AMSTERDAM (Reuters) - Dutch animal health authorities found bird flu in two samples taken from wild ducks, a government statement said, but it was unclear if that was the source of an outbreak at four chicken farms in the Netherlands.
Duck droppings from the central Dutch province tested positive for the highly contagious H5 strain of the disease, the deputy economic affairs minister wrote in a letter to parliament.
"Based on this information I am considering follow-up measures," deputy minister Sharon Dijksma wrote.
Dutch authorities said earlier on Monday they will slaughter 50,000 birds at a poultry farm after bird flu was discovered nearby. Separate testing indicated that farm infections, which have led to the culling of around 300,000 birds at four locations, were not all from the same source, the letter said.
The H5N8 strain of bird flu detected at the farms has never been founded in humans. It has led to the destruction of millions of farm birds in Asia, mainly South Korea, after an outbreak earlier this year.
A government statement said tests had confirmed an outbreak of the H5N8 strain at one farm in the western municipality of Zoeterwoude, where 28,000 laying hens were ordered destroyed on Sunday.
A cull at a nearby farm announced on Monday was a precautionary measure, it said. Animal health authorities are testing poultry at other farms in the area.
Transport restrictions were imposed on the sector two weeks ago that have hit around 2,000 poultry businesses. The Netherlands is the world's largest exporter of eggs and the largest exporter of poultry meat in the European Union.
Some experts believe that wild birds migrating from Asia carried the disease to Europe, where it infected flocks in Germany, Britain and the Netherlands.
Reporting by Anthony Deutsch; Editing by Robin Pomeroy