Diphtheria cases are rising in Australia, marking a concerning trend for the first time since the advent of widespread vaccination in the 1930s.

The nation has reported 230 cases
of this dangerous bacterial infection along with 1 related adult death this year. The surge is attributed to increasing case numbers, primarily affecting remote Indigenous communities in the Northern Territory and Western Australia, and smaller incidences in Queensland and South Australia. Historically, the annual infection rate hovered around zero.

According to Paul Burgess, the Chief Health Officer of the Northern Territory, the latest outbreak stems from an incident dating back to 2022 in Queensland, originally contracted overseas. This highly contagious disease has since spread to Indigenous communities across the Northern Territory and neighboring states, driven by vaccination gaps, high mobility between communities, and crowded living conditions.

Vaccination coverage for diphtheria among five-year-olds in the Northern Territory stands at approximately 92%, but only around 67% of 13-year-olds receive necessary booster shots available through school-based programs. Raina McIntyre from the University of New South Wales noted, “The effectiveness of the vaccine is waning, and booster immunizations are urgently needed.”

This trend partly explains why adolescents and young adults are increasingly falling ill with diphtheria.

Challenges in achieving optimal vaccination rates stem from “increased vaccine misinformation and backlash following the COVID-19 pandemic,” as McIntyre observed. The shortage of healthcare professionals in remote areas further complicates matters.

The diphtheria infection is caused by the Diphtheria bacterium, which affects the skin and respiratory system, producing a toxin that leads to severe complications. Symptoms include painful throat ulcers or a thick gray film in the throat that can obstruct breathing. When toxins enter the bloodstream, severe outcomes, including heart failure and paralysis, may occur.

This bacterium can be transmitted through contact with sores of an infected person or through respiratory droplets.

While treatment can include antibiotics and antitoxins that neutralize the diphtheria toxin, mortality can still occur despite medical intervention.

Before the diphtheria vaccine was introduced, the disease was a leading cause of child mortality worldwide. In Australia, over 4,000 deaths were attributed to diphtheria between the late 1920s and early 1930s.

The Australian government recently announced a funding package of A$7.2 million (£3.8 million) to combat the outbreak, deploying additional healthcare professionals to affected regions for increased vaccination efforts and treatment administration.

Burgess emphasized to the ABC: “We are encouraged by the strong community demand for vaccination in response to this outbreak.”

Globally, the largest diphtheria outbreak since routine immunization began occurred in countries of the former Soviet Union post-1991, with an alarming rate of 140,000 infections and 5,000 deaths resulting from a collapse in vaccination coverage, underscoring that “vaccine program disruptions can lead to outbreaks,” stated McIntyre.