100,00) reported in 2011 and a continuation of the downward trend in notification rates (Figure 3).

Geographical distribution

The highest rates were reported from the Northern Territory (2.1 per 100,000) and Tasmania (2.0 per 100,000) (Table 5).

Age and sex distribution

Overall, notification rates were higher among males than females, with a male to female ratio of 2.6:1. In 2012, the highest rate of newly acquired hepatitis B infection was observed among males aged 40–44 and 25–29 years (3.4 and 2.6 per 100,000 respectively) (Figure 4).

Figure 4: Notification rate of newly acquired hepatitis B, Australia, 2012, by age group and sex

* Excludes notifications for whom age and/ or sex were not reported.

Text version of Figure 4 (TXT 1 KB)

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Between 2002 and 2012, most age group specific notification rates were trending downwards. The most marked decreases occurring among those aged 15–19 years and 20–29 years. During this period, notification rates among the 15–19 years age group declined by 86% from 2.9 to 0.4 per 100,000 and notification rates among the 20–29 years age group declined by 74% from 5.4 to 1.4 per 100,000 (Figure 5). These declines are likely to be attributable in part to the adolescent hepatitis B vaccination program. The notification rates among people aged 40 years or over have stabilised, which may be attributable to rates of testing or immigration from countries with higher prevalence of hepatitis B.²²

Figure 5: Notification rate of newly acquired hepatitis B,* Australia, 2002 to 2012, by year and age group

* Data for newly acquired hepatitis B for the Northern Territory (2002–2004) includes some unspecified hepatitis B cases.

Text version of Figure 5 (TXT 1 KB)

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Table 11: Newly acquired hepatitis B cases,* selected jurisdictions, 2012, by sex and risk factors^†,‡

Risk factors	Number of risk factors reported			Percentage of total cases§ (n=108)
	Male	Female	Total
* Cases from New South Wales, the Australian Capital Territory, Tasmania and Victoria. † More than 1 exposure category for each case could be recorded. ‡ Analysis and categorisation of these exposures are subject to interpretation and may vary. § The denominator used to calculate the percentage is based on the total number of cases from all jurisdictions (New South Wales, the Australian Capital Territory, Tasmania and Victoria). As more than 1 exposure category for each notification could be recorded, the total percentage does not equate to 100%. || Includes both occupational and non-occupational exposures.
Injecting drug use	21	12	33	30.6
Imprisonment	3	0	3	2.8
Skin penetration procedure	6	4	10	9.3
Tattoos	3	2	5	4.6
Ear or body piercing	2	2	4	3.7
Acupuncture	1	0	1	0.9
Healthcare exposure	10	4	14	13.0
Surgical work	5	1	6	5.6
Major dental surgery	4	3	7	6.5
Blood/tissue recipient (Australia)	1	0	1	0.9
Sexual exposure	29	15	44	40.7
Hepatitis B positive partner – opposite sex	13	11	24	22.2
Hepatitis B positive partner – same sex	4	0	4	3.7
Partner with unknown hepatitis B status – opposite sex	3	0	3	2.8
Partner with unknown hepatitis B status – same sex	1	0	1	0.9
Unprotected sex – partner sex not recorded	6	3	9	8.3
Unprotected sex with a sex worker	2	0	2	1.9
Protected sex with a sex worker	0	1	1	0.9
Other	4	3	7	6.5
Needlestick or biohazardous injury||	2	0	2	1.9
Household contact	2	3	5	4.6
Cases with at least 1 exposure recorded	63	25	88	81.5
Undetermined	15	3	18	16.7
Unknown (not recorded)	2	0	2	1.9
Total exposures reported‡	90	41	131	–
Total number of cases	80	28	108	–

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Risk groups

Enhanced data on risk factors and country of birth was provided by New South Wales, Victoria, Tasmania and the Australian Capital Territory (Table 11). In 2012, 81.5% (n=88) of these cases had at least 1 risk factor recorded, with a potential source of exposure not recorded or unable to be determined for the remainder. Sexual contact was the most frequently reported potential source of infection (40.7%), followed by injecting drug use (30.6%), which remained stable from 2011 (31.0%).

