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Diseases / Diphtheria


What is it?: 

Diphtheria is caused by the bacterium Corynebacterium diphtheriae. 1

During major diphtheria epidemics in Europe and the United States in the 1880s, the case-fatality rates reached 50% in some areas. Case-fatality rates in Europe had dropped to about 15% during the First World War, mainly as a result of widespread use of diphtheria antitoxin (DAT) treatment. Diphtheria epidemics also ravaged Europe during the Second World War, causing about 1 million cases and 50 000 deaths in 1943. Diphtheria toxoid-based vaccines became available in the late 1940s in Europe and North America and were shown to reduce outbreaks in vaccinated populations. In the 1970s, before these vaccines became easily accessible and used worldwide, an estimated 1 million cases of diphtheria including 50 000–60 000 deaths occurred each year in low and middle income countries.2

Clinical features: 

Diphtheria is an acute infectious disease affecting mainly the respiratory tract (respiratory diphtheria), and occasionally the skin (cutaneous diphtheria), caused by the action of bacterial toxin. Symptoms will depend on the site of infection. 1

Persons with respiratory diphtheria may have fever, sore throat with patches of greyish membrane adhered to the throat, and breathing difficulty. In serious cases, it can cause airway obstruction, heart failure and nerve damage. Fatal cases can occur.1

Mode of transmission: 

It is spread by contact with patient or carrier. Less commonly, a person may get infected through contact with articles soiled with discharges from affected persons.1

Incubation period: 

The incubation period ranges from 1 – 10 days, usually 2 – 5 days1

  • Maintain good personal and environmental hygiene.1
  • Maintain good indoor ventilation.1
  • Keep hands clean and wash hands properly.1
  • Wash hands when they are dirtied by respiratory secretions e.g. after sneezing.1
  • Cover nose and mouth while sneezing or coughing and dispose of nasal and mouth discharge properly.1
  • Cleanse used toys and furniture properly.1
  • Disinfect soiled articles properly.1
  • Active immunization with diphtheria toxoid can provide long-lasting protection in the majority of immunized children (Please refer to the Hong Kong Childhood Immunisation Programme).1

Treatment for diphtheria includes diphtheria antitoxin, antibiotics and supportive care. Household members and people having close contact with the patient should be monitored closely for early signs and symptoms of infection.1


  1. Centre for Health Protection website. 22 July 2019. [ONLINE] Accessed on 12 Mar, 2021. 
  2.  World Health Organization. Diphtheria vaccines: WHO position paper. Aug 2017.