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Diphtheria is a rare but serious infectious disease caused by Corynebacterium diphtheriae. The bacterium usually causes infection of the throat and nose but can also cause skin infections.


While some cases may be mild, the bacteria can produce dangerous toxins that cause severe complications which can be life-threatening. Such complications include heart trouble, paralysis, and kidney failure. Cases of diphtheria in New Zealand have declined significantly over the last century with very few cases reported in the last 50 years.


Diphtheria is spread by close personal contact with someone who is infected or is a carrier of the bacteria and shows no symptoms. Spread commonly occurs via respiratory droplets, originating from a cough or a sneeze. The bacteria can also spread through contaminated objects or food.

Traditional tattooing has also been implicated in cases of skin infection in New Zealand.


Diphtheria causes inflammation of the upper respiratory tract, including the nose and throat. Symptoms may include sore throat, breathing problems, bloody or watery drainage from the nose, hoarseness, a bark-like cough and painful swallowing. Swelling of the throat and neck is characterised by a ‘bull neck’. Some cases will experience infection of the skin, resulting in skin lesions. However, some cases may not experience any symptoms.


People suspected of having diphtheria will be given an antitoxin injection to the muscle or into the vein. Infection is then treated with antibiotics, such as erythromycin or benzathine penicillin. Additional treatment may include intravenous fluids, oxygen, bed rest, heart monitoring, use of a breathing tube, and correction of any blocked airways.


The effects of diphtheria can range from mild to severe.

  • For those infected, there is the potential for the diphtheria bacteria to release harmful toxins which can spread through the blood stream and affect major organs
  • Diphtheria toxin can cause significant damage to the heart, nerves, and kidneys
  • Diphtheria can be fatal. 5-10% of those infected die, even with treatment


  • The person with diphtheria is excluded from school until they have recovered and had two negative throat swabs
  • Contacts of the person with diphtheria are given antibiotics and may also need to have a booster vaccination with a diphtheria-toxoid containing vaccine
  • Contacts who are children are excluded from early childhood education, daycare, school and community activities until throat swabs shown they do not have the disease
  • Adults who work with food or children are excluded from their work until throat swabs shown they do not have the disease

Complications of disease
  • Throat swelling and difficulty breathing
  • Sinusitis, otitis media (ear infection), pneumonia
  • Heart muscle inflammation and damage
  • Kidney damage and failure
  • Delayed nerve complications
  • Death, even with treatment

Responses to vaccine

Common responses

  • Decreased appetite
  • Vomiting or diarrhoea
  • Irritability, restlessness
  • Unusual crying
  • Limb swelling after the 4th or 5th vaccine dose
  • Muscle or joint stiffness or pain
  • Headache or nausea

Rare responses

  • Hives
  • Temporary low platelet count
  • Persistent inconsolable screaming in infants
  • Hypotonic, hyporesponsive episode (HHE) in infants
  • Convulsion
  • Sterile abscess at injection site

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