Results
Sexually transmissible infections
In 2006, sexually transmissible infections (STIs) reported to NNDSS were chlamydial infection, donovanosis, gonococcal infections and syphilis. Two categories of adult syphilis have been reported since 2004: syphilis – infectious (primary, secondary and early latent) 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.
Other national surveillance systems that monitor STI in Australia include the Australian Gonococcal Surveillance Programme, which is a network of specialist laboratories, and the National Centre in HIV Epidemiology and Clinical Research.
The national trends in the number and rates of STI notifications reported to NNDSS between 2001–2006 are shown in Table 4a. 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,5,6 more targeted screening, the use of more sensitive diagnostic tests, as well as periodic public awareness campaigns may contribute to changes in the number of notifications over time.
Age standardised notification rates were calculated for Indigenous and non-Indigenous populations for jurisdictions that had indigenous status data completed in more than 50% of notifications. These data however, have to be interpreted cautiously as STI screening occurs disproportionately among Indigenous populations. Similarly, rates between females and males need to be interpreted cautiously as rates of testing for STI differ between the sexes.
Chlamydial infection
| Case definition – Chlamydial infection
Only confirmed cases are reported. Confirmed case: Isolation of Chlamydia trachomatis or detection of Chlamydia trachomatis by nucleic acid testing or detection of Chlamydia trachomatis antigen. |
In 2006, chlamydial infection continued to be the most commonly notified disease. A total of 46,954 notifications of chlamydial infection were received; a rate of 228 cases per 100,000 population. This represents an increase of 12% on the rate reported in 2005 (203 cases per 100,000 population). The rate of chlamydial infection notifications has continued to increase since surveillance of the condition commenced in 1991. Between 2002 and 2006, chlamydial infection notification rates increased from 124 to 228 cases per 100,000 population, an increase of 79% (Table 4a). This ongoing increase provided impetus for the launch of Australia's first National STI Strategy in July 2005.7 While the prevalence of chlamydia varies by age group and other demographic and behavioural factors, no major section of the population is spared.8
Chlamydial infection notification rates were higher than the national average (228 cases per 100,000 population) in the Northern Territory (995 cases per 100,000 population), Queensland (302 cases per 100,000 population), Western Australia (288 cases per 100,000 population), and the Australian Capital Territory (250 cases per 100,000 population) (Table 3). At a regional level, the Northern Territory excluding Darwin had the highest chlamydial infection notification rate at 1,959 cases per 100,000 population (Map 3).
Map 3. Notification rates of chlamydial infection, Australia, 2006, by Statistical Division
In 2006, notification rates of chlamydial infection in males and females were 185 and 270 cases per 100,000 population, respectively. In 2006, notification rates increased by 11% in males and by 12% in females when compared with 2005. The male to female ratio in 2006 was 1:1.5, 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 24).
Figure 24. Notification rate of chlamydial infections, Australia, 2006, by age group and sex
Top of pageTrends in age and sex notification rates between 2002 and 2006 show increases in all age groups between 10 and 39 years in both males and females (Figure 25). Between 2002 and 2006, the notification rate in males in the 20–24 years age group increased by 433.5 cases per 100,000 population. In females of the same age, the notification rate increased by 732.2 cases per 100,000 population.
Figure 25. Trends in notification rates of chlamydial infection in persons aged 10–39 years, Australia, 2002 to 2006, by age group and sex
In 2006, data on indigenous status was complete in 43% of cases of chlamydia infection and this is comparable to the preceding 5-year indigenous status completeness average of 43% (range: 40%–44%). The combined chlamydial infection notifications in 5 jurisdictions with greater than 50% completeness of indigenous status (Northern Territory, South Australia, Victoria, Tasmania and Western Australia) showed that in 2006, the age adjusted notification rate was 1,250 cases per 100,000 population, and 223 cases per 100,000 non-Indigenous population (Figure 26). During 2006, the age standardised ratio of Indigenous to non-Indigenous chlamydial infection was 5.6:1 and this gap has increased slightly from 2005 (5.2:1), but since 2000, has improved significantly (ratio range: 8–23).
