What is Diphtheria?

Diphtheria is a potentially serious infectious disease caused by the Corynebacterium diphtheriae bacterium; humans are the reservoirs of the bacteria and are usually without symptoms. After being spread by coughing and sneezing or by direct contact with wounds or items contaminated by infected people, diphtheria infects the throat and upper airways or in some cases, the skin. While the disease is no longer prevalent in many parts of the world due to successful immunisation campaigns, cases continue to appear in regions without access to these programs and in communities with poor vaccination uptake.

There are different infecting strains of the bacteria and some produce toxins which can cause more severe disease affecting the nerves and heart, however the areas of the body most commonly affected are the upper respiratory tract (nose, pharynx, tonsils, larynx and trachea - respiratory diphtheria), skin (cutaneous diphtheria), or rarely, mucous membranes at other sites (eye, ear, vulva).

What are the symptoms?

The appearance of symptoms follows an incubation period of 2–5 days (range 1–10 days), beginning with malaise, loss of appetite, mild fever, swollen glands in the neck (bull neck) and a sore throat which makes breathing and swallowing difficult. After about 2 -3 days a firm, fleshy, grey coating (pseudomembrane) develops in the throat and nasal tissues, potentially blocking the airways - it will bleed if an attempt is made to remove it. If left untreated people with diphtheria have a high risk of suffocation, heart & kidney injury and severe nerve damage.

Where is it found?

Diphtheria is endemic in many countries of Asia, South Pacific, Middle East, Eastern Europe, Haiti and Dominican Republic and outbreaks continue to occur in these regions. Cutaneous diphtheria is found most commonly in tropical countries.

Risk to travellers

The risk to travellers is generally low, however both respiratory and cutaneous diphtheria have been reported in travellers.

Although diphtheria infection is now rare in Australia, vaccination remains paramount in reducing the risk of disease in unimmunised travellers, which can then be passed on to their contacts back home. The few notified cases seen in Australia have either been imported from overseas or associated with their contacts. In 2018, an unimmunised person who had never been overseas died from diphtheria myocarditis in Queensland.

How is Diphtheria transmitted?

Most often person-to-person spread from the respiratory tract. Rarely transmission may occur from skin lesions or articles soiled with discharges from lesions of infected persons. 

How is Diphtheria treated?

Treatment involves the use of antibiotics, an anti-toxin and supportive airway care while the patient is in isolation to prevent the infection passing to others.

What is Diphtheria Vaccination?

Australian children are vaccinated against diphtheria as part of the standard childhood immunisation schedule and the last dose is given at 11-15 years of age.

All travellers should ensure the status of their diphtheria toxoid vaccination is current before departure. Once a primary series of diphtheria-containing vaccines is given in childhood and adolescence, adult booster doses with a diphtheria toxoid–containing vaccine are recommended at 10-year intervals given either as dT (diphtheria-tetanus) or dTpa (diphtheria-tetanus-acellular pertussis, if not previously given). For adults who need protection against poliomyelitis, it is recommended they receive a dTpa-IPV vaccine.

Type: Injectable

The diphtheria vaccine is a bacterial toxoid, i.e. an inactivated toxin. In Australia, Adult and childhood immunisations containing diphtheria are only available in combination with other antigens such as pertussis, tetanus and polio.

  • Children under 10 years: Diphtheria toxoid given in combination with tetanus and others (Infanrix Hexa, Infanrix IPV, Hexaxim, Quadracel, Tripacel)
  • Adults: Diphtheria toxoid given in combination with tetanus (ADT), tetanus/pertussis (Adacel /Boostrix) or tetanus/ pertussis/ polio (Adacel Polio/ Boostrix IPV)

Contraindications:

The only absolute contraindications to diphtheria-containing vaccines are:

  • Anaphylactic reaction after a previous dose of any diphtheria-containing vaccine
  • Anaphylactic reaction after any component of a diphtheria-containing vaccine

Precautions:

People with latex allergy

Schedule

The primary childhood immunisation series is given from 6-8 weeks of age. Three doses are administered at least 4 weeks apart with boosters at 4 and 11-17 years of age.

A single booster of tetanus/diphtheria-containing vaccine (preferably also with pertussis) is given from 50 years of age, if the last dose was more than 10 years ago.

Please note: Simultaneous and consecutive administration of diphtheria-containing vaccines with Menactra and Nimenrix (meningococcal meningitis conjugate vaccines) should be discussed prior with your health care professional.

Level of protection

Over 95%

Possible Side Effects

Possible side effects:

Mild discomfort or pain at the injection site is common after receiving diphtheria-containing vaccine.

Other less common side effects include:

  • headache
  • lethargy
  • malaise
  • myalgia
  • fever

Very rare side effects include:

  • allergic reactions
  • hives
  • peripheral neuropathy

As with all vaccines, there is a small risk of allergic reactions.

References:

Australian Immunisation Handbook https://immunisationhandbook.health.gov.au/vaccine-preventable-diseases/diphtheria

Australian Institute of Health and Welfare https://www.aihw.gov.au/reports/immunisation/vaccine-preventable-diseases/contents

US Centers for Disease Control https://www.cdc.gov/diphtheria/vaccination.html

US Centers for Disease Control and Prevention: Chapter 4 Travel-Related Infectious Diseases – Diphtheria https://wwwnc.cdc.gov/travel/yellowbook/2020/travel-related-infectious-diseases/diphtheria

World Health Organization factsheet:  https://www.who.int/immunization/diseases/diphtheria/en/

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