Diphtheria is a disease caused by toxin-producing Corynebacterium diphtheriae (C. diphtheriae), and uncommonly other toxigenic strains of Corynebacterium. The toxin induces the symptoms which characterise the disease diphtheria. Diphtheria toxoid-containing vaccines prevent symptomatic toxin-mediated disease but do not consistently prevent carriage or transmission.
There is currently a multi-jurisdictional outbreak predominantly affecting Aboriginal people, including in South Australia. For more information see Diphtheria | Australian Centre for Disease Control and CDNA Interim guidance for diphtheria outbreak management (PDF 338KB).
The diphtheria outbreak response in South Australia aims to minimise and prevent diphtheria-associated morbidity and mortality through a multi-pronged approach including:
Note: this information will be updated as further information becomes available.
There are two main forms of diphtheria: respiratory and cutaneous. Milder illness is more common in persons who are vaccinated.
Respiratory diphtheria primarily affects the tonsils, pharynx, nose and larynx. In severe cases it causes a pseudomembrane at the back of the throat presenting a risk for airway obstruction.
Symptoms and signs of respiratory diphtheria may include:
Signs of severe respiratory diphtheria include:
Cutaneous diphtheria causes a non-healing ulcer or sore.
Symptoms and signs of cutaneous diphtheria may include:
Diphtheria can cause cardiac (cardiomyopathy, myocarditis), neurological (peripheral neuropathy and cranial neuropathies) and kidney complications.
The case fatality rate for untreated, never vaccinated cases of diphtheria is approximately 30% and between 5-10% for classic respiratory diphtheria, even with appropriate treatment.
Transmission occurs person to person via respiratory droplets or direct contact with respiratory secretions or cutaneous exudate of an infected person. It is also spread from indirect contact with items contaminated with nose, throat or wound discharges.
Usually 2 to 5 days (range 1-10 days)
The period of communicability is variable. It remains infectious while bacterial shedding occurs. However, persons who are asymptomatic carriers are generally considered less infectious.
The infectious period likely starts for respiratory cases 7 days prior to symptom onset and for cutaneous cases the date of skin infection.
Without treatment persons with diphtheria can remain infectious for weeks to several months.
Respiratory diphtheria is considered infectious until demonstration of two negative throat swabs.
Cutaneous diphtheria is considered infectious until at least 72 hours of appropriate antibiotics and the wound can be covered.
Preliminary diagnosis is usually made based on clinical presentation. Where diphtheria is suspected it is imperative to begin presumptive therapy quickly before confirmatory test results are available.
Diphtheria is diagnosed by testing (for PCR and culture) appropriate clinical specimens. Suitable samples include oropharyngeal or throat swabs, nasal and nasopharyngeal swabs, skin ulcer swabs, pseudomembrane tissue, sputum and sterile site samples. Ideally two samples should be collected from each suspected case. Where possible samples should be taken before antibiotics are commenced.
For patients with suspected or confirmed diphtheria the following measures should be taken:
For further details see:
Diphtheria is treated with antibiotics. Severe cases require hospitalisation and diphtheria antitoxin. For further details see: Interim Management of Diphtheria in Clinical Settings in South Australia (PDF 390KB).
Contacts of persons with diphtheria should be managed as per the:
Exclude persons with diphtheria as per isolation and exclusion period.
Vaccination recommended against diphtheria. For more information see Diphtheria Outbreak Response Immunisation Program.
The Communicable Disease Control Branch, South Australia, should be notified on suspicion of diphtheria on 1300 232 272 (24 hours/7 days) to enable prompt public health follow up.