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Communicable Diseases Surveillance consists of data from several 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'. Data from the LabVISE scheme are referred to as 'laboratory reports'.

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Vaccine preventable diseases

Although the epidemic of pertussis in Australia continues, the number of notifications is declining, which is consistent with the seasonal drop expected in the first few months of the year. The majority of reports of pertussis with onset in 1998 have been for children aged 0 to 4 years (15%), 5 to 9 years (20%) and 10 to 14 years (15%). The male:female ratio was 1:1.1.

Measles notifications have remained relatively low for the past 3 years, with a small increase in activity in the last quarter of 1997, as would be expected for the time of year (Figure 1). The majority of cases with onset in 1998 were reported from Victoria (34%), New South Wales (25%) and Queensland (18%). In 1997 and 1998 most cases were in children under 5 years of age (75%), with an overall male:female ratio of 1.0:1 (Figure 2).

Figure 1. Notifications of measles, 1991 to 1998, by month of onset


Figure 2. Notifications of measles, 1997 and 1998, by age group and sex

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Arboviruses

The number of notifications of Ross River virus infection remains low for the time of year (Figure 3). Similarly few cases of Barmah Forest virus infection have been notified compared to recent years (Figure 4).

Figure 3. Notifications of Ross River virus infection, 1991 to 1998, by month of onset

Figure 4. Notifications of Barmah Forest virus infection, 1995 to 1998, by month of onset

One hundred and seven cases of dengue were notified this period, bringing the total for the year so far to 183. All but 10 of the current notifications had a recorded date of onset before March (Figure 5). Of the 186 cases with onset since November 1997, 140 (75%) were residents of the Queensland Statistical Division of Far North. In the 1996-97 outbreak, a similar pattern was observed, a larger proportion (88%) being residents of the same Statistical Division of Far North. In the recent outbreak the male:female ratio was 1.3:1 and 66% of cases were aged between 25 and 59 years (Figure 6).

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Figure 5. Notifications of dengue, 1991 to 1998, by month of onset


Figure 6. Notifications of dengue, 1997 and 1998, by age group and sex


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Enteric infections

Hepatitis A was notified for 240 persons this period, of which 113 (47%) were from Queensland. The number of cases rose in January and February but remain below the peak seen in early 1997 (Figure 7). Of the 740 cases reported with onset in 1998 so far, 31% were for the 20 to 29 years age group, the male:female ratio for this group being 2.3:1 (Figure 8).

Figure 7. Notifications of hepatitis A, 1995 to 1998, by month of onset

Figure 8. Notifications of hepatitis A, 1998, by age group and sex

Fifty-six laboratory reports of hepatitis A were received by the sentinel laboratory scheme LabVISE this period, 68% of which were from Queensland. Included were 37 males and 19 females, a male:female ratio of 2.0:1. Forty-one per cent of reports were for those in the 25-44 years age group.

The number of notifications of salmonellosis rose in late 1997 and early 1998 but remain below the level seen for the same period last year (Figure 9). Overall for 1997, 6,830 notifications of this disease were reported with onset in that year, of which 36% were for children under the age of 5 years.

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Figure 9. Notifications of salmonellosis, 1996 to 1998, by month of onset



The number of cases of campylobacteriosis reported to the NNDSS remains low compared to the same period last year. One thousand eight-hundred and forty-one notifications with onset in 1998 have been received so far. Of these 18% of cases were under the age of 5 years and 22% were in the 20-29 years age group.

The LabVISE scheme recorded 5 cases of echovirus type 11 this reporting period, all from New South Wales. Of these 4 had specimen collection dates in January, which is usually the peak month for enterovirus activity in Australia. Included were 3 males aged 0 to 5 years and 2 females both of whom were in the 15-44 years age group.

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Rhinovirus

The number of rhinovirus laboratory reports has fallen in recent months after peaking last September. For 1997 a total of 550 laboratory reports was received of which 85% were for children under the age of 5 years.

This article was published in Communicable Diseases Intelligence Vol 22 No 4, 16 April 1998.