Where did the flu originate? How does it spread?
From wild birds. Wild waterfowl can be responsible for the primary introduction of infection into domestic poultry. This is different from SARS, which is caused not by an influenza virus but by a corona virus. Avian influenza spreads when infected birds shed the virus in the form of saliva or faeces. These then affect susceptible birds that come in contact with the contaminated matter, or contaminated food and water. Avian influenza virus spreads in the air and manure and survives longer in cold weather. There is no evidence that the virus can survive in well-cooked meat though. The incubation period is 3 to 5 days. Symptoms in animals vary, but strong strains can cause death within a few days.
