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Introduction | Methods | Results - Part 1 | Acknowledgements | Appendices | References
Results: Bloodborne diseases | Gastrointestinal | Quarantinable | Sexually transmissible | Vaccine preventable | Vectorborne | Zoonoses | Other bacterial infections
Results - Part 2
Bloodborne diseases
In 2011, 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 within 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 ‘greater than 2 years or unspecified’. The determination of a case as being ‘newly acquired’ was 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 notifications over time may not solely reflect changes in disease prevalence or incidence. Testing policies8 and screening programs, including the preferential testing of high risk populations such as persons in prison, 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) or risk factors of infection for hepatitis B and C was reported in a subset of diagnoses of newly acquired infections. The collection of these enhanced data were also dependant on the level of public health follow-up, which is variable by jurisdiction and over time.
Further information regarding the surveillance of these infections are described within the hepatitis B and hepatitis C sections.
Notifications of HIV and AIDS diagnoses are reported directly to the Kirby Institute, formerly the National Centre in HIV Epidemiology and Clinical Research, which maintains the National HIV Registry and the National AIDS Registry. Information on national HIV/AIDS surveillance can be obtained from the Kirby Institute web site (http://hiv.cms.med.unsw.edu.au/).
Hepatitis B
Hepatitis B notifications are classified as either ‘newly acquired’ or ‘unspecified’ as described above. The classification of hepatitis B cases is primarily based on serological evidence or evidence of a previously negative test within the 24 months prior to diagnosis.
Epidemiological situation in 2011
In 2011, there were 6,819 notifications of hepatitis B (both newly acquired and unspecified), equating to a rate of 30.1 per 100,000 (Figure 4). The Northern Territory recorded the highest hepatitis B rate in 2011 (70.8 per 100,000), followed by Victoria (35.3 per 100,000) and New South Wales (34.7 per 100,000).
Between 2001 and 2011 unspecified hepatitis B rates decreased by 22% from 37.7 to 29.3 per 100,000 and newly acquired hepatitis B rates decreased from a rate of 2.2 to 0.8 per 100,000 (Figure 4). The continued decline in hepatitis B notifications may be attributed to the ongoing hepatitis B vaccination program introduced nationally for infants in 2000. Approximately 92% of the 2012 Australian birth cohort received the full primary course of the hepatitis B vaccine by 15 months of age.9 The decline may also be attributable to the adolescent program introduced in 1997.
Figure 4: Notification rate for newly acquired hepatitis B* and unspecified hepatitis B,† Australia, 2001 to 2011, by year‡
* Data for newly acquired hepatitis B for the Northern Territory (2001–2004) includes some unspecified hepatitis B cases.
† Data for unspecified hepatitis B for all jurisdictions except the Northern Territory between 2001 and 2004.
‡ Year of diagnosis for newly acquired hepatitis B and for hepatitis B (unspecified) notifications, and not necessarily year of infection.
Text version of Figure 4 (TXT 1 KB)
Newly acquired hepatitis B
Epidemiological situation in 2011
In 2011, there were 190 notifications of newly acquired hepatitis B (0.8 per 100,000), a 17% decrease compared with the 228 cases (rate of 1.0 per 100,000) reported in 2010 and a continuation of a downward trend in notifications. (Figure 4).
Nationally, the proportion of all hepatitis B cases in 2011 that were documented as newly acquired continued to trend downward and was 2.8%, compared with 3.2% in 2010 and 5.5% in 2001.
The identification and classification of newly acquired hepatitis B is reliant upon public health follow-up of laboratory diagnoses, the extent of which varies between jurisdictions and over time.
Geographic distribution
The proportion of newly acquired infections compared with total hepatitis B infections varied substantially between jurisdictions, ranging from 1.2% in Tasmania and 24.5% in New South Wales.
