Results, continued

Sexually transmissible infections

In 2007, the sexually transmissible infections (STIs) reported to NNDSS were chlamydial infection, donovanosis, gonococcal infection and syphilis.

Since 2004, 2 categories of non-congenital syphilis have been reported: infectious syphilis (primary, secondary and early latent) of less than 2 years duration; and syphilis of greater than 2 years or unknown duration. Reports were also received by NNDSS on congenital syphilis. These conditions were notified in all states and territories, except in South Australia where cases of syphilis of greater than 2 years or unknown duration were not reported to the NNDSS.

Other national surveillance systems that monitor STIs in Australia include the Australian Gonococcal Surveillance Programme (AGSP); a network of specialist laboratories monitoring the laboratory based indices of infections; and NCHECR.

The national trends in the number and rates of STI notifications reported to the NNDSS between 2002 and 2007 are shown in Table 7. In interpreting these data it is important to note that changes in notifications over time may not solely reflect changes in disease prevalence. Increases in screening rates,^{26, 27} more targeted screening, the use of less invasive and more sensitive diagnostic tests, as well as periodic public awareness campaigns, may contribute to changes in the number of notifications over time.

Indirect age standardised notification rates, using the method described by the Australian Institute of Health and Welfare,²⁸ were calculated for Indigenous and non-Indigenous populations for jurisdictions that had indigenous status data completeness in more than 50% of notifications. Incomplete notifications were counted as non-Indigenous cases when analysing these jurisdictions. These data however, need to be interpreted cautiously as STI screening occurs disproportionately among Indigenous populations and high rates in Indigenous populations may be attributed to poorer access to primary health care services and not necessarily associated with increased levels of sexual activity among Indigenous persons.^29,30 Similarly, rates between females and males need to be interpreted with caution as rates of testing for STIs differs between the sexes.

Cases were excluded for chlamydial, gonococcal and non-congenital syphilis infections in cases aged less than 15 years where mode of transmission was available and the infection was deemed to be non-sexually acquired, e.g. perinatally acquired infections.

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Chlamydial infection

Chlamydial infection continues to be the most commonly notified disease in 2007. A total of 51,859 notifications of chlamydial infection were received; a notification rate of 246.8 cases per 100,000 population. This represents an increase of 8% on the rate reported in 2006 (229.2 cases per 100,000 population). The rate of chlamydial notifications has continued to increase since surveillance of the condition commenced in 1991 in all jurisdictions, except New South Wales where it became notifiable in 1997. Between 2002 and 2007, chlamydial infection notification rates increased from 124.5 to 246.8 cases per 100,000 population, an increase of 97% (Table 7). This ongoing increase provided the impetus for the launch of Australia's first National STI Strategy in July 2005.³¹ While the prevalence of chalmydial infection varies by age group and other demographic and behavioural factors, no major section of the population is spared.³²

Chlamydial infection notification rates were higher than the national average (246.8 cases per 100,000 population) in the Northern Territory (1,014 cases per 100,000 population), Western Australia (367.7 cases per 100,000 population), Queensland (307.9 cases per 100,000 population) and the Australian Capital Territory (266.4 cases per 100,000 population) (Table 3).

In 2007, sex was reported for 51,747 (99.8%) of the 51,859 cases of chlamydial infection. Of these cases, notification rates in males and females were 199.1 and 292.8 cases per 100,000 population respectively. In 2007, notification rates increased by 8% in both males and females when compared with 2006. The male to female ratio in 2007 was 0.7:1, which is similar to previous years. Rates in females exceeded those in males in the 0–29 years age range, but were higher in males in the 30 years or more age range (Figure 20).

Figure 20: Notification rate for chlamydial infection, Australia, 2007, by age group and sex*

* Excludes 112 cases whose sex was not reported.

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Trends in age and sex notification rates between 2002 and 2007 show increases in all age ranges, especially between 15 and 29 years in both males and females (Figure 21). Between 2002 and 2007, the notification rate in males in the 20–24 years age group increased by 531.5 cases per 100,000 population (115%); and for female cases, in the 15–19 years and 20–24 years age groups, the notification rate increased by 704.8 and 802.7 cases per 100,000 population or 104% and 101%, respectively.

