Avian Influenza Infection
What is Avian Influenza?
Avian influenza, or 'bird flu', is a contagious disease of animals caused by viruses that normally infect only birds and less commonly, pigs. While all bird species are thought to be susceptible to infection, domestic poultry flocks are especially vulnerable to infections that can rapidly cause epidemics in poultry.
Of particular concern, in terms of risks for human health, is the detection of a highly pathogenic strain, known as H5N1, as the cause of most outbreaks. More recently, other genotypes have also been found to cause serious illness in humans e.g. H7N9
How are Humans Infected?
Humans can be infected but this occurs rarely. Humans are usually infected through close contact with live infected birds. Birds shed influenza virus in their droppings so contact with droppings (for example by visiting enclosures or wet markets where birds have been recently kept) is also a possible transmission route.
The Illness in Humans
- The time from exposure to the source of infection to onset of influenza is likely to be between 3 and 5 days, with a maximum of 7 days.
- The severity of illness appears to vary. Underlying factors are not well understood.
- Early symptoms are likely to be similar to normal influenza such as fever and cough
- If you develop a respiratory illness severe enough to warrant treatment and have visited an infected country and have had contact with live poultry or pigs or places that house them in the 7 days prior to onset of illness, you should contact your General Practitioner.
Antiviral drugs, oseltamivir (Tamiflu) and zanamivir (Relenza) can be used for both prevention and treatment. Tamiflu has been stock-piled in the UK as part of the Government's Pandemic Flu Plan.
At present no vaccine is available against avian influenza in humans. Initial steps have been taken in the process of vaccine production but owing to the antigenic drift of circulating influenza virus the vaccine cannot be finalised at present. It is thought that a vaccine could be made available within 4 months when needed.
- An advice sheet recommending ways of reducing the risk from avian influenza has been prepared for travellers to areas reporting human cases of avian influenza.
- In special circumstances, antiviral drugs may be considered for those perceived to be at high risk.
- The European Centre for Disease Prevention and Control has advised that 'It is not recommended that travellers take Oseltamivir (Tamiflu) with them'.
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