Of the 93 cases for which the country of birth was reported, 62 were in Australian born persons (66.7%, n=62) and 31 cases were born overseas.

Unspecified hepatitis B

Epidemiological situation in 2012

In 2012, 6,509 cases of unspecified hepatitis B infection were notified to the NNDSS, a rate of 28.7 per 100,000, compared with 6,578 cases (29.1 per 100,000) reported in 2011.

Age and sex distribution

In 2012, the overall male rate (32.0 per 100,000) was higher than for females (24.9 per 100,000), a rate ratio of 1.28:1. Notification rates were higher among males in all age groups, except those aged 30–34 years where females (67.3 per 100,000) had slightly higher rates than males (67.1 per 100,000). For both males and females, the peak notification rate occurred among those aged 30–34 years (Figure 6).

Figure 6: Notification rate for unspecified hepatitis B,* Australia, 2002 to 2012, by age group^† and sex

* Data for unspecified hepatitis B for all states and territories, excluding the Northern Territory between 2002 and 2004.

† Excludes notifications for whom age was not reported.

Text version of Figure 6 (TXT 1 KB)

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Between 2002 and 2012, notification rates across all age groups have declined, with the biggest decrease (42%) among the 15–19 years age group; declining from a rate of 30.0 in 2002 to 17.3 per 100,000 in 2012 (Figure 7).

Figure 7: Notification rate for unspecified hepatitis B,* Australia, 2002 to 2012, by year and age group

* Excludes notifications for whom age and/ or sex were not reported.

Text version of Figure 7 (TXT 1 KB)

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Hepatitis C

Hepatitis C causes inflammation of the liver. In more than 90% of cases initial infection with hepatitis C virus is asymptomatic or mildly symptomatic. Approximately 50%–80% of cases go on to develop a chronic infection. Of those who develop a chronic infection, half will eventually develop cirrhosis or cancer of the liver.¹⁹

Hepatitis C notifications are classified as being either ‘newly acquired’ (evidence that infection was acquired within the 24 months prior to diagnosis) or ‘unspecified’ (infection acquired more than 24 months prior to diagnosis or not able to be specified). Ascertaining a person’s hepatitis C serostatus and clinical history usually requires active follow-up by public health units.

Epidemiological situation in 2012

Between 2002 and 2012, hepatitis C notifications declined by 42% from 15,126 (78 per 100,000) to 10,114 (45 per 100,000). This declining trend is reflected in both newly acquired and unspecified hepatitis C notifications (Figure 8).

Figure 8: Notification rate for newly acquired hepatitis C* and unspecified hepatitis C,^† Australia, 2002 to 2012, by year

* Data for newly acquired hepatitis C from all states and territories except Queensland 2002–2012 and the Northern Territory 2002–2004.

† Data for unspecified hepatitis C provided from Queensland (2002–2012) and the Northern Territory (2002–2004) includes both newly acquired and unspecified hepatitis C cases.

Text version of Figure 8 (TXT 1 KB)

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Newly acquired hepatitis C

Epidemiological situation in 2012

Cases of newly acquired hepatitis C were reported from all states and territories except Queensland, where all cases of hepatitis C are reported as unspecified, and the Northern Territory, where there were no notifications in 2012. Nationally, there were 466 notifications in 2012 (2.6 per 100,000) compared with 413 notifications in 2011 (2.3 per 100,000) (Figure 9). Of all hepatitis C cases in 2012, 4.6% were identified as having been newly acquired infections, a slighter higher proportion than the average of 3.5% reported since 2002 (range: 3.0%–4.0%).

Figure 9: Notification rate of newly acquired hepatitis C, Australia,* 2012, by age group and sex^†

* Data from all states and territories except Queensland.

† Excludes notifications for whom age and/or sex were not reported.

Text version of Figure 9 (TXT 1 KB)

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Geographical distribution

The highest rates of newly acquired hepatitis C infection were reported in Western Australia (5.1 per 100,000), South Australia (4.6 per 100,000) and Tasmania (4.5 per 100,000) (Table 5). The proportion of newly acquired infections compared with total hepatitis C diagnoses varied substantially among the states and territories ranging from less than 1% in the Northern Territory to 16% in South Australia. The identification and classification of newly acquired hepatitis C is reliant upon public health follow-up to identify testing and clinical histories. The method and extent of case follow-up, and the population groups targeted, vary among states and territories, with newly acquired infection more likely to be detected in population groups that are tested frequently, such as those in prison settings.

