Sexually transmissible diseases

Diseases generally classified as sexually transmissible under surveillance in the NNDSS are chancroid, chlamydial infection, donovanosis, gonococcal infection, lymphogranuloma venereum and syphilis.²² An additional national laboratory based surveillance system, the Australian Gonococcal Surveillance Programme (AGSP), documents the antibiotic sensitivity of gonococcal isolates, together with some clinical and demographic data.²³

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. The data presented in this section are more recent than the data presented in the Annual Surveillance Report, 1998, HIV/AIDS and related diseases in Australia.¹¹ This accounts for the difference in numbers and rates of diseases in this section.

Several 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.^{24, 25}

Chancroid

Only one case of chancroid was reported in 1997, from Western Australia. The case was a male in the 45 to 49 year age group.

Chlamydial infection

Chlamydial infection was not notifiable in New South Wales in 1997. It can be assumed that most of the 9,126 cases reported from the other seven States and Territories in 1997 were genital infections classified in accordance with the NHMRC case definition. However, it is likely that many of the cases reported in young children, particularly among the 42 cases reported in children less than 1 year of age, were cases of chlamydial conjunctivitis.

The adjusted rate for 1997 (74.5 per 100,000 population) was one of the highest (4th highest) reported for a notifiable disease and the highest among the STD's. This rate was 7 per cent higher than the rate reported for 1996 (Table 3). No seasonal trend was apparent.

Among notified cases the male:female ratio was 1:1.87. For both males and females, the highest rates of disease were recorded for the 20 to 24 age group; 38 per cent of cases in females and 33 per cent of cases in males, were in this age group (Figure 12).

High notification rates were reported across northern Australia, including rates over 300 per 100,000 in the Statistical Division of Kimberley in Western Australia, The Northern Territory and the Statistical Division of Far North Queensland (Map 5).

Figure 12. Notification rate of chlamydial infection, 1997, by age group and sex

Top of page

Map 5. Notification rate of chlamydial infection, 1997, by Statistical Division of residence

Donovanosis

Donovanosis was not notifiable in New South Wales or South Australia in 1997. A total of 45 notifications were received from Northern Territory, Queensland and Western Australia (Table 1); none were received from the other States and Territories. The cases reported from Queensland and Western Australia were from the Statistical Divisions in the tropical north of those States.

The male:female ratio was 1:2.8. Eighty-four per cent of the cases were reported in persons in the 15 to 44 years age range.

Gonococcal infection

In 1997, a total of 4,689 notifications of gonococcal infection were received from all States and Territories (Table 1). The notification rate of 25.3 per 100,000 was higher than in recent years (Table 3). However 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 1982.²⁶ No seasonal trend was apparent in 1997.

There was a wide geographical variation in the rate of notification of gonococcal infection (Table 2, Map 6). The highest rate (above 2,000 per 100,000) was reported from the Statistical Division of Kimberley. Rates above 250 per 100,000 population were reported from the Statistical Division of the Pilbara and South Eastern in Western Australia and the Northern Territory. The rates in the Statistical Division of Far North in Queensland were below 170 per 100,000 which is less than the rate reported for 1996.

The male:female ration of 1.6:1 was lower than those reported in recent years. This change, together with the increase in the number of notifications, may reflect increased levels of diagnosis rather than increased incidence of infection. However, notification rates remain higher in males than females in all adult age groups (Figure 13). Of the 107 notifications in children under 5 years, 25 (23%) were in infants under 1 year of age, 51 per cent of the cases were females.

Top of page

Map 6. Notification rate of gonococcal infection, 1997, by Statistical Division of residence

Figure 13. Notification rate of gonococcal infection, 1997, by age group and sex

Lymphogranuloma venereum

Lymphogranuloma venereum. was not notifiable in New South Wales, Western Australia, and South Australia in 1997. No cases were reported from the remaining States and Territories.

Syphilis

A total of 1,304 notifications of syphilis was received in 1997 (Table 1) a rate of 7 per 100,000 population. This was the lowest rate observed in Australia for over 20 years (Figure 14).

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, the Northern Territory, and the Queensland Statistical Divisions of North West and South West. There was a decrease in the rate observed in Far North Queensland as compared to last year.

The male: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 15). In 1997, 11 cases of congenital syphilis were reported including six infants under 1 year of age, and five adults over 40 years of age. There were 8 further cases of syphilis reported in children under 10 years of age, of which seven were infants under one year of age, and one was a child aged 3 years.

Caution should be exercised in interpreting syphilis surveillance data, which may include a mixture of new infections, old infections and treated cases in some jurisdictions.

Top of page

Map 7. Notification rate of syphilis, 1997, by Statistical Division of residence

Figure 14. Notifications of syphilis, 1970-1997

Figure 15. Notification rate of syphilis, 1997, by age group and sex

Discussion

The number of notifications of syphilis in Australia has continued to decline in recent years. However, the notifications of chlamydial and gonococcal infection were considerably higher in 1997 than recent years. This may reflect increased case finding activity in some states using PCR-based methods for screening urine specimens. Notification procedures, completeness of notifications and changing diagnostic tests can influence these numbers. Further discussion on HIV, AIDS and other sexually transmissible diseases is presented separately.¹¹

This article {extract} was published in Communicable Diseases Intelligence Vol 23 Number , 21 January 1999 and may be downloaded as a full version PDF from the Table of contents page. Volume 23 1999.