How does avian influenza spread among birds?

Dr. Thomas DeLiberto
National Wildlife Coordinator
Animal and Plant Health Inspection Service, USDA

Typically wild birds carry avian influenza in their gastro-intestinal tract and they spread it through their fecal droppings.  Under normal circumstances these viruses cause these birds no problem at all.  The birds ingest the virus, usually through contact with other birds or through contaminated water.  The rare case is this H5N1 virus that’s circulating through the world today.  Under these circumstances the virus is spread through not only their gastro-intestinal tract in their fecal droppings, but also more importantly, through their respiratory secretions.