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: 05 February 2020

Fortnight 01: 01 January to 17 January 2020

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Infectious Syphilis

Increases in infectious syphilis notifications are attributed to an on-going outbreak occurring in young Aboriginal and Torres Strait Islander people residing in northern and central Australia, continued increases among men who have sex with men (MSM) in urban areas of Victoria (Vic) and New South Wales (NSW), and increases in non-Indigenous women residing in urban areas of Vic, NSW, Queensland (Qld) and Western Australia (WA).

Outbreak in remote Australia

In January 2011, an increase of infectious syphilis notifications among young (15-29 years) Aboriginal and Torres Strait Islander people was identified in the North West region of 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, 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 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 Vic and NSW.

Increases among non-Indigenous women

Since 2016, increases in notifications of infectious syphilis have been reported in non-Indigenous women aged predominately 20-39 years of age residing in urban areas of NSW, Vic, Qld and WA. As noted in the outbreak in remote Australia, increases in women of child-bearing age is of significant public health concern given the increased risk of congenital syphilis.

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 is 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 (20 October 2019 to 17 January 2020) there were 783 cases of shigellosis notified, which 1.8 times the quarterly rolling five year mean (n=439). 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 2020 up to 17 January, there have been 2,829 laboratory‑confirmed influenza cases reported to the National Notifiable Diseases Surveillance System (NNDSS). This is higher than the mean number of cases reported in the same period over the previous 5 years (n=1,453). However, the number of cases reported to the NNDSS in 2020 year to date remains lower than the number reported in the same period in 2019 (n=3,740).

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 available on the Department’s website.

Measles

Measles cases in 2019 were higher in comparison to the number of cases reported in the previous 5 years, except in comparison to 2014. In the 2020 year to date, there have been 15 cases of measles reported to the NNDSS, which is the same when compared to the number of cases reported in the same period in 2019.

There has been a significant increase in measles cases worldwide, and significant outbreaks in the Asia-Pacific region.


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 20/10/2019 to 17/01/2020.
  2. The quarterly (90 day) five year rolling mean is the average of 5 intervals of 90 days up to 17/01/2020. 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 18/01/2019 to 17/01/2020.
  4. The yearly (365 day) five year rolling mean is the average of 5 intervals of 365 days up to 17/01/2020. 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