The Return of Diphtheria: A Preventable Tragedy
Diphtheria, a disease that once claimed hundreds of lives annually, is making an unwelcome comeback in Australia. This resurgence raises critical questions about vaccine hesitancy, public health strategies, and the broader implications for our society.
A Historic Perspective
Diphtheria's history is a stark reminder of the power of vaccines. Before their introduction, this bacterial infection was a leading cause of childhood mortality worldwide. In Australia alone, over 4,000 lives were lost between 1926 and 1935. However, the implementation of vaccination programs in the 1930s led to a dramatic decline in cases, with the disease becoming a rarity by the 1950s.
The Recent Outbreak
Fast forward to the present, and we find ourselves grappling with a diphtheria outbreak, particularly in the Northern Territory (NT) and Western Australia's Kimberley region. The NT has reported a staggering 17 cases of respiratory diphtheria in just one month, alongside 60 cases of the less severe cutaneous diphtheria in the past year. The situation in the Kimberley region is equally concerning, with 27 cases in the past month, a quarter of which are respiratory infections.
The Impact of Vaccine Hesitancy
What many might not realize is that this resurgence is closely tied to a decline in vaccine coverage, a trend that has been exacerbated by the COVID-19 pandemic. In 2025, routine childhood immunisation coverage hit a five-year low in Australia. This drop, though seemingly small, has significant consequences. It creates pockets of susceptibility, leaving children and vulnerable adults at risk.
The Disease's Progression and Treatment
Diphtheria is caused by a toxin produced by the bacteria Corynebacterium diphtheriae or Corynebacterium ulcerans. It can manifest as respiratory diphtheria, affecting the nose, throat, and airway, or cutaneous diphtheria, which impacts the skin. The disease spreads through respiratory droplets or direct contact with infected skin sores.
Respiratory diphtheria starts with fever, sore throat, and a general feeling of malaise, but it can rapidly escalate. A greyish-white membrane may form over the throat and tonsils, leading to breathing difficulties. If left untreated, it can be fatal, causing death by asphyxia. Cutaneous diphtheria, while generally non-fatal, can still cause chronic skin ulcers and act as a reservoir for bacteria, posing a risk to the unvaccinated or partially vaccinated.
Treatment involves antibiotics to clear the infection and, in respiratory cases, diphtheria antitoxin to neutralize the toxin. However, the latter is not readily available due to a global decline in diphtheria cases and reduced production. Even with treatment, respiratory diphtheria has a high mortality rate, with up to 10% of cases proving fatal.
Preventive Measures and Challenges
Diphtheria is preventable through vaccination. The diphtheria vaccine, often given as part of a combined vaccine with protection against whooping cough and tetanus, is highly effective in stimulating antibody production. In Australia, children receive this vaccine at various stages, from infancy to early adolescence, with boosters recommended for adults around age 50.
The recent diphtheria cases highlight the importance of maintaining high vaccination coverage. In the NT, for instance, only 91.9% of five-year-olds have received all recommended doses, the lowest among all states and territories. Interestingly, Aboriginal and Torres Strait Islander children in the NT have higher vaccine coverage, with 95.35% of five-year-olds vaccinated.
Reversing the Decline
The decline in immunisation coverage is multifaceted. Practical challenges, such as time constraints and travel difficulties, play a role, but concerns, beliefs, and social influences are significant factors. The rise in vaccine hesitancy, often fueled by mistrust in healthcare providers, is a growing concern.
To reverse this trend, we must invest in primary care. This includes funding models that encourage healthcare providers to have longer, dedicated conversations about vaccines with parents. Support for training in empathetic communication is also crucial. By addressing these barriers, we can help parents make informed decisions and restore confidence in vaccination.
A Call to Action
The resurgence of diphtheria serves as a stark reminder of the fragility of public health gains. It underscores the importance of maintaining high vaccination rates and the need to address vaccine hesitancy proactively. As healthcare professionals and researchers, we must advocate for improved access to vaccinations, educate the public about the benefits and risks, and address the root causes of vaccine hesitancy.
In conclusion, while diphtheria's return is concerning, it is also an opportunity to strengthen our commitment to public health. By learning from this outbreak, we can ensure that preventable diseases remain a thing of the past, safeguarding the health and well-being of our communities for generations to come.