Notification rates varied in states and territories: Tasmania (2.5 per 100,000), the Northern Territory (1.7 per 100,000), Victoria (1.2 per 100,000), Queensland (1.0 per 100,000), Western Australia (0.8 per 100,000), the Australian Capital Territory and South Australia (0.5 per 100,000) and New South Wales (0.4 per 100,000).
Age and sex distribution
Overall, notifications of newly acquired hepatitis B were more frequently reported amongst males. The highest rate of newly acquired hepatitis B infection was observed in males in the 30–34 and 35–39 year age groups (3.1 and 3.2 per 100,000 respectively) (Figure 5).
Figure 5: Notification rate for newly acquired hepatitis B, Australia, 2011, by age group and sex
Text version of Figure 5 (TXT 1 KB)
Between 2001 and 2011, most age group rates have been trending down with the most marked decrease occurring amongst the 20–29 year age range (Figure 6). Changes in hepatitis B notifications may be attributable to variations in levels of testing. Changes in immigration of people from countries where there is higher prevalence of hepatitis B may also impact on the number of cases diagnosed.10
Figure 6: Notification rate for newly acquired hepatitis B,* Australia, 2001 to 2011, by year and age group
* Data for newly acquired hepatitis B for the Northern Territory (2001–2004) includes some unspecified hepatitis B cases.
Text version of Figure 6 (TXT 1 KB)
Risk groups
Exposure histories were assessed for 126 of the 190 cases reported in 2011 (Table 8). In 2011, 72.2% (n=91) of these cases had at least 1 risk factor recorded, with the source of exposure not recorded or not determined for the remainder (Table 8). Injecting drug use remained the most frequently reported source of infection in 2011 (reported as a risk factor for 31% of cases) but has declined from 2007, when it was reported as a risk factor for 47% of cases. Skin penetration procedures were the next most frequently reported risk factor for infection in 2011 (34%), the majority of which were reported as tattoos.
| Number of exposure factors reported | ||||
|---|---|---|---|---|
| Exposure category | Male | Female | Total | Percentage of total cases*(n=126) % |
| * Cases from New South Wales, the Northern Territory, the Australian Capital Territory, Tasmania, South Australia 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 Northern Territory, the Australian Capital Territory, Tasmania, South Australia 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 |
28 |
11 |
39 |
31.0 |
Imprisonment |
8 |
0 |
8 |
6.3 |
| Skin penetration procedures | ||||
| Tattoos |
12 |
5 |
17 |
13.5 |
| Ear or body piercing |
4 |
3 |
7 |
5.6 |
| Acupuncture |
4 |
1 |
5 |
4.0 |
| Healthcare exposure | ||||
| Surgical work |
2 |
5 |
7 |
5.6 |
| Major dental surgery work |
4 |
3 |
7 |
5.6 |
| Blood/tissue recipient (overseas) |
0 |
1 |
1 |
0.8 |
| Sexual contact – hepatitis B positive partner | ||||
Opposite sex |
6 |
6 |
12 |
9.5 |
| Same sex |
6 |
0 |
6 |
4.8 |
| Other | ||||
Household contact |
3 |
3 |
6 |
4.8 |
Needlestick/biohazardous injury|| |
4 |
0 |
4 |
3.2 |
Perinatal transmission |
1 |
0 |
1 |
0.8 |
Other |
11 |
1 |
12 |
9.5 |
Cases with at least 1 risk factor |
65 |
26 |
91 |
72.2 |
Undetermined |
2 |
1 |
3 |
2.4 |
Unknown (not recorded) |
18 |
14 |
32 |
25.4 |
Total exposure factors reported† |
93 |
39 |
132 |
– |
Total number of cases |
85 |
41 |
126 |
– |
Additional information was collected on the country of birth (COB) from all jurisdictions except Queensland. Of the 116 cases for which COB was reported, the majority occurred amongst Australian-born persons (69%, 80 cases) with the remaining 36 cases being born overseas.
Unspecified hepatitis B notifications
Epidemiological situation in 2011
In 2011, there were 6,629 notifications of unspecified hepatitis B infection, a rate of 29.3 per 100,000, compared with 6,878 cases (and a rate of 31.2 per 100,000) in 2010.
