how transmitted the bird flu.

Direct bird-to-human transmission works like this:

Wild birds shed the virus. Infected migratory waterfowl, the natural carriers of bird flu viruses, shed the virus in their droppings, saliva and nasal secretions.


The virus spreads to domesticated birds. Domestic poultry become infected from contact with these birds or with contaminated water, feed or soil. They may also catch the disease the same way humans contract conventional flu - by inhaling the airborne virus. Bird flu spreads quickly and lethally within domestic flocks and is inadvertently transported from farm to farm on tractors and other equipment, on cages, and on workers' shoes and clothing. Heat destroys the virus, but it can survive for extended periods in cool temperatures


Markets provide pathways to humans. Open-air markets, where eggs and birds are often sold in crowded and unsanitary conditions, are hotbeds of infection and spread the disease into the wider community. Cockfighting, common throughout much of Asia, has also been implicated in the spread of bird flu because fighting roosters are often trucked long distances and smuggled across borders. At any point along the way, humans may pick up the virus through close contact with sick birds or contaminated surfaces.