One leading virologist in Brazil told the BBC the country was in an "emergency situation".

We identified about 100 genes, said Yoshihiro Kawaoka, a leading virologist and bird flu expert at the University of Tokyo in Japan.

For veterinary vaccines there is no such thing at this moment, said Albert Osterhaus, a leading virologist at the Erasmus Medical Center in Rotterdam.

A leading virologist is warning of the"inevitable"spread of swine flu throughout New Zealand, and the possibility of community transfer of the virus within days.