The overall rate of hepatitis B (unspecified) has been trending downward over the past 10 years with the majority of this decrease occurring between 2001 and 2004. Between 2006 and 2011 the rate has remained relatively stable with an average annual rate of 31 per 100,000 during this time. (Figure 4).
Age and sex distribution
In 2011, the overall male rate (32.2 per 100,000) was higher than for females (26.0 per 100,000), a rate ratio of 1.2:1, but females had the highest age specific rate amongst those in the 25–29 year age group (71 per 100,000) compared with the highest age specific rate amongst males of 65 per 100,000 in the 30–34 years age group (Figure 7).
Figure 7: Notification rate for unspecified hepatitis B,* Australia, 2011, by age group and sex
* Excludes notifications for whom age and/or sex were not reported.
Text version of Figure 7 (TXT 1 KB)
Rates of hepatitis B unspecified have declined across all age groups since 2001 with the majority of this decrease occurring in the first 3 years before stabilising (Figure 8). The biggest decrease (53%) occurred amongst the 15–19 year age group declining from a rate of 35 per 100,000 in 2001 to 16.5 per 100,000 in 2011.
Figure 8: Notification rate for unspecified hepatitis B,*,† Australia, 2001 to 2011, by year and age group
* Data for hepatitis B (unspecified) from all states except the Northern Territory between 2001 and 2004.
† Excludes notifications for whom age was not reported.
Text version of Figure 8 (TXT 1 KB)
Hepatitis C
Hepatitis C notifications are classified as either ‘newly acquired’ (infection acquired within 24 months prior to diagnosis) or ‘unspecified’ (infection acquired more than 24 months prior to diagnosis or not able to be specified). Current testing methods cannot distinguish between newly acquired (incident) and chronic infections (greater than 2 years or unspecified). The identification of newly acquired cases is therefore dependent on evidence of a negative test result within 24 months prior to laboratory diagnosis or clinical hepatitis within the 24 month prior to a positive diagnostic test where other causes of acute hepatitis have been excluded. Ascertainment of a person’s hepatitis C testing and clinical history usually requires active follow-up by public health units. Although initial infection with the hepatitis C virus is asymptomatic or mildly symptomatic in more than 90% of cases, approximately 50%–80% of cases will go on to develop a chronic infection. Of those who develop a chronic infection, half will eventually develop cirrhosis or cancer of the liver.4
Epidemiological situation in 2011
Between 2001 and 2011, total hepatitis C notification rates declined by 51% (93 to 45 per 100,000), with the greatest reductions observed in the earlier years, (a 16% decline between 2001 and 2002) (Figure 9). In 2011, it was estimated that 304,000 people living in Australia had been exposed to the hepatitis C virus. Of these, approximately 179,900 had chronic hepatitis C infection and early liver disease, 49,500 had chronic hepatitis C infection with moderate liver disease, 6,300 were living with hepatitis C related cirrhosis and 77,300 had cleared their infection.4
Figure 9: Notification rate for newly acquired hepatitis C* and unspecified hepatitis C,† Australia, 2001 to 2011
* Data for newly acquired hepatitis C from all states and territories except Queensland 2001–2011 and the Northern Territory 2001–2002.
† Data for unspecified hepatitis C provided from Queensland (2001–2011) and the Northern Territory (2001–2002) includes both newly acquired and unspecified hepatitis C cases.
Text version of Figure 9 (TXT 1 KB)
Newly acquired hepatitis C notifications
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.
Epidemiological situation in 2011
There were 400 notifications in 2011 compared with 401 in 2010, giving a rate of 2.2 per 100,000 (Figure 9). Of all hepatitis C cases in 2011, 3.9% were identified as newly acquired infections, which is comparable with previous years.