Figure 21: Trends in notification rates of chlamydial infection in persons aged 10–39 years, Australia, 2002 to 2007, by age group and sex

In 2007, data on indigenous status were complete in 43% of cases of chlamydia infection, which was the same as the preceding 5–year average of 43% (range: 40%–44%).

From 2002–2007 the rates of chlamydial infection diagnosis increased in both Indigenous and non-Indigenous populations as part of the overall increasing trend. In 2007, 5 jurisdictions had greater than 50% completeness of the indigenous status field: the Northern Territory, South Australia, Victoria, Tasmania and Western Australia. Among these jurisdictions, the age adjusted notification rate for the Indigenous population ranged from 64.5 to 1,782.2 cases per 100,000 population (Tasmania and the Northern Territory, respectively) with a median of 641.1 cases per 100,000 population. In comparison, for the non-Indigenous population, the age standardised notification rate ranged from 206.8 to 600.6 cases per 100,000 population (South Australian and the Northern Territory respectively) with a median of 237.9 cases per 100,000 population. During 2007, the age standardised ratio of Indigenous to non-Indigenous chlamydial infection notifications ranged between 0.27:1 and 3.5:1 (Tasmania and Western Australia respectively), median 3.0:1 (South Australia). This notification gap has improved substantially since 2000. It should be noted that indigenous status identification in the notification data is inconsistent and varies by jurisdiction. Research into high rates of STIs among the Indigenous population in the Northern Territory established that the disparity in notifications rates could be attributed to more targeted screening programs and to poorer access to primary health care services, rather than increased levels of sexual activity among Indigenous people.^29,30

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Donovanosis

Donovanosis is a sexually transmissible infection characterised by a chronic ulcerative genital disease. Although uncommon, it is a disease of public health importance in Australia because it predominantly occurs in Indigenous communities and has been identified as a potential co-factor in HIV transmission. Donovanosis has been targeted for elimination from Australia through the National Donovanosis Elimination Project.³³ In 2007, 3 cases of donovanosis (2 male and 1 female) were reported to the NNDSS. Cases were reported from Queensland (2) and the Northern Territory (1) and were aged 24, 41 and 58 years. Two of the cases were reported as Indigenous. In 2006, a total of 6 cases, 4 male and 2 female, with four of the cases reported as Indigenous, were notified (Figure 22).

Figure 22: Notifications of donovanosis, Australia, 1995 to 2007, by sex

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Gonococcal infections

In 2007, 7,605 notifications of gonococcal infection were received by the NNDSS. This represents a notification rate of 36.2 cases per 100,000 population, a decrease of 12% from the rate reported in 2006 (41.4 cases per 100,000 population). The male to female ratio in 2007 was 1.9:1, similar to the previous 5 years (2002 to 2006).

The highest notification rate in 2007 was in the Northern Territory at 744.4 cases per 100,000 population, compared with Western Australia, Queensland and South Australia (83.6, 32.0 and 28.8 cases per 100,000 population respectively) (Table 6). Considerable declines in the notification rate in 2007 compared with 2006, occurred in Victoria (24.9%), New South Wales (21.2%) and Queensland (15.2%). Notification rates in the Australian Capital Territory and Tasmania increased substantially compared with 2006 (34.1% and 109.6% respectively). At a regional level, gonococcal infection rates were highest in the Kimberley Statistical Division of Western Australia, and in the Central and Lower Top End Statistical Subdivisions of the Northern Territory (range: 812.3–2,014.9 cases per 100,000 population). In the Pilbara Statistical Division of Western Australia and the Barkly, Daly, Alligator and East Arnhem Statistical Subdivisions of the Northern Territory rates were also substantially higher than the national rate (316.3–812.2 cases per 100,000 population) (Map 4).

Map 4: Notification rates for gonococcal infection, Australia, 2007, by Statistical Division of residence and Statistical Subdivision for the Northern Territory

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The sex of cases was reported in 7,599 of 7,605 cases in 2007. Nationally, gonococcal infection rates for males and females were 47.9 and 24.5 cases per 100,000 population, respectively. The exception to this national pattern was the Northern Territory, where females had an overall higher notification rate than males (804.9 versus 688.4 cases per 100,000 population). Nationally, notification rates for gonococcal infection in males exceeded those in females in all age groups except in the 10–14 and 15–19 years age groups (Figure 23).

