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: 09 August 2018

Fortnight 15: 21 July to 03 August 2018

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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 and continued increases among men who have sex with men (MSM) in urban areas of Victoria and New South Wales (NSW).

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 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 - Infectious syphilis outbreak.

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) and NSW.

Influenza

Currently, influenza and influenza - like illness (ILI) activity are low and remain at inter - seasonal levels across Australia. While national notifications of laboratory confirmed influenza were higher than usual in January and February, consistent with high activity experienced in the Northern Hemisphere at that time, notifications returned to normal range by March. The Australian Government Department of Health continues to monitor influenza activity and a detailed analysis of influenza activity is available on the Department's website.

Invasive Meningococcal Disease (IMD)

The number of cases of IMD due to serogroup W and serogroup Y has been increasing across most jurisdictions in Australia in 2016 and 2017. The Australian Government Department of Health, in collaboration with the states and territories, is closely monitoring the incidence of IMD in Australia. For the latest information on IMD, refer to the Department’s website.

Invasive Pneumococcal Disease

Notifications of invasive pneumococcal disease (IPD) were around 29% higher over the past quarter (n=694), when compared to the quarterly rolling 5 year mean (n=538.2). IPD notifications consistently increase and peak over the winter months, and tend to correlate with the winter influenza seasons. A more detailed analysis of IPD notification trends in Australia up to 31 March 2018 is available in the IPD quarterly report.

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 2017, there were 1,745 cases of shigellosis notified in Australia, which was 1.9 times the 5 year rolling mean (n=914). In the past quarter (6 May 2018 to 3 August 2018) there were 579 cases of shigellosis notified, compared with the quarterly rolling five year mean of 280.4.

Rates of shigellosis in Australia are higher amongst Aboriginal and Torres Strait Islander peoples compared with non-Indigenous populations. In 2017, the rate of shigellosis in Aboriginal and Torres Strait Islander peoples was 100 cases per 100,000 population, compared with 4 cases per 1000,000 in non-Indigenous populations.

Tuberculosis

Notifications of tuberculosis (TB) over the past 365 day surveillance period (n=1,461) were around 10% higher when compared with the rolling 5 yearly mean (n=1,326.0). The incidence rate of TB in Australia is considered one of the lowest in the world (approximately 5 to 6 cases per 100,000 population). The majority (almost 90%) of new TB cases are diagnosed in people born overseas, with nearly half of these cases being diagnosed within four years of arrival in Australia.


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 06/05/2018 to 03/08/2018.
  2. The quarterly (90 day) five year rolling mean is the average of 5 intervals of 90 days up to 03/08/2018. 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 04/08/2017 to 03/08/2018.
  4. The yearly (365 day) five year rolling mean is the average of 5 intervals of 365 days up to 03/08/2018. 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