19/11/2014 09:47 GMT | Updated 17/01/2015 05:59 GMT

Avian Flu: Why We Should Be Cautious

The spectre of avian influenza has once again been raised by a double-strike in Europe. The highly contagious strain, H5N8, which could potentially affect people, has been discovered on a Dutch poultry farm, whilst a further case has been found on a duck breeding farm in Yorkshire, England, although the strain has yet to be confirmed.

Some are already trying to scapegoat wild birds as being responsible for bird flu and, on past form, using it as an excuse to support greater farm intensification is sure to follow. They claim that keeping poultry inside protects them from wild birds carrying disease. What this argument conveniently overlooks is that low-level avian flu is a perfectly natural disease in wild birds.

It is only when the bird flu virus enters the pressure-cooker environment of an intensive farm that the disease tends to mutate dangerously. Once a virus gets into an intensive poultry shed with many thousands of birds crowded together, it can move quickly through the flock, constantly replicating itself. Any 'errors' or changes to the genetic code during replication don't get repaired: this is how the virus mutates and new variant strains emerge. The tragedy is that while intensive farms provide ideal conditions for the emergence of new aggressive disease strains, wild birds can then become infected too.

Experience from the 2005 outbreak of highly pathogenic avian influenza (AI) H5N1 suggests that the disease is more likely spread along major road and rail routes than on the flight routes of migratory birds. In addition, the overwhelming majority of wild birds found infected with H5N1 were dead, preventing them from carrying the virus over long distances.

When H5N1 hit a Bernard Matthews turkey farm in Suffolk in 2007, there was no evidence of highly pathogenic AI in wild bird populations in Britain. Defra reported at the time that over 4,000 wild birds had been tested over the previous six months; only 0.4 per cent were found to be infected with AI, of which none were highly pathogenic strains.

Blaming wild birds is an excuse for doing nothing about the dominant source of the problem: the factory-farming system itself. Dr Aysha Akhtar, a neurologist and public-health specialist and Fellow of the Oxford Centre for Animal Ethics, sums it up like this: "By confining billions of animals on factory farms, we have created a worldwide natural laboratory for the rapid development of a deadly and highly infectious virus".