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Communicable Diseases Surveillance consists of data from various sources. The National Notifiable Diseases Surveillance System (NNDSS) is conducted under the auspices of the Communicable Diseases Network Australia New Zealand. The Virology and Serology Laboratory Reporting Scheme (LabVISE) is a sentinel surveillance scheme. The Australian Sentinel Practice Research Network (ASPREN) is a general practitioner-based sentinel surveillance scheme. In this report, data from the NNDSS are referred to as 'notifications' or 'cases', whereas those from ASPREN are referred to as 'consultations' or 'encounters' while data from the LabVISE scheme are referred to as 'laboratory reports'.
The number of notifications of meningococcal disease has increased again in this reporting period, as is expected at this time of the year (Figure 1). However, the number of notifications for this reporting period is lower than for the corresponding period in 1997, and the total number for the year (184) is 17% lower than for the same period in 1997 (222). This may reflect delays in reporting, a delay in the peak season of activity or a true decrease in the number of cases.
Figure 1. Notifications of meningococcal disease, 1994 to 1998, by month of onset
LegionellosisThere have been 25 reports of legionellosis in the current reporting period, compared with 8 reports for the corresponding period in 1997. Of these, 12 were Legionella longbeachae infections, 7 were Legionella pneumophila infections and in 6 the organism was unknown. Reports of Legionella longbeachae were received from New South Wales (2), Queensland (3) and South Australia (7). Reports of Legionella pneumophila were from New South Wales (2), Queensland (1), South Australia (1) and Victoria (3). The Victorian cases form part of the cluster reported on page 155 of this issue.
For the year to 21 July there have been 138 reports of legionellosis with an onset date during 1998. This is higher than reported for the corresponding periods in each year since 1992. The reported organism was Legionella longbeachae in 53, Legionella pneumophila in 55, 'other' in 1 and unknown in 29.
The geographic distribution of legionellosis was different for the two main organisms. The majority of reports of Legionella longbeachae were from South Australia (22) and Queensland (20) with smaller numbers from New South Wales (10) and Victoria (1). Legionella pneumophila was predominantly reported from Victoria (32) with smaller numbers from New South Wales (10), South Australia (7) and Queensland (6).
Males predominated for both organisms. The male:female ratio was 3.4:1 for Legionella longbeachae and 4:1 for Legionella pneumophila. The age range for Legionella longbeachae was 22 years to 85 years and 71% of males and 58% of females were aged 50 years or older. For Legionella longbeachae, the age range was 28 years to 76 years and 80% of cases for both males and females were aged 50 years or older.
Reports of parainfluenza virus type 1 have declined in recent weeks after peaking in April (Figure 2). The number of laboratory reports of parainfluenza virus type 3 is low for the time of year. Respiratory syncytial virus reports continue to rise but also remain lower than average for the time of year (Figure 3).
(See also National Influenza Surveillance, page 167).
Vaccine preventable diseases
Notifications for vaccine preventable diseases continue to remain low. The epidemic of pertussis which has persisted for the past couple of years has waned further with the number of notifications having onset in June 1998 being the lowest for any month since June 1996. Figure 4 compares notifications in the current period with historical data.
Figure 2. Laboratory reports of parainfluenza viruses, 1996 to 1998, by type and month of specimen collection
Figure 3. Laboratory reports of respiratory syncytial virus, 1996 to 1998, by month of specimen collection