Avian flu (bird flu) is a form of influenza that usually affects wild waterfowl. When there is an outbreak of avian flu with a high bird mortality it is called Highly Pathogenic Avian Influenza (HPAI). Very occasionally people catch HPAI from infected birds and in such circumstances the human mortality rate is high.
Course and symptoms
The time it takes to develop avian flu after having been exposed to it (the incubation period) is 3-5 days, 7 days at the longest.
The symptoms are much the same as influenza, with cough, cold symptoms and fever but there is no reason to suspect avian flu unless these symptoms are severe and you are at risk (see below).
In these rare circumstances you should contact your doctor as soon as possible.
Remember it is much more likely that you have ordinary influenza.
Causes
Avian flu is caused by a virus, a form of influenza. It is usually a disease of wild waterfowl such as geese and ducks and these are often only mildly affected.
It can, however, affect many other bird species and cause severe disease with a high mortality rate. When there is an outbreak of avian flu with a high bird mortality it is called Highly Pathogenic Avian Influenza (HPAI). Only very occasionally do people catch HPAI from infected birds and in such circumstances the human mortality rate is high.
Avian flu is not a major problem to us unless the virus changes its nature and becomes able to be passed from human to human. If that were to happen there is the chance that a worldwide epidemic (a pandemic) could follow.
Diagnosis
If you have flu like symptoms, but are not at risk of having been exposed to avian flu, then it is far more likely that you have ordinary flu.
A person is considered at risk if they have:
- returned within one week from a country where avian flu is currently known to be active
- and in the last 7 days have:
- been in direct contact with susceptible poultry or animals, or
- been exposed to a place where such animals have been housed, or
- been in contact with a confirmed human case of avian flu.
In these circumstances you should contact your doctor and it is likely that you will be referred for specialist diagnosis and treatment. For this they will take a specimen of fluid from the back of your nose or throat for viral tests.
Treatment
Avian flu is a type A influenza and usually responds to treatment with either zanamivir (Relenza) or oseltamivir (Tamiflu).
Otherwise treatment is aimed at easing the symptoms. At the time of writing it is likely that you would end up in isolation, under close medical supervision.
Prevention
The mainstay of prevention is killing all the susceptible animals. Millions of birds have been culled in the affected countries.
Migrating birds might spread avian flu and when this risk is at its maximum individual countries may issue extra instructions (such as keeping poultry inside). Restrictions have also been placed on the import and export of birds.
Travellers should avoid contact with live poultry or the places where they have been kept.
The standard influenza vaccination would not work against avian flu, but laboratories can develop a vaccine within a few months if a specific Highly Pathogenic Avian Influenza (HPAI) becomes a threat.