Age and sex distribution

Nationally in 2012, the notification rate of newly acquired hepatitis C in males was 3.4 per 100,000 and in females 1.8 per 100,000. The male to female ratio was 1.9:1. Notification rates in males exceeded those in females across almost age groups. The highest notification rates were among males aged 20–24 years (13.6 per 100,000) and 25–29 years (9.6 per 100,000), and females aged 25–29 years (6.3 per 100,000) and 20–24 years (5.2 per 100,000) (Figure 9).

Between 2002 and 2012, notification rates declined overall among those aged 15–19, 20–29 and 30–39 years. However rates among the 20–29 years age group have risen since 2010 (from 7.3 to 8.7 per 100,000), and rates among those aged 30–39 years have risen since 2011 (from 3.7 to 4.2 per 100,000). Notification rates among those in the under 15 years and 40 years or over age groups have remained relatively low and stable during the period 2002–2012 (Figure 10).

Figure 10: Notification rates for newly acquired hepatitis C, Australia,* 2002 to 2012, by year and age group^†

* Data from all states and territories except Queensland (2002–2012) and the Northern Territory (2002–2004).

† Excludes notifications for whom age was not reported.

Text version of Figure 10 (TXT 1 KB)

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Risk groups

Exposure histories for newly acquired hepatitis C cases reported in 2012 were analysed for all jurisdictions except Queensland (notified as unspecified hepatitis C) and Western Australia (no exposure data notified, n=125) (Table 12). In 2012, 86% of cases had at least 1 risk factor recorded, with the potential source of exposure not recorded or unable to be determined for the remainder. Approximately 98% of notifications had a history of injecting drug use, almost 65% of whom reported injecting drug use in the 24 months prior to diagnosis. Skin penetration procedures and imprisonment accounted for approximately 22% and 17% of reported exposures respectively, noting that screening rates are generally higher in the prison entry population than the general population. A screening survey of prison entrants conducted over a 2-week period found that the prevalence of hepatitis C based on hepatitis C antibody detection was 22% in 2012, a decrease from 35% in 2007.²³

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Table 12: Newly acquired hepatitis C notifications, selected jurisdictions,* 2012, by sex and risk factor^†,‡

Risk factors	Number of risk factors reported			Percentage of total cases (n=341)§
	Male	Female	Total
* Includes data from all states and territories except Queensland (not notified), Northern Territory (no cases) and Western Australia (no enhanced data on risk factors). † More than 1 exposure category for each notification could be recorded. ‡ Analysis and categorisation of these exposures are subject to interpretation and may vary. § The denominator used to calculate the percentage is based on the total number of notifications from all jurisdictions, except Queensland (notified as unspecified hepatitis C), the Northern Territory (n=0) and Western Australia (no exposure data notified, n=125). As more than 1 exposure category for each case could be recorded, the total percentage does not equate to 100%. || Healthcare worker with no recall of needlestick or biohazardous injury in the past 24 months prior to diagnosis. ¶ Includes both occupational and non-occupational exposures.
Injecting drug use	205	128	333	97.7
Imprisonment	48	11	59	17.3
Skin penetration procedure	44	32	76	22.3
Tattoos	33	13	46	13.5
Ear or body piercing	9	18	27	7.9
Acupuncture	2	1	3	0.9
Health care exposure	4	2	6	1.8
Major dental surgery	1	1	2	0.6
Surgical work	1	1	2	0.6
Blood/tissue recipient	1	0	1	0.3
Healthcare worker with no documented exposure||	1	0	1	0.3
Sexual exposure	27	22	49	14.4
Hepatitis C positive partner – opposite sex	8	16	24	7.0
HIV positive men who have sex with men	13	–	13	3.8
Hepatitis C positive partner – same sex	4	4	8	2.3
Hepatitis C positive partner – sex of partner unknown	1	1	2	0.6
Sex worker	0	1	1	0.3
Unprotected sexual contact – status and sex of partner unknown	1	0	1	0.3
Other	16	20	32	9.4
Household contact	6	12	18	5.3
Needlestick or biohazardous injury¶	6	5	7	2.1
Other – not further categorised	2	3	5	1.5
Perinatal transmission	2	0	2	0.6
Cases with at least 1 exposure recorded	189	105	294	86.2
Undetermined	6	5	11	3.2
Unknown (not recorded)	22	14	36	10.6
Total exposures reported	344	215	555	–
Total number of cases	217	124	341	–

