Results
Bloodborne diseases
Bloodborne viruses reported to the NNDSS include hepatitis B, C and D. HIV and AIDS diagnoses are reported directly to the National Centre in HIV Epidemiology and Clinical Research (NCHECR). Information on national HIV/AIDS surveillance can be obtained through the NCHECR website at www.nchecr.unsw.edu.au
Hepatitis B
Incident hepatitis B notifications
In 2006, 295 cases of incident hepatitis B infection were reported to NNDSS, which was higher than in 2005 (251). The Northern Territory recorded the highest notification rate in 2006 with 5.3 cases per 100,000 population. Over the past 10 years, the rate of notification of incident hepatitis B infection increased from 1.5 cases per 100,000 population in 1996 to 2.2 cases per 100,000 population in 2001, and then declined to 1.2 cases per 100,000 population in 2005 and increased to 1.4 cases per 100,000 population in 2006 (Figure 5).
Figure 5. Notification rate of incident hepatitis B and hepatitis B (unspecified), Australia, 1995 to 2006, by year*
* Year of onset for incident hepatitis B and year of report for hepatitis B (unspecified) notifications.
The increase in the number of incident hepatitis B notifications in 2006 may be a result of more complete case follow-up, as there was a corresponding decrease in hepatitis B (unspecified) notifications for the period.
In 2006, the 25–29 years age group among males had the highest rate of incident hepatitis B infection (5.5 cases per 100,000 population), whereas the 35–39 years age group had the highest notification rate among females (3.0 cases per 100,000 population; Figure 6). Notifications of incident hepatitis B infection in males exceeded those in females, with a male to female ratio of 1.6:1 in 2006.
Figure 6. Notification rate for incident hepatitis B infections, Australia, 2006, by age group and sex
Trends in incident hepatitis B infection by year and age group are shown in Figure 7. In 2000–2006, the notification rate of incident hepatitis B fell by 69% among cases in the 15–19 years age group, and by 52% among cases in the 20–29 years age group. The adolescent hepatitis B vaccination program for children aged 10–13 years that was introduced in 1997,1 may have played a role in this reduction for these age groups.
Figure 7. Notification rate of incident hepatitis B infections, Australia, 1995 to 2006, by year and age group
The source of exposure for cases of incident hepatitis B infection in 2006 was reported through health authorities in the Australian Capital Territory, South Australia, Tasmania and Victoria (Table 5). From 2002 to 2006, the proportion of notifications of incident hepatitis B infection associated with injecting drug use, remained relatively stable at approximately 51.0%. The proportion of diagnoses attributed to heterosexual contact decreased from about 21.0% between 2002 to 2005, to 11.4% in 2006. The source of exposure to hepatitis B was undetermined in approximately 26.0% of cases.
Table 5. Incident hepatitis B infection, Australia,* 2006, by exposure category†
Exposure category |
Number | Percentage |
|---|---|---|
| Injecting drug use | 68 |
51.5 |
| Sexual contact | 19 |
14.4 |
| Male homosexual contact | 3 |
2.3 |
| Heterosexual contact | 15 |
11.4 |
| Not specified | 1 |
0.8 |
| Blood/tissue recipient | 0 |
0.0 |
| Skin penetration procedure | 1 |
0.8 |
| Healthcare exposure | 0 |
0.0 |
| Household contact | 4 |
3.0 |
| Other | 5 |
3.8 |
| Undetermined | 35 |
26.5 |
| Total exposures | 132 |
100 |
Source: National Centre in HIV Epidemiology and Clinical Research 2007.
* Data include diagnosis in South Australia, Tasmania, Victoria and the Australian Capital Territory.
† More than one exposure category for each case could be recorded.
Hepatitis B (unspecified) notifications
| Case definition – Hepatitis B (unspecified)
Only confirmed cases are reported. Confirmed case: Detection of hepatitis B surface antigen or hepatitis B virus by nucleic acid testing in a case who does not meet any of the criteria for a newly acquired case. |
In 2006, a total of 6,296 cases of hepatitis B (unspecified) infection were notified to the NNDSS, compared with 6,336 in 2005. The Northern Territory recorded the highest notification rate (114.2 cases per 100 000 population), compared with other jurisdictions such as New South Wales (36.5 cases per 100,000 population) and Victoria (30.7 cases per 100,000 population). For 2006, the male to female ratio of notifications was 1.2:1. Among males, the highest notification rate was in the 25–29 and the 30–34 years age groups (66.1 and 66.0 cases per 100,000 population, respectively), whereas among females, the highest notification rate was in the 25–29 years age group (81.1 cases per 100,000 population), (Figure 8).
