According to the World Organization for Animal Health report IN-152079, Mute swans have yielded H5N1 highly pathogenic avian influenza from three different regions in Serbia during the period October 8th through 20th. The sequence of outbreaks and their location suggests northwest dissemination of virus parallel with the Danube River extending from Belgrade to Novi Sad. (See upper third of map of Serbia on the right)

Swans are known to be carriers of avian influenza and in addition may die of the infection hence the diagnoses.  The three cases confirm that H5 avian influenza strains are being shed by migratory waterfowl, presaging outbreaks among non-confined backyard and commercial poultry flocks in the Balkans and Eastern Europe in coming weeks.