Figure 23: Notification rate for gonococcal infections, Australia, 2007, by age group and sex*

* Excludes 7 cases whose sex was not reported.

Trends in sex specific notification rates show that in 2007 there has been a decrease in the rates in males in the 20–44 years age range compared with the general upward trend seen in previous years. In females, trends for all age groups appeared to remain relatively stable with a slight decrease occurring in the 15–19 and 20–24 years age groups (Figure 24).

Figure 24: Trends in notification rates of gonococcal infection in persons aged 10–44 years, Australia, 2002 to 2007, by age group and sex

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In 2007, the data completeness of indigenous status of gonococcal infection notifications was 70%, which is similar to previous years. In 2007, 6 jurisdictions had greater than 50% completeness of the indigenous status field: the Northern Territory, Queensland, South Australia, Tasmania, Victoria and Western Australia. Among these jurisdictions the age standardised notification rates for gonococcal infection in the Indigenous population ranged from 10.0 to 1,923.1 cases per 100,000 population (Victoria and the Northern Territory, respectively) with a median of 445.4 cases per 100,000 population. Whereas age standardised notification rates in the non-Indigenous population ranged from 7.4 to 131.9 cases per 100,000 population (Tasmania and the Northern Territory respectively) with a median of 19.5 cases per 100,000 population. During 2007, the age standardised ratio of Indigenous to non-Indigenous gonococcal infection notifications ranged between 0.5:1 and 63.4:1 (Victoria and Western Australia respectively), median 13.8:1.

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Other surveillance of gonococcal infections

The Australian Gonococcal Surveillance Programme is the national surveillance system for monitoring antimicrobial resistance of Neisseria gonorrhoeae isolates. The monitoring is undertaken via a network of reference laboratories located in each jurisdiction to determine the susceptibility of gonococcal isolates, from both the public and private sectors, to a core group of antibiotics using a standard methodology. The core group of antibiotics are penicillin, ceftriaxone, spectinomycin, quinolone and tetracycline. The following is a summary of the AGSP 2007 report.³⁴

In 2007, a total of 3,103 gonococcal isolates were tested for antibiotic susceptibility, approximately 20% fewer than the 3,937 examined in 2006. The decline in the number of gonococcal isolates available for susceptibility testing is noted as a consequence of the increasing use of non-culture based diagnosis methods.

There were 2,560 isolates from males, 541 isolates from females (male to female ratio 4.7:1) and there were 2 isolates where the sex was not reported. In males, 75% of isolates were obtained from the urethra, 14% from the rectum and 9% from the pharynx. In females, the majority of isolates (90%) were obtained from the cervix.

Data on the place of acquisition were available for 23% (n=96) of isolates with 'penicillinase-producing' N. gonorrhoeae (PPNG) and for 33% (n=495) of isolates with quinolone resistance to N. gonorrhoeae (QRNG). This showed that half of the infections with PPNG (48/96, 50%) were acquired overseas, principally from Western Pacific or South East Asian countries. Eighty-four per cent of QRNG (422/495) infections were locally acquired with the remainder from overseas sources similar to PPNG.

Trends in the proportion of isolates resistant to penicillin and quinolone were 40% and 50%, respectively, of all isolates and similar to previous years. There was also a historically high rate of gonococcal isolates with high-level tetracycline resistance. As in previous years, the pattern of gonococcal antibiotic susceptibility differed between states and territories, and rural and urban areas within each jurisdiction,³⁵ highlighting the need to continue the monitoring of treatment regime suitability on a regional basis.

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Syphilis (all categories)

In 2004, all jurisdictions except South Australia, began reporting to the NNDSS non-congenital syphilis infections categorised as infectious syphilis of less than 2 years duration and syphilis of more than 2 years or unknown duration. Detailed analyses are reported for these 2 categories, as well as for syphilis of these categories combined (syphilis – all categories) for the purpose of showing trends in previous years.