Top of pageFigure 26. Trends in age standardised notification rate of chlamydial infections, the Northern Territory, South Australia, Tasmania, Western Australia, and Victoria, 2000 to 2006, by indigenous status
* The rates in non-Indigenous peoples include diagnoses in people whose Indigenous status was not reported.
Donovanosis
| Case definition – Donovanosis
Both confirmed cases and probable cases are reported. Confirmed case: Requires demonstration of intracellular Donovan bodies on smears or biopsy specimens taken from a lesion or detection of Calymmatobacterium granulomatis by nucleic acid testing of a specimen taken from a lesion AND clinically compatible illness involving genital ulceration. Probable case: Requires compatible sexual risk history in a person from an endemic area or a compatible sexual risk history involving sexual contact with someone from an endemic area. |
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. It has been identified as a potential co-factor in HIV transmission, and it is preventable.9 Donovanosis is targeted for elimination from Australia through the donovanosis elimination project. In 2006, 4 cases of donovanosis (3 male and 1 female) were reported to NNDSS. Cases were reported from the Northern Territory (2) and Queensland (2). All 4 cases were among Indigenous people. In 2005, a total of 13 cases, 11 Indigenous, 4 male and 9 female, were notified (Figure 27). Cases in 2006 were aged 30, 31, 37 and 58 years.
Figure 27. Number of notifications of donovanosis, Australia, 1999 to 2006, by sex
Gonococcal infections
| Case definition – Gonococcal infection
Only confirmed cases are reported. Confirmed case: Requires isolation of Neisseria gonorrhoeae, or detection of Neisseria gonorrhoeae by nucleic acid testing or detection of typical Gram-negative intracellular diplococci in a smear from a genital tract specimen. |
In 2006, 8,547 notifications of gonococcal infection were received by NNDSS. This represents a rate of 41.5 cases per 100,000 population, an increase of 4% from the rate reported in 2005 (39.8 cases per 100,000 population). The male to female ratio in 2006 was 2:1, unchanged in the previous 5 years (2001 to 2005) and reflecting ongoing transmission among men who have sex with men (MSM) in Australia's larger cities.2
The highest notification rate in 2006 was in the Northern Territory at 860 cases per 100,000 population (Table 3). The largest increase in the notification rate in 2006 (compared with 2005) occurred in South Australia, where a 24% overall increase in notification rates was reported. Notification rates in Tasmania decreased by 49% compared with 2005. In 2006 nationally, gonococcal infection rates for males and females were 57 and 26 cases per 100,000 population respectively. The exception to this pattern was the Northern Territory, where females had higher notification rates than males (929 versus 796 cases per 100,000 population). The regional distribution of gonococcal infection notification shows that the highest rate occurred in the Northern Territory excluding Darwin at 75 per 100,000 population.
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 28).
Top of pageFigure 28. Notification rate of gonococcal infection, Australia, 2006, by age group and sex
Trends in sex specific notification rates show that an increase in the rates in males in the 20–24 and 25–29 years age groups has continued. However, in 2006 the sex specific notification rates for the males in the 15–19 years age group decreased. In females, an increase occurred in the 20–24 and 30–34 years age groups, and there was a slight decrease in the 15–19 years age group (Figure 29).
Figure 29. Trends in notification rates of gonococcal infection in persons aged 10–44 years, Australia, 2002 to 2006, by age group and sex
In 2006, the data completeness of indigenous status of gonococcal infection notifications was 68%; the same as in 2005. The combined gonococcal infection notifications of 6 jurisdictions with more than 50% data completeness of indigenous status (Northern Territory, Queensland, South Australia, Western Australia, Tasmania and Victoria) shows that in 2006, the age adjusted notification rate in the Indigenous population was 1,206.1 cases per 100,000 population and 24.1 cases per 100,000 non-Indigenous population: a ratio of Indigenous to non-Indigenous of 50:1.
