Seasonal Influenza (flu) is a highly infectious disease of the respiratory tract caused by influenza viruses. In Hong Kong, the disease is more common in periods from January to March/April and from July to August. Three types of Influenza viruses are recognised, among which influenza A and B viruses are more common than influenza C virus to cause human infection. Symptoms include fever, headache, muscle pain, runny nose, cough, sore throat and fatigue. For healthy individuals, influenza is usually self-limiting with recovery in 2-7 days.
Avian Influenza is caused by the influenza A viruses affecting mainly birds and poultry, such as chickens or ducks. Although transmission of avian flu virus to human has been observed, human-to-human transmission is inefficient.
Influenza Pandemic occurs when there is a major change (antigenic shift) in the influenza virus resulting in efficient human-to-human transmission. As the population will have very little or no immunity to the novel strain of virus, the virus spreads rapidly and extensively that affects a large number of people, resulting in higher severity of illness and a higher death toll worldwide.
Seasonal influenza spreads through droplets when infected people cough, sneeze or talk. The infection may also spread by direct contact with the secretions of infected persons. Avian influenza transmits through contact with infected birds and poultry (live or dead) or their droppings, or contact with contaminated environments such as wet markets, live poultry markets or farms. Apart from flu-like symptoms in the early stage, people infected with avian influenza may have eye infection (conjunctivitis) or gastrointestinal symptoms (e.g. nausea, vomiting and diarrhoea). Since there is little or no immunity against avian influenza viruses in humans, high fever and complications such as chest infection, respiratory failure, multi-organ failure and death are more likely to result.
Influenza pandemic occurs roughly every 10-50 years and there were three pandemics during the last century. In April 2009, influenza A (H1N1) pdm09 virus from the United States emerged to cause illness in human and resulted in a pandemic. A pandemic can occur if the viruses acquired the capacity to spread easily from person to person, either through adaptation or acquisition of certain genes from human viruses. Since the timing of a future pandemic is unpredictable, everyone should be prepared and take preventive measures.
To prevent seasonal influenza:
to prevent avian influenza:
If you have flu-like symptoms, you should
When the influenza pandemic comes, you should
Can "flu shots" prevent avian flu?
Receipt of an influenza vaccine cannot prevent human infection with avian influenza. However, the vaccine provides a safe and effective way for preventing seasonal influenza and its complications, reducing the chances of hospitalization. Except those with known contraindications, individuals aged 6 months or above are recommended to receive the influenza vaccine to protect their health, especially the elderly who are having a higher risk of infection and complications.
Should I self medicate Oseltamivir (Tamiflu) to prevent infection?
Oseltamivir (neuraminidase inhibitor) is a type of prescription-only oral antiviral drug which reduces the replication of influenza A and B viruses. Self-medication is not advised because of the potential side effects and contraindications. Moreover, inappropriate use may give rise to antiviral resistance.
|8 Steps to Protect Yourself|
|Step 1 Be prepared at home||Step 2 Get vaccinated|
|Step 3 Keep hands clean||Step 4 Maintain cough manners|
|Step 5 Use surgical masks properly||Step 6 Live a healthy lifestyle|
|Step 7 Maintain good environmental hygiene||Step 8 Prevent avian influenza|
For details, please visit the Centre for Health Protection Website at www.chp.gov.hk
Elderly Health Service
Department of Health