HAMBURG (Reuters) - No signs of bird flu have been found anywhere else in the region around the farm in east Germany where it was discovered on Nov. 4, but the source of the infection there is still unknown, German authorities said on Thursday.
On Monday the highly contagious H5N8 strain of bird flu was also confirmed on an English duck farm, the same form of the virus already discovered in Germany and the Netherlands.
In Germany, none of the 3,353 tests on birds outside the farm in the eastern state of Mecklenburg-Vorpommern where the disease was discovered were positive, the state agriculture ministry said in a statement. This included extensive tests on wild birds including swans and ducks.
The search for the source of infection continues, it said.
"Cross connections to the farms affected abroad have not been found up to now," said state agriculture minister Till Backhaus.
Tests show that the bird flu viruses found in Germany, the Netherlands and Britain are similar to one that devastated poultry flocks in South Korea earlier this year, the World Organization for Animal Health (OIE) said on Wednesday.
German authorities were also examining other possible infection sources other than wild birds, such as animal feed, stable straw, animal slaughtering vehicles and farms which have various links to the infected farm, the state ministry said.
"So long as we have not identified a source, we must investigate in all directions and cannot take part in the sometimes wild speculation (about the contamination source)," Backhaus said.
Reporting by Michael Hogan; Editing by Pravin Char