Diphtheria case in APY lands

10 April 2026

Key points

  • One case of toxigenic respiratory diphtheria has been notified in a resident from the APY lands, in the context of an ongoing outbreak in the Northern Territory and Western Australia.
  • Respiratory diphtheria is extremely rare in SA, this is the first notified case since 2021.
  • Clinicians should be vigilant for patients presenting with sore throat, fever, and pharyngeal exudate, or non-healing skin sores, especially in people from the APY lands or who have travelled to the Kimberley, Pilbara or Northern Territory within 10 days before symptom onset.
  • Urgently notify all suspected or confirmed respiratory cases and confirmed cutaneous cases to Communicable Disease Control Branch (CDCB) by phone on 1300 232 272 for assistance with case and contact management.

Background

Diphtheria is caused by toxigenic strains of Corynebacterium diphtheriae or C. ulcerans. It is spread from human to human via respiratory droplets or contact with skin lesions, causing respiratory or cutaneous infections. The bacteria produce a toxin that can cause life-threatening complications including upper airway obstruction from pseudo-membrane formation and airway inflammation, myocarditis and neuropathy. The case fatality rate for respiratory diphtheria is 5-10%.

Notifications of cutaneous diphtheria have also been increasing since October 2025, with cases recorded in NT, WA and Queensland. Since January 2026, there have been 65 cases notified nationally, which is the highest annual total since notifications began in 1991. This outbreak involves a single strain of C. diphtheriae which appears to be specific to Australia, with over 80% of cases being cutaneous and high levels of penicillin resistance. Respiratory cases have so far all been in people aged under 25 years. Over 90% of cases have been reported among Indigenous people.

Signs and symptoms

Respiratory diphtheria presents with sore throat, malaise, low-grade fever, and can cause grossly enlarged cervical lymph nodes, neck oedema, and a pseudo-membrane on the tonsils, pharynx, larynx and nose.

Cutaneous diphtheria causes chronic, non-healing, shallow ulcers on exposed limbs, often with grey slough. Cutaneous diphtheria is rarely associated with systemic toxicity. Transmission from cutaneous lesions can cause respiratory disease in cases and contacts.

Testing and treatment

  • Test all suspected respiratory and cutaneous cases with bacterial culture swab of the throat (ideally under the pseudo-membrane if present) and any purulent skin lesions. Clearly label each specimen with collection site (e.g. throat or site of lesion). Include clinical details and contact with any confirmed or suspected cases on the pathology request form.
  • Treat respiratory cases with azithromycin as per Therapeutic Guidelines (preferred empiric treatment due to increasing penicillin resistance) and seek urgent input from local Infectious Disease specialists.
  • Treat cutaneous cases according to advice from local Infectious Disease specialists.

Infection prevention and control

  • Suspected or confirmed respiratory cases require contact and droplet precautions until two negative nasopharyngeal cultures are returned at least 24 hours apart, and 24 hours after appropriate antibiotic course is completed.
  • Suspected or confirmed cutaneous cases require contact precautions with wounds covered by occlusive waterproof dressing until healed and 72 hours of appropriate antibiotic course is received. Use droplet precautions as well until a throat swab returns negative, or until 72 hours of antibiotics is received.
  • Contact tracing is required for all confirmed cases, with contact management (e.g. isolation, testing, antibiotic prophylaxis and vaccination) to be coordinated by CDCB.

Vaccination

Vaccination against diphtheria is effective at preventing severe disease, and is available on the National Immunisation Program. Ensure children, adolescents and adults are up-to-date with appropriate DTPa or dTpa vaccination in the past 10 years. See the Australian Immunisation Handbook for age-appropriate vaccine recommendations.

For more information on diphtheria, see the NSW Health Diphtheria control guideline, and contact the Aboriginal Health Council of SA for information targeted to Aboriginal people.

For all enquires please contact the CDCB on 1300 232 272 (24 hours/7 days) Dr David Johnson, Acting Medical Lead, Communicable Disease Control Branch