The farms are located near the town of Plock, according to a report from the World Organization for Animal Health (OEI). Plock is about 60 miles northwest of Warsaw. The outbreaks, which began on Nov. 30, killed 60 birds on one farm and 300 on the other. A total of 4,245 remaining birds were culled on the two farms, the OEI report said.
Poland last found H5N1 in birds in the spring of 2006, when it was detected in wild swans and other waterfowl.
With the latest outbreak, Poland becomes the eighth European country to report an H5N1 outbreak this year. In October, the United Nations Food and Agriculture Organization warned that apparently healthy ducks and geese in Europe could be harboring the H5N1 virus.