Other diseases

Legionellosis

This classification includes notifications of infections caused by all Legionella species. There were 161 notifications received in 1997 with an annual rate of 0.9 per 100,000 population. This rate is similar to previous years.

The highest numbers of notifications were reported by South Australia (39), Western Australia (38) and New South Wales (38). More males (113) were reported than females (48) resulting in a male:female ratio of 2.4:1 (Figure 28). Fifty per cent of reports were in the 60 to 80 year age range (Figure 29).

The reported species were Legionella pneumonphila (58 notifications) and Legionella longbeachae (47 notifications). Six cases were reported as other species; the remaining 50 were not reported separately by some States and Territories.

For the States and Territories reporting Legionellosis by species breakdown, Victoria reported the highest number of L. pneumophila (24 cases), followed by New South Wales (18), South Australia (11) and Queensland (5). The profile is different for L. longbeachae with the highest number being reported from South Australia (27) followed by New South Wales (14), Queensland (5) and Victoria (1). Generally, the epidemiology for each species of Legionella is different with L. pneumophila being reported to peak in autumn and L. longbeachae being reported to peak in spring. The 1997 notifications for L. pneumophila reflect this trend, however the highest reporting of L. longbeacheae occurs over the summer months.

For notifications of L. pneumophila, 42 were male and 16 were female, giving a male:female ratio of 2.6:1. Notifications of L. longbeachae, 32 were male and 15 were female giving a male:female ratio of 2.1:1.

Figure 28. Notifications of legionellosis, 1997, by State

Figure 29. Notification rate of legionellosis, 1997, by age group and sex

Leprosy

There were 14 reports of leprosy in 1997 from six States and Territories (five of which were from Queensland), and a notification rate of 0.1 per 100,000 population, the same as last year. Four reports were received for females and ten for males.

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Meningococcal infection

There were 499 notifications of meningococcal infection in 1997, a rate of 2.7 per 100,000 compared with 2.3 per 100,000 in 1996. The Australian Meningococcal Surveillance Programme (AMSP) recently published a detailed report for 1997 to which readers are referred.⁴⁸

Tuberculosis

There are 3 national surveillance systems through which tuberculosis (TB) notifications are handled.

The NNDSS provides the most timely information on national TB notifications, but demographic information is limited. The National Mycobacterial Surveillance System (NMSS), a surveillance system dedicated to tuberculosis and atypical mycobacterial notifications, is used to produce an annual report on TB notifications with detailed information on risk factors, diagnostic methods, drug therapy and relapse status. The 1997 annual report for the NMSS will be published in 1999. The Australian Mycobacterial Reference Laboratory Network (MRLN) maintains national data on drug susceptibility profiles, site of disease, age, sex and laboratory method of diagnosis for all mycobacterial isolates. These data are published annually in conjunction with the NMSS surveillance report.

In 1997, 1,008 notifications of TB were reported nationally, and the corresponding rate was 5.4 per 100,000. The highest disease rates of 18.2 per 100,000 were reported in the Northern Territory. These data are consistent with those reported since 1991.

Rates of TB were highest in males over the age of 65 years and females over the age of 70 years. A smaller peak in age-specific rates was reported in the 25 to 29 year age group (Figure 30).

Males accounted for 542 (54%) of the 1,005 notifications in which sex was reported.

Figure 31. Notifications of tuberculosis, 1997, by age group and sex

Discussion

TB rates in Australia have been stable over the last decade. Published surveillance reports, based on data collected by the NMSS have consistently identified elderly Australian born persons, migrants from high prevalence countries, and Indigenous Australians as those at increased risk of TB disease.⁴⁹

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.