As of 11 May 2026, a total of 194 diphtheria infections have been notified in Australia in 2026, including 2 probable cases, according to the Australian Centre for Disease Control.
Current case numbers are well above the historical pandemic-adjusted 5-year monthly mean and pre-pandemic levels.
Notifications of diphtheria have been increasing since October 2025, with a marked increase since February 2026. The number of cases notified so far in 2026 is 29.8 times the number of cases for the equivalent periods in 2022 to 2025.
Among cases reported in 2026, 60.3% (117/194) were reported in the Northern Territory, a third (36.6%; 71/194) in Western Australia, 2 cases in Queensland, and 4 cases in South Australia.
In 2026, among locally acquired cases (98.9%; 192/194), 81.8% resided in areas classified as ‘remote’ and ‘very remote’, while a further 15.1% resided in ‘outer regional’ areas.
In 2026, the predominant clinical presentation continues to be cutaneous diphtheria (69.1%; 134/194), with respiratory diphtheria accounting for 29.9% (58/194) of cases, and two cases reported with an unknown clinical presentation type. Over the past month, there has been an increase in the number and proportion of cases diagnosed as respiratory diphtheria.
So far in 2026, 93.8% (182/194) of cases have been reported among Aboriginal and/or Torres Strait Islander people.
So far in 2026, a slightly lower proportion (24.7%; 48/194) of all diphtheria cases have been hospitalised. The most recent confirmed diphtheria associated death was reported in 2018 and involved an unvaccinated adult who had respiratory diphtheria.
A patient in a remote part of the Northern Territory reportedly died from diphtheria several weeks ago, according to Dr John Boffa of the Central Australian Aboriginal Congress. NT Health stated it is awaiting autopsy results before confirming the cause of death.
National diphtheria–tetanus–pertussis (DTP) vaccination coverage rates as at September 2025, based on the National Immunisation Program Schedule, was:
• 93.4% (range: 91.9% to 94.8%) among all children aged 5 years
• 94.7% (range: 92.9% to 96.3%) among Aboriginal and Torres Strait Islander children aged 5 years.
However, ‘fully immunised’ rates among the 5-year-old cohort, regardless of Indigenous status, have been gradually declining since peaking in 2020.