The nature of avian flu: Summary
- Avian influenza or 'bird flu' is a contagious disease of birds caused by influenza A viruses. Domestic poultry are particularly susceptible.
- Avian flu was believed to infect people only rarely, and then to cause only mild disease until 1997 when the highly pathogenic avian flu virus, A/H5N1, infected 18 people in Hong Kong, killing six of them.
- A/H5N1 re-appeared in Korea in mid-December 2003 and has since affected poultry flocks in nine countries in Asia. In three of these countries - Cambodia, Thailand and Viet Nam - it has infected 55 people, killing 42 of them (to date).
- Of the 15 different HA subtypes of influenza A, H5 is the most virulent and poses the greatest threat to human health.
- Experts fear that A/H5N1 could trigger the next flu pandemic by mutating to become capable of passing easily from person to person.
- Despite isolated reports of human-to-human spread, so far there is no strong evidence of sustained person-to-person transmission.
- Work is under way to produce a vaccine against A/H5N1. However, if the virus mutates significantly, the vaccine may not prove effective.
- There is evidence that one antiviral drug, oseltamivir is effective against A/H5N1, but until a pandemic flu virus derived from H5N1 emerges and spreads it is not possible to predict how effective it will be against it.
- So far, there have been no human cases associated with the current outbreak of A/H5N1 in the UK.
- For more information on avian flu, visit:
