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Bloodborne diseasesThe bloodborne viruses notified to the NNDSS are hepatitis B, C and D. Notification of new HIV diagnoses is made through the National Centre in HIV Epidemiology and Clinical Research (NCHECR), which reports separately in its Annual Surveillance Report.12 Information on the HIV data collection can be obtained through the NCHECR Website at: http://www.med.unsw.edu.au/nchecr.
National case definitions for incident hepatitis B and hepatitis C require the presence of current illness together with serological evidence of infection, or alternatively specific serological evidence of recent infection or seroconversion. Notifications of hepatitis B and hepatitis C that do not meet the incidence case definition are recorded as 'unspecified.' Collectively, these hepatitis cases represented 31% of all notifications to the NNDSS in 1998; similar to 1997.
Hepatitis BIncident cases of hepatitis B have been notified nationally since 1994. In 1998, 261 incident cases were reported to the NNDSS with a national notification rate of 1.4 per 100,000; consistent with the rates of 1997 (1.3 per 100,000) and 1996 (1.2 per 100,000). The highest rates were reported from the Northern Territory (9.5 per 100,000), Victoria (1.9 per 100,000) and Western Australia (1.7 per 100,000). The majority of notifications were in the 15-34 years age groups (Figure 1). Incident infections in males exceeded females with a male to female ratio of 1.8:1.
Unspecified hepatitis B has been notified to the NNDSS by all jurisdictions since 1997. In 1998, 6,682 unspecified cases were notified at a rate of 35.6 per 100,000 (Tables 1 and 2), slightly lower than the rate of 38.4 per 100,000 in 1997. The male to female ratio for unspecified cases was 1.2:1 (Figure 1). The highest rates of notification were in New South Wales (51.5 per 100,000), Victoria (44.9 per 100,000) and Queensland (28.9 per 100,000).
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Figure 1. Notification rate of hepatitis B (incident), 1998, by age group and sex
Hepatitis CIn 1998, all States and Territories reported unspecified cases of hepatitis C. Incident cases were reported by all jurisdictions with the exception of Queensland and Northern Territory.
There were 343 incident cases of hepatitis C reported in 1998, with a rate of 2.2 per 100,000. The total number of hepatitis C notifications (incident and unspecified) was similar in 1998 and 1997. However, the proportion of all notifications that are known incident cases increased from 0.1% (81/19,700) in 1997 to 1.7% (343/19,604) in 1998. The highest rates of incident hepatitis C infection were reported from Western Australia (6.8 per 100,000) and South Australia (4.4 per 100,000). The majority of notifications were in the 15-29 years age groups (Figure 2).
Unspecified hepatitis C accounted for 19,261 notifications; a notification rate of 102.7 per 100,000, similar to 106.3 per 100,00 in 1997. Thirty-nine per cent of notifications came from New South Wales. The highest notification rates were in the Northern Territory (147.4 per 100,000), Victoria (121.9 per 100,000), New South Wales (120.0 per 100,000) and the Australian Capital Territory (94.0 per 100,000). The male to female ratio was 1.6:1. Most notifications were between the ages of 20 and 49 years, for both males (84%) and females (79%).
Figure 2. Notification rate of hepatitis C (unspecified), 1998, by age group and sex
Hepatitis DThere were 14 notifications of hepatitis D to the NNDSS for 1998, at a notification rate of 0.07 per 100,000. All cases were males aged from 20 to 59 years.
DiscussionSurveillance efforts to identify which notified cases are incident cases of hepatitis C are evident in the increased proportion of incident cases of hepatitis C in 1998. However, under-reporting remains an important issue.
The age distributions for incident hepatitis C and incident hepatitis B notifications were similar, being most prevalent in the 15-34 years age groups. For incident hepatitis C there was a male predominance in the 20-29 year age group but a predominance of females in the 15-19 years age group. For incident hepatitis B there was a male predominance in the 20-29 years age groups and similar levels for males and females in the 15-19 years age group. For both incident hepatitis B and C notification rates were relatively constant for females in the 15-29 years age groups. In contrast, for males the notification rates were higher in the 20-29 years age groups than the 15-19 years age group. Overall the 15-34 years age groups in particular those with higher notification rates, are at risk of transmission and are appropriate targets for public health interventions. As the main route of transmission of hepatitis B and C is via intravenous drug use in Australia,16 appropriate public health interventions are based around this route of transmission.
This article was published in Communicable Diseases Intelligence Volume 23, No 11, 28 October 1999.
CDI Vol 23, No 11, 28 October 1999
NNDSS Annual report 1998