As nations across the world either brace for what is now seen as the inevitable spread of the H5N1 strain of avian influenza, which has proven deadly to a high percentage of the few human beings who have contracted the virus, some are taking aim at migratory birds. But wild birds might not be the most likely means of delivery for the aggressive virus.

It is widely thought that migratory wild birds are carrying the disease across continents and across borders. So, authorities at the UN and in the US Department of Homeland Security are concerned wild birds will be the means of transfer and are reportedly examining means of mitigating the likelihood of such an eventuality.

But not everyone is convinced. Avian influenza, especially a highly evolved strain with the adaptive properties of H5N1, needs a breeding ground in order to emerge into the world. It needs concentrated populations, and the competition with immune properties of animals which have developed resistance to other strains.

It is the messy and dirty environment in which much of the world's poultry are kept that makes the most ideal breeding ground for dangerous mutant flu strains. And poultry routinely crosses international borders. As the International Herald Tribune notes:

Recently a shipment of chicken feet was smuggled into the United States from Thailand, arriving in Connecticut marked "jellyfish." Luckily, our trade surveillance system worked and the chicken parts were confiscated.

That is one example, but it is not the only means of travel for potentially contaminated birds or bird parts, and it is not the only evidence that poultry industry regulation might be a more important tool in stopping the spread of H5N1 than tracking migratory birds.

While acknowledging that wild birds can carry the disease, and that it can kill them and they can spread it, the IHT reports "Yet the spread of H5N1 did not result from the activities of wild birds, but from a very human activity — trade." There is little amiguity about their findings. First the trade in wild birds, then the trade in poultry, both legal and illegal, has fomented and spread the development of the pandemic.

Robert Cook and William Karesh, of the Field Veterinary Program and the Wildlife Conservation Society, Bronx Zoo, believe that no matter what security measures are taken to prevent wild birds from spreading the disease or human carriers from transmitting it through travel, only a tough look at the role of trade will protect society from the spread of H5N1. [s]

• IHT: "Don't blame the wild birds"