This extract of the NNDSS annual report 2010 was published in Communicable Diseases Intelligence Vol 36 No 1 March 2012. A print friendly full version may be downloaded as a PDF 1862 KB.
The full issue of CDI is available as a PDF file (2586 KB) or by individual articles from this issue's table of contents
Results, cont'd
Sexually transmissible infections
In 2010, 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 2005 and 2010 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 as changes in screening programs,30,31 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. Rates for STIs, are particularly susceptible to overall rates of testing as well as targeted testing in certain high risk population sub-groups.32 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 Welfare33 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 2005 to 2010. Where the Indigenous status of a notification was not completed, these notifications were counted as non-Indigenous in the analyses. 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 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.34,35 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.32
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).36 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 2010. Since chlamydial infection became a nationally notifiable disease in 1991 (1997 in New South Wales), the rate has increased in each consecutive year. In 2010, there were 74,305 notified cases of chlamydial infection, equating to a rate of 333 per 100,000 population. This represents an increase of 17% compared with the rate reported in 2009 (285). Between 2005 and 2010, chlamydial infection rates increased by 64%, from 203 to 333 per 100,000 population (Table 6).
Increasing rates of chlamydia were reported from all states and territories with the Northern Territory (1,159 per 100,000), Western Australia (443 per 100,000) and Queensland (426 per 100,000) substantially higher than the national rate (Table 5). At a regional level, chlamydial rates were highest in the Central NT SSD of the Northern Territory (2,004 per 100,000; n = 827) followed by the Kimberley SD of Western Australia (1820 per 100,000; n = 650). However, rates in geographic areas where the estimated residential population and case numbers are small, should be interpreted with caution. Rates were substantially higher than the national rate in the remaining SSDs of the Northern Territory, the North and North West SDs in Queensland and the Pilbara, Central and South Eastern SDs in Western Australia (Map 2).
Map 2: Rates and counts* for chlamydial infection, Australia, 2010, 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.
In 2010, rates of chlamydial infection in males and females were 279 and 384 per 100,000 population respectively. When compared with 2009, rates increased by 19% in males and 15% in females. The male to female rate ratio in 2010 was 0.7:1, which was similar to previous years. Rates for females exceeded those for males in the under 30 age range, especially in the 10–14 year age group with a ratio of 0.1:1, while males had higher rates in the older age groups (Figure 16).
Figure 16: Rate for chlamydial infection, Australia, 2010, by age group and sex*
* Excludes 246 notifications for whom age and or sex were not reported.
Between 2005 and 2010, there was an increasing trend in chlamydia notification rates across both sexes and in all age groups (Figure 17). The greatest increase in rates amongst those aged 15–39 years occurred in both males and females in the 15–19 age group (114% and 75% respectively). Those aged 15–29 years accounted for approximately 80% of the annual number of notified cases during the period 2005 to 2010.
Figure 17: Rate for chlamydial infection in persons aged 10-39 years, Australia, 2005 to 2010, by sex, year and age group
Nationally in 2010, data on Indigenous status were complete for 50% of notifications, which was higher than the preceding 5-year mean of 45% (range: 40%–49%). 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 2005 to 2010 period. These were the Northern Territory, South Australia, Tasmania and Western Australia. Amongst these jurisdictions, the combined age standardised notification rate ratio between Indigenous and non-Indigenous populations in 2010 was 3.8:1, with the disparity in notification rates improving substantially since 2000.
After a 40% increase between 2005 and 2006, rates amongst the Indigenous population remained fairly consistent between 2006 and 2009, with an average rate during this period of 1,193, but in 2010 there was a 12% increase to 1,342 compared with this average. In contrast, rates amongst the non-Indigenous population have been trending upwards from a rate of 205 in 2005 to 356 in 2010, representing a 74% increase over this period.
In 2010, chlamydia rates increased compared with 2009 in all 4 states and territories in which Indigenous status was more than 50% complete, ranging from 14% (Tasmania) to 49% (South Australia) amongst the Indigenous population and 11% (Western Australia) to 39% (Northern Territory) amongst the non-Indigenous population (Figure 18). The overall high Indigenous population rates observed in the Northern Territory, Western Australia and South Australia may be partly explained by the high level of screening, which take place in remote Indigenous communities.
Figure 18: Age standardised rate for chlamydial infection, selected states and territories,* 2005 to 2010, by Indigenous status, year and state or territory
* Includes notifications in the Northern Territory, South Australia, Tasmania and Western Australia where Indigenous status was reported for more than 50% of cases over a 5-year period.
