Introduction | Methods | Results - Part 1 | Appendices | Acknowledgements and abbreviations| References
Results part 2: Bloodborne diseases | Gastrointestinal | Quarantinable | Sexually transmissible | Vaccine preventable | Vectorborne | Zoonoses | Other bacterial infections
Results - Part 2
Bloodborne diseases
In 2013, 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 outlined in the national surveillance case definitions.18 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 notified cases over time may not solely reflect changes in disease prevalence or incidence. National testing policies developed by the Australian Society for HIV Medicine19,20 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 diagnoses 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/).
Hepatitis B
- 7,151 cases of hepatitis B were notified in 2013.
- Over the past 11 years, notifications of newly acquired hepatitis B have declined.
Infection with hepatitis B virus causes inflammation of the liver.21 Notifications of acute hepatitis B are classified as ‘newly acquired’ and chronic infections as ‘unspecified’.
Epidemiological situation in 2013
In 2013, there were 7,151 notified cases of hepatitis B (both newly acquired and unspecified), equating to a rate of 30.9 cases per 100,000 (Figure 3).
Figure 3: Notification rate for newly acquired hepatitis B* and unspecified hepatitis B,† Australia, 2003 to 2013, by year
* Data for newly acquired hepatitis B for the Northern Territory (2003–2004) includes some unspecified hepatitis B cases.
† Data for unspecified hepatitis B for all states and territories, excluding the Northern Territory between 2003 and 2004.
Text version of Figure 3 (TXT 1 KB)
Between 2003 and 2013, newly acquired hepatitis B rates decreased 57% from 1.7 to 0.7 per 100,000 (Figure 3). The continued decline in newly acquired 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 1997.22 As at 30 June 2014, approximately 92% of children 12–15 months of age in Australia were assessed as being fully immunised for hepatitis B.23 A 2007 study showed significant improvements in immunity for the 12–17 years age range in jurisdictions with established school-based programs, compared with those jurisdictions without such programs.24
In Australia, hepatitis B vaccination was also recommended for certain at-risk adults from the 1980s, with the list of groups and occupations identified as at-risk varying over time.25 Some jurisdictions implemented vaccination programs to target identified at-risk adults in a variety of settings and at various times.22 The full impact of Australian vaccination programs from the 1990s should be reflected in trends in chronic infection and reductions in hepatitis B related complications in the near future.26
Between 2003 and 2013, unspecified hepatitis B rates remained relatively stable, increasing slightly by 4.2% from 29.0 to 30.2 per 100,000. It is important to note the significant impact of immigration on rates for unspecified hepatitis B. In 2011, an Australian study found that more than 95% of new cases of chronic hepatitis B virus infection entered the population through migration.27 While many cases of unspecified hepatitis B go undiagnosed, there is also the potential for duplication, with the National Hepatitis B Testing Policy encouraging clinicians to use patient records to prevent duplication of testing for people from culturally and linguistically diverse backgrounds.19
Newly acquired hepatitis B
- 172 cases of newly acquired hepatitis B were notified in 2013.
- The highest rates were in males aged 25–44 years.
Epidemiological situation in 2013
In 2013, 172 newly acquired hepatitis B notifications (0.7 per 100,000) were reported to the NNDSS, a 15% decrease compared with the 198 cases (0.9 per 100,000) reported in 2012 and a continuation of the downward trend in notification rates (Figure 3).
Geographical distribution
The highest rates were reported from the Northern Territory (2.5 per 100,000) and Western Australia (1.5 per 100,000).
Age and sex distribution
Overall, notification rates were higher among males than females, with a male to female ratio of 3.3:1. In 2013, the highest rates of newly acquired hepatitis B infection were observed among males aged 40–44 years, 30–39 years and 25–29 years (2.5, 2.3 and 2.2 per 100,000 respectively) (Figure 4).
Figure 4: Notification rate for newly acquired hepatitis B, Australia, 2013, by age group and sex*
* Excludes 1 notification where sex was not reported.
Text version of Figure 4 (TXT 1 KB)
Exposure to hepatitis B may be more common in certain high risk groups, including men who have sex with men; injecting drug users; Aboriginal and Torres Strait Islander peoples; prisoners; and immigrants from endemic regions.21,27 The greater representation of males in some of these groups may contribute to the higher notification rates among males.
Between 2003 and 2013, most age group specific notification rates were trending downwards. The most marked decreases occurred among those aged 15–19 years and 20–29 years. During this period, notification rates among the 20–29 years age group declined by 78% from 4.5 to 1.0 per 100,000 and notification rates among the 15–19 years age group declined by 75% from 2.2 to 0.5 per 100,000 (Figure 5). These declines are likely to be attributable in part to the adolescent hepatitis B vaccination program.28
Figure 5: Notification rate for newly acquired hepatitis B,* Australia, 2003 to 2013, by year and selected age groups
* Data for newly acquired hepatitis B for the Northern Territory (2003–2004) includes some unspecified hepatitis B cases.
