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Bloodborne diseases

In 2001, bloodborne viruses reported to the NNDSS included hepatitis B, C, D and hepatitis (NEC). Diagnoses of infections with human immuno-deficiency virus (HIV) and acquired immune deficiency syndrome (AIDS) 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: http//www.med.unsw.edu.au/nchecr.

When reported to NNDSS, newly acquired hepatitis C and hepatitis B virus infections (referred to as 'incident') were differentiated from those where the timing of disease acquisition was unknown (referred to as 'unspecified'). As considerable time may have elapsed between onset and report date for chronic hepatitis infections, the analysis of unspecified hepatitis B and unspecified hepatitis C infections in the following sections is by report date, rather than by onset date.

Hepatitis B

Incident hepatitis B notifications

Since 1994, all states and territories, except the Australian Capital Territory, have reported incident cases of hepatitis B to the NNDSS. The Australian Capital Territory began reporting hepatitis B in 1995. The rate of incident hepatitis B notification between 1995 and 2000 ranges from around 1 to 2 cases per 100,000 population (Figure 5). In total, 424 incident cases were reported to the NNDSS with an onset date in 2001, giving a national notification rate of 2.2 cases per 100,000 population for the year. In 2001, the highest rates were reported from Tasmania (4.7 cases per 100,000 population) and Victoria (4.1 cases per 100,000 population).

Figure 5. Trends in notification rates, incident and unspecified* hepatitis B virus infection, Australia, 1995 to 2001



The highest rate of incident hepatitis B notifications were in the 20-24 year age group for both males and females (Figure 6). The highest notification rate for men was 9.8 cases per 100,000 population, while the highest notification rate for women was 5.8 cases per 100,000 population. Overall, there were more infections in males than in females, with a male to female ratio of 1.7:1.

Top of pageFigure 6. Notification rates for incident hepatitis B virus infections, Australia, 2001, by age group and sex



Trends in the age distribution of incident hepatitis B virus infections are shown in Figure 7. Rates in children aged 0-14 years and adults over 40 years of age have remained relatively stable, while increases have been observed in the 20-39 year age range.

Figure 7. Trends in notification rates of incident hepatitis B virus infections, Australia, 1995 to 2001, by age group



Risk factor information for incident hepatitis B virus infection was available from all states and territories, except New South Wales and Queensland. The data are summarised in Table 5.

Table 5. Risk factors identified in notifications of incident hepatitis B virus infection, Australia, 2001, by reporting state or territory

Risk factor	ACT		NT		SA		Tas		Vic		WA
	n	%	n	%	n	%	n	%	n	%	n	%
Injecting drug use*	1	50	0	-	5	21.7	15	68	94	48.0	13	33.3
Sexual contact with hepatitis   B case	0	-	0	-	7	30.4	2	9	66	33.7	9	23.1
Household/other contact with hepatitis   B	0	-	0	-	0	-	0	-	1	0.5	1	2.6
Overseas travel	0	-	0	-	1	4.3	0	-	0	-	2	5.1
Other	0	-	0	-	4	17.4	3	14	22	11.2		-
None identified	1	50	0	-	6	26.1	2	9	13	6.6	3	7.7
No information available	0		3	100	0	-	0	-	0	-	11	28.2
Total	2		3		23		22		196		39

* Injecting drug users may have multiple risk factors for hepatitis B virus infection.

In response to an outbreak of incident hepatitis B observed in Victoria during the second quarter of the year, the Victorian Department of Human Services commenced enhanced surveillance to obtain detailed risk factor information directly from cases. A public alert was released through needle and syringe programs, and a strategy implemented to provide free hepatitis B vaccine to people known to be injecting drug users.

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Unspecified hepatitis B notifications

Hepatitis B notifications have been reported to the NNDSS since 1991 by all jurisdictions except the Northern Territory, with unspecified cases separately notified from incident cases in most jurisdictions since 1994. The notification rate of unspecified hepatitis B cases ranged from 20 to 40 cases per 100,000 population between 1995 and 2001 (Figure 5). In 2001 there were 8,424 unspecified hepatitis B virus infection cases notified, at a rate of 43.7 cases per 100,000 population. The male to female ratio for unspecified hepatitis B cases was 1.3:1. By state and territory, the highest rates of notification were in New South Wales (71.3 cases per 100,000 population), Western Australia (34.1cases per 100,000 population) and Victoria (39.4 cases per 100,000 population). The highest rates were in the 40-44 year age group for men (93.9 cases per 100,000 population) and the 25-29 year age group for women (87.0 cases per 100,000 population, Figure 8).

Figure 8. Notification rates for unspecified hepatitis B virus infections, Australia, 2001, by age and sex*

* By report date.