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Unspecified hepatitis C

Epidemiological situation in 2012

In 2012, 9,648 cases of unspecified hepatitis C infections were notified to the NNDSS (45.1 per 100,000), which was similar to the 9,832 cases in 2011 (45.7 per 100,000). Notification rates have decreased annually since 2002, with an overall decline of 42% between 2002 (77.5 per 100,000) and 2012 (45.1 per 100,000) (Figure 8). Several factors may account for the decrease including changes in surveillance practices, removal of duplicate notifications and a gradual decline in the prevalent group of hepatitis C cases accumulated prior to the introduction of hepatitis C testing in the early 1990s.^24,25 The continuing decline in the notification rate may also be attributable to reductions in risk behaviours related to injecting drug use, especially among young people, and increased access to sterile injecting equipment through needle and syringe programs.²⁶

Geographical distribution

In 2012, the Northern Territory continued to have the highest notification rate (82.9 per 100,000) followed by Queensland (52.0 per 100,000) (Table 5).

Age and sex distribution

Nationally in 2012, the notification rate of unspecified hepatitis C in males was 55.1 per 100,000 and in females was 29.6 per 100,000, a male to female ratio of 1.9:1. Notification rates in males exceeded those in females across almost all age groups. The highest notification rates were among males aged 30–34 years (112.5 per 100,000), 35–39 years (108.8 per 100,000) and 40–44 years (102.5 per 100,000). The highest notification rates among females were in those aged 30–34 years (64.2 per 100,000), 35–39 years (54.5 per 100,000) and 25–29 years (52.3 per 100,000) (Figure 11).

Figure 11: Notification rate for unspecified hepatitis C,*^,† Australia, 2012, by age group and sex

* Data provided from Queensland includes both newly acquired and unspecified hepatitis C cases.

† Excludes notifications for whom age and/or sex were not reported.

Text version of Figure 11 (TXT 1 KB)

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Between 2002 and 2012, the notifications rates of unspecified hepatitis C declined overall across all age groups (Figure 12). The largest decreases occurred in those aged 20–29 years (from 153.2 to 60.9 per 100,000), 30–39 years (155.8 to 85.5 per 100,000) and 15–19 years (51.3 to 14.9 per 100,000). Notification rates in the 0–4, 5–14 and the 40 years or over age groups remained relatively stable over this time.

Figure 12: Notification rate for unspecified hepatitis C,*^† Australia, 2002 to 2012, by year and age group

* Data provided from Queensland (2002–2012) and the Northern Territory (2002–2004) includes both newly acquired and unspecified hepatitis C cases.

† Excludes notifications for whom age was not reported.

Text version of Figure 12 (TXT 1 KB)

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Hepatitis D

Hepatitis D is a defective single-stranded RNA virus that replicates in the presence of the hepatitis B virus. Hepatitis D infection can occur as either an acute co-infection with hepatitis B or as a super-infection with chronic hepatitis B infection. The modes of hepatitis D transmission are similar to those for hepatitis B: exposure to infected blood or blood products, using contaminated needles or via sexual transmission. Household contact with people who are hepatitis B surface antigen positive is a major risk factor for transmission of hepatitis D.¹⁹

Epidemiological situation in 2012

In Australia, the notification rate of hepatitis D remains low. In 2012, there were 30 notified cases of hepatitis D; a rate of 0.14 per 100,000. Over the preceding 5 years, notifications of hepatitis D remained relatively stable with an average of 37 cases notified per year (range: 33–41).

