May 2026
The Communicable Diseases Network Australia (CDNA) and the Australian Centre for Disease Control (ACDC) have issued an interim guidance package for diphtheria outbreak management after cases have been identified in the Northern Territory, SA, WA and Queensland.
Diphtheria notifications in Australia have been increasing since October 2025, with a marked increase since February 2026.
There have been 230 cases of diphtheria notified in Australia this year, representing an approximately 30‑fold increase compared with the same period from 2022 to 2025.
This interim guidance has been developed and released as a priority to respond to the current situation, while the development of the Diphtheria Series of National Guidelines (SoNG) is underway.
The case fatality rate for severe respiratory diphtheria is estimated to be approximately five to 10 per cent, even with treatment.
Children under the age of five are more at risk than adults over 20 years old of dying from diphtheria.
Public health units have been advised to consider the following factors in assessing whether cases constitute an outbreak:
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the baseline epidemiology for the region;
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the type of clinical presentations, i.e. whether cases have cutaneous or respiratory infections or toxin-related disease;
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the temporal, geographic or genomic relationship of cases.
Outbreak response focuses on case and contact management as household-like contacts are at highest risk of developing disease.
Compared with asymptomatic carriage, symptomatic diphtheria infection increases bacterial shedding and poses an increased risk to exposed people.
For outbreaks which affect Aboriginal and Torres Strait Islander communities, it is essential to include appropriate Aboriginal and Torres Strait Islander stakeholders in outbreak team meetings, in developing communications and in other decision-making processes.
Early engagement, co-design and co-leadership of outbreak response activities is crucial to building a culturally safe and effective response.
For further information, the guideline is available online via
CDNA & ACDC interim guidance information.