National Notifiable Diseases Surveillance System - current CDNA fortnightly report

The Communicable Diseases Network Australia (CDNA) holds fortnightly teleconferences to share and evaluate the latest information and developments in communicable diseases surveillance. This report provides a fortnightly summary on diseases of current interest and notifications of Australia's nationally notifiable diseases.

Page last updated: 16 October 2019

Fortnight 18: 31 August to 13 September 2019

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Infectious Syphilis

Increases in infectious syphilis notifications are attributed to an ongoing outbreak occurring in young Aboriginal and Torres Strait Islander people residing in northern and central Australia and continued increases among men who have sex with men (MSM) in some urban areas throughout Australia.

Outbreak in remote Australia

In January 2011, an increase of infectious syphilis notifications among young Aboriginal and Torres Strait Islander people was identified in the North West region of Queensland (QLD), following a steady decline at a national level in remote communities. Subsequent increases in infectious syphilis notifications were reported in the Northern Territory (NT) in 2013, Western Australia (WA) in 2014 and South Australia (SA) in 2016, following sustained periods of low notification rates. The outbreak is of significant public health concern given the: elevated rates of infectious syphilis among women of child-bearing age, increasing the risk and the rate of congenital syphilis; and the concomitant risk of HIV transmission.

For the latest information on the infectious syphilis outbreak, refer to the Department’s website.

Increases among MSM

Since 2010, increases in notifications of infectious syphilis have been reported in MSM, predominately 20-39 years of age, residing in urban areas of Victoria (VIC), Qld and NSW. Since 2015, increases have been reported in MSM in urban areas in South Australia.

Shigellosis

From 1 July 2018, the shigellosis surveillance case definition was changed to require notification of both confirmed and probable cases. This change in case definition was expected to result in an increase in notifications of shigellosis from 1 July 2018. Additionally, since 2014 there has been an increasing trend in national notifications of shigellosis. In the past quarter (16 June 2019 to 13 September 2019) there were 663 cases of shigellosis notified, which 1.7 times the quarterly rolling five year mean (n=391.2). Rates of shigellosis in Australia are higher amongst Aboriginal and Torres Strait Islander peoples compared with non-Indigenous populations. In 2018, the rate of shigellosis in Aboriginal and Torres Strait Islander peoples was 115.5 cases per 100,000 population, compared with 7.3 cases per 100,000 in non-Indigenous populations.

Influenza

In the 2019 year to date, there has been a high number of laboratory‑confirmed influenza cases reported to the National Notifiable Diseases Surveillance System (NNDSS), compared to the same period in previous years. This is due to heightened interseasonal activity that has resulted in an unusually early start to the 2019 influenza season. In the past quarter (16 June 2019 to 13 September 2019), there were 182,598 cases of laboratory confirmed influenza reported to the NNDSS, which is 2.6 times the quarterly rolling five year mean (n= 69,915.6). This ratio has decreased since the previous fortnight.

The Department of Health closely monitors national influenza activity throughout the year, including during the inter-seasonal period. The Australian Influenza Surveillance Reports for 2019 are now available on the Department’s website.


Interpretative Notes

Selected diseases are chosen each fortnight based on either exceeding two standard deviations from the 90 day and/or 365 day five year rolling mean or other disease issues of significance identified during the reporting period. All diseases reported are analysed by notification receive date. Data are extracted each Monday of a CDNA week.

Totals comprise data from all States and Territories. Cumulative figures are subject to retrospective revision so there may be discrepancies between the number of new notifications and the increment in the cumulative figure from the previous period.

  1. The past quarter (90 day) surveillance period includes the date range 16/06/2019 to 13/09/2019.
  2. The quarterly (90 day) five year rolling mean is the average of 5 intervals of 90 days up to 13/09/2019. The ratio is the notification activity in the past quarter (90 days) compared with the five year rolling mean for the same period.
  3. The past year (365 day) surveillance period includes the date range 14/09/2018 to 13/09/2019.
  4. The yearly (365 day) five year rolling mean is the average of 5 intervals of 365 days up to 13/09/2019. The ratio is the notification activity in the past year (365 days) compared with the five year rolling mean for the same period.

The five year rolling mean and the ratio of notifications compared with the five year rolling mean should be interpreted with caution. Changes in surveillance practice, diagnostic techniques and reporting may contribute to increases or decreases in the total notifications received over a five year period. Ratios are to be taken as a crude measure of current disease activity and may reflect changes in reporting rather than changes in disease activity.

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Table of communicable disease notifications reported to the NNDSS for this fortnight