Other surveillance of gonococcal infections
The Australian Gonococcal Surveillance Programme (AGSP) is the national surveillance system of antibiotic susceptibility of gonococcal isolates. In each state and territory, a network of reference laboratories determines the susceptibility of isolates to a core group of antibiotics using a standard methodology. The following is the summary of their 2006 report.
In 2006, a total of 3,850 isolates of gonococci were tested for antibiotic susceptibility. Eighty-four per cent of isolates were from men (mainly MSM), of which 75% were obtained from the urethra, 15% from the rectum and 9% from the pharynx. In females, 93% of isolates were obtained from the cervix. Proportions for site of infection were similar to those reported in 2005.
Trends in the proportion of isolates resistant to penicillin, quinolones and tetracycline are shown in Table 10.
Table 10. Proportion of gonococcal isolates showing antibiotic resistance, Australia, 1998 to 2006
| Year | Penicillin resistance (% resistant) |
Quinolone resistance (% resistant) |
High level tetracycline resistance (% resistant) |
|
|---|---|---|---|---|
| Plasmid mediated | Chromosomally mediated | |||
| 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 |
| 2001 | 7.5 |
15.3 |
17.5 |
9.4 |
| 2002 | 7.1 |
10.9 |
10.0 |
11.4 |
| 2003 | 9.0 |
9.0 |
14.4 |
11.2 |
| 2004 | 11.1 |
10.6 |
23.3 |
13.8 |
| 2005 | 10.5 |
19.0 |
30.6 |
13.8 |
| 2006 | 9.0 |
25.0 |
37.8 |
12.0 |
NR Not resistant
In 2006, the proportion of isolates resistant to penicillin by plasmid mediated resistance decreased by 5% and the proportion of isolates resistant to penicillin by chromosomally mediated increased by 24% compared with 2005. Quinolone resistance also increased by 23% to 37.8% from 30.6% in 2005 (Figure 30).
Figure 30. Trend in percentage of gonococcal isolates showing antibiotic resistance, Australia, 1998 to 2006
Information on the country where resistant strains were acquired were available in 23% of infections by strains with plasmid mediated resistance to penicillin and 22% of infections by strains resistant to quinolone. This showed that 43% (34/80) of plasmid mediated resistance were locally acquired with the rest acquired from Western Pacific countries and South East Asia. Eighty-one per cent of quinolone resistant strains were acquired locally and the remaining from overseas.
Resistance to both the penicillin and quinolone groups of antibiotics has reached historical highs. Nationally, one third of gonococci were penicillin resistant by at least one mechanism, and a slightly higher proportion was quinolone resistant.
The distribution of infections with strains resistant to different antibiotic agents varies from jurisdiction to jurisdiction and urban to rural areas within each jurisdiction. The AGSP recommends that treatment regimes should be tailored to the local patterns of susceptibility.
Syphilis (all categories)
In 2004, all jurisdictions began reporting to NNDSS adult 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 the 2 categories, as well as for syphilis of all categories for the purpose of showing trends in keeping with reports in previous years.
