After decades of being largely under control, diphtheria — a serious but vaccine-preventable disease — is making an unexpected return in parts of Australia.
Health officials have reported outbreaks across the Northern Territory and Western Australia, with numbers steadily rising over recent months. According to the latest data mentioned by The Melbourne Vaccine Education Centre, 17 cases of respiratory diphtheria have been recorded in the Northern Territory since March 23, 2026, along with 60 cases of cutaneous diphtheria since May 2025. In the Kimberly region of Western Australia, cases have already been reported this year.
The resurgence is particularly striking given that diphtheria had been rare in Australia since the 1950s, following widespread vaccination efforts that began in the 1930s.
DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. Always consult your health practitioner before starting any routine.
A similar reminder of the disease’s danger emerged closer home in Rajasthan’s Deeg, where a diphtheria outbreak in 2024 led to the deaths of seven children. The incident highlighted how quickly the infection can turn fatal in communities with gaps in immunisation and delayed access to treatment.
According to the World Health Organization, “Diphtheria is a contagious disease that is caused by toxin-producing bacteria. It can spread from person to person when an infected person coughs or sneezes. Some people may not develop disease manifestations but can still transmit the bacteria to others. Others will develop mild disease, although severe disease, complications and death can also occur. Diphtheria can affect anyone but was most common in unvaccinated children.”
In response to such risks, India has also strengthened its vaccination efforts. Union Health Minister Jagat Prakash Nadda recently launched an indigenously manufactured Tetanus and Adult Diphtheria (Td) vaccine, aimed at improving adult immunisation coverage and reducing vulnerability to infections like diphtheria.
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The situation raises pressing questions about why a long-controlled disease is resurfacing and what individuals need to know to stay protected.
What exactly is diphtheria, and how does it spread in communities?
Dr Palleti Siva Karthik Reddy, MBBS, MD general medicine, FAIG, consultant physician at Elite Care Clinic, tells indianexpress.com, “Diphtheria is a bacterial infection caused by Corynebacterium diphtheriae that primarily affects the throat and upper airways, producing a toxin that can damage the heart and nerves. It spreads through respiratory droplets, close physical contact, and in some cases through contaminated objects or skin lesions.”
He continues, “Its reappearance after decades of low incidence is often linked to gaps in vaccination coverage, waning immunity in adults who have missed booster doses, and increased global travel that allows the bacteria to circulate across regions.”
Early warning signs and symptoms
Dr Reddy states, “Early symptoms typically include sore throat, mild fever, and fatigue, but what distinguishes diphtheria is the formation of a thick greyish membrane over the throat or tonsils, which can obstruct breathing. Patients may also develop swollen neck glands, sometimes referred to as a bull neck appearance.”
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In cutaneous diphtheria, he says, non-healing skin ulcers with a dirty grey membrane can be seen. “Unlike routine respiratory infections, the progression can be more rapid and systemic due to toxin production, which makes early recognition critical.”
How effective are current treatments like antitoxin and antibiotics?
“Treatment is highly effective when initiated early,” stresses Dr Reddy, adding that the diphtheria antitoxin neutralises circulating toxin, while antibiotics such as penicillin or erythromycin eliminate the bacteria and prevent further transmission.
“However, treatment does not reverse damage already caused by the toxin, which is why timely intervention is essential. Vaccination remains the most reliable form of prevention, with childhood immunisation providing strong protection and booster doses in adolescence and adulthood maintaining immunity. High vaccination coverage not only protects individuals but also limits community spread, which is key to preventing outbreaks,” concludes the expert.
DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. Always consult your health practitioner before starting any routine.
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