In 2007, a total of 2,999 cases of syphilis infection of all categories was reported, representing a notification rate of 14.3 cases per 100,000 population, an increase of 10.0% on the 13.0 cases per 100,000 population reported in 2006 (Figure 25). The Northern Territory continued to have the highest notification rate for syphilis (130.7 cases per 100,000 population), compared with Victoria and New South Wales (16.3 and 16.1 cases per 100,000 population respectively). The Australian Capital Territory reported an increase in the notification rate for syphilis of 129.5% compared with 2006 (28 cases 2007; 12 cases 2006). There were also increases in notification rates in Tasmania (62.5%), Victoria (39.8%) and Western Australia (13.7%). As in other developed countries, syphilis infection rates have continued to rise in Australia among men who have sex with men.^{36, 37}

Figure 25: Notification rate for syphilis infection (all categories), Australia, 2002 to 2007

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Syphilis – infectious (primary, secondary and early latent), less than 2 years duration

In 2007, a total of 1,381 cases of infectious syphilis (less than 2 years duration) were reported. This represents a notification rate of 6.6 cases per 100,000 population, an increase of 56.2% compared with 2006 (4.2 cases per 100,000 population) (Table 7). The Northern Territory had the highest notification rate at 55.4 cases per 100,000 population in 2007, a decrease of 22.3% compared with 2006. The Australian Capital Territory reported a substantial increase in their notification rate from 0.6 (in 2006, 2 cases) to 2.6 (in 2007, 9 cases) cases per 100,000 population. Increases in notification rates also occurred in Western Australia (101.5%), New South Wales (93.5%), Victoria (82.9%), Tasmania (58.9%) and Queensland (35.1%) (Table 7).

At a regional level, infectious syphilis rates were highest in the Central Statistical Subdivision of the Northern Territory (191.1 cases per 100,000 population, 77 cases). In the Kimberley and South Eastern Statistical Divisions of Western Australia; and in the Barkly, Lower Top End, Daly, Alligator and East Arnhem Statistical Subdivisions of the Northern Territory, notification rates of infectious syphilis (16.6–63.7 cases per 100,000 population) were also substantially above the national rate⁸ (Map 5).

Map 5: Notification rates for infectious syphilis, Australia, 2007, by Statistical Division of residence and Statistical Subdivision for the Northern Territory

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The notification rates for infectious syphilis for males and females were 11.8 and 1.4 cases per 100,000 population respectively (Table 15). Nationally, the male to female ratio was 8.2:1. Notification rates in males peaked in the 35–39 years age group (29.6 cases per 100,000 population) and in females in the 15–19 years age group (4.1 cases per 100,000  population). Notification rates were higher in males than in females in all jurisdictions, and across all age groups, except the 10–14 years age group where the rate was slightly higher in females (0.6 cases per 100,000 population) than in males (0.4 cases per 100,000 population) (Figure 26).

Table 15: Number and rate of notifications of infectious syphilis (less than 2 years duration), Australia, 2007, by sex and state or territory

State or territory	Male		Female		Total
	n	Rate	n	Rate	n	Rate
ACT/ NSW	416	11.6	27	0.7	443	6.1
NT	72	64.5	47	45.5	119	55.4
Qld	204	9.8	28	1.3	232	5.5
SA	43	5.5	8	1.0	51	3.2
Tas	7	2.9	1	0.4	8	1.6
Vic	408	15.8	19	0.7	427	8.2
WA	81	7.6	20	1.9	101	1.9
Total	1,231	11.8	150	1.4	1,381	6.6

Figure 26: Notification rate for infectious syphilis (less than 2 years duration), Australia, 2007, by age group and sex

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Over the period 2004 to 2007 notification rates have increased substantially in most age groups for males. Increases ranged between 59%–126% in the 20–50 years or over age groups in males compared with 2006. In females, rates remained steady except in the 10–14 and 15–19 years age groups where they decreased by 66.6% and 53.2%, respectively, compared with 2006 (Figure 27). Increases in notifications of infectious syphilis occurred mainly in populations of men who have sex with men.⁴

Figure 27: Trends in notification rates of infectious syphilis (less than 2 years duration) in persons aged 10 years or over, Australia, 2004 to 2007, by age group and sex

