Diphtheria

Causative agent

It is caused by the bacterium Corynebacterium diphtheriae.

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 depend on the site of infection. 

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.

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.

Incubation period

The incubation period ranges from 1 to 10 days, usually 2 to 5 days.

Management

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.

Prevention

• Active immunisation with diphtheria toxoid can provide long-lasting protection in the majority of immunised children (Please refer to the Hong Kong Childhood Immunisation Programme).

• Perform hand hygiene frequently, especially before touching the mouth, nose or eyes; after touching public installations such as handrails or door knobs; or when hands are contaminated by respiratory secretion after coughing or sneezing.
• Wash hands with liquid soap and water, and rub for at least 20 seconds. Then rinse with water and dry with a disposable paper towel or hand dryer. If hand washing facilities are not available, or when hands are not visibly soiled, hand hygiene with 70 to 80% alcohol-based handrub is an effective alternative.
• Cover your mouth and nose with tissue paper when sneezing or coughing. Dispose of soiled tissues into a lidded rubbish bin, then wash hands thoroughly.
• When having respiratory symptoms, wear a surgical mask, refrain from work or attending class at school, avoid going to crowded places and seek medical advice promptly. 
• Build up good body immunity by having a balanced diet, regular exercise, adequate rest, reducing stress, do not smoke and avoid alcohol consumption.
• Clean the broken skin immediately and cover properly with waterproof adhesive dressings. Wash hands before and after touching wounds. Consult doctor promptly if symptoms of infection develop.

• Regularly clean and disinfect frequently touched surfaces such as furniture, toys and commonly shared items with 1:99 diluted household bleach (mixing 1 part of 5.25% bleach with 99 parts of water), leave for 15 to 30 minutes, and then rinse with water and keep dry. For metallic surface, disinfect with 70% alcohol.
• Use absorbent disposable towels to wipe away obvious contaminants such as respiratory secretions, and then disinfect the surface and neighbouring areas with 1:49 diluted household bleach (mixing 1 part of 5.25% bleach with 49 parts of water), leave for 15 to 30 minutes and then rinse with water and keep dry. For metallic surface, disinfect with 70% alcohol.
• Maintain good indoor ventilation. Avoid going to crowded or poorly ventilated public places; high-risk individuals may consider putting on surgical masks while in such places.