A print friendly PDF version is available from this Communicable Diseases Intelligence issue's table of contents.

Sexually transmitted infections

A number of systems are involved in sexually transmitted infection (STI) surveillance in Australia, including the NNDSS, the Laboratory Virology and Serology Reporting Scheme (LabVISE) and specialist laboratory networks such as the Australian Gonococcal Surveillance Programme (AGSP). The NCHECR has an interest in STI surveillance, and have further analysed data from the NNDSS and other reporting sources in their annual surveillance report.

In 2000, STI reports accounted for 24,319 notifications to the NNDSS, which was 27 per cent of all notifications.

STIs reported to the NNDSS in 2000 included chancroid, chlamydial infection, donovanosis, gonococcal infection, lymphogranuloma venereum and syphilis. Laboratory diagnoses of chlamydia and syphilis were also reported via LabVISE. Other STIs not subject to national surveillance through the NNDSS or via LabVISE include genital herpes (herpes simplex virus type I and II), genital warts (human papilloma virus, several types), trichomoniasis and parasitic infestations such as pubic lice and scabies.

The trends in the number and rates of STI notifications reported to the NNDSS between 1991 and 2000 are shown in Tables 14 and 15. Notification rates for chancroid, lymphogranuloma venereum and syphilis remained relatively stable over the decade. The number of donovanosis notifications decreased over time, while increased numbers of chlamydia and gonococcal infections were reported. Some of the increases may be due to higher levels of infections. Changes in surveillance methods and laboratory tests (particularly the use of nucleic acid testing) may also account for some of the observed increases.

Table 14. Trends in notifications of sexually transmitted infections, Australia, 1991 to 2000*

Disease	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000
Chancroid	1	4	0	0	2	1	1	1	0	0
Chlamydial infection	-	-	-	6,153	6,407	8,366	9,239	10,927	14,045	16,866
Donovanosis	72	80	71	121	87	51	49	31	17	12
Gonococcal infection	2,705	2,889	2,811	2,968	3,308	4,144	4,684	5,469	5,644	5,686
Lymphogranuloma venereum	0	3	1	2	1	0	0	0	0	0
Syphilis	1,974	2,683	2,260	2,275	1,735	1,449	1,296	1,683	1,844	1,755

* All jurisdictions reported for all years with the following exceptions:
Chlamydial infection not reported from New South Wales (1994 to 1998).
Donovanosis not reported from New South Wales or South Australia (all years) or Tasmania (1991 to 1992).
Lymphogranuloma venereum not reported from Western Australia.

Table 15. Trends in notification rates of sexually transmitted infections, Australia, 1991 to 2000* (rate per 100,000 population)

Disease	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000
Chancroid	< 0.1	< 0.1	0.0	0.0	< 0.1	< 0.1	< 0.1	< 0.1	0.0	0.0
Chlamydial infection	-	-	-	52.2	53.7	69.1	75.4	88.2	74.1	88.0
Donovanosis	0.8	0.8	0.7	1.2	0.8	0.5	0.5	0.3	0.2	0.1
Gonococcal infection	15.7	16.5	15.9	16.6	18.3	22.6	25.3	29.2	29.8	29.7
Lymphogranuloma venereum	0.0	< 0.1	< 0.1	< 0.1	< 0.1	0.0	0.0	0.0	0.0	0.0
Syphilis	11.4	15.3	12.8	12.7	9.6	7.9	7.0	9.0	9.7	9.2

* All jurisdictions reported for all years with the following exceptions:
Chlamydial infection not reported from New South Wales (1994 to 1998).
Donovanosis not reported from New South Wales or South Australia (all years) or Tasmania (1991 to 1992).
Lymphogranuloma venereum not reported from Western Australia.

Chancroid

Cases of chancroid (a bacterial infection causing genital ulcers) have rarely been reported to the NNDSS since 1991. No cases of chancroid were reported in Australia in 2000, and in 2001 this disease was removed from the list of nationally notifiable diseases.

Top of page

Chlamydial infection

Chlamydial infections were the most commonly reported STI and the second most commonly reported notifiable disease in Australia in 2000. In this year 16,866 notifications of chlamydial infection were reported, an increase on the 14,045 cases reported in 1999 (Table 14). There were 81 cases reported in children aged less than 10 years. Notifications reported in young children may be cases of chlamydial conjunctivitis. In 2000, Queensland had a campaign of screening for chlamydial infections, including PCR testing of samples from young women and Indigenous people.

The notification rate for chlamydial infections in 2000 was 88 cases per 100,000 population, while in 1999 the rate was 74.1 cases per 100,000 population. This reflects an upward trend in the number of syphilis notifications reported to the NNDSS since 1997. In 2000, the male to female ratio was 0.7:1. In both males and females the highest rate of disease was recorded for the 20-24 year age group (Figure 20). High rates of notification were reported from northern Australia (including the Northern Territory, Western Australia and Queensland), with rates over 490 cases per 100,000 population in the Northern Territory in 2000 (Map 3).