Between May 2007 and June 2010, the Australian Government Department of Health and Ageing funded a pilot program called the Australian Collaboration for Chlamydia Enhanced Sentinel 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 2010, ACCESS identified that chlamydia positivity amongst people who accessed the sentinel sites, was 11% amongst males and 10% amongst females, with positivity highest in the 16–19 year age group across most of the sentinel sites.13 The chlamydia positivity rate increased between 2% and 3% amongst young heterosexual men and women and amongst men who have sex with men between 2006 and 2010. Between 2007 and 2010, the number of people who accessed these sentinel sites and were tested increased by 21%. Notification rates for chlamydia and other STIs are particularly susceptible to overall rates of testing as well as targeted testing in high-risk groups.
Donovanosis
Donovanosis was targeted for elimination in Australia through the National Donovanosis Elimination Project.37 The disease predominantly occurred in rural and remote Indigenous communities in central and northern Australia and is now relatively uncommon. In 2010, 1 notified case was reported to the NNDSS of a male from Queensland (Figure 19).
Figure 19: Notified cases of donovanosis, Australia, 1991 to 2010, by year and sex
Gonococcal infection
In 2010, there were 9,971 notified cases of gonococcal infection reported to the NNDSS; a rate of 45 per 100,000 population. This was a 23% increase compared with 2009. Due to a technical processing error, gonococcal data for Queensland were under-reported in 2009 and 2010 and therefore should be interpreted with caution.
The highest rate in 2010 was in the Northern Territory (841 per 100,000 population), which was almost 19 times higher than the national rate (Table 5). Between 2008 and 2009 considerable declines in rates were observed in Western Australia (23%), South Australia (25%) and Tasmania (17%) with increases for the same period reported in Victoria (64%), New South Wales (22%), and the Australian Capital Territory (157%). In 2010, all states and territories except Tasmania and the Australian Capital Territory reported increases ranging from 2% in Western Australia to 38% in New South Wales when compared with 2009.
Nationally, there was an increase in the gonococcal infection rates in both males (26%) and females (17%) compared with 2009. The male to female rate ratio in 2010 was 2.2:1 (61 and 28 respectively), which is similar to the previous 5 years. Nationally, the rate of gonococcal infection in males exceeded those in females in all age groups except those aged less than 20 years (Figure 20). As in previous years, the exception to this pattern was the Northern Territory, where females had an overall higher notification rate than males (889 compared with 797 per 100,000).
Figure 20: Rate for gonococcal infections, Australia, 2010, by age group and sex*
* Excludes 20 notifications for whom age or sex were not reported.
Age specific rates amongst males increased in all age groups except the 10–14 year age group in contrast to females for which rates increased in the 15–19 and 20–29 year age groups but otherwise remained relatively stable (Figure 21).
Figure 21: Rate for gonococcal infection in persons aged 10–49, Australia, 2005 to 2010, by and sex, year and age group
In 2010, the data completeness of the Indigenous status field for gonococcal infection notifications was 65%, the same as in 2009 but a decrease compared with the previous few years (around 70%). All jurisdictions except New South Wales and the Australian Capital Territory had greater than 50% completeness of the Indigenous status field. Amongst these jurisdictions the combined age standardised notification rate for gonococcal infection in the Indigenous population had been steadily declining from 919 per 100,000 in 2006 to 629 per 100,000 in 2009 before increasing to 878 per 100,000 in 2010. In the non-Indigenous population, rates have been stable at around 22 to 23 per 100,000 between 2005 and 2009 before also increasing by 40% to 32 per 100,000 in 2010. Between 2005 and 2010 the Indigenous to non-Indigenous rate ratio has decreased 31% from 40:1 to 27:1. In 2010, rates of gonococcal infection in the Indigenous and non-Indigenous populations increased compared with 2009 in all jurisdictions except Tasmania (Figure 22). The overall high Indigenous population rates observed in the Northern Territory may be partly explained by the high level of screening which take place in remote Indigenous communities.
Figure 22: Age standardised rate for gonococcal infection, selected states and territories,* 2005 to 2010, by Indigenous status, year and state or territory
* Includes notifications in the Northern Territory, Queensland, South Australia, Tasmania, Victoria and Western Australia where Indigenous status 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 using a standardised methodology is performed on gonococcal isolates to a core group of antibiotics: penicillin, ceftriaxone, spectinomycin, quinolone and tetracycline.
In 2010, the AGSP38 reported that 4,101 gonococcal isolates were tested for antibiotic susceptibility, representing approximately 41% of notified cases of gonococcal infection and a similar proportion to 2009 (40%) and 2008 (42%).
Of the isolates collected through the AGSP in 2010, the majority (n = 3,381) were from males with the remaining 720 from females (ratio 4.7:1). In males, 65% of isolates were obtained from the urethra, 20% from the rectum and 12% from the pharynx. In females, the majority of isolates (89%) were obtained from the cervix.
