The threat to humans from avian flu has not changed, writes Dr Muiris Houston
Avian influenza is an infectious disease of birds caused by type A strains of the influenza virus.
Influenza A viruses have 16 H subtypes and 9 N subtypes.
The current outbreak of highly infectious avian influenza is caused by the H5N1 version of the virus.
It began in southeast Asia in 2003 and is now endemic in parts of Indonesia and Vietnam.
Since the beginning of 2006, more than 30 countries have reported outbreaks, in most cases involving wild birds but also occurring in poultry.
Since the virus first infected humans in 1997 in Hong Kong, H5N1 has killed some 134 people out of 232 known to be infected.
Direct contact with infected poultry or surfaces contaminated by their faeces is the main route of human infection.
There is currently no evidence of sustained person-to-person transmission of avian influenza.
The threat to humans from bird flu has not altered in recent months.
According to the World Health Organisation (WHO), the level of pandemic alert remains unchanged at phase 3.
This is defined as a virus new to humans that is causing infection, but does not spread easily from one person to another.
But infectious disease experts emphasise that because avian influenza continues to spread among birds, there is a growing risk that the virus will alter genetically and become more easily transmitted to humans.
However, they point out that the next flu pandemic could just as easily come from an existing flu virus as a rapidly changing H5N1 strain linked to avian influenza.
There was good news this week from the US Centres for Disease Control when an experiment to splice a common flu virus with the H5N1 avian influenza failed to make an infectious strain. But the researchers warned that bird flu still posed a serious risk to humanity.
As part of preparations for a possible flu pandemic, doctors here have been advised how to diagnose avian influenza in humans.
A patient must have signs of acute respiratory infection (cough, sore throat and runny nose) with a temperature greater than 38 degrees Celsius.
In addition, they must have been either in contact with poultry or wild birds or been within one metre of a person diagnosed with H5N1 influenza or have worked in a laboratory where there is a potential exposure to the avian flu virus.
Patients meeting these criteria will be admitted to hospital and placed in strict respiratory isolation or will be treated in the community.
They will start treatment with the antiviral drug oseltamivir (Tamiflu), supplies of which the Government has stockpiled as part of our pandemic planning. Contacts of patients will be given Tamiflu prophylactically.
While it will take about four months to develop an effective vaccine following an outbreak of avian flu in humans, it is likely a pre-pandemic H5N1 vaccine will be available for use at the beginning of the outbreak.