Australia’s top medical body has urged the public to ensure they are fully vaccinated and boosted against diphtheria amid what health authorities describe as the country’s largest outbreak of the disease in decades.

The outbreak, which began in remote Aboriginal communities in the Northern Territory, has now spread across three state borders, with a total of 223 confirmed cases reported so far.

One person in the Northern Territory has died, although the exact cause of death remains under investigation.

The Australian Medical Association (AMA) has called on Australians to check their vaccination status and ensure their families are protected against the highly contagious disease.

AMA President Dr. Danielle McMullen warned that falling vaccination rates are allowing previously controlled diseases to re-emerge.

“Immunisation is one of the greatest achievements in modern medicine, but when vaccination rates fall, serious diseases that were once largely eliminated can return,” she said.

Health authorities believe declining childhood vaccination rates following the COVID-19 pandemic may be contributing to the resurgence.

Data shows the number of fully vaccinated children in Australia has gradually declined since 2020, with vaccination coverage among two-year-olds falling below the critical 90 percent threshold in 2024.

The outbreak has now spread throughout all five regions of the Northern Territory, with genomic sequencing linking the strain to smaller outbreaks previously recorded in Western Australia’s Kimberley region and North Queensland.

According to officials, 133 cases have been reported in the Northern Territory, 79 in Western Australia, six in South Australia and five in Queensland.

Australian Health Minister Mark Butler described the situation as “serious” and said most of the cases in the Northern Territory involved Indigenous Australians.

Medical experts have warned that the outbreak highlights the dangers posed by immunity gaps and declining vaccination coverage.

Diphtheria is a highly infectious bacterial disease spread through respiratory droplets and skin sores. Early symptoms resemble a cold or flu, but severe respiratory cases can cause swelling of the throat, breathing difficulties and potentially death.

Health experts stress that vaccination remains the most effective protection against the disease, although prompt treatment with antibiotics and antitoxins is required once infection occurs.