Data on indigenous status were complete in 94% of cases of infectious syphilis. In 2007, all jurisdictions except the Australian Capital Territory had greater than 50% completeness of the indigenous status field. Across these jurisdictions, the age standardised notification rate was 30.7 cases per 100,000 Indigenous population and 5.8 cases per 100,000 non-Indigenous population. These age adjusted notification rates ranged substantially across jurisdictions. For the Indigenous population the age standardised notification rate ranged from 0.0 to 146.0 cases per 100,000 population (Tasmania and the Northern Territory respectively). Whereas in the non-Indigenous population, the age standardised notification rate ranged from 1.7 to 9.9 cases per 100,000 population (Tasmania and the Northern Territory respectively). Across these jurisdictions the ratio of Indigenous to non-Indigenous age standardised rates were 5.3:1. Again this ratio varied between the individual jurisdictions from 0.0:1 to 14.7:1 (Tasmania and the Northern Territory respectively). This notification gap has decreased compared with previous years. Analysis of age specific notification rates show that compared with the non-Indigenous population, rates of infectious syphilis in the Indigenous population are higher and peak in a younger age group, 15–34 years age range compared with 34–49 years age range. Caution should be applied when interpreting these figures due to the wide variation in Indigenous and non-Indigenous population distributions for each jurisdiction, the completeness of the indigenous status field, and as noted in the methods section, where there are unknown indigenous status cases these have been counted as non-Indigenous.

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Syphilis of more than 2 years or unknown duration

In 2007, a total of 1,618 cases of syphilis of more than 2 years or unknown duration were reported, a notification rate of 8.3 cases per 100,000 population. This rate represents a decrease by 12.6% compared with 2006 (9.5 cases per 100,000 population). The Northern Territory again had the highest notification rate at 75.4 cases per 100,000 population in 2007, which was an increase of 32.3% compared with 2006 (57.0 cases per 100,000 population).

In 2007, the sex of cases was reported in 1,608 of the 1,618 cases. Notification rates for syphilis of more than 2 years or unknown duration in males and females were 10.3 and 6.2 cases per 100,000 population, respectively (Table 16). Notification rates were higher in males than in females in all jurisdictions except Queensland, where males had a slightly lower rate than females (4.9 and 5.0 cases per 100,000 population, respectively). Nationally, the male to female ratio was 1.6:1. Notification rates in males and females were similar in the younger age groups up to 34 years. In females the rate peaked in the 30–34 years age group while in males it remained high from 35 years, with a peak in the 80–84 years age group (Figure 28).

Table 16: Number and rates of notifications of syphilis of more than 2 years or unknown duration, Australia, 2007, by state or territory and sex

State or territory	Male		Female		Total*
	n	Rate	n	Rate	n	Rate
ACT	12	7.1	7	4.1	19	5.6
NSW	451	13.2	218	6.3	672	9.8
NT	91	81.6	71	68.7	162	75.4
Qld	103	4.9	105	5.0	208	5.0
Tas	20	8.2	8	3.2	28	5.7
Vic	263	10.2	146	5.6	416	8.0
WA	58	5.5	55	5.3	113	2.2
Total	998	10.3	610	6.2	1,618	8.3

* Sex was not reported for 10 cases.

Figure 28: Notification rate for syphilis of more than 2 years or unspecified duration, Australia, 2007, by age group and sex*

* Excludes 10 cases where sex was not reported.

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Over the period 2004 to 2007, notification rates increased substantially between 2005 and 2006 and then decreased to 2005 rates in 2007 for males aged over 30 years. In females, rates have remained relatively stable, except in females aged 10–14 years where the rates have increased between 2004 and 2007 from 0.5 to 1.1 cases per 100,000 population (Figure 29).

Figure 29: Notification rate for syphilis of more than 2 years or unspecified duration, Australia, 2004 to 2007, by age group and sex

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Congenital syphilis

There were 8 cases of congenital syphilis notified in 2007, 5 males, 2 females and 1 case where the sex was not reported. Six of the cases were reported in New South Wales and three in the Northern Territory. Three were Indigenous, 2 non-indigenous and three were reported as unknown indigenous status. Notifications of congenital syphilis reached a plateau between 2003 and 2006 following a decline from a peak in 2001. In 2007 the number of cases decreased by 38% compared with 2006 (Figure 30).

Figure 30: Trends in notifications of congenital syphilis, Australia, 1998 to 2007