Figure 20. Notification rates of chlamydia, Australia, 2000, by age and sex



Map 3. Notification rates of chlamydial infection, Australia, 2000, by Statistical Division of residence



Some important surveillance issues must be taken into account when analysing the trends in chlamydia notification rates. Firstly, in New South Wales, reporting of genital chlamydial infection commenced in September 1998, so that the reporting of this infection was national for the first time in 1999. Secondly, chlamydial infections may be under-reported because of the high proportion of asymptomatic infections, particularly among women.²⁷ The introduction of screening programs can have a marked effect on notification rates over time. Thirdly, the use of nucleic acid tests for chlamydia may also explain increases in notifications.

Based on NNDSS data, the NCHECR reported rates of chlamydial disease in Indigenous Australians.³⁶ Using data from the Northern Territory, South Australia and Western Australia (the only jurisdictions to report Indigenous status in more than half of notifications), the estimated crude rate of chlamydial infection among Indigenous Australians in 2000 was 1,207 cases per 100,000 population compared with a rate of 95 cases per 100,000 population in non-Indigenous Australians. For these jurisdictions, 831 of notifications did not have Indigenous status reported. Trends in notification rates of chlamydia in Indigenous and non-Indigenous Australians between 1993 and 2000 are shown in Figure 21.

Top of pageFigure 21. Trends in notification rates of chlamydia, the Northern Territory, South Australia and Western Australia, 1993 to 2000, by Indigenous status

Lymphogranuloma venereum

Lymphogranuloma venereum is a sexually acquired chlamydial infection caused by certain serovars of Chlamydia trachomatis. There were no cases of lymphogranuloma venereum reported from any State or Territory in 2000. In Australia, there have only been 7 reports of lymphogranuloma venereum to the NNDSS since 1991 and none since 1995. In 2001 lymphogranuloma venereum was removed from the list of nationally notifiable diseases in Australia.

Donovanosis

Donovanosis is a relatively uncommon STI, characterised by genital ulceration which may develop into a chronic ulcerative disease if untreated. Lesions may be extensive and extra-genital in some cases, and may be associated with secondary bacterial infection. Donovanosis is generally found in tropical countries, and in Australia occurs mostly in Indigenous people in rural and remote communities. The causative organism, formerly known as Calymmatobacterium granulomatis, has been redesignated Klebsiella granulomatis.

Donovanosis is a notifiable disease in all jurisdictions except New South Wales and South Australia. Notifications of donovanosis have fallen over the past 10 years, and particularly since 1994. Eradication of donovanosis was proposed as part of the 1997 National Indigenous Australians' Sexual Health Strategy, and since then significant advances have been made in the control of this disease in Indigenous Australians.³⁷ The decreases in notifications are due to earlier diagnosis and treatment (including the introduction of more sensitive and acceptable testing methods and more effective treatment with azithromycin), better education strategies, with a partnership approach encompassing Aboriginal and Torres Strait Islander people.

A total of 12 notifications of donovanosis were received in 2000, including five from the Northern Territory, six from Queensland and one from Western Australia. This represents a decrease from 1999, when 17 notifications were received nationally. In 2000, the highest rate of notifications was in the 25-34 year age range. The male to female ratio was 1:1, a change from 1999, when the male to female ratio was 1:7.

Gonococcal infection

The number of notifications of gonococcal infection in Australia has increased over the past decade. In 2000, a total of 5,686 notifications of gonococcal infection were received nationally (Table 14), similar to the 5,644 received in 1999. The notification rate of gonococcal infection has increased steadily from around 16 cases per 100,000 population in 1993 to around 30 cases per 100,000 population in 1998 to 2000 (Figure 22). This rate remains far below the very high rates recorded in the 1970s and early 1980s, which peaked at 84.4 cases per 100,000 population in 1982.³⁸ In 2000, Queensland and the Northern Territory had screening programs for gonococcal infection in Indigenous communities.

Figure 22. Trends in notification rates of gonococcal infections, Australia, 1991 to 2000



In 2000, the male to female ratio for gonococcal notifications was 2:1, similar to the ratio in previous years (in 1999 the ratio was 2.2:1). Peak notification rates for females (97 cases per 100,000 population) occurred in the 15-19 year age group. For males the corresponding group was the 25-29 year age group, where the notification rate was 105 cases per 100,000 population (Figure 23). There was a wide geographical variation in the rate of notification of gonococcal infection (Map 4). The highest rates of notification were from the Northern Territory (577 cases per 100,000 population) and from northern Statistical Divisions in Western Australia (Map 4).

Top of pageFigure 23. Notification rates of gonococcal infection, Australia, 2000, by age and sex



Map 4. Notification rates of gonococcal infections, Australia, 2000, by Statistical Division of residence



The increase in the number of gonococcal notifications is due in part to an ongoing outbreak of gonorrhoea among men who have sex with men.³⁹ The proportion of male cases of gonococcal infection associated with homosexual contact was reported in four jurisdictions and varied from 28 per cent in metropolitan Western Australia to 75 per cent in Tasmania. Increased acceptance of non-invasive sample collection for nucleic acid testing may also increase testing rates and encourage opportunistic screening, leading to increased diagnoses. Increased testing may also result from the introduction of sexual health programs and other health promotion activities.

