Diphtheria, once one of Australia’s most feared childhood infections, caused thousands of deaths before vaccines became widely available, but it had remained extremely rare for decades.
That situation has now changed, with the disease re-emerging in parts of Australia, including the Northern Territory, Western Australia, South Australia, and Queensland.
In 2026, more than 230 cases have been reported, mostly in the Northern Territory, marking the country’s largest diphtheria outbreak since national records began.
In response, the federal government has announced a $7.2 million package to help manage and contain the outbreak.
Public health experts note that diphtheria is only one of several infectious diseases making a comeback in Australia.
Diphtheria, measles, scarlet fever, and whooping cough were once common and feared illnesses, but improved living standards, sanitation, and vaccination significantly reduced their impact over the past two generations.
However, experts warn that these public health gains are not permanent and can be reversed when vaccination rates fall or health systems weaken.
In 2024, Australia’s national childhood vaccination coverage dropped below 90 per cent for the first time in years, reducing community protection against diseases such as diphtheria.
Whooping cough has also surged, with more than 57,000 cases recorded in 2024 and over 25,000 in 2025, following disruptions caused by COVID-19 and declining immunity levels.
Measles has reappeared as well, with around 100 cases reported between January and May 2026, mostly linked to unvaccinated individuals and overseas travel.
Health authorities warn that measles remains highly contagious, requiring around 95 per cent population immunity to prevent outbreaks, while Australia’s current vaccination coverage has fallen slightly below that threshold.
Meanwhile, syphilis cases have also risen sharply over the past decade, with congenital syphilis causing infant deaths due to gaps in testing, treatment, and access to healthcare.
Public health experts emphasise that disease control requires sustained investment in vaccination, surveillance, healthcare access, and social conditions such as housing and sanitation.
They caution that without maintaining these protections, diseases once thought to be under control can quickly return.
