This article {extract} was published in Communicable Diseases Intelligence Vol 29 No 1 March 2005 and may be downloaded as a full version PDF from the Table of contents page.
Results, continued
Sexually transmitted infections
Sexually transmitted infections reported to NNDSS in 2002 were chlamydial infection, donovanosis, gonococcal infections and syphilis. Congenital syphilis was reported separately. All states and territories conducted surveillance of these infections.
Other surveillance systems that monitor STI in Australia are specialist laboratory networks, such as the Australian Gonococcal Surveillance Programme. The National Centre in HIV Epidemiology and Clinical Research also collates and analyses data on STI, including data from NNDSS, for its annual surveillance report.6
The number of notifications and notification rates of STI reported to the NNDSS between 1998 and 2002 are shown in Table 4. In interpreting these data it is important to note that changes in notifications over time may not indicate changes in disease prevalence. Increases in screening and the use of more sensitive screening tests for STI as well as periodic public awareness campaigns may explain the change in the number of notifications across years. Comparisons of STI notifications between males and females and Indigenous and non-Indigenous status have to be interpreted cautiously by taking into account that data from STI screening are biased towards high risk groups.
Chlamydial infection
In 2002, a total of 24,039 notifications of chlamydial infection were received by NNDSS, a rate of 122.3 cases per 100,000 population. This rate represents an increase of 19 per cent compared with the rate reported in 2001 (102.8 cases per 100,000 population). From 1998 through 2002, notification rates of chlamydial infection increased annually at an average rate of 11.3 per cent (range 14.5-22.1%). Between 1998 and 2002, notification rates of chlamydial infection increased from 92.7 to 122.3 cases per 100,000 population (Table 4).
Chlamydial infection notification rates were above the national average in the Northern Territory (732 cases per 100,000 population), Queensland (174 cases per 100,000 population), Western Australia (153.9 cases per 100,000 population) and the Australian Capital Territory (142.9 cases per 100,000 population). Compared to 2001, the Australian Capital Territory had the largest percentage increase in the chlamydial infection notification rate in 2002 (54%), most likely, as a result of contact tracing and awareness raising campaigns.
At the regional level, the Kimberley region of Western Australian (1,199 cases per 100,000 population) the Northern Territory (776 cases per 100,000 population), and Far North Queensland (545.5 cases per 100,000 population) had the highest notification rates (Map 3).
Map 3. Notification rates of chlamydial infection, Australia, 2002, by Statistical Division of residence
Increase in the notification of chlamydial infection was higher in males. Compared to 2001, notification rates increased by 22.2 per cent among males (from 82.1 to 99.4 cases per 100,000 males) and by 18.8 per cent among females (from 122.3 to 144.2 cases per 100,000 females). Although higher rates among women suggest that a greater number of women were screened for the disease, the higher increase among men likely reflects a trend that they are increasingly being diagnosed with Chlamydia. Contact tracing of sex partners of women with chlamydial infection, chlamydial infection awareness campaigns, and the availability of non-invasive tests increase the number of men diagnosed with Chlamydia. For example, in the Australian Capital Territory (the jurisdiction with the highest increase in notification rates in 2002), where contact tracing was conducted, chlamydial infection notifications increased among males in all age groups, while in females increase occurred only in the 15-29 year age group.
Adolescents and young adults continue to have the highest notification rate of chlamydial infection. In 2002, 76 per cent of notified cases were in the 15-29 year age range. The 20-24 year age group accounted for 31.7 per cent of all notifications among males, and 36.3 per cent of all notifications among females. The male to female ratio in this age group was 0.6:1. The highest notification rate occurred among females in the 20-24 year age group (782 cases per 100,000 population), followed by females in the 15-19 year age group (640.8 cases per 100,000 population). Among males, the highest notification rate occurred among the 20-24 year age group (449.9 cases per 100,000 population) (Figure 27). The trend in notification rates of chlamydial infection from 1995 to 2002 shows a steady increase in all age groups in the 15-29 year age range. In 2002, the largest percentage increase from the previous year occurred among females in the 25-29 year age group (26.3% increase) and among males in the 20-24 year age group (23.7% increase) (Figure 28).