The NCHECR reported rates of gonococcal disease in Indigenous Australians, based on the NNDSS data.³⁶ These analyses are based on data from the Northern Territory, South Australia and Western Australia, which were the only jurisdictions to report Indigenous status in more than half of notifications. From these three jurisdictions, 11 per cent of notifications did not have Indigenous status recorded. It is estimated that in 2000 the rate of gonococcal infections among Indigenous Australians was 1,608 per 100,000 population, compared with a rate of 36 per 100,000 population in non-Indigenous Australians, largely explaining the geographic variation in notifications of gonococcal infection. This represents an increase in gonococcal notification rates since 1993 for Indigenous Australians (Figure 24). Small increases were also observed in non-Indigenous Australians.

Top of pageFigure 24. Trends in notification rates of gonococcal infections, the Northern Territory, South Australia and Western Australia, 1993 to 2000, by Indigenous status



The Australian Gonococcal Surveillance Programme is the national laboratory-based surveillance system that documents the antibiotic sensitivity of gonococcal isolates. The program is undertaken by a network of reference laboratories in each state and territory, using agreed standard methodology to quantitatively determine the susceptibility of gonococci to a core group of antibiotics. Surveillance of antibiotic resistance in gonococci is important, as resistance rates can be quite volatile, and it is recommended that a particular treatment regime be discontinued once 5 per cent of isolates are resistant to that agent.

A survey of the antibiotic susceptibility of Neisseria gonorrhoeae by the AGSP in 2000, has been published.⁴⁰ The proportion of Neisseria gonorrhoea isolates with antibiotic resistance in the WHO Western Pacific Region for 2000 have been compared.⁴¹ Table 16 shows the trends in antibiotic resistance in Australia between 1998 and 2000. As in previous years, antibiotic susceptibility patterns in 2000 varied significantly between regions. Generally, rates of resistance to penicillin and quinolone groups of antibiotics were higher in urban than in rural areas. Quinolone resistance became more widespread in 2000, with increases in Queensland, Western Australia and South Australia. A high rate of quinolone resistant gonococci isolated from homosexually active men was observed in 1999 in New South Wales and Victoria. High rates were again seen in 2000 in Victoria, but not in New South Wales.

Table 16. Proportion of gonococcal isolates showing antibiotic resistance, Australia, 1998 to 2000

Year	Penicillin (% resistant)		Quinolone resistance (% resistant)	High level tetracycline resistance (% resistant)
	Plasmid mediated resistance	Chromosomally mediated resistance
1998	5.3	21.8	5.2	NR
1999	7.4	14.3	17.2	7.9
2000	8.7	10.6	17.8	9.1

NR not recorded

Top of page

Syphilis

In 2000, all jurisdictions reported syphilis (including primary, secondary and latent syphilis) and congenital syphilis to the NNDSS. A total of 1,755 notifications of syphilis were received in 2000 (Tables 14 and 15) with a rate of 9.2 cases per 100,000 population, consistent the rate in 1999 (1,844 notifications, a rate of 9.7 cases per 100,000 population). The peak notification rate occurred in 1992. Rates have since decreased and been relatively stable since 1998 (Table 15).

In 2000, there was wide geographical variation in the notification rate for syphilis (Table 14, Map 5). The highest rate was described in the Northern Territory (89.5 cases per 100,000 population). The male to female ratio for syphilis notifications was 1.2:1. Notification rates were higher among females in the 25-29 year age group (21.8 cases per 100,000 population). In comparison, the corresponding peak age group for males was the 50-54 year age group, where the rate was 17.4 cases per 100,000 population, although the reporting rates in all age groups for adult males is generally quite similar (Figure 25).

Map 5. Notification rates of syphilis, Australia, 2000, by Statistical Division of residence


Figure 25. Notification rates of syphilis, Australia, 2000, by age and sex



In 2000, there were 5 cases of syphilis reported in the 0-4 year age group, and 2 cases in 5-9 year age group. Of these, 2 cases (one each in New South Wales and Queensland) were confirmed as congenital syphilis.

The NCHECR has reported rates of syphilis in Indigenous Australians based on NNDSS data.³⁶ These estimates are based on data from the Northern Territory, South Australia and Western Australia, which were the only jurisdictions to report indigenous status in more than half of notifications. Of the reports from these jurisdictions, only 4 per cent did not have Indigenous status identified. The estimated rate of syphilis among Indigenous Australians in 2000 was 176 per 100,000 population compared with a rate of 2.8 per 100,000 population in non-Indigenous Australians. Trends in notification rates of syphilis in Indigenous and non-Indigenous Australians from these states and territories between 1993 and 2000 are shown in Figure 26.

Figure 26. Notification rates of syphilis, the Northern Territory, South Australia and Western Australia, 1993 to 2000, by Indigenous status




This article was published in Communicable Diseases Intelligence Volume 26, No 2, June 2002