This article was published in Communicable Diseases Intelligence Vol 35 Number 2, June 2011 and may be downloaded as a full version PDF file (1854 KB).
Sexually transmissible infections
In 2009, the sexually transmissible infections (STIs) reported to the NNDSS were chlamydial infection, donovanosis, gonococcal infection and syphilis. Other national surveillance systems that monitor STIs in Australia include the Australian Gonococcal Surveillance Programme (AGSP), which is a network of specialist laboratories monitoring antimicrobial susceptibility patterns of gonococcal infection, and the Kirby Institute, which maintains the National HIV Registry and the National AIDS Registry.
The national trends in the number and rates of STI notifications reported to the NNDSS between 2004 and 2009 are shown in Table 6. In interpreting these data it is important to note that changes in notifications over time may not solely reflect changes in disease prevalence: changes in screening programs,38,39 the use of less invasive and more sensitive diagnostic tests and periodic public awareness campaigns may influence the number of notifications that occur over time. For some diseases, changes in surveillance practices may also need to be taken into account when interpreting national trends.
Direct age standardised notification rates, using the method described by the Australian Institute of Health and Welfare,40 were calculated for Indigenous and non-Indigenous notifications for jurisdictions that had Indigenous status data completed for more than 50% of notifications over the period 2004 to 2009. Where the Indigenous status of a notification was not completed, these notifications were counted as non-Indigenous in the analysis. These data however, should be interpreted with caution as STI screening occurs predominately in specific high risk groups, including in Indigenous populations. Previous research into high rates of STIs amongst the Indigenous population in the Northern Territory suggested that the disparity in notification rates could be attributed to more targeted screening programs and poorer access to primary health care services, rather than to increased levels of transmission amongst Indigenous people.41,42 Similarly, the differences in rates between females and males should be interpreted with caution, as rates of testing for STIs, symptom status, health care-seeking behaviours, and partner notification differ between the sexes.43
In the national case definitions for chlamydial, gonococcal and syphilis infections the mode of transmission cannot be inferred from the site of infection. Infections in children may be acquired perinatally (e.g. gonococcal conjunctivitis).44 Notifications of chlamydial, gonococcal and non-congenital syphilis infections were excluded from analysis where the case was aged less than 13 years and the infection was able to be determined as non-sexually acquired.
Chlamydial infection
Chlamydial infection continued to be the most commonly notified disease in 2009. Since chlamydial infection became a nationally notifiable disease in 1991 (1997 in New South Wales), the rate has increased in each consecutive year. In 2009, there were a total of 62,660 notifications of chlamydial infection, equating to a rate of 286 per 100,000 population. This represents an increase of 5% compared with the rate reported in 2008 (273 per 100,000 population). Between 2004 and 2009, chlamydial infection notification rates increased by 61%, from 180 to 286 per 100,000 population (Table 6).
Map 2: Notification rates and counts* for chlamydial infection, Australia, 2009, by Statistical Division and Statistical Subdivision of residence in the Northern Territory
* Numbers in the shaded Statistical Divisions and Statistical Subdivisions represent the count of notifications.
Chlamydial infection notification rates were substantially higher than the national rate in the Northern Territory (941 per 100,000 population), Western Australia (395 per 100,000 population) and Queensland (379 per 100,000 population) (Table 5). At a regional level, chlamydial infection notification rates were highest in the Central NT Statistical Subdivision of the Northern Territory and the Kimberley Statistical Division of Western Australia (range: 1,152–1,692 notifications per 100,000 population), noting that notification rates in geographic areas where the estimated residential population and case numbers are small, should be interpreted with caution. Notifications rates were also substantially higher than the national rate (range: 446–1,152 notifications per 100,000 population) in the Statistical Divisions of the Far North West and Northern Queensland, the Pilbara, Central and South Eastern Western Australia, and the remaining Northern Territory Statistical Subdivisions, (Map 2).
In 2009, notification rates of chlamydial infection in males and females were 236 and 336 per 100,000 population respectively. When compared with 2008, notification rates increased by 7% in males and 4% in females. The male to female ratio in 2009 was 0.7:1, which was similar to previous years. Rates in females markedly exceeded those in males, especially in the 10–14 and 15–19 years age groups with ratios of 0.1:1 and 0.3:1, respectively (Figure 25).
Figure 25: Notification rate for chlamydial infection, Australia, 2009, by age group and sex*
* Excludes 115 notifications for whom age or sex were not reported.