Text version of Figure 5 (TXT 1 KB)
Risk groups
Enhanced data on risk factors and country of birth was provided by the Australian Capital Territory, New South Wales, South Australia, Tasmania, Victoria and Western Australia* (Table 10). In 2013, 44% (n=76) 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. Injecting drug use was the most frequently reported potential source of infection (47%), followed by skin penetration procedures (20%), which includes tattoos, ear or body piercing and acupuncture. Of the 106 cases for which country of birth was reported, 82 were in Australian born persons (77.4%) and 24 cases were born overseas.
* Prior to 2009 enhanced hepatitis B surveillance data were reported to the Kirby Institute from health authorities in the states and territories.
| Exposure category | Number of exposure factors reported | Percentage of total cases (n=76)|| | ||
|---|---|---|---|---|
| Male | Female | Total§ | ||
| * Cases from the Australian Capital Territory, New South Wales, South Australia, Tasmania, Victoria and Western Australia. While these jurisdictions provided enhanced data on risk factors, not all cases had this information recorded. † More than 1 exposure category for each case could be recorded. ‡ Analysis and categorisation of these exposures are subject to interpretation and may vary. § Total includes cases where no sex was reported. || The denominator used to calculate the percentage is based on the total number of cases from all jurisdictions that provide enhanced data (Australian Capital Territory, New South Wales, South Australia, Tasmania, Victoria and Western Australia). As more than 1 exposure category for each notification could be recorded, the total percentage does not equal 100%. ¶ Includes both occupational and non-occupational exposures. |
||||
Injecting drug use |
27 |
9 |
36 |
47 |
Imprisonment |
2 |
0 |
2 |
3 |
Skin penetration procedure |
12 |
3 |
15 |
20 |
Tattoos |
8 |
1 |
9 |
12 |
Ear or body piercing |
3 |
2 |
5 |
7 |
Acupuncture |
1 |
0 |
1 |
1 |
Healthcare exposure |
1 |
2 |
3 |
4 |
Surgical work |
1 |
0 |
1 |
1 |
Major dental surgery work |
0 |
2 |
2 |
3 |
Sexual exposure |
8 |
1 |
9 |
12 |
Sexual contact (hepatitis B positive partner) – opposite sex |
3 |
1 |
4 |
5 |
Sexual contact (hepatitis B positive partner) – same sex |
5 |
0 |
5 |
7 |
Other |
22 |
4 |
28 |
37 |
Household contact |
1 |
0 |
1 |
1 |
Needlestick/biohazardous injury¶ |
2 |
0 |
2 |
3 |
Perinatal transmission |
1 |
1 |
3 |
4 |
Other – not further categorised |
18 |
3 |
22 |
29 |
Cases with at least 1 exposure |
54 |
15 |
69 |
91 |
Undetermined |
5 |
2 |
7 |
9 |
Unknown* |
12 |
6 |
18 |
– |
Total exposure factors reported |
77 |
21 |
100 |
– |
Total number of cases |
59 |
17 |
76 |
– |
Unspecified hepatitis B
- 6,979 cases of unspecified hepatitis B were notified in 2013.
- The highest rates were in males aged 30–34 years.
Epidemiological situation in 2013
In 2013, 6,979 cases of unspecified hepatitis B infection were notified to the NNDSS, a rate of 30.2 per 100,000, compared with 6,538 cases (28.8 per 100,000) reported in 2012.
Geographical distribution
In 2013, the Northern Territory had the highest rate of unspecified hepatitis B infection (134.7 per 100,000) (Table 5).
Age and sex distribution
In 2013, the overall male rate (34.9 per 100,000) was higher than for females (25.2 per 100,000), a rate ratio of 1.4:1. Notification rates were higher among males in most age groups, peaking in males aged 30–34 years. For females, the peak notification rate occurred among those aged 25–34 years (Figure 6).
Figure 6: Notification rate for unspecified hepatitis B, Australia, 2013, by age group and sex*
* Excludes 41 cases where age and/or sex were not reported.
Text version of Figure 6 (TXT 1 KB)
Between 2003 and 2013, notification rates for unspecified hepatitis B remained relatively stable for most age groups. However, there has been a slight upward trend in the notification rate for the 15–19 years age group (from 16.5 to 21.7 per 100,000) and the 30–39 years age groups (from 53.9 to 62.6 per 100,000) (Figure 7).
Figure 7: Notification rate for unspecified hepatitis B,* Australia, 2003 to 2013, by year and age group†
* Data for hepatitis B (unspecified) from all states and territories except the Northern Territory between 2003–2004.