In 2006, a total of 2,436 cases of syphilis infection of all categories was reported, representing a notification rate of 11.8 cases per 100,000 population, an increase of 8.2% on the 10.9 cases per 100,000 population reported in 2005 (Table 4a, Figure 31). The Northern Territory continued to have the highest notification rate of syphilis (130 cases per 100,000 population), an increase of 14.7% from the previous year. South Australia reported an increase in the notification rate of syphilis of 133.0% compared with 2005. There were also increases in notification rates in Victoria (19.4%), Queensland (9.0%) and New South Wales (2.4%) and decreases in notification rates in Tasmania (27.2%) and Western Australia (by 11.2%) and the Australian Capital Territory (1.1%). At the regional level, the highest notification rate was in the Northern Territory excluding Darwin at 284 cases per 100,000 population (Map 4). As in other developed countries syphilis infection rates are rising in Australia among men who have sex with men.10,11
Figure 31. Notification rate of syphilis infection, Australia, 2001 to 2006
Top of pageMap 4. Notification rates of syphilis infection, Australia, 2006, by Statistical Division of residence
Syphilis – infectious (primary, secondary and early latent), less than 2 years duration
| Case definition – Syphilis – infectious (primary, secondary and early latent), less than 2 years duration
Only confirmed cases are reported. Confirmed case: Requires seroconversion in past 2 years (specific treponemal test (e.g. IgG enzyme immunoassay, Treponema pallidum haemagglutination assay, Treponema palladium particle agglutination, Treponema pallidum immobilisation assay), or fluorescent treponemal antibody absorption reactive when previous treponemal test non-reactive within past 2 years OR a fourfold or greater rise in non-specific treponemal antibody titre (e.g. Venereal Diseases Research Laboratory, Rapid Plasma Reagin) in the past 2 years, and a reactive specific treponemal test (e.g. IgG enzyme immunoassay, Treponema pallidum haemagglutination assay, Treponema pallidum particle agglutination, Treponema pallidum immobilisation assay, or fluorescent treponemal antibody absorption) OR demonstration of Treponema pallidum by darkfield microscopy (not oral lesions), direct fluorescent antibody tests, equivalent microscopic methods (e.g. silver stains), or nucleic acid testing or non-specific treponemal test (e.g. Venereal Diseases Research Laboratory, Rapid Plasma Reagin) reagin titre of greater than or equal to 1:8 AND presence of a primary chancre (or ulcer) or clinical signs of secondary syphilis. |
In 2006, a total of 813 cases of syphilis of less than 2 years duration were reported. This represents a notification rate of 3.9 cases per 100,000 population, an increase of 25.8% compared with 2005 (Table 4a). The Northern Territory had the highest notification rate at 72.6 cases per 100,000 population in 2006, an increase of 56.5% compared with 2005. Western Australia reported an increase in the notification rate for infectious syphilis of 142% compared with 2005. Increases in notifications also occurred in Victoria (88.3%), and Queensland (16.9%) and decreases occurred in South Australia (77.8%), the Australian Capital Territory (50.5%), Tasmania (17.3%) and New South Wales (14.2%) (Table 3).
The notification rates of syphilis of less than 2 years duration for males and females were 6.2 and 1.7 cases per 100,000 population respectively (Table 11). Notification rates were higher in males than in females in all jurisdictions, except in the Northern Territory where rates were higher in females (89.3 versus 57.7 cases per 100,000 population). Nationally, the male to female ratio was 3.6:1. Notification rates in males peaked in the 35–39 years age group (15.1 cases per 100,000 population) and in females in the 15–19 years age group (7 cases per 100,000 population) (Figure 32).
Top of pageTable 11. Number and rates of notifications of syphilis of less than 2 years duration Australia, 2006, by state or territory and sex
| Male | Female | Total | ||||
|---|---|---|---|---|---|---|
| n | Rate | n | Rate | n | Rate | |
| ACT | 1 |
0.6 |
1 |
0.6 |
2 |
0.6 |
| NSW | 190 |
5.6 |
19 |
0.6 |
210 |
3.1 |
| NT | 63 |
57.7 |
87 |
89.3 |
150 |
72.6 |
| Qld | 137 |
6.8 |
28 |
1.4 |
165 |
4.1 |
| SA | 2 |
0.3 |
0 |
0.0 |
4 |
0.3 |
| Tas. | 4 |
1.7 |
1 |
0.4 |
5 |
1.0 |
| Vic. | 208 |
8.3 |
23 |
0.9 |
231 |
4.5 |
| WA | 34 |
3.3 |
14 |
1.4 |
48 |
2.3 |
| Total | 639 |
6.2 |
173 |
1.7 |
813* |
3.9 |
* Sex unknown for one case.