Geographical distribution

In 2012, Victoria reported the highest number of cases (9) followed by South Australia (8), Queensland (6), New South Wales (5) and Western Australia (2). Between 2007 and 2012, the majority of cases were from Victoria (67), Queensland (62) and New South Wales (59), with fewer cases reported from Western Australia (14), South Australia (10) and the Northern Territory (1). No cases were reported from the Australian Capital Territory or Tasmania during this period.

Sex distribution

The male to female ratio in 2012 was 2.3:1. This was less than the average ratio of 2.8:1 over the preceding 5 years, but greater than the 1.5:1 ratio reported in 2011 (Figure 13).

Figure 13: Notifications of hepatitis D, Australia, 2002 to 2012, by year and sex

Text version of Figure 13 (TXT 1 KB)

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Gastrointestinal diseases

In 2012, gastrointestinal diseases notified to the NNDSS and discussed in this section 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 decreased from 32,784 in 2011 to 31,155 in 2012. None of the rates of gastrointestinal disease notified to NNDSS in 2012 were notably higher compared with the 5-year mean (exceeded the mean by more than 2 standard deviations).

Surveillance systems overview

The Australian Government established OzFoodNet—Australia’s enhanced foodborne disease surveillance system—in 2000 as a collaborative network of epidemiologists and microbiologists who conduct enhanced surveillance, epidemiological outbreak investigations and applied research into foodborne disease across Australia. OzFoodNet’s mission is to apply concentrated effort at the national level to investigate and understand foodborne disease, to describe its epidemiology more effectively and to identify ways to minimise foodborne illness in Australia. The data and results summarised in the following sections will be reported in more detail in the OzFoodNet annual report 2012.

Botulism

Botulism is a rare but extremely serious intoxication resulting from the ingestion of toxins produced by Clostridium botulinum (commonly toxin types A, B and E). Four forms of botulism are recognised; infant, foodborne, wound and adult intestinal toxaemia.¹⁹

Epidemiological situation in 2012

There were no notifications of botulism in 2012. This compared with 2 notified cases in 2011 (both were infant botulism) and no notified cases in 2010.

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Campylobacteriosis

The bacterium Campylobacter is a common cause of foodborne illness (campylobacteriosis) in humans. The severity of this illness varies and is characterised by diarrhoea (often bloody stools), abdominal pain, fever, nausea and or vomiting.¹⁹ Campylobacteriosis is notifiable in all Australian states and territories, except New South Wales.

Epidemiological situation in 2012

There were 15,653 notifications of campylobacteriosis in 2012 making it the most frequently notified enteric infection (101.6 per 100,000). This was a decrease of 12% on the number of notifications received for 2011 (n=17,725) and a 6% decrease on the 5-year mean (n=16,669). Notification rates ranged from 74.4 per 100,000 in the Northern Territory to 172.2 per 100,000 in Tasmania.

Age and sex distribution

Campylobacteriosis was most frequently notified among the 0–4 years age group for both males (198 per 100,000) and females (136 per 100,000). The median age of notified cases was 34.5 years (range 0–101 years) and 54% (n=8,522) were male. Notification rates were higher among males compared with females in nearly all age groups (Figure 14).

Figure 14: Notification rate for campylobacteriosis, Australia, 2012, by age group and sex

Text version of Figure 14 (TXT 1 KB)

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Cryptosporidiosis

Cryptosporidiosis is a parasitic infection characterised by abdominal cramping and usually large-volume watery diarrhoea. Ingesting contaminated water, typically from a recreational source like a community swimming pool or lake, is a major risk factor for infection.¹⁹

Epidemiological situation in 2012

There were 3,124 notifications of cryptosporidiosis in 2012 (13.8 per 100,000). This represents a 73% increase over the 1,810 notifications reported in 2011, and a 23% increase over the 5-year mean of 2,544 notifications. Notification rates ranged from 5.1 per 100,000 in the Australian Capital Territory to 99.5 per 100,000 in the Northern Territory. Increases in notifications over 2011 levels were seen in most jurisdictions, particularly in Queensland and the Northern Territory. Queensland’s increase was all in sporadic notifications whereas the Northern Territory reported an increase in sporadic notifications as well as 6 outbreaks, spread person-to-person in the child care setting.

