A breakthrough in the development of a bird flu drug that could treat humans in the event of an outbreak has been announced by scientists.
However they have warned that the final version of the drug to be used to treat the H5N1 virus would probably take another five years to be produced.
The 238 cases of human infection have all been from direct contact with infected birds. Scientists say that so far no evidence exists that the virus is mutating towards a state where it is transmissible among humans, although this could happen at any time.
About 60 percent of those infected with the deadly H5N1 virus have died. The best known drugs to fight the H5N1 infection in humans are zanamivir known as Relenza and oseltamivir commonly known as Tamiflu, both of which were originally developed to fight other forms of human flu.
Now lead scientist by John Skehel of London's National Institute of Medical Research and his team of researchers announced the finding of a cavity in the N1 or neuraminidase part of the H5N1 virus which could be exploited as a potential weak point in its destruction.
Mr Skehel said: "It is a race. You have got to try to keep ahead of variation and in the case of H5N1 particularly the emergence of transmission from human to human".