In 2010, approximately 29% of gonococcal isolates had some level of resistance to the penicillins, a decrease from the 36% identified in 2009. In addition, 35% had some level of resistance to quinolones, representing a further decrease in the proportion of quinolone resistance from 43% in 2009 and 54% detected in 2008. Since 2001, low but increasing numbers of isolates with decreased susceptibility to ceftriaxone have been identified in Australia with 4.8% observed nationally in 2010. There were no resistant ceftriaxone isolates reported in 2010. For more details see the AGSP annual report series published in CDI.
Syphilis (non-congenital categories)
In 2004, all jurisdictions except South Australia 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. South Australia, only report cases of infectious syphilis. 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 2010, there were 2,364 notified cases of syphilis infection of all non-congenital categories reported to NNDSS, representing a rate of 10.6 per 100,000 population; a 14% decrease compared with 2009 (12.3 per 100,000 population) (Table 6, Figure 23). The Northern Territory continued to have the highest rate of syphilis (61 per 100,000 population), consistent with the rate in 2009. In 2010, there were decreases in rates from Tasmania (26%), New South Wales (21%), Queensland (19%), Western Australia (17%), South Australia (16%), and Victoria (5%). While national rates have declined since 2007, overall between 2005 and 2010 there has been an 11% increase, and as in other developed countries, predominantly affecting men who have sex with men.39,40
Figure 23: Rate for non-congenital syphilis infection (all categories), Australia, 2005 to 2010, by year
Syphilis – infectious (primary, secondary and early latent), less than 2 years duration
In 2010, there were 1,099 notified cases of infectious syphilis (primary, secondary and early latent), less than 2 years duration reported to NNDSS. This represents a notification rate of 4.9 per 100,000, a decrease of 18% compared with 2009 (6.0 per 100,000 population) (Table 5). The rate of infectious syphilis notifications increased from 3.2 per 100,000 in 2005 to a peak of 6.7 per 100,000 in 2007 and has been gradually declining since then (Figure 23). The Northern Territory had the highest notification rate at 19 per 100,000 population in 2010, an 11% increase compared with 2009, but an overall 59% decrease compared with 2005.
Nationally, the rates of infectious syphilis for males and females were 8.9 and 1.0 per 100,000 population respectively, representing a male to female ratio of 9:1 (Table 14). Rates in males were highest in the 40–44 year age group (19 per 100,000), closely followed by the 30–34 and 35–39 year age groups (18 and 17 per 100,000 respectively), whereas in females the highest notification rates were observed in the 20–24 year age group followed by the 25–29 and 30–34 year age groups (2.8, 2.2 and 2.1 per 100,000) (Figure 24).
Table 14: Notified cases and rates* for infectious syphilis (less than 2 years duration), Australia, 2010, by state or territory†
State or territory |
Male | Female | Total | |||
|---|---|---|---|---|---|---|
| Count | Rate* | Count | Rate* | Count | Rate* | |
| ACT/NSW | 410 |
10.9 |
19 |
0.5 |
430 |
5.7 |
| NT | 29 |
24.4 |
14 |
12.7 |
43 |
18.7 |
| Qld | 192 |
8.5 |
29 |
1.3 |
221 |
4.9 |
| SA | 16 |
2.0 |
5 |
0.6 |
21 |
1.3 |
| Tas | 6 |
2.4 |
1 |
0.4 |
7 |
1.4 |
| Vic | 264 |
9.6 |
26 |
0.9 |
291 |
5.2 |
| WA | 71 |
6.1 |
15 |
1.3 |
86 |
3.7 |
| Total | 988 |
8.9 |
109 |
1.0 |
1,099 |
4.9 |
* Notification rate per 100,000 population.
Figure 24: Rate for infectious syphilis (primary, secondary and early latent), less than 2 years duration, Australia, 2010, by age group and sex
Over the period 2005 to 2007, notification rates amongst males increased substantially, in the 20–29, 30–39 and 40–49 year age groups but since then have either decreased or remained relatively stable. The overall increases observed during this period were mainly attributed to men who have sex with men.18 In females, for the 2005 to 2010 period, rates remained relatively steady, except in the 15–19 year age group where they decreased from a peak of 7.5 per 100,000 in 2006 to 1.6 per 100,000 in 2010 (Figure 25).