Trends in the age distribution of unspecified hepatitis B virus infections are shown in Figure 9. There have been moderate decreases in the number of reports of unspecified hepatitis B cases in the 0-14 year age range, while all other age groups have shown an upward trend in reporting rates over time.

Figure 9. Trends in notification rates of unspecified hepatitis B virus infections, Australia, 1994 to 2001, by age group



There were nine cases of unspecified hepatitis B virus infection in children in the 0-4 year age group reported from New South Wales, South Australia, Queensland and Western Australia. No unspecified hepatitis B cases were identified in children aged 0-4 years in the Australian Capital Territory, the Northern Territory, Tasmania or Victoria. Infant hepatitis B immunisation for Indigenous infants was introduced in the Northern Territory in 1988 and then expanded to all infants in this jurisdiction in 1990. Universal infant hepatitis B immunisation was introduced in the rest of Australia in May 2000. The effect of vaccination may take a number of years to become observable in childhood rates of the disease. Data on vaccination coverage, provided by the Australian Childhood Immunisation Register, indicates approximately 95 per cent of infants are currently receiving hepatitis B vaccination in Australia.

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Hepatitis C

Unspecified hepatitis C notifications

Hepatitis C infection has been notifiable in all Australian states and territories since 1995. While the rate of unspecified hepatitis C notifications has ranged from 1.5 to 3 cases per 100,000 population in 1997 and 2000 respectively, (Figure 10), 2001 is the first year since 1997 where the number of notifications has decreased. Improved surveillance practice, such as better classification of incident cases and increased duplicate checking may account for some of the decrease in unspecified hepatitis C notifications. Whether the decrease represents a smaller pool of infected individuals previously undiagnosed will only become apparent in coming years.

Figure 10. Trends in notification rates, incident and unspecified* hepatitis C infection, Australia, 1995 to 2001

* By report date.

In 2001 there were 19,586 unspecified hepatitis C infections reported to NNDSS, a notification rate of 100.5 cases per 100,000 population. Of the total notifications of unspecified hepatitis C, 43 per cent of the notifications were from New South Wales. The highest notification rates were from the Northern Territory (106.5 cases per 100,000 population) and Victoria (103.1 cases per 100,000 population). The male to female ratio was 1.7:1. The highest reporting rate was in the 40-44 year age group for males (269.1 cases per 100,000 population), although there was little variation across the 25-44 year age range, from 240 to 269.1 cases per 100,000 population. The highest notification rate for females (175.1 cases per 100,000 population) was in the 20-24 year age group (Figure 11), while again there was little variation across the 20-44 year age range.

Figure 11. Notification rates for unspecified hepatitis C infections, Australia, 2001, by age group and sex*

* By report date.

Trends in the age distribution of unspecified hepatitis C infections are shown in Figure 12. Overall, the highest rates are in the 20-39 year age range. The most notable trends are the increase in notification rates in the 15-24 year age range and a decrease in the 30-39 year age group between 1998 and 2000. Between 2000 and 2001 there were decreases in all groups in the 15-39 year age range.

Top of pageFigure 12. Trends in notification rates of unspecified hepatitis C infections, Australia, 1995 to 2001, by age group*

* By report date.

Incident hepatitis C notifications

Reporting of incident hepatitis C notifications from New South Wales and Western Australia commenced in 1993, from the Australian Capital Territory in 1994, from South Australia and Tasmania in 1995 and from Victoria in 1997. Incident hepatitis C cases are not differentiated from unspecified hepatitis C cases in Queensland or the Northern Territory. For the purposes of this report, only incident hepatitis C cases from 1997 onwards were analysed.

In total there were 600 incident cases of hepatitis C reported with an onset date in 2001, giving a rate of 3.8 cases per 100,000 population. The proportion of all hepatitis C infection notifications that were identified as incident cases was three per cent in 2001, which continues the upward trend of this proportion since 1997, when the proportion was 0.9 per cent. The highest rates of incident hepatitis C infection in 2001 were reported from Western Australia (8.3 cases per 100,000 population), the Australian Capital Territory (5.6 cases per 100,000 population and South Australia (5.3 cases per 100,000 population). The majority of incident hepatitis C notifications were in the 20-24 year age group for both males and females, with rates of 20.3 and 13.7 cases per 100,000 population, respectively (Figure 13). Overall, the male to female ratio was 1.5:1.

Figure 13. Notification rates for incident hepatitis C infections, Australia, 2001, by age group and sex



Trends in the age distribution of incident hepatitis C infections are shown in Figure 14. While rates in the 0-14 year and over 40 year age groups have remained stable, increases were observed in the 15-39 year age range, with steep increases in the 20-39 year age range between 2000 and 2001.