Figure 32. Rates of notification of syphilis of less than 2 years duration, Australia, 2006, by age group and sex
Top of pageOver the period 2004 to 2006 notification rates have increased in most age groups for both males and females. In 2006, the largest increase in males occurred in the 40–49 years age group and in females in the 10–19 years age group (Figure 33). Increases in notifications of infectious syphilis occurred mainly in homosexual men.2
Figure 33. Rates of notification of syphilis of less than 2 years duration, Australia, 2004 to 2006, by age group and sex
Data on indigenous status was complete in 95% of cases of syphilis of less than 2 years duration. The age adjusted notification rate was 47.9 cases per 100,000 Indigenous population, and 3.1 cases per 100,000 non-Indigenous population, a ratio of Indigenous to non-Indigenous of 15:1. Age specific notification rates show that compared with the non-Indigenous population, rates of syphilis of less than 2 years duration in the Indigenous population are in an order of magnitude higher and peak in a younger age group (Figure 34).
Figure 34. Notification rate of syphilis of less than 2 years duration, Australia, 2006, by indigenous status
Syphilis of more than 2 years or unknown duration
| Case definition – Syphilis of more than two years or unknown duration
Only confirmed cases are reported. Confirmed case: Does not meet the criteria for a case of less than 2 years duration AND either a reactive specific treponemal test (e.g. IgG enzyme immunoassay, Treponema pallidum haemagglutination assay, Treponema pallidum particle agglutination, Treponema pallidum immobilisation assay, or fluorescent treponemal antibody absorption) which is confirmed either by a reactive non-specific treponemal test (e.g. Venereal Diseases Research Laboratory, Rapid Plasma Reagin) OR a different specific treponemal test if the non-specific treponemal test is non-reactive AND the absence of a history of documented previous adequate treatment of syphilis, or endemic treponemal disease (e.g. Yaws). |
In 2006, a total of 1,623 cases of syphilis of more than 2 years or unknown duration were reported: a notification rate of 7.9 cases per 100,000 population. The Northern Territory had the highest notification rate at 57.6 cases per 100,000 population.
In 2006, notification rates of syphilis of more than 2 years or unknown duration in males and females were 10.1 and 5.6 cases per 100,000 population, respectively (Table 12). Notification rates were higher in males than in females in all jurisdictions, except in the Northern Territory, where males had a higher rate than females (53.1 and 57.6 cases per 100,000 population, respectively). Nationally, the male to female ratio was 1.8:1. Notification rates in males and females were similar in the younger age groups up to 30–34 years. In females, the rate peaked in the 30–34 years age group while in males it remained high from 35 years (Figure 35).
Figure 35. Notification rate of syphilis of more than 2 years or unknown duration, Australia, 2006, by age group and sex
Top of pageTable 12. Number and rates of notifications of syphilis of more than 2 years or unknown duration, Australia, 2006, by state or territory and sex
| Male | Female | Total | ||||
|---|---|---|---|---|---|---|
| n | Rate | n | Rate | n | Rate | |
| ACT | 8 |
4.9 |
4 |
2.4 |
12 |
3.6 |
| NSW | 439 |
12.9 |
225 |
6.6 |
666 |
9.8 |
| NT | 58 |
53.1 |
61 |
62.6 |
119 |
57.6 |
| Qld | 166 |
8.2 |
105 |
5.2 |
271 |
6.7 |
| SA | 33 |
4.3 |
8 |
1.0 |
41 |
2.6 |
| Tas. | 11 |
4.6 |
6 |
2.4 |
17 |
3.5 |
| Vic. | 246 |
9.8 |
117 |
4.5 |
366 |
7.2 |
| WA | 74 |
7.2 |
57 |
5.6 |
131 |
6.4 |
| Total | 1,035 |
10.1 |
583 |
5.6 |
1,623* |
7.9 |
* Sex unknown for 5 cases.
Over the period 2004 to 2006 notification rates have remained stable in most age groups for both males and females, except in females aged 20 to 39 years, which have shown a large decrease. In 2006, the largest increase in rates occurred in males in the 20–29 and 30–39 years age groups (Figure 36).