Geographic distribution
The proportion of infections that were newly acquired compared with total hepatitis C diagnoses varied substantially between the states and territories ranging from 1.4% in the Northern Territory to 11.8% in Tasmania. The highest rates of newly acquired hepatitis C infection were reported in Tasmania (5.3 per 100,000), followed by Western Australia (5.1 per 100,000) and Victoria (2.9 per 100,000). 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 between 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
The male to female ratio was 2.1:1. Age group specific rates for males were highest in the 20–24 year age group followed by the 15–19 year age group (Figure 10). Age group specific rates for females were highest in the 15–19 year, 10–14 year and 20–24 year age groups (Figure 10).
Figure 10: Notification rate for newly acquired hepatitis C, Australia,* 2011, by age group and sex
* Data from all states and territories except Queensland.
Text version of Figure 10 (TXT 1 KB)
Between 2001 and 2011, rates of newly acquired hepatitis C infection in the 15–19 year, 20–29 year and 30–39 year age groups have been trending down (Figure 11). Rates amongst other age groups have remained relatively stable over the same period.
Figure 11: Notification rate for newly acquired hepatitis C, Australia,* 2001 to 2011, by age group and year
* Data from all states and territories except Queensland (2001–2011) and the Northern Territory (2001–2002).
Text version of Figure 11 (TXT 1 KB)
Risk groups
Exposure history for all newly acquired hepatitis C cases reported in 2011 was assessed from all jurisdictions except Queensland (Table 9). In 2011, 72% of these cases had at least 1 risk factor recorded, with the source of exposure not recorded or unable to be determined for the remainder of these cases. Approximately 60% of cases had a history of injecting drug use (62% of which reported injecting drug use in the 24 months prior to diagnosis). Skin penetration procedures and imprisonment accounted for approximately 32% and 21% of reported risk factors 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 in 2010 found that the prevalence of hepatitis C based on hepatitis C antibody detection was 22%, a decrease compared with the 35% reported in 2007.11
| Number of cases with exposure factor | ||||
|---|---|---|---|---|
| Exposure category | Male | Female | Total | Percentage of total cases*,§(n=400) % |
| * Includes diagnoses in all states and territories except Queensland as newly acquired cases are reported as unspecified cases † 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. As more than 1 exposure category for each case could be recorded, the total percentage does not equate to 100%. || Includes both occupational and non-occupational exposures. | ||||
Injecting drug use |
175 |
65 |
240 |
60.0 |
Imprisonment |
80 |
5 |
85 |
21.3 |
| Skin penetration procedures | ||||
| Tattoos |
50 |
12 |
62 |
15.5 |
| Ear or body piercing |
23 |
17 |
40 |
10.0 |
| Acupuncture |
3 |
2 |
5 |
1.3 |
| Healthcare exposure | ||||
| Surgical work |
6 |
4 |
10 |
2.5 |
| Major dental surgery work |
10 |
1 |
11 |
2.8 |
| Blood/tissue recipient (overseas) |
1 |
0 |
1 |
0.3 |
| Sexual contact – hepatitis C positive partner | ||||
Opposite sex |
26 |
20 |
46 |
11.5 |
| Same sex |
1 |
1 |
2 |
0.5 |
| Other | ||||
Household contact |
13 |
7 |
20 |
5.0 |
Needlestick/biohazardous injury|| |
6 |
3 |
9 |
2.3 |
Perinatal transmission |
15 |
5 |
20 |
5.0% |
Other |
15 |
7 |
22 |
5.5 |
Cases with at least 1 risk factor |
207 |
82 |
289 |
72.3 |
Undetermined |
3 |
3 |
6 |
1.5 |
Unknown (not recorded) |
60 |
45 |
105 |
26.3 |
Total exposure factors reported† |
424 |
149 |
573 |
– |
Total number of cases |
270 |
130 |
400 |
– |
Unspecified hepatitis C notifications
Epidemiological situation in 2011
In 2011, there were 9,861 notifications of unspecified hepatitis C infections, a rate of 43.6 per 100,000 compared with 10,916 cases in 2010 and a rate of 49.0 per 100,000. This continues a downward trend and represents a 51% decline compared with 2001 when the rate was 89.5 per 100,000 (Figure 9).