Age and sex distribution

In 2012, notifications of cryptosporidiosis most frequently occurred in the 0–4 years age group (46%, n=1,437), and of these 59% (n=848) were male. This was consistent with 2011 where notifications of cryptosporidiosis were also most frequent in the 0–4 years age group (43%, n=780), and the majority of these were male (57%, n=446).

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Haemolytic uraemic syndrome

HUS is a rare but serious illness that is characterised by acute renal impairment; with 50% of patients requiring dialysis and about 5% resulting in death.¹⁹ Whilst not all diagnoses of HUS are related to enteric pathogens, Australian cases are commonly associated with STEC infection.²⁷

Epidemiological situation in 2012

There were 20 notifications of HUS in 2012 compared with 13 in 2011 and a mean of 17.2 notifications per year between 2007 and 2011.

Age and sex distribution

In 2012, HUS was most frequently notified among the 0–4 years age group (n=6). The median age of all notified HUS cases was 13 years (range 1–87 years) and 70% (n=14) were male, including all cases in the 0–4 years age group.

Hepatitis A

Hepatitis A is an acute viral infection primarily of the liver that can develop into chronic liver disease including liver failure. Infection is usually spread from person to person via the faecal-oral route but can also be foodborne or waterborne.¹⁹

Epidemiological situation in 2012

There were 165 notified cases of hepatitis A in 2012 (0.7 per 100,000). This was a 14% increase on the number of notifications in 2011 (n=145), but 42% less than the 5-year mean of 283. The mean reflects the impact of a 2009–2010 outbreak of hepatitis A associated with the consumption of semi-dried tomatoes.

Age and sex distribution

Hepatitis A was most frequently notified among the 25–29 years age group (16%, n=27) in 2012. The median age of notified cases was 28 years (range 0–92 years), and 52% (n=85) were female.

Indigenous status

Indigenous status was known for 90% (n=148) of cases of hepatitis A. However, none of these identified as being Indigenous.

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Place of acquisition

Overseas travel was the primary risk factor for notified cases in 2012. Infection was considered to be overseas acquired in 66% (n=109) of notified cases.

In 2012, 18% (n=30) of notified cases were locally acquired. This was a decrease from 2011 where 27% (n=39) of notified cases were locally acquired (Table 13). The 2009–2010 multi-state outbreak associated with the consumption of semi-dried tomatoes contributed to an increase in locally acquired hepatitis A cases in both 2009 and 2010.²⁸

Table 13: Notifications of hepatitis A, Australia, 2007 to 2012, by place of acquisition

Year	Locally		Overseas		Unknown		Total
	n	%	n	%	n	%
2007	65	39.2	77	46.4	24	14.5	166
2008	91	33.0	128	46.4	57	20.7	276
2009	349	61.9	137	24.3	78	13.8	564
2010	111	41.7	144	54.1	11	4.1	266
2011	39	26.9	97	66.9	9	6.2	145
2012	30	18.2	109	66.1	26	15.8	165

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Hepatitis E

Hepatitis E is an acute viral infection primarily of the liver. The virus is transmitted by the faecal-oral route, most often via food or water.¹⁹ Infection is usually acquired overseas among travellers to endemic areas.

Epidemiological situation in 2012

There were 32 notified cases of hepatitis E in 2012, compared with a 5-year mean of 34.6 notifications.

Age and sex distribution

Hepatitis E was most frequently notified among the 25–39 years age group (60%, n=19), the median age of notified cases was 30 years (range 24–61 years), and 75% (n=24) of total notifications were male.

Place of acquisition

Hepatitis E in Australia has traditionally been associated with overseas travel. In 2012, 84% of cases (n=27) reported overseas travel during their incubation period and were considered overseas acquired. Of these, 59% (n=16) reported travel to India. The place of acquisition for the remaining 5 cases was inadequately described or unknown.

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Listeriosis

Invasive listeriosis is caused by infection with Listeria monocytogenes. It commonly affects the elderly or immunocompromised, typically among people with serious underlying illnesses. Listeriosis can also affect pregnant women and their unborn babies, sometimes resulting in miscarriage or foetal death. Laboratory confirmed infections in a mother and her unborn child or neonate are notified separately in the NNDSS.

