163 cases. That's how many diphtheria infections the Northern Territory recorded between January 2025 and May 2026, according to leaked internal health data obtained by the ABC. The documents show cases began climbing sharply from the last week of February, more than a month before NT Health issued a public alert on March 25, 2026, and national totals have already topped 240 this year, the BBC reported. Authorities later scaled up vaccination campaigns that delivered 10,407 doses from March 30 and the federal government announced a AU$7.2 million support package for affected areas.

Delayed awareness appears to have slowed the initial response, leaving remote clinics under pressure and hampering early vaccine outreach.

The leaked NT Health document, circulated to service providers on a Thursday and confirmed as legitimate by the department, contains a daily epidemiological curve that records only a handful of cases in early January before a sustained week on week rise across Darwin, the Top End and the Katherine region from late February. NT Health told the ABC the chart was intended for clinicians and service providers and not for public distribution, and the department acknowledged the daily charts were frequently revised upward, meaning early public figures were conservative compared with later counts.

Where the outbreak has hit

The outbreak has been concentrated in the Northern Territory and Western Australia, with smaller numbers in South Australia and Queensland. The BBC reported about 60 percent of national cases have been in the NT and roughly 36 percent in WA, and The Guardian put the national total at more than 230 cases, reporting at least 85 cases in WA and seven confirmed cases in the APY Lands in South Australia.

Northern Territory Chief Health Officer Paul Burgess told ABC reporters the disease "is actually all over the five regions of the Northern Territory," and public health officials say most cases have been detected in remote Indigenous communities. But that geographic pattern is central to why clinicians and Aboriginal-controlled providers described early constraints on vaccine supply and workforce when the surge began.

Mastheads

Health impact and system strain

An autopsy confirmed a diphtheria death in April at Royal Darwin Hospital, the first such death in the NT since 2018, the BBC reported. The Guardian and other coverage say up to one third of respiratory cases have required hospitalisation, placing pressure on local health services.

Clinicians and Aboriginal-controlled health providers described delayed awareness at local clinics. Dr John Boffa, chief medical officer at the Central Australian Aboriginal Congress, said clinicians only became aware of widespread local transmission in late March and that outreach and surge workforce capacity were needed to reach remote communities. The briefings and contemporaneous reporting show that where outreach and vaccine supply were slow to arrive, the disease spread faster and hospital admissions rose.

Federal Health Minister Mark Butler told the ABC the Northern Territory government requested Commonwealth assistance in late April. The federal government announced a AU$7.2 million package to support vaccinations and resources in affected areas, according to the BBC, and NT Health worked with peak Aboriginal health bodies to prioritise vaccine delivery.

Vaccination uptake strengthened once supply and outreach improved. This BBC reported 10,407 vaccine doses had been administered since March 30 under intensified campaigns that set up pop-up clinics in Darwin, Katherine and Alice Springs. Local providers reported strong uptake once supply and outreach capacity improved, and the leaked epi curves indicate aggregate case numbers fell in the three weeks before late May, which NT health officials have publicly noted as a recent downturn.

The data packet also makes clear how reporting lags and revisions can shape public perception of an outbreak. NT Health said the daily charts were frequently revised upward. That suggests early public briefings understated the full scale of transmission at a moment when clinical teams were already seeing cases rising in multiple regions.

For remote Indigenous communities, the combination of higher case numbers and service constraints has been acute. The leaked material and contemporaneous journalism underline that the outbreak has chiefly affected those communities, and that reaching them required surge workforce deployments and targeted pop-up vaccination sites. That operational complexity helps explain why the territory first alerted the public on March 25 despite rising case counts from late February in the internal charts.

The national dimension matters too. With more than 240 cases reported nationally this year, the NT and WA account for the bulk of infections, and cases in South Australia and Queensland show the outbreak isn't strictly localised. Public health authorities say vaccination remains the most important tool to prevent and reduce transmission, and the stepped-up campaigns are the main lever used since the alarm was raised.

Related Articles

A concrete figure from the stepped-up response is 10,407 vaccine doses administered since 30 March, alongside a federal AU$7.2 million package to support vaccinations and resources in affected areas.

This article was created with AI assistance.