Several factors may account for the decrease: changes in surveillance practices, including duplicate notification checking; a gradual decline in the prevalent group of hepatitis C cases accumulated prior to the introduction of hepatitis C testing in the early 1990s; general reductions in risk behaviours relating to injecting drug use, particularly amongst young people; and increased access to sterile injecting equipment through need exchange programs.10–13
Geographic distribution
In 2011, the Northern Territory continued to have the highest rate of unspecified hepatitis C infections (89.4 per 100,000) followed by Queensland (53.2 per 100,000) and the Australian Capital Territory (49.8 per 100,000), noting that Queensland’s rate includes both newly acquired and unspecified cases. The lowest rate was in South Australia (25.7 per 100,000).
Age and sex distribution
The male to female ratio remained consistent with historical trends at 1.8:1 in 2011. Amongst males, rates were highest across age groups between 30 and 54 years ranging from 102 to 118 per 100,000. Similarly, rates for females were highest amongst adults in the 30–34 year age group (64 per 100,000) followed by the 25–29 year age group (57 per 100,000) and the 35–39 year age group (56 per 100,000) (Figure 12).
Figure 12: Notification rate for unspecified hepatitis C,*,† Australia, 2011, 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 12 (TXT 1 KB)
Between 2001 and 2011 the rate of unspecified hepatitis C has declined in all age groups with the biggest decreases occurring in the 15–19 year (81%), 20–29 year (70%) and the 30–39 year (50%) age groups; the majority of this decline occurred in the early part of the decade (Figure 13). Trends in the 0–4, 5–14 and the 40 years or over age groups have remained relatively stable over this time (Figure 13).
Figure 13: Notification rate for unspecified hepatitis C,*,† Australia, 2001 to 2011, by age group
* Data provided from Queensland (2001–2011) and the Northern Territory (2001–2002) includes both newly acquired and unspecified hepatitis C cases.
† Excludes notifications for whom age was not reported.
Text version of Figure 13 (TXT 1 KB)
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 either as a co-infection with hepatitis B or as a super-infection with chronic hepatitis B infection.14 The modes of hepatitis D transmission are similar to those for hepatitis B. In countries with low hepatitis B prevalence, injecting drug users are the main group at risk for hepatitis D.
Epidemiological situation in 2011
In Australia, the rate of hepatitis D remains low. In 2011, there were 43 notifications of hepatitis D, a rate of 0.2 per 100,000. Over the past 5 years, the number of notifications of hepatitis D has remained relatively stable with an average of 37 cases notified per year (range 33–43).
Geographic distribution
Victoria reported the highest number of cases (n=17) followed by New South Wales (n=9), South Australia (n=8), Queensland (n=7) and Western Australia (n=2).
Sex distribution
The male to female ratio in 2011 was 1.7:1 which was lower than the average ratio of 3.0:1 in the preceding 5 years (Figure 14).
Figure 14: Notifications of hepatitis D, Australia, 2001 to 2011, by sex
Text version of Figure 14 (TXT 1 KB)
Gastrointestinal diseases
In 2011, gastrointestinal diseases notified to 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 increased from 31,483 in 2010 to 32,784 in 2011. Notifications of typhoid and Campylobacter infections were notably higher compared with the 5-year historical mean (exceeded the mean by more than 2 standard deviations).
Surveillance system 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 2011.
Botulism
Botulism is a rare but extremely serious intoxication resulting from toxins produced by Clostridium botulinum (commonly toxin types A, B and E). Three forms of botulism are recognised; infant, foodborne and wound.14
Epidemiological situation in 2011
There were 2 notifications of botulism in 2011. Both were infant botulism. There were no notifications reported in 2010 and 1 case reported in 2009.
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.14 Campylobacteriosis is notifiable in all Australian jurisdictions, except New South Wales.