Top of pageFigure 36. Rates of notification of syphilis of more than 2 years or unknown duration, Australia, 2004–2006, by age group and sex
Data on indigenous status were complete in 69.2% of cases of syphilis of more than 2 years or unknown duration. The combined age adjusted rate for the jurisdictions with greater than 50% data completeness of indigenous status (all jurisdictions except the Australian Capital Territory) was 78 cases per 100,000 Indigenous population, and 7 cases per 100,000 non-Indigenous population: a ratio of Indigenous to non-Indigenous of 12:1. Age specific notification rates showed a similar pattern with age and no single distinct peak for either Indigenous or non-Indigenous groups. Overall, rates in the Indigenous population were higher than those in the non-Indigenous by an order of magnitude (Figure 37).
Figure 37. Notification rate of syphilis of more than 2 years or unknown duration, Australia, 2006, by indigenous status
Syphilis – congenital
| Case definition – Congenital syphilis
Both confirmed cases and probable cases are reported. Confirmed case: Requires treponemal-specific antibody titres (e.g. Treponema pallidum haemagglutination assay, pallidum particle agglutination, fluorescent treponemal antibody absorption in infant serum greater than fourfold higher than in maternal serum OR treponemal specific antibody titres in infant serum comparable with those in maternal serum and specific treponemal IgM enzyme-linked immunosorbent assay or immunofluorescence assay positive OR T. pallidum DNA in normally sterile specimen from infant (CSF, tissue) by nucleic acid testing. OR dark field microscopy of infant lesion exudate or node aspirate smears (not oral lesions) to demonstrate characteristic morphology and motility of T. pallidum OR demonstration of T. pallidum in infant tissues by special (e.g. silver) stains OR detection of T. pallidum DNA from an infant non-sterile site by nucleic acid testing OR reactive fluorescent treponemal absorbed-19S-IgM antibody test or IgM enzyme linked immunosorbent assay and Treponemal non-specific antibody titre (e.g. RPR) in infant serum greater than fourfold higher than in maternal serum AND asymptomatic infection (in the infant of an infected mother) OR foetal death in utero OR stillbirth, which is a foetal death that occurs after a 20-week gestation or in which the foetus weighs greater than 500 g and the mother is untreated or inadequately treated for syphilis at delivery. Inadequate treatment is a non-penicillin regimen or penicillin treatment given less than 30 days prior to delivery OR clinical evidence of congenital syphilis on examination on: a. age <2years: Hepatosplenomegaly, rash, condyloma lata, snuffles, jaundice (non-viral hepatitis), pseudoparalysis, anaemia, oedema b. age >2 years: Interstitial keratitis, nerve deafness, anterior bowing of shins, frontal bossing, mulberry molar, Hutchinson teeth, saddle nose, rhagades or Clutton joints c. evidence of congenital syphilis on long bone X-ray d. evidence of congenital syphilis on cerebrospinal fluid (CSF) examination Probable case: An infant (regardless of clinical signs) whose mother has been inadequately treated for syphilis during pregnancy or an infant or child who has a reactive treponemal antibody test for syphilis and any one of the following: (1) any evidence of congenital syphilis on physical examination, (2) any evidence of congenital syphilis on radiographs of long bones, (3) a reactive cerebrospinal fluid Venereal Disease Research Laboratory Titre, (4) an elevated CSF cell count or protein (without other cause), (5) reactive fluorescent treponemal antibody absorbed assay –19S-IgM antibody test or IgM enzyme-linked immunosorbent assay. |
There were 14 cases of congenital syphilis notified in 2006, 6 males, 7 females and 1 unknown. Eight of the cases were reported in the Northern Territory, 5 in New South Wales, and 1 in Queensland. Six were Indigenous, 4 non-Indigenous and 4 were unknown. Notifications of congenital syphilis have plateaued over the last 4 years following a decline from a peak in 2001 (Figure 38). In the Northern Territory where rates of infectious syphilis of less than 2 years duration are highest, the highest number of cases of congenital syphilis continue to be reported.
Figure 38. Trends in notifications of congenital syphilis, Australia, 1999 to 2006
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Communicable Diseases Surveillance
This issue - Vol 32 No 2, June 2008
NNDSS Annual report 2006
Communicable Diseases Intelligence