Figure 25: Rate for infectious syphilis (primary, secondary and early latent), less than 2 years duration, in persons aged 10 years or over, Australia, 2005 to 2010, by sex, year and age group
In 2010, data on Indigenous status were complete for 95% of cases. All jurisdictions except the Australian Capital Territory had greater than 50% completeness of the Indigenous status field between 2005 and 2010. The age standardised notification rate was 23 per 100,000 in the Indigenous population and 5.2 in the non-Indigenous population, representing a rate ratio of 5:1. Nationally, there was a 29% decrease in rates for the Indigenous population (from 32.6 per 100,000 to 23.2 per 100,000) between 2005 and 2010 in contrast to the 80% increase (2.5 to 4.5 per 100,000) in the non-Indigenous population during the same period. However, rates varied widely across jurisdictions. In 2010, Indigenous rates in Queensland increased by 34% compared with 2009 but were 20% lower than in 2005, while in the remaining states and territories rates either stayed relatively stable or decreased when compared with 2009. The increase evident in Indigenous rates in Western Australia in 2008 was largely attributable to an outbreak that occurred in 2008 in the Pilbara region amongst Indigenous people (Figure 26).41 In 2010, rates of infectious syphilis in the Indigenous population were highest in the 20–24 year age group, while in the non-Indigenous population the highest rates were amongst the 30–34 and 40–44 year age groups.
Figure 26: Age standardised rate for infectious syphilis, selected states and territories,* 2005 to 2010, by Indigenous status, year and state or territory
* Includes notifications in the Northern Territory, Queensland, South Australia, Tasmania, Victoria, Western Australia and New South Wales where Indigenous status was reported for more than 50% of cases over a 5-year period.
Syphilis of more than 2 years or unknown duration
In 2010, there were 1,241 notified cases of syphilis of more than 2 years or unknown duration reported to the NNDSS, giving a rate of 6.0 per 100,000 population, which was similar to the rate in 2009 (6.8 per 100,000). The Northern Territory continued to have the highest notification rate (42.7 per 100,000), consistent with 2009 but was a 43% decrease compared with 2008.
In 2010, notification rates of syphilis of more than 2 years or unknown duration in males and females were 7.9 and 4.0 per 100,000, respectively (Table 15), representing a male to female ratio of 1.9:1 (Figure 27). Rates in males were higher than in females across all ages, except in the 85 years or over age group, and were 3 times higher amongst those in the 45–54 and 60–64 year age groups. The distribution of notification rates across age groups in females was bimodal, with the highest rate (9.8 per 100,000) in the 85 years or over age group, followed by those in the 30–34 year age group (6.7 per 100,000). In males, rates remained high in those aged 30 years or over and peaks occurred in the 45–49 and 80–84 year age groups at 13.0 and 16.0 respectively.
Table 15: Notified cases and rates* for syphilis of more than 2 years or unknown duration, Australia,† 2009, by state or territory and sex
State or territory |
Male | Female | Total | |||
|---|---|---|---|---|---|---|
| n | Rate | n | Rate | n | Rate | |
| ACT/NSW | 223 |
5.9 |
119 |
1.6 |
345 |
4.5 |
| NT | 57 |
47.9 |
41 |
17.9 |
98 |
42.7 |
| Qld | 114 |
5.1 |
69 |
1.5 |
183 |
4.1 |
| SA | NDP |
NDP |
NDP |
NDP |
NDP |
NDP |
| Tas | 9 |
3.6 |
5 |
1.0 |
14 |
2.8 |
| Vic | 365 |
13.3 |
163 |
2.9 |
532 |
9.6 |
| WA | 45 |
3.9 |
24 |
1.0 |
69 |
3.0 |
| Total | 813 |
7.9 |
421 |
4.1 |
1,241 |
6.0 |
* Notification rate per 100,000 population.
† Data from all states and territories except South Australia.
NDP No data provided.
Figure 27: Rate for syphilis of more than 2 years or unknown duration, Australia,* 2010, by age group and sex
* Data from all states and territories except South Australia.
Over the period 2005 to 2010, rates increased amongst males in all age groups over 19 years but particularly in the 20–29 year age group, which increased by 30% during this time. During this same period a substantial decrease of 57% was observed amongst males in the 15–19 year age group. In contrast, rates for females during this period decreased in all age groups less than 40 years but had a 40% increase amongst those 50 years or older (Figure 28).
Figure 28: Rate for syphilis of more than 2 years or unknown duration, Australia,* 2005 to 2010, by sex, year and age group
* Data from all states and territories except South Australia.
Congenital syphilis
Following a peak of 19 notified cases in 2001, notifications of congenital syphilis have continued to decline (Figure 29). There were 3 notified cases of congenital syphilis reported in 2010, 2 males from Queensland and 1 female from Western Australia. Two of the cases were reported as Indigenous and one was non-Indigenous.
Figure 29: Trends in notifications of congenital syphilis, Australia, 1999 to 2010, by year
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Communicable Diseases Surveillance
This issue - Vol 36 No 1, March 2012
NNDSS Annual report 2010