Figure 27. Notification rates of chlamydial infections, Australia, 2002, by age group and sex
Figure 28. Trends in notification rates of chlamydial infection in persons aged 15-29 years, Australia, 1995 to 2002, by sex
Whether the increase reported in 2002 was the result of changes in surveillance or a true increase in prevalence could not be determined from surveillance data. NNDSS data need to be considered in the context of public health and surveillance activities in states and territories. In 2002, Chlamydia awareness programs were carried out in the Australian Capital Territory and in Victoria. In the Australian Capital Territory, as noted above, contact tracing of all notifications of chlamydial infection was carried out in cooperation with diagnosing general practitioners. In Victoria, the Chlamydia awareness campaign was the first phase of The Chlamydia Strategy for Victoria (2001 to 2004) prepared by the Victorian Department of Human Services.7 The focus of this first phase was prevention through education targeted at young people less than 24 years of age, through schools and health services. In Queensland, the 'notification period' for chlamydial infection, that is, the exclusion period beyond which subsequent positive laboratory test for a case is counted as a newly acquired infection, was reduced from two months to one. In Tasmania, there was a 14 per cent increase (from 7,020 in 2001 to 7,976 in 2002) in Chlamydia testing.
The extent to which public health initiatives, changes in surveillance practices and increases in testing for Chlamydia contributed to an increase in reporting is unknown. The pattern observed in surveillance data, that is, increase overtime across gender, age and jurisdictions, signal a need for research to determine the true prevalence of chlamydial infection in the population.
Indigenous status was reported in 88.7 per cent of the Northern Territory notifications, 99.4 per cent in South Australia and 51.3 per cent in Western Australia. These jurisdictions together reported 6,159 cases of chlamydial infection (25.5% of all chlamydial infection notifications received by NNDSS in 2002) of which 1,678 cases were Indigenous, 2,862 non-Indigenous, and 1,619 were of unknown Indigenous status. Based on these data, the age standardised notification rate of chlamydial infection was 957 cases per 100,000 population among Indigenous people, and 137 cases per 100,000 population among non-Indigenous people, a ratio of 7:1 (Figure 29).
Figure 29. Trends in age standardised notification rates of chlamydial infection the Northern Territory, South Australia and Western Australia (combined), 1997 to 2002, by Indigenous status
Source : National Centre in HIV Epidemiology and Clinical Research HIV/AIDS Annual report, 2003.
Note that cases with missing Indigenous status were added to non-Indigenous population.
Donovanosis
Donovanosis is a sexually transmitted infection characterised by a chronic ulcerative genital disease. Although relatively 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.8,9 In 2001, donovanosis was targeted for elimination from Australia within three years through the donovanosis elimination project. The centrepiece of this project is the activity of project officers, located in Cairns (Queensland), Perth (Western Australia), and Darwin and Alice Springs (Northern Territory), and includes active case follow up, case ascertainment and treatment through primary health care and raising community and medical practitioner awareness of ulcerative STI.10 In 2002, South Australia commenced surveillance of donovanosis, while Queensland, the Northern Territory and Western Australia continued the enhanced surveillance of donovanosis as part of the donovanosis elimination project.
In 2002, 16 cases of donovanosis, six males and 10 females, were reported to NNDSS. Compared to 2001, the number of notifications decreased by 52 per cent. In 2001, following the implementation of enhanced surveillance for the elimination of donovanosis in Queensland, the Northern Territory and Western Australia, donovanosis notifications had increased by 57 per cent (Figure 30).
Figure 30. Number of notifications of donovanosis, Australia 1998 to 2002, by sex
Donovanosis cases reported in 2002 were four females and one male from Far North and northern Queensland respectively, two males from Western Australia (one each from Central and the Kimberley region) and, three males and six females from the Northern Territory from areas other than Darwin and Alice Springs. All but two cases notified in the Northern Territory were Indigenous people. The majority of cases were in the 15-39 year age range (Figure 31).
Figure 31. Notifications of donovanosis, Australia 2002, by age group and sex
Gonococcal infection
In 2002, 6,247 notifications of gonococcal infection were received by NNDSS. This represents a rate of 31.8 cases per 100,000 population, a marginal increase (0.6%) from the rate reported in 2001 (31.6 cases per 100,000 population). Increases occurred in the Northern Territory (9%), New South Wales (4%), and Victoria (17%) while there were decreases in all other jurisdictions. Despite enhanced gonococcal infection surveillance in southern Queensland including Brisbane and the Gold Coast, the notification rate in Queensland decreased by 16 per cent compared to 2001 (From 30 to 25 cases per 100,000 population).