Epidemiological situation in 2011
Campylobacteriosis was the most frequently notified enteric infection with 17,717 notifications; a rate of 116 per 100,000. This is an increase of 4% on the number of notifications received for 2010 (n=16,969) and a 9% increase on the 5-year historical mean (n=16,196). Notification rates ranged from 69.5 per 100,000 in the Northern Territory to 169.2 per 100,000 in Tasmania.
Age and sex distribution
Notification rates were highest amongst males in nearly all age groups. The highest age-specific rate for both males and females was in the 0–4 year age group (221.6 and 165.2 per 100,000, respectively) with secondary peaks occurring in the 20–24 year and 70 years or over age groups (Figure 15).
Figure 15: Notification rate for campylobacteriosis, Australia, 2011, by age group and sex
Text version of Figure 15 (TXT 1 KB)
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.14
Epidemiological situation in 2011
In 2011, there were 1,808 notifications of cryptosporidiosis; a national rate of 8 per 100,000. This represents a 22% increase over the 1,479 notifications reported in 2010; however it is below the 5-year historical mean of 2,823 notifications. Notification rates ranged from 3.6 per 100,000 in the Australian Capital Territory to 40.8 per 100,000 in the Northern Territory.
Age and sex distribution
Notifications for cryptosporidiosis were most frequently in the 0–4 year age group (43%, n=780). Of these, 57% (n=446) were male.
Haemolytic uraemic syndrome
HUS is a rare but serious illness that is characterised by acute renal impairment, and results in chronic complications in 40% of cases.14 Not all diagnoses of HUS are related to enteric pathogens, but Australian cases are commonly associated with STEC infection.15
Epidemiological situation in 2011
In 2011, there were 13 notifications of HUS compared with 9 in 2010 and a mean of 17.4 notifications per year between 2006 and 2010.
Age and sex distribution
The median age of notified cases of HUS between 2006 and 2011 was 11 years (range 0–89 years). Cases were most frequently reported amongst children in the 0–4 year age group (n=38).
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 by person-to-person transmission via the faecal-oral route but can be foodborne or waterborne. 14
Epidemiological situation in 2011
There were 144 notifications of hepatitis A in Australia; a rate of 0.65 notifications per 100,000. This was a 46% decrease in the number of cases compared with the 267 notifications in 2010.
Age and sex distribution
Hepatitis A was most frequently notified amongst the 25–34 year age range (n=40) in 2011. The median age of notified cases was 29 years (range 0–97 years), and 59% (n=85) were male.
Indigenous status
Indigenous status was known for 94% (135/144) of notified cases of hepatitis A. Of these, 2 cases were identified as being of Indigenous origin.
Place of acquisition
Overseas travel was the primary risk factor for notified cases in 2011. Infection was acquired overseas in 68% (n=96) of notified cases, compared with 54% (n=143) in 2010.
In 2011, 39 notified cases were locally acquired. This was a decrease from 2010 where 111 notified cases were locally acquired (Table 10). In 2009–2010 an outbreak associated with the consumption of semi-dried tomatoes contributed to an increase in locally acquired hepatitis A cases in both 2009 and 2010.16
| Year | Locally acquired | Overseas acquired | Unknown | Total | |||
|---|---|---|---|---|---|---|---|
| n | % | n | % | n | % | ||
2006 |
164 |
58.4 |
47 |
16.7 |
70 |
24.9 |
281 |
2007 |
63 |
38.0 |
50 |
30.1 |
53 |
31.9 |
166 |
2008 |
91 |
32.9 |
82 |
29.6 |
104 |
37.5 |
277 |
2009 |
349 |
61.9 |
69 |
12.2 |
146 |
25.9 |
564 |
2010 |
111 |
41.6 |
143 |
53.6 |
13 |
4.9 |
267 |
2011 |
39 |
27.1 |
96 |
66.7 |
9 |
6.3 |
144 |
Hepatitis E
Hepatitis E is an acute viral infection primarily of the liver that is transmitted by the faecal-oral route, most often via food or water.14 The infection is usually acquired overseas amongst travellers to endemic areas.
