New flu threat emerges
This week The Times reported the findings of work in the United States on avian influenza which shows that in addition to the H5N1 strain, a few H7 strains of the virus have also started to evolve some of the traits they would need to infect people easily.
The findings, from a team at the US Centres for Disease Control and Prevention (CDC) in Atlanta, show that while there is no immediate indication that H7 flu is about to acquire potentially damaging mutations, it is critical that global surveillance and research covers this virus class as well as the more obvious H5N.
The H5N1 strain has been regarded as the most deadly strain since it appeared in Asia in 2003. Although it has a death rate of more than 60 per cent, it has not yet acquired the ability to move from person to person, thereby generating a pandemic.
The H7 family of flu viruses also primarily affects birds. A deadly version of the H7N7 strain hit poultry in the Netherlands in 2003, and a less severe form, H7N2, broke out in the UK last year.In each of these incidents a few human cases of infection were reported. One vet died during the Dutch outbreak and about 80 people suffered conjunctivitis.