Between 2004 and 2009, there was an increasing trend in chalmydia notification rates across all age groups, except the 10–14 years age group, and in both males and females (Figure 26). The greatest increase in notifications rates occurred in both males and females in the 15–19 (10% and 68% respectively) and the 20–29 (55% and 51% respectively) years age groups. These age groups accounted for around 80% of the annual number of notifications over the period 2004 to 2009.
Figure 26: Notification rate for chlamydial infection in persons aged 10-39 years, Australia, 2004 to 2009, by age group and sex
From 2004 to 2009, the rates of chlamydial infection diagnoses increased in both Indigenous and non-Indigenous populations. Nationally in 2009, data on Indigenous status were complete in 49% of notifications; higher than the preceding 5-year average of 44% (range: 40%–48%). It should be noted that the completeness of Indigenous status identification in the notification data varies by year and by jurisdiction. Four jurisdictions had greater than 50% completeness of the Indigenous status field across the 2004 to 2009 period: the Northern Territory, South Australia, Tasmania and Western Australia. Among these jurisdictions, the combined age standardised notification rate ratio between Indigenous and non-Indigenous populations in 2009 was 3.6:1, with the disparity in notification rates improving substantially since 2000.
Between 2006 and 2008, rates of chlamydial infection notifications amongst these jurisdictions remained relatively stable at around 1,226 per 100,000 in the Indigenous population, but increased in the non-Indigenous population by 32%. In 2009, the rate of notifications in the Indigenous population declined by 10% compared with 2008, with relatively no change observed in the non-Indigenous population. At the jurisdictional level, between 2008 and 2009, chlamydia notification rates in the Indigenous population decreased in the Northern Territory, South Australia and Western Australia, while rates in their non-Indigenous counterparts remained relatively stable (Figure 27). The overall high Indigenous rates observed in the Northern Territory may be partly explained by high levels of screening, which take place in remote Indigenous communities.
Figure 27: Notification rate for chlamydial infection, selected states and territories,* 2004 to 2009, by Indigenous status
* Includes notifications in the Northern Territory, South Australia, Tasmania and Western Australia where Indigenous status completeness was reported for more than 50% of cases between 2004 and 2009.
Between May 2007 and June 2010, the Australian Department of Health and Ageing funded a pilot program called the Australian Collaboration for Chlamydia Enhanced Surveillance (ACCESS). The aim of the program was to monitor the uptake and outcome of chlamydia testing in Australia through a range of sentinel sites including sexual health services, general practices and laboratories. In 2009, ACCESS identified that chlamydia positivity, amongst people who accessed the sentinel sites, was 10.6% amongst males and 9.3% amongst females, with positivity highest in the 16–19 years age group across most of the sentinel sites.18, 45 Enhanced surveillance of chlamydial notifications undertaken in Tasmania during 2008 identified that 57% of males presented as asymptomatic compared with 70% of females (personal communication, David Coleman, Tasmanian Department of Health and Human Services, 2 July 2010). Enhanced chlamydial surveillance data in Tasmania for the period 2001 to 2007 noted that females were more likely to have been tested for chlamydial infection as a result of screening, and males were more likely to have been tested when presenting with symptoms or as a result of contact tracing.43 Therefore, notification rates for chlamydia, and other STIs, are particularly susceptible to overall rates of testing as well as targeted testing in certain high risk population sub-groups.
Donovanosis
Donovanosis was targeted for elimination in Australia through the National Donovanosis Elimination Project.46 It predominantly occurred in rural and remote Indigenous communities in central and northern Australia and is now relatively uncommon. In 2009, one notification was reported to the NNDSS in an Indigenous male from Queensland (Figure 28).
Figure 28: Notifications of donovanosis, Australia, 1991 to 2009, by sex and year
Gonococcal infections
In 2009, 8,059 notifications of gonococcal infection were reported to the NNDSS, equating to a notification rate of 36.8 per 100,000 population. This was a slight increase compared with 2008 (35.7 per 100,000 population). Due to a reporting issue, gonococcal notification data for Queensland is under-reported in 2009 and therefore should be interpreted with caution.
The highest notification rate in 2009 was in the Northern Territory (669 per 100,000 population), which was almost 18 times higher than the national rate (Table 5). Considerable declines in notification rates between 2008 and 2009 were observed in Western Australia (23%), South Australia (20%) and Tasmania (17%). Increases in notification rates for the same period were observed in Victoria (64%) and New South Wales (22%), with the Australian Capital Territory reporting an increase from 6.1 to 15.7 per 100,000 population.