Figure 8. Notification rate for hepatitis B (unspecified) infection, Australia, 2006, by age group and sex
Notification rates of hepatitis B (unspecified) infection increased from 19.4 in 1996 to 42.8 in 2000 then declined to 30.6 cases per 100,000 population in 2006 (Figure 9). In 2006, rates of hepatitis B (unspecified) notifications continued to remain in the range of rates seen in 2003 to 2005 (29.2–31.2 cases per 100,000 population). Trends in hepatitis B (unspecified) infection by age group, sex and year are shown in Figure 9. Rates in the 15–19 years age group decreased in 2006 by 17.6% compared with 2005 (19.6 and 23.8 cases per 100,000 population, respectively).
Figure 9. Notification rate for hepatitis B (unspecified) infection, Australia, 1995 to 2006, by year and age group
In 2006, 5 cases of hepatitis B (incident) and 33 cases of hepatitis B (unspecified) infection were notified in children in the 0–4 years age group and represented 1.6% and 0.5% of all hepatitis cases notified respectively. Approximately 94% of infants born in Australia in 2006 received the hepatitis B vaccination.
Hepatitis C
Incident hepatitis C notifications
Case definition – Incident hepatitis COnly confirmed cases are reported. Confirmed case: Requires detection of anti-hepatitis C antibody or detection of hepatitis C virus in a case with a negative test recorded in the last 24 months OR detection of anti-hepatitis C antibody in a case aged 18 to 24 months or detection of hepatitis C virus in a case aged 1 to 24 months OR detection of anti-hepatitis C antibody or hepatitis C virus AND clinical hepatitis within the last 24 months (defined as jaundice, urine bilirubin or ALT seven times the upper limit of normal) where other causes of acute hepatitis have been excluded. |
Notifications of incident hepatitis C were received from all jurisdictions except Queensland, where all cases of hepatitis C are reported as hepatitis C (unspecified). A total of 431 cases of incident hepatitis C were notified in 2006 (374 cases in 2005), giving a rate of notification of 2.6 cases per 100,000 population (Figure 10). The proportion of all hepatitis C notifications in 2006 that were documented as incident cases was 3.5%, compared with 3% in 2005. The highest rates of incident hepatitis C infection were reported from Western Australia (5.3 cases per 100,000 population) and the Australian Capital Territory (4.9 cases per 100,000 population).
Top of pageFigure 10. Notification rate of hepatitis C infection (incident* and unspecified† ), Australia, 1995 to 2006
* Data from all states and territories except Queensland.
† Data provided from Queensland includes both incident and unspecified hepatitis C cases.
The increase in the number of incident hepatitis C notifications in 2006 may be a result of more complete case follow-up, as there was a corresponding decrease in hepatitis C (unspecified) notifications for the period.
In 2006, as in 2005, the highest rates of incident hepatitis C notifications were in the 25–29 years age group in males (11.6 cases per 100,000 population) and in the 20–24 and 25–29 years age groups in females (6.5 cases per 100,000 population) (Figure 11).
Figure 11. Notification rate of incident hepatitis C infection,* Australia, 2006, by age group and sex
* Data from all states and territories except Queensland.
Trends in the age distribution of incident hepatitis C infection are shown in Figure 12. From 2001 to 2006, notification rates declined by 56% in the 15–19 years age group, by 42% in the 20–29 years age range and by 21% in the 30–39 years age range. In 2005 to 2006, notification rates increased by 8.8% in the 20–29 years age range and by 29.6% in the 30–39 years age range.
Figure 12. Notification rate of incident hepatitis C infection,* Australia, 1997 to 2006, by age group and year
* Data from all states and territories except Queensland.
The exposure history of cases of incident hepatitis C were collected in the Australian Capital Territory, New South Wales, South Australia, Tasmania, Victoria and Western Australia in 2006 (Table 6). At least 62% of incident hepatitis C infections were among people with a history of injecting drug use.
Top of pageTable 6. Incident hepatitis C infection, Australia,* 2006, by exposure category†
Exposure category |
Number | Percentage |
|---|---|---|
| Injecting drug use | 295 |
62.2 |
| Sexual contact | 26 |
5.5 |
| Blood/tissue recipient | 2 |
0.4 |
| Skin penetration procedure | 37 |
7.8 |
| Healthcare exposure | 12 |
2.5 |
| Household contact | 2 |
0.4 |
| Other‡ | 30 |
6.3 |
| Undetermined | 70 |
14.8 |
| Total exposures | 474 |
100 |
Source: National Centre in HIV Epidemiology and Clinical Research 2007.