Epidemiological situation in 2011
There were 40 notifications of hepatitis E in 2011, compared with a 5-year historical mean of 31.2 notifications.
Age and sex distribution
Hepatitis E was most frequently notified amongst the 20–39 year age group (n=27), the median age of notified cases was 29 years (range 5–63 years), and 70% (n=28) were male.
Place of acquisition
Hepatitis E in Australia is associated with overseas travel. In 2011, 80% of cases (n=32) were known to have been acquired overseas, and of those, 66% (n=21) were acquired in India. The place of acquisition for the remaining 8 cases was not supplied or was unknown. No cases were reported to have been locally-acquired.
Listeriosis
Invasive listeriosis is caused by a bacterial infection that commonly affects the elderly or immunocompromised, and typically occurs amongst people with serious underlying illnesses. Listeriosis can also affect pregnant women and infect their unborn baby. Laboratory-confirmed infections in a mother and unborn child or a neonate are notified separately in the NNDSS.
Epidemiological situation in 2011
There were 70 notifications of invasive Listeria monocytogenes infection in 2011 compared with a 5-year mean of 68 notifications. This represented a national rate of 0.3 per 100,000.
Age and sex distribution
Notifications for listeriosis were highest in the 80–84 year age group (23%, n=16), and 59% (n=41) of notified cases were male (Figure 16).
Figure 16: Notifications for listeriosis, Australia, 2011, by age group and sex
Text version of Figure 16 (TXT 1 KB)
Enhanced surveillance in 2011
OzFoodNet collects enhanced surveillance data on all notified cases of listeriosis in Australia. Enhanced surveillance commenced in 2010. It collects detailed information on the characterisation of Listeria monocytogenes isolates by molecular subtyping methods, food histories and exposure data on all notified listeriosis cases in Australia. The overall aim of this enhanced surveillance is to enable timely detection of illness and subsequent public health response.15
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 the rapid development of 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.14
Epidemiological situation in 2011
There were 12,267 notifications of salmonellosis in Australia in 2011; a rate of 54.2 notifications per 100,000, compared with the 5-year historical mean of 9,479.8 notifications. In 2011, notifications continued to rise with a 2.9% increase over the 11,924 notifications in 2010. The number of notifications for 2011 was the highest recorded in NNDSS since 1991. Notification rates ranged from 38.2 per 100,000 in Tasmania to 174.9 per 100,000 in the Northern Territory.
Age and sex distribution
In 2011, 51% (n=6,213) of notifications were in females, with the greatest proportion of notifications in the 0–4 year age group (25%, n=3,118).
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.14
Epidemiological situation in 2011
There were 494 notifications of shigellosis in 2011; a national rate of 2.2 per 100,000, with notifications being less than the 5-year historical mean of 627 notifications. As in previous years, the highest notification rate was in the Northern Territory (33.4 per 100,000).
Age and sex distribution
Notifications for shigellosis were highest in the 0–4 year age group (21%, n=102), and 55% (n=270) of all notified cases were male.
Indigenous status
Information on Indigenous status was available for 89% (n=429) of shigellosis notifications. This proportion varied by state or territory, with New South Wales, Queensland and Victoria being less than 85% complete. Amongst jurisdictions with greater than 85% completeness, the proportion of notified cases who identified as being of Aboriginal or Torres Strait Island origin was 55% (114/206).
Place of acquisition
Twenty-seven per cent (n=133) of notified cases of shigellosis were reported as being acquired overseas. The most frequently reported countries of acquisition for imported cases were Indonesia (33%, n=43) and India (17%, n=23).