Figure 14. Trends in notification rates of incident hepatitis C infections, Australia, 1997 to 2001, by age group



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Enhanced surveillance for incident hepatitis C infection notifications

In 1998 CDNA established the Hepatitis C Surveillance Committee. The committee was given the responsibility for improving the national capacity to monitor the occurrence of the infection and its consequences, by the development and implementation of a national hepatitis C surveillance strategy.⁷ In 2001, its terms of reference were extended to include the development of national surveillance for hepatitis B virus infection, and the name was changed to the CDNA Viral Hepatitis Surveillance Committee.

In reviewing existing procedures in the course of developing the surveillance strategy, the committee identified the lack of standard case definitions across jurisdictions, and the absence of information on risk factors for hepatitis C as key weaknesses in national surveillance. The committee endorsed standard case definitions, and a set of categories that would be used to classify exposure for all cases determined to be incident. Despite competing priorities and resource limitations, in 2001 some states and territories were able to introduce enhanced surveillance for incident hepatitis C infections.

Surveillance of incident hepatitis C infection cases is difficult due to the asymptomatic nature of the disease and the need to collect paired sera to diagnose recent infection by seroconversion. Detection of incident cases prior to 2001 was on the basis of seroconversion or clinical illness. In recognition that cases of transmission from mother to child would not usually be detected by either seroconversion or clinical illness, in 2001 perinatal cases were included as incident infections. Enhanced surveillance, where all hepatitis C notifications are further investigated to ascertain the likely time of infection, is time and labour intensive, due to the large number of notifications. Trends in the number of incident cases are affected by surveillance practice, and it is recognised that the number of hepatitis C notifications may vastly underestimate the true incidence of hepatitis C in Australia. The increase in incident hepatitis C notifications to the NNDSS should not necessarily be interpreted as evidence of increasing transmission in the Australian community. Instead the increase in the number of notifications may be a product of improved surveillance, increased awareness, and more widespread testing.

Incident hepatitis C cases have been separately reported by all jurisdictions except Queensland and the Northern Territory since 1997. In 2001, Western Australia, South Australia, Victoria, New South Wales and Tasmania undertook enhanced surveillance for incident cases. Enhanced surveillance has operated in South Australia and Tasmania for several years. Western Australia commenced enhanced surveillance for incident hepatitis C infections in 2001, incorporating new nationally agreed variables from the hepatitis C surveillance strategy. Data collection forms were sent to:

• doctors who notify cases as incident;
• doctors of patients identified by the major public laboratory as seroconverting within the past two years;
• a 30 per cent sample of doctors who notified unspecified hepatitis C infection cases.

All Public Health Units in New South Wales introduced enhanced surveillance in 2001. All hepatitis C notifications were followed up in a two phase process. Firstly, a form was sent to all doctors notifying a hepatitis C positive case, asking the doctor to indicate if the case was an incident infection. If a positive response was received, either the doctor or the case (with consent of the diagnosing doctor) were contacted, for collection of additional risk factor information. Efforts were taken to improve data quality by coordination and cleaning of the data at the New South Wales Health Department Central Office.

In Victoria, enhanced hepatitis C surveillance commenced in February 2001. In this populous state with a centralised reporting system, a 10 per cent random sample of all hepatitis C notifications were followed up with the diagnosing physician to determine if they were incident infections.

In 2001, additional data collected on incident hepatitis C infections were available from the Australian Capital Territory, South Australia, Tasmania and Victoria. The following analyses refer only to incident hepatitis C cases reported in these jurisdictions in 2001, thus the figures reported below may vary from the analysis by onset date. In total there were 209 cases: 18 cases from both the Australian Capital Territory and Tasmania, 86 cases from South Australia and 87 cases from Victoria. Most incident hepatitis C infections (165 of 209, 79%) were diagnosed by seroconversion alone (Table 6). Some cases were diagnosed both clinically and by seroconversion. One perinatal case was identified in South Australia.

Table 6. Method of diagnosis, incident hepatitis C cases, the Australian Capital Territory, South Australia, Tasmania and Victoria, 2001

Method of diagnosis	State or territory				Total
	ACT	SA	Tas.	Vic.
Seroconversion	18	71	14	62	165
Clinical	0	6	4	14	24
Seroconversion and clinical	0	8	0	11	19
Perinatal	0	1	0	0	1
Total	18	86	18	87	209

The majority (176/209, 84%) of cases of incident hepatitis C were associated with injecting drug use (IDU) (Table 7). Further analysis of exposure in people who did not report injecting drug use are shown in Table 8. Multiple exposures were recorded. Cases not reported to be associated with injecting drug use include transmission via blood transfusion (n=1), needle stick injuries in a healthcare worker (n=2), surgery (n=1), perinatal transmission (n=1), tattoos (n=1), ear or body piercing (n=1), imprisonment (n=5), and sexual partner with hepatitis C infection (n=4). One case with an exposure identified as 'other' was a victim of domestic violence by a partner with hepatitis C. In total, an exposure could not be identified for 16 non-IDU cases.