† Excludes 43 cases where age was not known.
Text version of Figure 7 (TXT 1 KB)
Hepatitis C
- 10,715 cases of hepatitis C were notified in 2013.
- Over the past 11 years, notifications of hepatitis C have declined by 33%.
Infection with hepatitis C virus 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.21
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 2013
Between 2003 and 2013, hepatitis C notifications declined by 33% from 13,748 (69.7 per 100,000) to 10,715 (46.8 per 100,000). This declining trend is reflected in both newly acquired and unspecified hepatitis C notifications (Figure 8).
Figure 8: Notification rate for hepatitis C (newly acquired* and unspecified†), Australia, 2003 to 2013, by year
* Data for newly acquired hepatitis C from all states and territories except Queensland 2003–2013 and the Northern Territory 2003–2004.
† Data for unspecified hepatitis C provided from Queensland (2003–2013) and the Northern Territory (2003–2004) includes both newly acquired and unspecified hepatitis C cases.
Text version of Figure 8 (TXT 1 KB)
Newly acquired hepatitis C
- 407 cases of newly acquired hepatitis C were notified in 2013.
- The majority of newly acquired cases in 2013 had a history of injecting drug use.
- The highest notification rates in 2013 were among males in the 20–24 years age group.
Epidemiological situation in 2013
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. Nationally, there were 407 notifications in 2013 (2.2 per 100,000) compared with 486 notifications in 2012 (2.7 per 100,000).
Geographical distribution
The highest rates of newly acquired hepatitis C infection were reported in Western Australia (4.9 per 100,000), South Australia, Tasmania and the Australian Capital Territory (all 3.7 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.
Age and sex distribution
Nationally in 2013, the notification rate for newly acquired hepatitis C in males was 3.0 per 100,000 and in females was 1.4 per 100,000, a male to female ratio of 2.2:1. Notification rates in males exceeded those in females across all age groups for which there were cases. The highest notification rates among males and females were in the 20–24 years (9.3 and 4.3 per 100,000 respectively), 25–29 years (8.8 and 4.5 per 100,000 respectively), and 30–34 years (6.5 and 3.5 per 100,000 respectively) age groups (Figure 9).
Figure 9: Notification rate for newly acquired hepatitis C, Australia,* 2013, by age group and sex†
* Data from all states and territories except Queensland.
† Excludes 2 cases where age and/or sex were not reported.
Text version of Figure 9 (TXT 1 KB)
Between 2003 and 2013, notification rates for newly acquired hepatitis C have declined overall among those in the 15–39 years age groups The largest decreases from 2003 to 2013 occurred in the 15–19 years age groups (from 6.5 to 3.5 per 100,000), and the 20–29 years age groups (from 11.7 to 6.9 per 100,000). A recent survey suggested there has been a decrease in the prevalence of injecting drug use among young people in Australia.28 Notification rates in the 0–4 and the 40 years or over age groups have remained low and relatively stable over this time (Figure 10).
Figure 10: Notification rate for newly acquired hepatitis C, Australia,* 2003 to 2013, by year and selected age groups
* Data from all states and territories except Queensland (2003–2013) and the Northern Territory (2003–2004).
Text version of Figure 10 (TXT 1 KB)
Risk groups
Exposure histories for newly acquired hepatitis C cases reported in 2013 were analysed for all jurisdictions except Queensland (notified as unspecified hepatitis C), Western Australia (no exposure data notified) and the Northern Territory (data not available at time of analysis) (Table 11). In 2013, 71.5% 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. Of the cases for which exposure history was reported, approximately 67% had a history of injecting drug use and approximately 32% reported skin penetration procedures.
