This article {extract} was published in Communicable Diseases Intelligence Volume 23 Number 11 - 28 October 1999 and may be downloaded as a full version PDF from the Table of contents page.

Results continued

Sexually transmissible diseases (STDs)

Based on NHMRC surveillance case definitions,¹ the diseases classified as sexually transmissible for surveillance in the NNDSS are chancroid, chlamydial infection, donovanosis, gonococcal infection, lymphogranuloma venereum and syphilis.

Other important diseases are commonly or usually spread by sexual contact, but are not subject to national surveillance through the NNDSS. These include genital herpes (herpes simplex virus types I and II), genital warts (human papilloma virus, several types), trichomoniasis, and parasitic infestations such as pubic lice and scabies.²²

In addition to the STD surveillance by NNDSS the Australian Gonococcal Surveillance Programme (AGSP), a national laboratory based surveillance system, documents the antibiotic sensitivity of gonococcal isolates. The AGSP includes some clinical and demographic data.¹³ National data on HIV and AIDS are collected and reported separately by the National Centre in HIV Epidemiology and Clinical Research. This Centre also reports on trends in sexually transmissible diseases.¹²

Chancroid

Only one case of chancroid, from Western Australia, was reported in 1998. The case was a female in the 35-39 year age group.

Chlamydial infection (NEC)

In 1998, 11,405 notifications were received for chlamydial infection (NEC) (Table 1). There has been a steady increase in the number of notifications since 1994. In New South Wales, reporting of genital chlamydial infection commenced in September 1998. It can be assumed that most of the reported cases from the other seven States and Territories in 1998 were genital infections, classified in accordance with the NHMRC case definition. Ninety-six per cent of reported cases were in the 15-39 years age groups. It is likely that many of the cases reported in young children were cases of chlamydial conjunctivitis.

The rate for 1998 was 87.7 cases per 100,000 population higher than the rate of 74.5 per 100,000 in 1997. This was the third highest rate reported for any notifiable disease and the highest among the STD's (Table 2). There is an apparent trend for the number of notifications of chlamydial infection to increase over the past decade (Figure 15). There has been an 80% increase in the rate per 100,000 population between 1991 and 1998. Among notified cases the male: female ratio was 1:1.6. For both males and females, the highest rates of disease were recorded for the 20-24 years age group. Thirty-five per cent of cases in females and 32% of cases in males were in this age group (Figure 16). High notification rates were reported across northern Australia, including rates over 400 per 100,000 in the Statistical Divisions of Kimberley and the Pilbara in Western Australia, the Statistical Division of Far North Queensland, and in the Northern Territory (Map 5).

Figure 15. Notifications of chlamydial infection, 1991-1998, by month of onset

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Figure 16. Notification rate of chlamydial infection, 1998, by age group and sex



Map 5. Notification rate of chlamydial infection, 1998, by Statistical Division of residence

Donovanosis

Donovanosis was not notifiable in South Australia in 1998, and only became notifiable in New South Wales in September 1998. A total of 31 notifications were received from Northern Territory, Queensland and Western Australia (Table 1). Reported cases from Queensland and Western Australia were from the tropical north regions of those States. The male to female ratio was 1:6.8 with a noted increase in female cases. Fifty-four per cent of the cases were in the 15-29 years age groups.

Gonococcal infection

In 1998, a total of 5,428 notifications of gonococcal infection were received nationally (Table 1). The notification rate of 29.0 cases per 100,000 was higher than in recent years (Table 3). This rate remains far below the very high rates recorded in the 1970s and early 1980s which peaked at 84.4 per 100,000 population in 1982²³ There is an apparent trend for the number of notifications of gonococcal infection to increase over the past decade (Figure 17). There has been a 98% increase in the rate per 100,000 between 1991 and 1998.

Figure 17. Notifications of gonococcal infection, 1991-1998, by month of onset



There was a wide geographical variation in the rate of notification of gonococcal infection (Table 2, Map 6). The highest rate, 2,193.7 per 100,000, was reported from the Statistical Division of Kimberley. Rates above 50 per 100,000 population were reported from the Statistical Divisions of the Pilbara and South Eastern in Western Australia, the Statistical Divisions of Far North and North West in Queensland and the Northern Territory.

Map 6. Notification rate of gonococcal infection, 1998, by Statistical Division of residence



The male to female ratio of 1.5:1 was similar to 1997. As in 1997 the rate for females in the 15-19 years age group was higher than for males in the same age group (Figure 18). A similar pattern was seen for the number of notifications in the Northern Territory.
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Figure 18. Notification rate of gonococcal infection, 1998, by age group and sex

Lymphogranuloma venereum

No cases were reported from any State or Territory in 1998. Lymphogranuloma venereum was not notifiable in Western Australia or South Australia. In New South Wales the disease became notifiable in September.

Syphilis

A total of 1,689 notifications of syphilis were received (Table 1), with a rate of 9.0 per 100,000 population in 1998, representing a 28.6% increase in the rate compared to the previous year (1,304 notifications and a rate of 7.0 per 100,000). This increase is a reversal of the trends since 1992.⁴ However, the rate remains lower than those seen in the 1980's.²³ Specifically rates of syphilis increased in the Northern Territory, Queensland and the Australian Capital Territory.

There was wide geographical variation in the notification rate (Table 2, Map 7). High notification rates were reported for the Western Australian Statistical Division of Kimberley and the Northern Territory.

Map 7. Notification rate of syphilis, 1998, by Statistical Division of residence



The male to female ratio was 1:1.1. Among younger persons, notification rates were higher in females, and among older persons, rates were higher in males (Figure 19).

In 1998, there were two reported cases of congenital syphilis.

Figure 19. Notification rate of syphilis, 1998, by age group and sex

Discussion

Transmission of sexually transmitted infections appears to be on the rise. There is an apparent trend in the rates of gonococcal infection to increase over the past decade.²⁴ In general males predominated except for in the 15-19 years age group. Of concern is the accompanying reported increase in antibiotic resistance.²⁵ A rise in chlamydial infection and syphilis notifications was also seen. There is no reason to believe that these increases were due to any changes in surveillance, reaffirming the need for ongoing surveillance and management strategies. The syphilis surveillance raised issues around case definitions that may include a mixture of new infections, old infections and treated cases depending on the reporting jurisdiction.