Nationally, there was an increase in the gonococcal infection notification rates in males (6%) and a decrease in females (3%). Gonococcal infection notification rates were over two times higher amongst males compared with females (49.7 and 24.0 per 100,000 population respectively). The male to female rate ratio in 2009 was 2:1, which is similar to the previous 5 years. As in previous years, the exception to this pattern was the Northern Territory, where females had an overall higher notification rate than males (677 compared with 242 per 100,000 population). Nationally, notification rates of gonococcal infection in males exceeded those in females in all age groups except in the 10–14 and 15–19 years age groups (Figure 29).
Figure 29: Notification rate for gonococcal infections, Australia, 2009, by age group and sex*
* Excludes 20 notifications for whom age or sex were not reported.
Trends in age specific notification rates show that there was an increase in gonococcal notifications amongst males in the 20–29 years age range in 2009 compared with 2007 and 2008. The notification rate of gonococcal infection in females across most age groups continued to have slight declines, with a small increase observed in the 20–29 years age group between 2008 and 2009 (Figure 30).
Figure 30: Notification rate for gonococcal infection in persons aged 10-49 years, Australia, 2004 to 2009, by age group and sex
In 2009, the data completeness of the Indigenous status field for gonococcal infection notifications was 65%, which was a decrease compared with previous years (around 70%). Six jurisdictions had greater than 50% completeness of the Indigenous status field: the Northern Territory, Queensland, South Australia, Tasmania, Victoria and Western Australia. Amongst these jurisdictions the combined age standardised notification rate for gonococcal infection was 634 per 100,000 in the Indigenous population and 24 per 100,000 in the non-Indigenous population resulting in an Indigenous to non-Indigenous rate ratio of 27:1. Between 2008 and 2009, rates of gonococcal infection notifications in the Indigenous population declined by 40% in Western Australia and 30% in Queensland, with a small decline also observed in the Northern Territory (3%). For the same period, an increase in the Indigenous notification rate of gonococcal infections was observed in South Australia (20%). Rates in the non-Indigenous population remained relatively stable over the 2004 to 2009 period, with declines observed in the Northern Territory between 2006 and 2009 (Figure 31). The overall high Indigenous rates observed in the Northern Territory may be partly explained by high levels of screening which take place in remote Indigenous communities.
Figure 31: Notification rate for gonococcal infection, selected states and territories,* 2004 to 2009, by Indigenous status and year
* Includes notifications in the Northern Territory, Queensland, South Australia, Tasmania, Victoria and Western Australia where Indigenous status completeness was reported for more than 50% of cases over a 5-year period.
Other surveillance of gonococcal infections
The AGSP is the national surveillance system for monitoring the antimicrobial resistance of Neisseria gonorrhoeae isolates, via a network of public and private reference laboratories located in each jurisdiction. Susceptibility testing to a core group of antibiotics: penicillin, ceftriaxone, spectinomycin, quinolone and tetracycline is performed on gonococcal isolates using a standardised methodology.
In 2009, the AGSP reported47 a total of 3,220 gonococcal isolates that were tested for antibiotic susceptibility, representing approximately 40% of gonococcal infection notifications. The decreasing number of gonococcal isolates available for susceptibility testing is affected by the increasing use of non-culture based diagnosis methods.
Of the total number of isolates collected through the AGSP in 2009, there were 2,622 isolates from males, 596 isolates from females (male to female ratio 4.4:1) and there were 2 isolates for which the sex was not reported. In males, 71% of isolates were obtained from the urethra, 17% from the rectum and 10% from the pharynx. In females, the majority of isolates (89%) were obtained from the cervix.
In 2009, approximately 36% of gonococcal isolates had some level of resistance to the penicillins and 43% had some level of resistance to the quinolone antibiotic group. Since 2001, low numbers of isolates with decreased susceptibility to ceftriaxone have been identified in Australia, with 2% of isolates being ‘non-susceptible’ in 2009. As in previous years, the pattern of gonococcal antibiotic susceptibility differed between states and territories, and rural and urban areas within each jurisdiction,48 where for example, in remote areas of some jurisdictions with high disease rates, penicillin-based treatments continue to be effective.
