Human noses too cold for bird flu

Bird flu may not have become the threat to humans that some predicted because our noses are too cold for the virus to thrive

Tests in a laboratory recreation of the environment in the nose found that at 32 degrees Celsius, avian flu viruses lose function and cannot spread.

It is likely that the viruses have adapted to suit the warmer 40 degree environments in the guts of birds.

A mutation would be needed before bird flu became a human problem, they said.

It is certainly part of the explanation of why avian viruses, such as H5N1, fail to transmit readily to humans

"Animal viruses that spread well at low temperatures in these cultures could be more likely to cause the next pandemic than those which are restricted."

She said swine flu - which was spreading from person to person, seemingly through upper respiratory tract infection - was probably an example of a virus which had adapted to cope with the cooler temperatures in the nose.