Shiga toxin-producing Escherichia coli infections
Shiga toxin-producing Escherichia coli are types of toxin-producing E. coli that cause diarrhoeal illness in humans. People can become infected via faecal-oral transmission, ingesting contaminated food, through animal contact or from environmental exposures. Severe illness can progress to HUS. Children under 5 years of age are most frequently diagnosed with infection and are at greatest risk of developing HUS.14
Epidemiological situation in 2011
There were 95 notifications of STEC in Australia in 2011; a rate of 0.4 per 100,000 population. Detection of STEC infection is strongly influenced by jurisdictional practices regarding the screening of stool specimens.15 In South Australia, and more recently the Australian Capital Territory, single pathology providers are participating in screening studies of bloody stools using polymerase chain reaction (PCR) for genes coding for Shiga toxins and other virulence factors. Notification rates for these jurisdictions are the highest in the country (Table 3). These differences mean that meaningful comparison of notification data by jurisdiction and over time are not valid.
Age and sex distribution
In 2011, 57% (n=54) of notified STEC cases were male. The median age of notified cases was 26 years (range 0–85 years).
Typhoid
Typhoid is a disease caused by S. enterica serotype Typhi. The transmission mode is the same as for salmonellosis, however typhoid differs in that humans are the reservoir for the bacterium.14
Epidemiological situation in 2011
There were 134 notifications of typhoid (0.6 per 100,000) in 2011, compared with the 5-year historical mean of 97 cases. This was a 42% increase compared with the 96 notifications in 2010.
Age and sex distribution
Typhoid was most frequently notified amongst the 20–34 year age range (n=57), the median age of notified cases was 25 years (range 1–88 years), and 60% (n=81) were male.
Place of acquisition
As in previous years, overseas travel was the primary risk factor for notified cases of typhoid in 2011, with 87% (n=117) of notified cases known to have been acquired overseas. India continues to be the most frequently reported country of acquisition, accounting for 50% (n=67) of overseas-acquired cases in 2011.
Quarantinable diseases
Human diseases covered by the Quarantine Act 1908, and notifiable in Australia and to the WHO in 2011 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 to avoid infection. More information on quarantinable diseases and travel health can be found on the Department of Health’s web site (www.health.gov.au/internet/main/publishing.nsf/Content/health-pubhlth-strateg-quaranti-index.htm) and the Department of Foreign Affairs and Trade’s 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 2011. While there were notifications of imported cases of cholera (n=6) and yellow fever (n=2) in 2011, Australia remains free of all the listed quarantinable diseases (Table 11).
| 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 192317 |
Rabies |
Free | Last case (overseas acquired) recorded in Australia in 199018 |
Smallpox |
Free | Last case recorded in Australia in 1938, last case world-wide in 1977, declared eradicated by the World Health Organization 198019,20 |
Yellow fever |
Free | Two cases in 2011 are the first recorded, related to overseas travel |
SARS |
Free | Last case recorded in Australia in 200321 |
HPAIH |
Free | No cases recorded22 |
| Viral haemorrhagic fevers | ||
Ebola |
Free | No cases recorded |
Marburg |
Free | No cases recorded |
Lassa |
Free | No cases recorded |
Crimean–Congo |
Free | No cases recorded |
Cholera
There were 6 notifications of cholera in Australia in 2011, five from Queensland and one from Western Australia. The 5 cases notified in Queensland all acquired their infection in Papua New Guinea and were overseas residents, while the case in Western Australia was acquired in the Philippines. There were 19 cases of cholera in Australia between 2006 and 2010 (Table 5).
All cases of cholera reported since the commencement of the NNDSS in 1991 were acquired outside Australia except for 1 case of laboratory-acquired cholera in 199623 and 3 cases in 2006 linked to imported whitebait.24
Yellow fever virus infection
There were 2 notifications of yellow fever in 2011, both from Queensland. The cases had recently returned from travel to yellow fever endemic areas (one from Colombia and the other from Ghana), were IgM positive, had a clinically-compatible illness and had received yellow fever vaccine in the 3 months prior to onset. Treating clinicians considered that both were likely to be vaccine related, but met the national case definition, and the possibility that they were true cases could not be excluded.
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