Gonococcal infection notification rates were higher than the national level in the Northern Territory (772.7 cases per 100,000 population) and Western Australia (69.6 cases per 100,000 population). In the Northern Territory, supplementary PCR for the diagnosis of gonococcal infection was not available for a period of five months in 2002, possibly resulting in over reporting since culture negative but PCR positive samples were notified during the period.
The highest notification rates in 2002 occurred in the Kimberley Statistical Division (1,383 per 100,000 population), the Northern Territory (773 per 100,000 population) and the Pilbara Statistical Division (634 per 100,000 population), (Map 4).
Map 4. Notification rates of gonococcal infection, Australia, 2002, by Statistical Division of residence
The notification rates of gonococcal infection in 2002, were 43 cases per 100,000 population for males and 21 cases per 100,000 population for females. The male to female ratio was 2:1, the same rate as reported in 2001. As in previous years, the notification rate of gonococcal infection in females was higher in the 10-14 and 15-19 year age groups, with a male to female ratio of 0.2:1 and 0.7:1, respectively. Higher rates were observed in males compared to females in all other adult age groups (Figure 32).
Figure 32. Notification rates of gonococcal infection, Australia, 2002, by age group and sex
The trends in the notification rate of gonococcal infection (Figure 33) show that among males, after an overall decrease in 2001, there was an increase among persons aged 20-39 years while rates in the 15-19 year age group fell slightly. The reason for the decrease observed in males in 2001 is not clear and does not appear to be characteristic of the long-term trend. Among females, notification rates declined in the 15-19 year age group, remained unchanged among the 20-24 and 25-29 year age groups and increased in the 30-39 year age group.
Figure 33. Trends in notification rates of gonococcal infection in persons aged 15-39 years, Australia, 1991 to 2002, by sex
In 2002, Indigenous status was reported in 91.4 per cent of cases of gonococcal infection in the Northern Territory, 100 per cent in South Australia and 82.2 per cent in Western Australia. The combined number of notifications of gonococcal infection in these jurisdictions was 3,063 cases, representing 49.0 per cent of all gonococcal infection notifications received by NNDSS. Of these cases, 2,117 were identified as Indigenous, 585 non-Indigenous and 362 of unknown Indigenous status. Based on these data, the age standardised notification rate of gonococcal infection was 1,266 cases per 100,000 Indigenous population and 28 cases per 100,000 non-Indigenous population, a ratio of 45:1 (Figure 34).
Figure 34. Trends in the age standardised notification rates of gonococcal infection, the Northern Territory, South Australia and Western Australia (combined), 1997 to 2002, by Indigenous status
Source: National Centre in HIV Epidemiology and Clinical Research HIV/AIDS Annual report, 2003.
Note that cases with missing Indigenous status were added to non-Indigenous population.
Other surveillance activities for gonococcal infections
The Australian Gonococcal Surveillance Program is the national laboratory-based surveillance system that monitors the antibiotic susceptibility of gonococcal isolates. A network of reference laboratories in each state and territory contribute to the program, using an agreed and standardised methodology to quantitatively determine susceptibility of the organism to a core group of antibiotics.
The annual results of the Australian Gonococcal Surveillance Programme for 2002 have recently been published.11 A total of 3,951 gonococcal isolates were analysed by the Australian Gonococcal Surveillance Programme, an increase of 7 per cent on the total isolates analysed in 2001. For males, the most common anatomical site from which isolates were obtained was the urethra (78%) and for females, the cervix (92%). Rectal isolates were only obtained from males, and comprised 13 per cent of all isolates. Of the total number of isolates, 84 per cent were from men, a proportion that has remained unchanged since 2000.
Table 8 shows trends in the proportion of isolates resistant to penicillin, quinolones and tetracycline. In 2002, the proportion of isolates resistant to penicillin by chromosomally-mediated resistance decreased by 56 per cent (from 15.3% of all isolates in 2001 to 10.9 per cent in 2002. The level of quinolone resistance in gonococci remains unacceptably high although the rate decreased by 39.6 per cent compared to the previous year. Quinolone resistance is of special concern in Australia because it continues to spread among sub-populations with high rates of STI, and because rates of resistance are high in countries in South East Asia and West Pacific Region, which are the source of cases imported to Australia.12
Table 8. Proportion of gonococcal isolates showing antibiotic resistance, Australia, 1998 to 2002
| Penicillin resistance (% resistance) |
Quinolone resistance % resistance) |
High level tetracycline (% resistance) |
||
|---|---|---|---|---|
| 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 |
Source: Australian Gonococcal Surveillance Programme, Annual report 2002.
