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: 22 January 2021

Fortnight 26: 21 December to 03 January 2021

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Infectious and congenital 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.

Legionellosis

In the past 12 months (4 January 2020 to 3 January 2021), there have been 524 cases of legionellosis reported to the National Notifiable Diseases Surveillance System (NNDSS). This is higher than the mean number of cases reported for the historical five-year mean (n=403.6). In the past fortnight (21 December 2020 to 3 January 2021), 23 cases of legionellosis were notified compared to 11 in the same reporting period in the previous year. Of the 23 cases reported in the past fortnight, 19 cases have had species identification reported, with 10 cases identified as Legionella longbeachae (53%) and nine cases identified as Legionella pneumophila (47%). It is difficult to determine the extent to which the increase in legionellosis notifications is associated with increased testing of individuals with influenza-like symptoms or pneumonia in response to COVID-19, or other factors.


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 06/10/2020 to 03/01/2021.
  2. The quarterly (90 day) five year rolling mean is the average of 5 intervals of 90 days up to 03/01/2021. 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 04/01/2021 to 03/01/2021.
  4. The yearly (365 day) five year rolling mean is the average of 5 intervals of 365 days up to 03/01/2021. 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