* Data includes diagnoses in the Australian Capital Territory, New South Wales, South Australia, Tasmania, Victoria, Western Australia and the Northern Territory.
† More than one exposure category for each case could be recorded.
‡ Includes cases for which the only reported risk factor was having been born to a woman with hepatitis C infection.
Hepatitis C (unspecified) notifications
| Case definition – Hepatitis C (unspecified)
Only confirmed cases are reported. Confirmed case: Requires detection of anti-hepatitis C antibody or detection of hepatitis C virus in a case who does not meet any of the criteria for a newly acquired case and is aged more than 24 months. |
In 2006, 12,057 hepatitis C (unspecified) infections were notified to NNDSS (12,023 in 2005). This figure differs slightly from figures reported in the National Centre in HIV Epidemiology and Clinical Research National Surveillance Report 20072 due to the late exclusion of 38 cases that did not meet the national case definition.
The national notification rate for hepatitis C (unspecified) infection declined from 104.0 cases per 100,000 population in 2001 to 58.5 cases per 100,000 population in 2006 (Figure 10). Improved surveillance practices, such as more complete follow-up and classification of incident cases and increased duplicate notification checks may account for some of the decrease in hepatitis C (unspecified) notifications.
In 2006, the Northern Territory continued to have the highest notification rate (110.8 cases per 100,000 population). Nationally, the male to female ratio was 1.7:1. The highest notification rates occurred in the 25–29, 30–34 and 45–49 years age groups (156.0, 150.2 and 152.6 cases per 100,000 population, respectively) among males and in the 25–29 years age group (99.3 cases per 100,000 population) among females (Figure 13).
Figure 13. Notification rate for hepatitis C (unspecified) infection,* Australia, 2006, by age group and sex
* Data provided from Queensland includes both incident and unspecified hepatitis C cases.
Trends in the age distribution of hepatitis C (unspecified) infection are shown in Figure 14. From 2000 to 2006, the notification rates of hepatitis C (unspecified) among the 15–19 years age group decreased by 78.8%. Notification rates also fell on average by 12% per year for the same period among cases in the 20–29 years age group and by 8.0% compared with 2005. In the 30–39 years age group, notification rates have also been declining on average by 9.7% per year since 2000. The decline in the population rate of notification of hepatitis C infection may be attributable to a reduction in risk behaviour related to injecting drug use, but changes in the rates of testing and percentage classified as incident cases may also have contributed to the decline.
Figure 14. Notification rate of hepatitis C (unspecified) infection,* Australia, 1995 to 2006, by age group
* Data provided from Queensland includes both incident and unspecified hepatitis C cases.
Although initial hepatitis C infection may be asymptomatic (more than 90% of cases) or mildly symptomatic, a high percentage (50%–80%) of cases develop a chronic infection. Of chronically infected persons, approximately 50% will eventually develop cirrhosis or cancer of the liver.3 In 2006, it is estimated that 271,000 people, living in Australia, had been exposed to the hepatitis C infection. Of these cases approximately 157,000 had early liver disease (stage F0/1), and 40,000 had moderate liver disease (stage F2/3) associated with chronic hepatitis C infection; 5,400 were living with hepatitis C related cirrhosis; and 68,500 had cleared their infection.2
Hepatitis D
| Case definition – Hepatitis D
Only confirmed cases are reported. Confirmed case: Detection of IgM or IgG antibodies to hepatitis D virus or detection of hepatitis D on liver biopsy in a case known to be hepatitis B surface antigen positive. |
Hepatitis D is a defective single-stranded RNA virus that requires the presence of the hepatitis B virus to replicate. Hepatitis D infection can occur either as a co-infection with hepatitis B or as a super-infection with chronic hepatitis B infection.3 People co-infected with hepatitis B and hepatitis D may have more severe acute disease and a higher risk of fulminant hepatitis compared with those with hepatitis B alone. The modes of hepatitis D transmission are similar to those for hepatitis B, and in countries with low hepatitis B prevalence, injecting drug users are the main risk group for hepatitis D.
There were 31 notifications of hepatitis D to the NNDSS in 2006, compared with 30 notifications in 2005, giving a notification rate of 0.15 cases per 100,000 population. The male to female ratio was 2.4:1. Of the 31 notifications, 15 were reported from New South Wales, 8 from Queensland, 7 from Victoria and 1 from Western Australia.
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Communicable Diseases Surveillance
This issue - Vol 32 No 2, June 2008
NNDSS Annual report 2006
Communicable Diseases Intelligence