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Avian flu (bird flu)

What is avian influenza (bird flu)?
Control of avian flu
Human cases of avian flu
Why is the current outbreak of avian flu H5N1 worrying?
Travelling to an area with avian flu outbreaks in poultry?

A pandemic is a rapidly-spreading epidemic of a disease that affects most countries and regions of the world. Pandemics of influenza affecting many thousands and sometimes millions of people world-wide, with high mortality, occurred in 1918 ('Spanish'), 1957 (Asian), and 1968 (Hong Kong). New subtypes of influenza, probably formed by combination of genes from both avian and human influenza viruses, caused these pandemics. Because the virus is a new strain, people will have very little immunity to it, and therefore many more will catch it.

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Scientists predict that another pandemic will happen, although they cannot say exactly when that will be. The World Health Organization is on constant lookout for the first signs of a pandemic emerging so steps can be taken to try to contain it. However, with the numbers of people now flying all around the world the chances of it reaching the UK are much increased since the last pandemic in 1968. So once a flu pandemic affects other countries it will almost certainly reach the UK. Once in the UK, a flu pandemic will spread across the country in a matter of weeks.

Pandemic flu has similar symptoms to normal flu for most people, although the symptoms are more likely to be severe. The most common symptoms of influenza are an abrupt onset of high temperature, shivering, headache, muscle ache and dry cough.

It is difficult to tell in advance how serious a pandemic may be as this depends on the nature and severity of the new virus causing it. However a pandemic may cause:

	high levels of influenza
	intense pressure on health services
	disruption to many aspects of daily life
	many deaths.

Flu vaccines take several months to produce, and have to be made specifically for the particular subtype causing an epidemic or pandemic. That is why a vaccine is unlikely to be available for the first wave of illness in a pandemic. The current ‘ordinary’ flu vaccine does not provide any protection against bird flu or any pandemic strain of virus.

There are some basic but important measures that you can take to reduce the risk of getting or spreading flu (either ordinary or pandemic), as well as many other bugs:

	maintain good hygiene – washing hands frequently really does help protect you
	cover your mouth and nose when coughing or sneezing
	stay at home while you are ill

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Avian influenza (bird flu) naturally circulates in wild waterfowl such as ducks and geese, often causing little or no symptoms. Many other bird species, including domestic poultry, can catch these flu viruses. Some strains cause severe disease in poultry with very many birds dying, and this is called Highly Pathogenic Avian Influenza (HPAI). Other strains are not so severe. HPAI has been known for a very long time and large outbreaks in poultry happened, for example, in Pennsylvania in 1982 (H5N2), Mexico in 1993 (H5N2), Hong Kong in 1997 (H5N1) and The Netherlands in 2003 (H7N7). (Different strains (subtypes) of avian influenza viruses, like other influenza viruses, are given different H and N numbers to describe them.)

In January 2004 avian influenza, caused by the H5N1 subtype of influenza A virus, was confirmed in poultry in Vietnam. Since then, there have been very large outbreaks in poultry in various countries in central, south and south east Asia. In August 2005 this strain has spread to areas of Russia and neighbouring states, most likely brought by migrating birds. In October 2005 H5N1 outbreaks have been confirmed in Turkey and suspected in Romania and Greece.

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The risk of avian flu reaching Northern Ireland is thought to be small, but nonetheless the Department of Agriculture and Rural Development has a plan in place for the control of avian flu, including watching carefully for any signs that it has arrived in Northern Ireland. When outbreaks of HPAI happen in poultry there are a range of control measures put in place, including destroying affected flocks and restricting movements around the poultry farms.

Imports of poultry and poultry products are banned from countries with current outbreaks of avian flu. In any case it is not possible to catch avian flu from properly cooked poultry. Normal hygiene measures, especially washing hands and work surfaces carefully, should be taken after any preparation of raw chicken at any time.

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Very infrequently, people may catch avian influenza. In the outbreak in Hong Kong in 1997 there were 18 confirmed human cases with 6 deaths. In the Netherlands in 2003 there were 83 confirmed mild human cases and 1 death. Given the scale of the outbreaks in poultry the virus does not infect humans easily. All these cases were in close contact with live infected poultry, and did not spread the infection to other people. In the current outbreak of avian influenza 119 human cases, with 60 of these dying, due to H5N1 have been reported from four countries with outbreaks of influenza H5N1 in poultry stocks. This is a small number of cases relative to the millions of affected birds. All human cases are investigated to determine the likely source of the infection.

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Influenza viruses are very good at combining and changing to make new subtypes of virus. For example, an avian and a human flu virus may combine to make a totally new subtype of virus which would infect humans easily and spread rapidly – leading to a pandemic. However it is not possible to predict if this will happen with any particular strains of virus, or when this might happen – it may not happen during the current outbreaks of avian flu at all, but they do make this more likely. Future pandemics are inevitable at some stage.

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There is very little risk of catching avian flu as a traveller as direct close contact is needed with infected live, or dead but uncooked, birds before there is even a slight risk. However sensible precautions are advisable if you are travelling to a currently affected country. Up to date travel advice:
Department of Health
National Travel Health Network and Centre
An up-to-date list of countries affected by outbreaks of H5N1 influenza in poultry: Health Protection Agency
World Organisation for Animal Health

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