Australia is currently facing a diphtheria outbreak in the Northern Territory, the Kimberly, Goldfields and Pilbara regions in Western Australia, and for north-west South Australia.
While the risk of diphtheria spreading in Victoria is very low, it is important to check that you are up to date with diphtheria vaccination, especially if you are living, working or travelling to an outbreak area.
Some vaccinations, like the diphtheria, tetanus and whooping cough vaccination start to lose effect over time and need to be updated regularly.
The State Government is encouraging at-risk groups to get a time-limited free diphtheria booster vaccination to support diphtheria prevention measures.
What is diphtheria?
Diphtheria is an infection caused by a toxin-producing bacteria, Corynebacterium diphtheriae. The bacteria can infect the respiratory tract (nose, throat, airways), skin or, can also be carried in the body without causing symptoms. Toxins made by the bacteria can cause severe illness which can be life-threatening. Vaccination prevents illness and the severe complications from the diphtheria toxin.
Diphtheria is generally spread during close or prolonged contact when a person ingests or breathes in droplets from the cough or sneeze from someone who has diphtheria. It can take between two and five days to start showing symptoms. An infected person can be contagious for about six weeks, even with mild to no symptoms.
Antibiotics can shorten the period of contagiousness. To prevent further spread, people with diphtheria are isolated and treated with antibiotics, and people who have been in contact with them offered preventative antibiotics and vaccination.
Prevention against diphtheria
Vaccination is the best way people can protect themselves and minimise spread. Although diphtheria is rare in Australia, outbreaks still happen, so it is important to keep both childhood vaccination and adult booster rates high.
Diphtheria vaccination is part of free routine child and adolescent vaccination and is given as a combined vaccine with tetanus and whooping cough. Catch-up vaccination is recommended for people who missed doses.
Some vaccinations, like the diphtheria vaccine, start to lose effect over time. Therefore, booster vaccination for adults is recommended:
- Every 5 years for adults living in or travelling to higher risk areas (i.e. Australian outbreak areas or overseas endemic countries), or
- Adults if their last dose was more than 10 years ago.
To promote booster vaccination uptake in at-risk groups, free vaccination are being offered for eligible adults:
- Anyone traveling to live or work in a higher risk area who has not had a vaccine in the last 5 years
- Aboriginal and Torres Strait islander people travelling to a higher risk area and have not had a vaccine in the last 5 years
- Aboriginal and Torres strait islander people aged over 20 who have not received 3 doses or who last had a vaccine more than 10 years ago
Other prevention methods include maintaining healthy skin and promptly treating wounds, good hygiene, including hand washing especially around preparing or eating food.
For professionals:
The current outbreak of diphtheria in northern and central Australia is characterised by a high proportion of cutaneous diphtheria, with about 30% classified as respiratory diphtheria. Most cases have been relatively mild, likely reflecting the protective effect of prior vaccination.
The majority of the cases have been amongst Aboriginal and Torres Strait Islander people and in outer regional and remote areas.
The risk of diphtheria spreading in Victoria remains very low. Cases are likely to occur in people who have lived or worked in areas at higher risk for diphtheria.
Clinical illness is mediated by the toxin which causes local tissue necrosis.
- Respiratory diphtheria commonly presents with sore throat, low‑grade fever, malaise and cervical lymphadenopathy, followed by development of a white exudate and adherent grey pseudomembrane, which can lead to airway obstruction.
- Cutaneous diphtheria typically presents as a shallow skin ulcer with a grey membrane.
- Asymptomatic cases or cases with mild respiratory infection (without a pseudomembrane) are usually vaccinated persons as the vaccine is protective against the effects of the toxin.
When to consider diptheria
Clinicians should consider diphtheria in patients with compatible respiratory or cutaneous illness, particularly those with recent travel to, or contact with people from areas at higher risk for diphtheria. As well as the current Australian outbreak, diphtheria also remains endemic in many low income countries.
If diphtheria is suspected:
- Collect a throat swab for diphtheria culture.
- Use a bacterial swab (without viral transport medium) and note on the request slip that diphtheria is suspected. This is because the laboratory uses selective media to culture C. diphtheriae.
- Swab beneath part of the pseudomembrane if one is present.
- If also testing for respiratory pathogens, collect an additional sample dedicated to respiratory pathogen testing.
- For cutaneous diphtheria, also collect a swab of the lesion.
- Notify your Local Public Health Unit by calling 1300 651 160.
Checking diphtheria vaccination status
Vaccination is the best way to protect against illness and severe complications from diphtheria.
Diphtheria-toxoid containing vaccines (dTpa, DTPa and dT vaccines) protect against illness and severe toxin-mediated disease.
Vaccinated people can still carry toxigenic bacteria and transmit to others, but transmission is reduced.
Clinicians are recommended to check that people are up-to-date with diphtheria vaccines, especially if travelling to area at higher risk for diphtheria.
Diphtheria vaccination is part of routine vaccination in infants, children and adolescents . Catch-up vaccination is recommended for missed doses. Diphtheria vaccination is recommended for pregnant women in each pregnancy.
Booster vaccination is recommended:
- every 5 years for people living in or travelling to higher risk areas.
- for all adults if their last dose was more than 10 years ago.
In addition to diphtheria vaccination as part of the National Immunisation Program (NIP), Victoria an expanded state-funded diphtheria vaccination (Boostrix®) campaign to provide additional protection during this outbreak.
In addition to diphtheria vaccination as part of the National Immunisation Program (NIP), Victoria has launched an expanded state-funded diphtheria vaccination (Boostrix®) campaign to provide additional protection during this outbreak. Immunisation providers can order Boostrix for this campaign via the usual OneLink process. Order limits apply. Providers that want to order more than the order limit can email the Immunisation Program ([email protected]) prior to submitting their order request.
Who is eligible for free vaccination in Victoria:
| Groups eligible for free diphtheria vaccination under the National Immunisation Program | Recommendation |
| Infants and children at:
•2, 4 and 6 months as a primary course •18 months and 4 years as booster doses |
Offer age-appropriate diphtheria vaccination in accordance with the Australian Immunisation Handbook using National Immunisation Program funded diphtheria toxoid containing vaccines (DTPa/dTpa) |
| Adolescents at 12 or 13 years as a booster dose | |
| People aged less than 20 years who have missed childhood vaccination as catch-up vaccination | |
| Refugees and humanitarian entrants (any age) who have missed diphtheria vaccination | |
| Pregnant women – single dose recommended each pregnancy between 20 to 32 weeks (may be given up until delivery) as part of pertussis vaccination | Offer a single dose of National Immunisation Program funded Adacel® or Boostrix® each pregnancy |
| Groups eligible for free state-funded Boostrix® under the Diphtheria Booster Vaccination Campaign | Recommendation |
| Aboriginal and Torres Strait Islander people aged 20 years and over who have not previously received 3 doses of diphtheria toxoid containing vaccine | Offer further doses to complete a primary course (3 doses) using state-funded Boostrix® |
| Aboriginal and Torres Strait Islander people aged 20 years and over who have previously received at least 3 doses of diphtheria toxoid containing vaccine with the most recent dose being more than 10 years ago | Offer a state-funded booster dose of Boostrix® |
| Aboriginal and Torres Strait Islander people travelling to a higher risk area for any reason who have not had a booster dose of diphtheria toxoid containing vaccine in the last 5 years | |
| Anyone travelling to live or work in a higher risk area who has not had a booster dose of diphtheria toxoid containing vaccine in the last 5 years |