| Exposure category | Number of exposure factors reported | Percentage of total cases (n=291)§ | ||
|---|---|---|---|---|
| Male | Female | Total | ||
| * Includes data from all states and territories except Queensland (not notified), the Northern Territory (data not available at time of analysis) and Western Australia (no enhanced data on risk factors). While 5 jurisdictions provided enhanced data on risk factors, not all cases had this information recorded. † 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 notified cases from all jurisdictions, except Queensland (notified as unspecified hepatitis C), 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%. || Includes both occupational and non-occupational exposures. |
||||
Injecting drug use |
142 |
53 |
195 |
67 |
Imprisonment |
100 |
11 |
111 |
38 |
Skin penetration procedure |
71 |
22 |
93 |
32 |
Tattoos |
54 |
13 |
67 |
23 |
Ear or body piercing |
17 |
9 |
26 |
9 |
Health care exposure |
9 |
7 |
16 |
6 |
Surgical work |
5 |
6 |
11 |
4 |
Major dental surgery work |
3 |
1 |
4 |
1 |
Haemodialysis |
1 |
0 |
1 |
<1 |
Sexual exposure |
21 |
20 |
41 |
14 |
Sexual contact (hepatitis B positive partner) – opposite sex |
9 |
19 |
28 |
10 |
Sexual contact (hepatitis B positive partner) – same sex |
12 |
1 |
13 |
5 |
Other |
68 |
35 |
103 |
35 |
Household contact |
14 |
10 |
24 |
8 |
Needlestick/biohazardous injury|| |
10 |
3 |
13 |
5 |
Perinatal transmission‡ |
17 |
15 |
32 |
11 |
Other – not further specified‡ |
27 |
7 |
34 |
12 |
Cases with at least 1 exposure |
202 |
81 |
283 |
97 |
Undetermined |
2 |
6 |
8 |
3 |
Unknown‡ |
3 |
4 |
7 |
– |
Total exposure factors reported |
411 |
148 |
559 |
– |
Total number of cases |
204 |
87 |
291 |
– |
Approximately 38% (n=111) of cases with exposure history had reported imprisonment. Of these cases, approximately 47% (n=52) had also reported a history of injecting drug use. However, it is important to note that screening rates are generally higher in the prison entry population than the general population. A screening survey of prison entrants conducted over a two-week period found that the prevalence of hepatitis C, based on hepatitis C antibody detection, was 22% in 2012, a decrease from 35% in 2007.29
Unspecified hepatitis C
- 10,308 cases of unspecified hepatitis C were notified in 2013.
- The highest notification rates in 2013 were among males in the 30–39 years age groups.
Epidemiological situation in 2013
In 2013, 10,308 cases of unspecified hepatitis C infections were notified to the NNDSS (44.6 per 100,000) compared with 9,641 cases in 2012 (42.4 per 100,000). Apart from the slight rise from 2012 to 2013, notification rates have decreased annually since 2003, with an overall decline of 33% between 2003 (66.5 per 100,000) and 2013 (44.6 per 100,000) (Figure 11).
Figure 11: Notification rate for unspecified hepatitis C, Australia,* 2003 to 2013, by selected age groups†
* Data provided from Queensland (2003–2013) and the Northern Territory (2003–2004) includes both newly acquired and unspecified hepatitis C cases.
† Excludes 80 cases where age was not reported.
Text version of Figure 11 (TXT 1 KB)
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.24,30 The continuing decline in the notification rate may also be attributable to an apparent decrease in the prevalence of injecting drug use among young people in Australia.28
Geographical distribution
In 2013, the Northern Territory continued to have the highest notification rate (106.1 per 100,000).
Age and sex distribution
Nationally in 2013, the notification rate for unspecified hepatitis C in males was 58.5 per 100,000 and in females 30.4 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 in the 35–39 year (112.3 per 100,000) and 30–34 year (111.8 per 100,000) age groups. The highest notification rates among females were for those in the 30–34 years (71.2 per 100,000) and 35–39 years (57.8 per 100,000) age groups (Figure 12).
Figure 12: Notification rate for unspecified hepatitis C,* Australia, 2013, by age group and sex†
* Data provided from Queensland includes both newly acquired and unspecified hepatitis C cases.
† Excludes 38 cases where age and/or sex was missing or unknown.
Text version of Figure 12 (TXT 1 KB)
Between 2003 and 2013, notifications rates for unspecified hepatitis C have declined overall across all age groups, except for the 0–4 years, 5–14 year and 40+ years age groups for which rates have remained relatively stable (Figure 11). The largest decreases have occurred in the 20–29 years (from 133.5 to 62.4 per 100,000), 30–39 years (135.4 to 88.7 per 100,000) and 15–19 years (37.9 to 19.0 per 100,000) age groups.
Hepatitis D
- 53 cases of hepatitis D were notified in 2013.
- Hepatitis D is always associated with hepatitis B co-infection.
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.21
Epidemiological situation in 2013
In Australia, the notification rate for hepatitis D remains low. In 2013, there were 53 notified cases of hepatitis D, a rate of 0.2 per 100,000. Over the preceding 10 years, notifications of hepatitis D remained relatively low with an average of almost 35 cases notified per year (range: 26 to 53).
Geographical distribution
In 2013, Victoria reported the highest number of cases (22) followed by Queensland (13), New South Wales (9), South Australia and Western Australia (both 4) and the Northern Territory (1). No cases were reported from the Australian Capital Territory or Tasmania during this period.
Age and sex distribution
The male to female ratio in 2013 was 1.8:1. This was less than the average ratio of 2.7:1 over the preceding 5 years (Figure 13).
Figure 13: Notified cases of hepatitis D, Australia, 2003 to 2013, by year and sex
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