Top of pageTable 7. Assessment of injecting drug use, incident hepatitis C cases, Australian Capital Territory, South Australia, Tasmania and Victoria, 2001

Injecting drug use	State or territory
	ACT	SA	Tas.	Vic.
Only in previous 2 years	0	79	0	15
More than 2 years ago	0	0	0	50
IDU, but time not specified	14	0	18	0
No history of IDU	0	7	0	8
IDU status unknown	4	0	0	14
Total	18	86	18	87

IDU Injecting drug use

Table 8. Exposure assessment, incident hepatitis C cases, Australian Capital Territory, South Australia, Tasmania and Victoria, 2001

Risk factor	State or territory
	ACT		SA		Tas.	Vic.
	All cases (n=18)	Non-IDU* (n=4)	All cases (n=86)	Non-IDU* (n=7)	All cases (n=18)	All cases (n=87)	Non-IDU* (n=22)
Injecting drug use (IDU)	14	na	79	na	18	65	na
Household contact with hepatitis   C	1	0	0	0	0	0	0
Received blood product in Australia	0	0	1	1	0	0	0
Needlestick injury, healthcare worker	0	0	2	2	0	0	0
Surgical work	0	0	0	0	0	4	1
Perinatal	0	0	1	1	0	0	0
Tattoos	0	0	0	0	4	6	1
Ear/body piercing	0	0	0	0	2	4	1
Sexual partner with hepatitis C	1	0	0	0	4	14	4
Imprisonment	0	0	0	0	3	16	5
Household contact with hepatitis   C	0	0	0	0	1	0	0
Other risk identified	0	0	1	1	0	0	0
Non-IDU risk identified, but not in past 2 years	0	0	0	0	0	1	0
Unable to determine risk	4	4	2	2	0	10	10

Note: Some people may have more than one exposure.
* Includes those whose injecting drug use status was unable to be determined.

There may be selection bias in the analysis of exposure for incident cases, as injecting drug users are more likely to undergo regular testing, due to the recognised risk in this group. The most likely route of infection is difficult to determine when multiple possible exposures are recorded.

Projections of hepatitis C in Australia

It is recognised that notifications of hepatitis C infection do not provide an accurate estimate of the number of people in Australia living with hepatitis C infection. To plan an appropriate public health response to the epidemic, accurate estimates of incidence and prevalence, and projections of the long-term sequelae of infection, are required.

In 2001 the Hepatitis C Virus Projections Working Group undertook mathematical modelling of the epidemiology and natural history of hepatitis C infection in Australia, in order to estimate hepatitis C infection incidence and prevalence rates in Australia up to the end of 2001. Future trends in the long-term sequelae of hepatitis C infection were also modelled.⁸

It was estimated that in Australia in 2001 there would be 16,000 incident cases of hepatitis C infection, and that 210,000 (range 157,000-252,000) people will have antibodies to the virus. It was estimated that in 2001, 6,500 people were living with hepatitis C related cirrhosis, that 175 people developed hepatitis C associated liver failure, and that 50 people developed hepatitis C related hepatocellular carcinoma. Finally, it was estimated that 22,500 quality adjusted life years will have been lost in Australia in 2001 due to chronic hepatitis C infection, the majority (77%) in people with early (stage 0/1) liver disease. These models suggest that by 2020 the prevalence of hepatitis C related cirrhosis and the incidence of hepatitis C related liver failure and hepatocellular carcinoma will more than triple in Australia.

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Hepatitis D

The hepatitis D virus is a defective single-stranded RNA virus that requires the hepatitis B virus to replicate. Infection with the hepatitis D virus can be acquired either as a co-infection with hepatitis B virus infection or as a super-infection of persons with chronic hepatitis B virus infection. People co-infected with hepatitis B virus infection and hepatitis D may have more severe acute disease and a higher risk of fulminant hepatitis compared with those infected with hepatitis B virus alone. The modes of hepatitis D transmission are similar to those for other bloodborne viruses, and in countries with low prevalence of hepatitis B virus infection, such as Australia, intravenous drug users are the main group at risk.

In Australia in 2001, there were 21 notifications of hepatitis D to the NNDSS, a notification rate of 0.1 cases per 100,000 population. Of the 21 notifications, 12 were reported from New South Wales, seven from Victoria, and two from Queensland. The majority (16/21, 76%) of cases were for males, with the highest rate reported in the 35-39 year age group (0.5 cases per 100,000 population).


This article was published in Communicable Diseases Intelligence Volume 27, No 1, March 2003.