Syphilis (non-congenital)
In 2004, all jurisdictions began reporting to the NNDSS non-congenital syphilis infections categorised as: infectious syphilis (primary, secondary or early latent) of less than 2 years duration; and syphilis of more than 2 years or unknown duration. However, in South Australia, only notifications of infectious syphilis are reported to the NNDSS. Detailed analyses are reported for these two categories, as well as for syphilis of the combined categories (syphilis – all categories) for the purpose of showing trends in previous years.
In 2009, a total of 2,676 notifications of syphilis infection of all non-congenital categories were reported, representing a notification rate of 12.2 per 100,000 population; a slight decrease compared with 2008 (12.5 per 100,000 population) (Table 6, Figure 32). The Northern Territory continued to have the highest notification rate of syphilis (61 per 100,000 population), although the rate was 47% lower than in 2008. In 2009, there were increases in notification rates in Tasmania (26%), Queensland (15%), Victoria (7%), New South Wales (7%) and South Australia (5%). As in other developed countries, syphilis infection rates have continued to rise in Australia, predominantly affecting men who have sex with men.49,50
Syphilis – infectious (primary, secondary and early latent), less than 2 years duration
In 2009, 1,291 cases of infectious syphilis (primary, secondary and early latent), less than 2 years duration, were reported to the NNDSS. This represents a notification rate of 5.9 per 100,000 population, a decrease of 4% compared with 2008 (6.1 per 100,000 population) (Table 5). The rate of infectious syphilis notifications increased from 3.1 per 100,000 population in 2004 to 6.7 in 2007 and then declined to 5.9 in 2009 (Figure 32). Although the Northern Territory had the highest notification rate at 17 per 100,000 population in 2009, this was a substantial decrease compared with 2008 (38 per 100,000 population). The decrease was approximately the same in both sexes, even though there continued to be more cases in males than in females.51
Figure 32: Notification rate for non-congenital syphilis infection (all categories), Australia, 2004 to 2009, by year
Nationally, the notification rates of infectious syphilis for males and females were 10.8 and 1.4 per 100,000 population respectively, and represented a male to female ratio of 8:1 (Table 15). Notification rates in males were highest in the 40–44 years age group (27 per 100,000 population), closely followed by the 35–39 years age group (23 per 100,000), whereas in females the highest notification rates were observed in the 20–24 and 25–29 years age groups (3.0 and 2.9 per 100,000 population respectively) (Figure 33).
Table 15: Notifications and rates* for infectious syphilis (less than 2 years duration), Australia, 2009, by state or territory and sex†
| Male | Female | Total† | ||||
|---|---|---|---|---|---|---|
State or territory |
Count | Rate* | Count | Rate* | Count | Rate* |
| ACT/NSW | 504 |
13.7 |
22 |
0.6 |
533 |
7.2 |
| NT | 18 |
15.4 |
34 |
31.4 |
38 |
16.9 |
| Qld | 168 |
7.6 |
20 |
0.9 |
179 |
4.1 |
| SA | 44 |
5.5 |
7 |
0.9 |
53 |
3.3 |
| Tas | 10 |
4.0 |
2 |
0.8 |
10 |
2.0 |
| Vic | 369 |
13.7 |
17 |
0.6 |
390 |
7.2 |
| WA | 62 |
5.5 |
47 |
4.3 |
88 |
3.9 |
| Total | 1,175 |
10.8 |
149 |
1.4 |
1,291 |
5.9 |
* Notification rate per 100,000 population.
† Total includes 1 notification for whom sex was not reported.
Figure 33: Notification rate for infectious syphilis (primary, secondary and early latent), less than 2 years duration, Australia, 2009, by age group and sex
* Excludes 1 notification for whom sex was not reported.
Over the period 2005 to 2007, notification rates amongst males increased substantially, in the 20–29, 30–34 and 40–49 years age groups but have remained relatively stable since. The overall increases observed during this period were mainly attributed to men who have sex with men.18 In females, for the 2004 to 2009 period, rates remained relatively steady, except in the 15–19 years age group where they decreased from a peak of 7.8 per 100,000 population in 2006 to 1.4 per 100,000 population in 2009 (Figure 34).