Epidemiological situation in 2012

There were 93 notified cases of invasive L. monocytogenes infection in 2012 (0.4 per 100,000). This was a 33% increase over 2011 (n=70) and a 32% increase compared with the 5-year mean of 70.2 notifications.

Age and sex distribution

Notifications for listeriosis were highest in the 80 years or over age group (41%, n=38), with 61% (n=57) of all notified cases being female (Figure 15).

Figure 15: Notifications of listeriosis, Australia, 2012, by age group and sex

Text version of Figure 15 (TXT 1 KB)

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Enhanced surveillance in 2012

OzFoodNet collects enhanced surveillance data on all notified cases of listeriosis in Australia. The information collected includes the characterisation of L. monocytogenes isolates by molecular subtyping methods, food histories and exposure data. The overall aim of this enhanced surveillance is to enable timely detection of outbreaks and subsequent public health response.²⁷

Analysis of the enhanced data is covered in the OzFoodNet annual reports from 2010 onwards.

Salmonellosis (non-typhoidal)

Salmonellosis is a bacterial disease characterised by symptoms including abdominal pain, fever, diarrhoea, muscle pain, nausea and/or vomiting. People can become infected via faecal-oral transmission, ingesting contaminated food, through animal contact and from environmental exposures.

Epidemiological situation in 2012

There were 11,265 notified cases of salmonellosis in 2012 (49.6 per 100,000). This represents an 8.2% decrease in notifications compared with 2011 (n=12,270 and the highest yearly notifications since salmonellosis became nationally notifiable in 1991), but a 9.5% increase compared with the 5-year mean of 10,289 notifications. In 2012, notification rates ranged from 40.4 per 100,000 in New South Wales to 173.1 per 100,000 in the Northern Territory.

Age and sex distribution

Salmonellosis was most frequently notified among the 0–4 years age group (25%, n=2,771). The median age of notified cases was 25 years (range 0–100 years) and 50% (n=5,673) of notifications were in females.

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Shigellosis

Shigellosis is a bacterial disease characterised by acute abdominal pain and fever, small-volume loose stools, vomiting and tenesmus. Shigella is transmitted via the faecal-oral route, either directly (such as male-to-male sexual contact) or indirectly through contaminated food or water.¹⁹

Epidemiological situation in 2012

There were 547 notified cases of shigellosis in 2012 (2.4 per 100,000) with the number of notifications being less than the 5-year mean of 617 notifications. As in previous years, the highest notification rate was in the Northern Territory (45.5 per 100,000).

Age and sex distribution

Notifications for shigellosis were highest in the 0–4 years age group (18%, n=100). In 2012, the median age of notified cases was 27 years (range 0–85 years) and 51% (n=277) were male.

Indigenous status

Information on Indigenous status was available for 88% (n=479) of shigellosis notifications. This proportion varied by state or territory, with data for New South Wales, Queensland and Tasmania being less than 80% complete. Among states and territories with greater than 80% completeness, the proportion of notified cases who identified as being of Aboriginal or Torres Strait Islander origin was 36% (119/334).

Place of acquisition

Thirty-one per cent (n=167) of notified cases of shigellosis were reported as being acquired overseas. The most frequently reported countries of acquisition for imported cases were Indonesia (22%, n=37) and India (22%, n=37). Twenty-seven per cent of notified cases of shigellosis (n=147) were acquired in Australia and the place of acquisition for the remaining 43% of notified cases (n=233) was inadequately described or unknown.

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Shiga toxin-producing Escherichia coli infections

STEC is a cause of diarrhoeal illness in humans. People can become infected via faecal-oral transmission, ingesting contaminated food, through animal contact and from environmental exposures. Severe illness can progress to HUS. Children under 5 years of age are the most frequently diagnosed with STEC infection and are at greatest risk of developing HUS.¹⁹

Epidemiological situation in 2012

There were 111 notified cases of STEC in 2012 (0.5 per 100,000); a 10% increase compared with the 5-year mean of 101 notifications. Detection of STEC infection is strongly influenced by jurisdictional practices regarding the screening of stool specimens.²⁷ South Australia tests all bloody stools for Shiga toxin encoding genes and subsequently has the highest notification rate in Australia; 2.7 cases per 100,000, compared with 0.0–1.4 per 100,000 in other states and territories. Comparison of STEC notification data between jurisdictions and over time requires careful interpretation.