NR Not recorded.
Syphilis
In 2002, 1,613 cases of syphilis infections were reported to NNDSS, a notification rate of 8.3 cases per 100,000 population (Table 3). This represents an increase of 14.1 per cent compared with the notification rate of 7.3 cases per 100,000 population reported in 2001. Small increases in the notification rates occurred in the Australian Capital Territory, New South Wales, Queensland, South Australia and Victoria. In Western Australia the syphilis notification rate fell by 23 per cent while in the Northern Territory it remained stable .
Increases in New South Wales, Queensland and Victoria could be the result of public health activities that were under taken in 2002. In Victoria, active HIV and STI testing had been carried out at selected sex-on premise venues. In New South Wales, a targeted syphilis campaign was carried out to coincide with the Gay Games in Sydney in 2002. In Queensland, a syphilis registry was established in July 2001 and was fully operational in 2002. The registry collects laboratory results for syphilis regardless of test positivity to assess and classify cases. The registry also had the task of reviewing all past syphilis notifications, a task which was ongoing in 2002.
Map 5 displays notification rates of syphilis in 2002, by Statistical Division. The highest rates of syphilis notification occurred in the Kimberley Statistical Division of Western Australia, (338 cases per 100,000 population), the Northern Territory (208 cases per 100,000 population), and North-west Queensland (132 cases per 100,000 population).
Map 5. Notification rates of syphilis infection, Australia, 2002, by Statistical Division of residence
The sex specific notification rates for 2002 were 9.8 cases per 100,000 population for males and 6.6 cases per 100,000 population for females. Compared to 2001, these represent an overall increase of 16.6 per cent among males and of 11 per cent among females. An exception to this trend was the Northern Territory, where syphilis notification rates among males fell by 9 per cent (from 211 to 193.8 cases per 100,000 population), but rose among females by 15.6 per cent (from 181 to 212 cases per 100,000 population). Nationally, the male to female notification ratio was 1.5:1, with the highest male to female notification ratio reported in Victoria (4:1) followed by New South Wales (2.3:1).
In 2002, the age specific notification rates among females had a bimodal distribution, with the first peak occurring in the 15-19 and 20-24 year age groups (17.2 and 16.4 cases per 100,000 population respectively) and the second peak in the 80-84 year age group (8.5 cases per 100,000 population). Seventy-two per cent of the cases in this female age group were notified in New South Wales. None of the cases had primary or secondary syphilis confirming that these are cases with late manifestations of syphilis. Manifestations of the disease may continue 5 to 20 years after initial infection or throughout life.13
Among males, the peak age specific notification rate shifted from the 20-24 year age group in 2001, to the 30-34 year age group, with a notification rate of 17 cases per 100,000 population (Figure 35). There were three cases of genital syphilis in children under the age of one year, all in northern Queensland.
Figure 35. Notification rates of syphilis, Australia, 2002, by age group and sex
Data on Indigenous status in 2002 were available for 85 per cent of notified cases of syphilis from the Northern Territory, 84 per cent from South Australia and 64 per cent from Western Australia. The combined number of notifications of syphilis infections from these jurisdictions was 593 cases, 36.8 per cent of all notifications of syphilis infections received by NNDSS. Of these, 468 cases were Indigenous, 60 non-Indigenous and 65 did not state their Indigenous status. Based on these data, the age standardised notification rate was 324 cases per 100,000 population among Indigenous and four cases per 100,000 population among non-Indigenous populations. The ratio of Indigenous to non-Indigenous cases was 85:1 compared to 93:1 in 2001 (Figure 36).
Figure 36. Trends in age standardised notification rates of syphilis, the Northern Territory, South Australia and Western Australia (combined), 1997 to 2002, by Indigenous status
Source: National Centre in HIV Epidemiology and Clinical Research HIV/AIDS Annual report, 2003.
Note that cases with missing Indigenous status were added to non-Indigenous population.
Congenital syphilis
There were 14 notifications of congenital syphilis reported to NNDSS in 2002, seven males, six females and one for whom gender was not stated. All reported cases were under one year of age, except one case in a 2-year-old female. All cases were from the Northern Territory, except for one case in New South Wales. In 2001, there were 21 cases of congenital syphilis notified.
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This issue - Vol 28 No 1, March 2004
NNDSS Annual report 2003
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