Backyard or free-range poultry are not fuelling the current wave of bird flu outbreaks stalking large parts of the world. The deadly H5N1 strain of bird flu is essentially a problem of industrial poultry practices. Its epicentre is the factory farms of China and Southeast Asia and -- while wild birds can carry the disease, at least for short distances -- its main vector is the highly self-regulated transnational poultry industry, which sends the products and waste of its farms around the world through a multitude of channels. Yet small poultry farmers and the poultry biodiversity and local food security that they sustain are suffering badly from the fall-out. To make matters worse, governments and international agencies, following mistaken assumptions about how the disease spreads and amplifies, are pursuing measures to force poultry indoors and further industrialise the poultry sector. In practice, this means the end of the small-scale poultry farming that provides food and livelihoods to hundreds of millions of families across the world. This paper presents a fresh perspective on the bird flu story that challenges current assumptions and puts the focus back where it should be: on the transnational poultry industry.
They have a much more extensive document called: Fowl play: The poultry industry's central role in the bird flu crisis
If what they have found is really the case then this is a problem we have promulgated for ourselves with our practices of mass production without regard to what is natural for the chickens.