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Presentation of NNDSS data

In the March 2000 issue an additional summary table was introduced. Table 1 presents 'date of notification' data, which is a composite of three components: (i) the true onset date from a clinician, if available, (ii) the date the laboratory test was ordered, or (iii) the date reported to the public health unit. Table 2 presents data by report date for information only. In Table 2 the report date is the date the public health unit received the report.

Table 1 now includes the following summary columns: total current month 2000 data; the totals for previous month 2000 and corresponding month 1999; a 5 year mean which is calculated using previous, corresponding and following month data for the previous 5 years (Morb Mortal Wkly Rep, 2000:49;139-146); year to date (YTD) figures; the mean for the year to date figures for the previous 5 years; and the ratio of the current month to the mean of the last 5 years.

Highlights for June 2000

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 CDI Virology and Serology Laboratory Reporting Scheme (LabVISE) is a sentinel surveillance scheme. In this report, data from the NNDSS are referred to as 'notifications' or 'cases', whereas those from the LabVISE scheme are referred to as 'laboratory reports'.

Three types of data are included in National Influenza Surveillance, 2000. These are sentinel general practitioner surveillance conducted by the Australian Sentinel Practice Research Network (ASPREN), the Department of Human Services (Victoria), the Department of Health (New South Wales) and the Tropical Influenza Surveillance Scheme, Territory Health (Northern Territory); laboratory surveillance data from the Communicable Diseases Intelligence Virology and Serology Laboratory Reporting Scheme (LabVISE); and the World Health Organization Collaborating Centre for Influenza Reference and Research; and absenteeism surveillance conducted by Australia Post. Data from ASPREN are referred to as 'consultations' or 'encounters'. For further information about these schemes, see Commun Dis Intell 2000;24:9-10.

Compared with the 5-year mean, in June 2000 there was an increase in the number of cases of chlamydial infection (ratio 1.2), legionellosis (ratio 1.3) and meningococcal infection (ratio 1.3) (Figure 1).

Figure 1. Selected¹ diseases from the National Notifiable Diseases Surveillance System, comparison of provisional totals for the period 1 to 30 June 2000 with historical data²

1. Selected diseases are chosen each calendar month according to current activity

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Chlamydial infections

There were 996 notifications of chlamydial infection in June 2000 - a notification rate of 63.02/100,000 population (Figure 2); the Northern Territory and Queensland contributed most to the increase in notifications for this month (447.94/100,000 and 125.39/100,000 respectively). Part of this increase can be explained through the use of PCR urine-testing technology and screening programs in several States.

Figure 2. Notification rate of chlamydial infection, Australia, 1 January 1991 to 30 June 2000, by month of notification



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Encephalitis

A renewed warning was issued in June 2000 by the Northern Territory government regarding Australian Encephalitis in the top end. There have been no further cases since May 2000 in Western Australia or the Northern Territory.

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Foodborne illness outbreaks

There is currently an increase in Salmonella Typhimurium phage-type 9 in Victoria. A common source of infections has not been identified. Two family clusters of 4 and 5 cases each have been identified one of which was thought to be related to a home cooked meal of chicken.

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Legionellosis

There were 22 notifications of legionellosis in June 2000 - a notification rate of 1.39/100,000 population. In Victoria there were three confirmed cases and one unconfirmed case of L. pneumophila serogroup1 associated with a spa pool at a football club. The other cases were sporadic with no obvious sources.

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Listeriosis

There were three cases of Listeria in Western Australia. One case was a pregnant woman resulting in the still birth of her baby, who also tested positive, and another was a woman with end stage renal failure who was on haemodialysis. The Health Department of Western Australia issued a reminder to pregnant women, the elderly and people with lowered immunity to take special care to avoid food that may contain the bacterium Listeria. The reminder followed a recent state- wide survey of sandwiches served at cafes, bakeries and lunchbars, which found Listeria monocytogenes present in 11 of 228 samples.

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Meningococcal infections

There were 57 notifications of meningococcal infection in June 2000 - a notification rate of 3.61/100,000 population (Figure 3). Of these cases 33% were under 5 years of age and 39% were in the 15-24 age range. The serogroups were available for 41 cases; of these 56%, 42% and 2% were serogroup B, C and Y respectively.

Figure 3. Notification rates of meningococcal infections, Australia, 1 January 1991 to 30 June 2000, by month of notification



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Vaccine preventable diseases

All vaccine preventable diseases (except mumps) had fewer cases this month compared with the 5-year mean for June. There were two male and two female cases of Haemophilus influenzae type b reported in June, an increase in the number of notifications from May (one case). Of the June cases, one was a child aged less than 1 year, and the others were aged 33, 40 and 84 years; the immunisation status of all was unknown. For measles, the last 3 months have had the lowest number of notifications since the national notification system began (Figure 4). Of the seven cases in June, two were in children under 5 years and one was confirmed as having been imported from the United Kingdom.

Figure 4. Notification rate of measles, Australia, 1 January 1991 to 30 June 2000, by month of notification



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Influenza

The New South Wales sentinel surveillance network reported the highest rate of consultations for influenza (10/1,000 patients). There were 113 laboratory reports for June 2000 - a decrease from 352 in June 1999 (Figure 5). Of the laboratory reports received in June 2000 (weeks 23-26), 70 were Influenza A and 40 were Influenza B with the percentage of influenza B increasing from 13% in week 23 to 44% in week 26 (Figure 6). Compared with June 1999, the percentage of Australia Post employees absent in June 2000 (weeks 23-26) for three or more consecutive days in 1 week increased (Figure 7). However, to date in 2000, there were fewer reports from laboratories of influenza - and from ASPREN of influenza-like illness - compared with 1999 (Figures 5 and 8).

Figure 5. Laboratory reports of influenza, 1999 to 2000, by month of specimen collection



Figure 6. Laboratory reports of influenza, Australia, week 1 1999 to week 26 2000, by week of specimen collection



Figure 7. Absenteeism rates in Australia Post, 1999 and 2000 to June 30



Figure 8. Sentinel general practitioner influenza consultation rates, week 1 1999 to week 26 2000, by scheme¹

1. Week 26, 2000, ASPREN data are for Australia other than the Northern Territory

This article was published in Communicable Diseases Intelligence Volume 24, No 7, July 2000.