Age and sex distribution

In 2012, 53% (n=59) of notified STEC cases were male. The median age of notified cases was 46 years (range 1–95 years).

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Typhoid

Typhoid is a bacterial disease caused by Salmonella enterica serotype Typhi. Symptoms include sustained fever, marked headache, malaise and constipation more often than diarrhoea in adults. The transmission mode is the same as for non-typhoidal salmonellosis, however humans are the only reservoir for S. Typhi.¹⁹

Epidemiological situation in 2012

There were 123 notifications of typhoid in 2012 (0.5 per 100,000); a 14% increase compared with the 5-year mean of 108.2 cases, but a 9% decrease on the number of notifications in 2011 (n=135).

Age and sex distribution

Typhoid was most frequently notified among the 20–34 years age group (51%, n=63), the median age of notified cases was 26 years (range 0–61 years), and 60% (n=74) were male.

Place of acquisition

As in previous years, overseas travel was the primary risk factor for notified cases. In 2012, 89% (n=109) of notified cases reported overseas travel during their incubation period and were considered overseas acquired. India was the most frequently reported country of acquisition, accounting for 56% (n=61) of overseas-acquired cases in 2012.

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Quarantinable diseases

Human diseases covered by the Quarantine Act 1908, and notifiable in Australia and to the WHO in 2012 were cholera, plague, rabies, yellow fever, smallpox, highly pathogenic avian influenza in humans (HPAIH), severe acute respiratory syndrome (SARS) and 4 viral haemorrhagic fevers (Ebola, Marburg, Lassa and Crimean–Congo). These diseases are of international public health significance.

Travellers are advised to seek information on the risk of contracting these diseases at their destinations and to take appropriate measures. More information on quarantinable diseases and travel health can be found on the Department of Health web site (http://www1.health.gov.au/internet/main/publishing.nsf/Content/health-pubhlth-strateg-quaranti-index.htm) and on the Department of Foreign Affairs and Trade Smartraveller web site (www.smartraveller.gov.au/).

There were no cases of plague, rabies, smallpox, SARS, HPAIH or viral haemorrhagic fevers reported in Australia in 2012. While there were cases of cholera (n=5) reported in 2012, Australia retained its official status as being free of all the listed quarantinable diseases (Table 14).

Table 14: Australia’s status for human quarantinable diseases, 2012

Disease	Status	Date of last record and notes
Cholera	Free	Small number of cases are reported annually and related to overseas travel or imported food products
Plague	Free	Last case recorded in Australia in 192329
Rabies	Free	Last case (overseas acquired) recorded in Australia in 199030
Smallpox	Free	Last case recorded in Australia in 1938, last case world-wide in 1977, declared eradicated by the World Health Organization 198031,32
Yellow fever	Free	Two cases in 2011 are the first recorded, related to overseas travel33
Severe acute respiratory syndrome	Free	Last case recorded in Australia in 200334
Highly pathogenic avian influenza in humans	Free	No cases recorded35
Viral haemorrhagic fevers
Ebola	Free	No cases recorded
Marburg	Free	No cases recorded
Lassa	Free	No cases recorded
Crimean–Congo	Free	No cases recorded

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Cholera

Epidemiological situation in 2012

In 2012, there were 5 notifications of cholera in Australia. Between 2007 and 2011 there were 17 cases of cholera in total in Australia. The following details relate to the exposures or place of acquisition for the 5 cases in 2012:

Two cases were reported by South Australia. Both had travelled separately to Phuket, Thailand during their incubation period, with visits to Phi Phi Island.

New South Wales reported 2 cases, one with place of acquisition being Bangladesh and the other India.

Queensland reported a case acquired in India.

Cases ranged in age between 0 and 59 years.

All cases of cholera reported since the commencement of the NNDSS in 1991 to 2012 have been acquired outside Australia except for a single case of laboratory-acquired cholera in 1996³⁶ and 3 cases in 2006 linked to imported whitebait.³⁷