Figure 34: Notification rate for infectious syphilis (primary, secondary and early latent), less than 2 years duration, in persons aged 10 years or over, Australia, 2004 to 2009, by age group and sex
In 2009, data on Indigenous status were complete for 96% of infectious syphilis notifications. All jurisdictions except the Australian Capital Territory had greater than 50% completeness of the Indigenous status field between 2004 and 2009. The age standardised notification rate was 23.7 per 100,000 in the Indigenous population and 5.6 per 100,000 in the non-Indigenous population, representing a ratio of 4:1. Age standardised notification rates varied widely across jurisdictions. Since 2006, Indigenous notification rates decreased across all of these jurisdictions except Western Australia, where the notification rate increased between 2005 and 2008 from 11–84 notifications per 100,000 population and declined to 39 per 100,000 population in 2009. This increase in Indigenous rates was largely attributable to an outbreak that occurred in 2008 in the Pilbara region amongst Aboriginal people (Figure 35).52 Rates of infectious syphilis in the Indigenous population are highest in the 25–29 and 30–34 years age groups, compared with the non-Indigenous population where notification rates are highest in the 40–44 years age group.
Figure 35: Notification rate for infectious syphilis, selected states and territories,* 2004 to 2009, by Indigenous status and year
* Includes notifications in the Northern Territory, Queensland, South Australia, Tasmania, Victoria, Western Australia and New South Wales where Indigenous status completeness was reported for more than 50% of cases over a 5-year period.
Syphilis of more than 2 years or unknown duration
In 2009, a total of 1,385 notifications of syphilis of more than 2 years or unknown duration were reported to the NNDSS, giving a notification rate of 6.8 per 100,000 population, which was similar to the rate in 2008 (6.9 per 100,000 population). The Northern Territory continued to have the highest notification rate at 44 per 100,000 population, however, this was a decrease of 43% compared with 2008 (78 per 100,000 population).
In 2009, notification rates of syphilis of more than 2 years or unknown duration in males and females were 8.4 and 5.1 per 100,000 population, respectively (Table 16). Nationally, the male to female ratio was 1.7:1 (Figure 36). The distribution of notification rates across age groups in females was bimodal, with peaks in the 30–34 and 80–84 years age groups. In males, rates remained high from 30 years and over and peaks occurred in the 45–49 and 85 or over age groups. Rates in males were substantially higher than in females, especially in the 35–79 years age groups.
Table 16: Notifications and rates* for syphilis of more than 2 years or unknown duration, Australia,† 2009, by state or territory and sex
| Male | Female | Total‡ | ||||
|---|---|---|---|---|---|---|
State or territory |
Count | Rate* | Count | Rate* | Count | Rate* |
| ACT/NSW | 248 |
6.7 |
159 |
4.2 |
410 |
5.5 |
| NT | 52 |
44.6 |
47 |
43.5 |
99 |
44.0 |
| Qld | 166 |
7.5 |
130 |
5.9 |
296 |
6.7 |
| SA | NDP |
– |
NDP |
– |
NDP |
– |
| Tas | 14 |
5.6 |
4 |
1.6 |
18 |
3.6 |
| Vic | 314 |
11.7 |
145 |
5.3 |
468 |
8.6 |
| WA | 57 |
5.0 |
37 |
3.4 |
94 |
4.2 |
| Total | 851 |
8.4 |
522 |
5.1 |
1,385 |
6.8 |
* Notification rate per 100,000 population.
† Data from all states and territories except South Australia.
‡ Total includes 12 notifications for whom sex was not reported.
NDP No data provided.
Figure 36: Notification rate for syphilis of more than 2 years or unknown duration, Australia,* 2009, by age group and sex†
* Data from all states and territories except South Australia.
† Excludes 14 notifications for whom age or sex was not reported.
Over the period 2004 to 2009, notification rates increased amongst males in the 30–39 and 40–49 years age groups, with a substantial decrease observed in the 15–19 years age group. In females for the same period, increases were observed in the 40 years or over age groups and substantial decreases were observed in the 15–19 and 20–29 years age groups (72% and 40% respectively) (Figure 37).
Figure 37: Notification rate for syphilis of more than 2 years or unknown duration, Australia,* 2004 to 2009, by age group and sex
* Data from all states and territories except South Australia.
Congenital syphilis
Following a peak of 19 notifications in 2001, notifications of congenital syphilis have continued to decline in 2009 (Figure 38). There were 3 notifications of congenital syphilis reported in 2009, 1 male and 2 females. All 3 notifications were from the Northern Territory. Two of the notifications were Indigenous and one was non-Indigenous.
Figure 38: Notifications of congenital syphilis, Australia, 1999 to 2009
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This issue - Vol 35 No 2, June 2011
NNDSS Annual report 2009