Influenza

Clinical features

Influenza is an acute illness of the respiratory tract, characterised by three main symptoms, namely fever, sore throat and cough. Headache, muscle pain, runny nose and other symptoms like tiredness, diarrhoea and vomiting may also appear.
The disease is usually self-limiting with recovery in 2 to 7 days. However, influenza can be a serious disease to the weak and frail or elderly persons, and may be complicated by bronchitis and pneumonia or even death.

Mode of transmission

The disease is mainly spread through droplets in crowded or poorly ventilated areas. The infection may also be spread from person to person by direct contact with the secretions of infected persons.

Incubation period

The incubation period is usually around 1 to 3 days.

Management

Infected persons should take adequate rest and drink plenty of water. Supportive treatment can relieve symptoms. Antiviral agents can reduce the severity and duration of illness but must be used under doctor's prescription and given in the early stage of illness. Antibiotics are unnecessary unless influenza is complicated by bacterial infection. If symptoms persist, one should consult a doctor.

Prevention

Build up body resistance helps to prevent influenza infection. Therefore, one should maintain balanced diet, exercise regularly, take adequate rest, and avoid overstress and smoking. In addition, one should observe hygiene practices and consider to have vaccination as indicated.

1. Observe personal hygiene

- Keep hands clean and wash hands properly. Alcohol-based handrub is also effective when hands are not visibly soiled.
- Wash hands with liquid soap promptly if they are contaminated by respiratory tract secretions, e.g. after sneezing or coughing.
- Cover nose and mouth when sneezing or coughing.
- No spitting. Always wrap nasal and mouth discharges with tissue paper, and dispose of the tissue paper properly in a lidded rubbish bin.
- Wear mask when symptoms of respiratory tract infection or fever develop. Seek medical advice promptly.
- Refrain from work or school if develop symptoms of influenza..

2. Observe environmental hygiene

- Maintain good ventilation of indoor areas.
- When influenza is prevalent, avoid attending crowded and poorly ventilated public places.

3. Vaccination

There is effective influenza vaccine to prevent influenza and its complications. The vaccination should be repeated every year to maintain the protection. Please refer to the latest recommendation given by the Scientific Committee on Vaccine Preventable Diseases in the Centre for Health Protection Website (www.chp.gov.hk) or consult your family doctors.